# EDGAR Filing Document

**Accession Number:** 0001390478
**File Stem:** 0001104659-23-024765
**Filing Date:** 2023-2
**Character Count:** 287753
**Document Hash:** 523cc938a3bfbcfd58b4d3052bcebba6
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001104659-23-024765.hdr.sgml**: 20230223

**ACCESSION NUMBER**: 0001104659-23-024765

**CONFORMED SUBMISSION TYPE**: 424B5

**PUBLIC DOCUMENT COUNT**: 4

**FILED AS OF DATE**: 20230223

**DATE AS OF CHANGE**: 20230223

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** SELLAS Life Sciences Group, Inc.
- **CENTRAL INDEX KEY:** 0001390478
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **IRS NUMBER:** 000000000
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 424B5
- **SEC ACT:** 1933 Act
- **SEC FILE NUMBER:** 333-255318
- **FILM NUMBER:** 23659721

**BUSINESS ADDRESS:**
- **STREET 1:** 7 TIMES SQUARE
- **STREET 2:** SUITE 2503
- **CITY:** NEW YORK
- **STATE:** NY
- **ZIP:** 10036
- **BUSINESS PHONE:** 6462005278

**MAIL ADDRESS:**
- **STREET 1:** 7 TIMES SQUARE
- **STREET 2:** SUITE 2503
- **CITY:** NEW YORK
- **STATE:** NY
- **ZIP:** 10036

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** Galena Biopharma, Inc.
- **DATE OF NAME CHANGE:** 20110926

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** RXi Pharmaceuticals Corp
- **DATE OF NAME CHANGE:** 20110926

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** GALENA BIOPHARMA, INC.
- **DATE OF NAME CHANGE:** 20110922

**Filed Pursuant to Rule 424(b)(5)**

**Registration No. 333-255318**

**The information in this preliminary prospectus supplement is not complete and may be changed. A registration statement relating to these securities has been filed with the Securities and Exchange Commission and is effective. This preliminary prospectus supplement and the accompanying prospectus are not an offer to sell these securities and they are not soliciting an offer to buy these securities in any jurisdiction where the offer or sale is not permitted.**

**Subject to completion, dated February 23, 2023**

**Preliminary Prospectus Supplement**

**(To prospectus dated April 29, 2021)**

**Shares**

**Warrants to Purchase up to Shares**

![](tm237388d1_424b5img001.jpg)

**Common stock**

We are offering shares of our common stock and warrants to purchase up to shares of our common stock (and the shares of common stock issuable from time to time upon exercise of such warrants) pursuant to this prospectus supplement and the accompanying prospectus. Each share of common stock sold in this offering will be accompanied by a warrant to purchase one share of our common stock at an exercise price of $ per share. The shares of common stock and warrants can only be purchased together in this offering but will be issued separately and will be immediately separable upon issuance. Subject to certain ownership limitations, the warrants will be exercisable immediately, and the warrants will expire on the fifth anniversary of the date of issuance. We refer to the shares of common stock issued in this offering and the accompanying warrants to purchase shares of common stock issued in this offering, collectively, as the securities.

Our common stock is currently trading on The Nasdaq Capital Market, or Nasdaq, under the stock symbol "SLS." On February 22, 2023, the closing price for our common stock, as reported on Nasdaq, was $3.82 per share.

There is no established public trading market for the warrants, and we do not expect a market to develop. In addition, we do not intend to list the warrants, nor do we expect the warrants to be quoted, on Nasdaq or any other national securities exchange or any other nationally recognized trading system. Without an active trading market, the liquidity of the warrants will be limited.

**Investing in our securities involves a high degree of risk. See "[Risk Factors](#a_003)" beginning on page S-6 of this prospectus supplement, as well as those risks described in our most recent Annual Report on Form 10-K for the year ended December 31, 2021 and in our other filings with the Securities and Exchange Commission that are incorporated by reference into this prospectus supplement.**

---

| | | |
|:---|:---|:---|
|  | **Per**<br> **share and<br> accompanying<br> Warrant (1)** | **Total (2)** |
| Public offering price | $— | $— |
| Underwriting discounts and commissions (3) | $— | $— |
| Proceeds to SELLAS Life Sciences Group, Inc., before expenses | $— | $— |

---

(1) Includes $ per warrant for the accompanying warrants.

(2) Assumes no exercise of the underwriters' option described below.

(3) We have agreed to reimburse the underwriters for certain expenses. See "Underwriting."

We have granted the underwriters an option for a period of 30 days to purchase up to additional shares of our common stock and/or warrants to purchase up to additional shares, in each case at the public offering price, less underwriting discounts and commissions. If the underwriters exercise the option in full, the total proceeds to us, before expenses, will be $, excluding the proceeds, if any, for the exercise of the warrants issued pursuant to this offering.

**Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.**

The underwriters expect to deliver the securities to purchasers on or about February , 2023.

*Sole Book-Running Manager*

**Cantor**

**The date of this prospectus supplement is , 2023**

**TABLE OF CONTENTS**

**<u>Page</u>**

**Prospectus supplement**

---

| | |
|:---|:---|
|  | **<u>Page</u>** |
| [ABOUT THIS PROSPECTUS SUPPLEMENT](#a_001) | [S-<u>ii</u>](#a_001) |
| [PROSPECTUS SUPPLEMENT SUMMARY](#a_002) | [S-1](#a_002) |
| [RISK FACTORS](#a_003) | [S-6](#a_003) |
| [SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS](#a_004) | [S-9](#a_004) |
| [USE OF PROCEEDS](#a_005) | [S-11](#a_005) |
| [DIVIDEND POLICY](#a_006) | [S-12](#a_006) |
| [DILUTION](#a_007) | [S-13](#a_007) |
| [MATERIAL U.S. FEDERAL INCOME TAX CONSIDERATIONS](#a_008) | [S-14](#a_008) |
| [DESCRIPTION OF CAPITAL STOCK](#a_009) | [S-19](#a_009) |
| [UNDERWRITING](#a_010) | [S-24](#a_010) |
| [<u>NOTICE TO INVESTORS</u>](#a_011) | [<u>S-28</u>](#a_011) |
| [LEGAL MATTERS](#a_012) | [S-34](#a_012) |
| [EXPERTS](#a_013) | [S-34](#a_013) |
| [WHERE YOU CAN FIND MORE INFORMATION](#a_014) | [<u>S-34</u>](#a_014) |
| [INCORPORATION OF CERTAIN INFORMATION BY REFERENCE](#a_015) | [S-35](#a_015) |

---

**Prospectus**

---

| | |
|:---|:---|
| [ABOUT THIS PROSPECTUS](#a_001) | [ii](#a_001) |
| [PROSPECTUS SUMMARY](#a_002) | [1](#a_002) |
| [RISK FACTORS](#a_003) | [7](#a_003) |
| [SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS](#a_004) | [7](#a_004) |
| [USE OF PROCEEDS](#a_005) | [9](#a_005) |
| [DILUTION](#a_006) | [9](#a_006) |
| [DESCRIPTION OF CAPITAL STOCK](#a_007) | [9](#a_007) |
| [DESCRIPTION OF DEBT SECURITIES](#a_008) | [13](#a_008) |
| [DESCRIPTION OF WARRANTS](#a_009) | [19](#a_009) |
| [DESCRIPTION OF RIGHTS](#a_010) | [21](#a_010) |
| [DESCRIPTION OF UNITS](#a_011) | [23](#a_011) |
| [LEGAL OWNERSHIP OF SECURITIES](#a_012) | [24](#a_012) |
| [PLAN OF DISTRIBUTION](#a_013) | [27](#a_013) |
| [LEGAL MATTERS](#a_014) | [29](#a_014) |
| [EXPERTS](#a_015) | [29](#a_015) |
| [WHERE YOU CAN FIND MORE INFORMATION](#a_016) | [29](#a_016) |
| [INCORPORATION BY REFERENCE](#a_017) | [30](#a_017) |

---

S-i

**ABOUT THIS PROSPECTUS SUPPLEMENT**

This document is in two parts. The first part is this prospectus supplement, which describes the terms of this offering of securities and also adds to and updates information contained in the accompanying prospectus and the documents incorporated by reference into this prospectus supplement and the accompanying prospectus. The second part, the accompanying prospectus dated April 29, 2021, including the documents incorporated by reference therein, provides more general information. Generally, when we refer to this prospectus, we are referring to both parts of this document combined. To the extent there is a conflict between the information contained in this prospectus supplement, on the one hand, and the information contained in the accompanying prospectus or in any document incorporated by reference that was filed with the Securities and Exchange Commission, or the SEC, before the date of this prospectus supplement, on the other hand, you should rely on the information in this prospectus supplement. If any statement in one of these documents is inconsistent with a statement in another document having a later date—for example, a document incorporated by reference in the accompanying prospectus—the statement in the document having the later date modifies or supersedes the earlier statement.

This prospectus supplement is part of a registration statement that we filed with the SEC using a "shelf" registration process. Under the shelf registration process, we may from time to time offer and sell any combination of the securities described in the accompanying prospectus up to a total dollar amount of $150 million, of which this offering is a part.

We have not, and the underwriters have not, authorized anyone to provide any information other than that contained or incorporated by reference in this prospectus supplement or the accompanying prospectus. We and the underwriters take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. This prospectus supplement and the accompanying prospectus do not constitute an offer to sell, or a solicitation of an offer to purchase, the securities offered by this prospectus supplement and the accompanying prospectus in any jurisdiction to or from any person to whom or from whom it is unlawful to make such offer or solicitation of an offer in such jurisdiction. The information contained in this prospectus supplement and the accompanying prospectus, including the documents incorporated by reference herein or therein is accurate only as of the respective dates thereof, regardless of the time of delivery of this prospectus supplement and the accompanying prospectus or of any sale of our common stock. It is important for you to read and consider all information contained in this prospectus supplement and the accompanying prospectus, including the documents incorporated by reference herein and therein, in making your investment decision. You should also read and consider the information in the documents to which we have referred you in the sections titled "Where you can find more information" and "Incorporation of certain information by reference" in this prospectus supplement and in the accompanying prospectus.

We and the underwriters are offering to sell, and seeking offers to buy, the securities only in jurisdictions where offers and sales are permitted. The distribution of this prospectus supplement and the accompanying prospectus and the offering of the securities in certain jurisdictions may be restricted by law. Persons outside the United States who come into possession of this prospectus supplement and the accompanying prospectus must inform themselves about, and observe any restrictions relating to, the offering of the securities and the distribution of this prospectus supplement and the accompanying prospectus outside the United States.

Except as otherwise indicated herein or as the context otherwise requires, references in this prospectus supplement, the accompanying prospectus and the information incorporated by referenced herein or therein to "Sellas," "the Company," "we," "us," "our" and similar terms refer to SELLAS Life Sciences Group, Inc. and, where appropriate, our subsidiaries.

S-ii

**PROSPECTUS SUPPLEMENT SUMMARY**

*This summary highlights information contained elsewhere or incorporated by reference in this prospectus supplement. This summary does not contain all of the information you should consider before investing in our securities. Before you decide to invest in our securities, you should carefully read the prospectus supplement and the accompanying prospectus, including the section titled "Risk factors" contained in this prospectus supplement and in the documents incorporated by reference into this prospectus supplement. You should also carefully read the information incorporated by reference into this prospectus supplement and the accompany prospectus, including our consolidated financial statements, and the exhibits to the registration statement of which this prospectus supplement and the accompanying prospectus are a part.*

**Overview**

We are a late-stage clinical biopharmaceutical company focused on the development of novel therapeutics for a broad range of cancer indications. Our product candidates currently include galinpepimut-S, or GPS, a peptide immunotherapy directed against the Wilms tumor 1, or WT1, antigen, and GFH009, a highly selective small molecule cyclin-dependent kinase 9, or CDK9, inhibitor.

***Galinpepimut-S***

Our lead product candidate, GPS, is a cancer immunotherapeutic agent licensed from Memorial Sloan Kettering Cancer Center, or MSK, that targets the WT1 protein, which is present in 20 or more cancer types. Based on its mechanism of action as a directly immunizing agent, GPS has potential as a monotherapy or in combination with other immunotherapeutic agents to address a broad spectrum of hematologic, or blood, cancers and solid tumor indications.

In January 2020, we commenced in the United States an openlabel randomized Phase 3 clinical trial, the REGAL study, for GPS monotherapy in patients with acute myeloid leukemia, or AML, in the maintenance setting after achievement of second complete remission, or CR2, following successful completion of second-line antileukemic therapy. Patients are randomized to receive either GPS or best available treatment, or BAT. We expect this study will be used as the basis for submission of a Biologics License Application, or BLA, subject to a statistically significant and clinically meaningful data outcome and agreement with the U.S. Food & Drug Administration, or the FDA. The primary endpoint of the clinical trial is overall survival, or OS. We plan to enroll approximately 125 to 140 patients at approximately 95 clinical sites in the United States, Europe and Asia with a planned interim safety, efficacy and futility analysis after 60 events (deaths). Under our current assumptions with respect to completion of enrollment and the estimated survival times for both the treated and control groups in the study, we believe, after discussions with our external statisticians and experts, that the planned interim analysis after 60 events (deaths) per the protocol will occur by the end of 2023 or early 2024 and the final analysis after 80 events will occur by the end of 2024. Because these analyses are event driven, they may occur at a different time than currently expected.

In December 2020, we entered into an exclusive license agreement with 3D Medicines Inc., or 3D Medicines, a China-based biopharmaceutical company developing next-generation immuno-oncology drugs, for the development and commercialization of GPS, as well as the Company's next generation heptavalent immunotherapeutic GPS+, which is at preclinical stage, across all therapeutic and diagnostic uses in mainland China, Hong Kong, Macau and Taiwan, which we refer to as Greater China. We have retained sole rights to GPS and GPS+ outside of Greater China. In November 2022, we announced that we have agreed with 3D Medicines for 3D Medicines to participate in the REGAL study through the inclusion of approximately 20 patients from mainland China. Such participation by 3D Medicines will trigger two development milestone payments totaling $13.0 million, which we expect to receive in the first half of 2023. If the REGAL study meets its primary endpoint for efficacy and the Chinese regulatory authorities determine that the REGAL data is sufficient for approval in China, GPS could potentially reach the market in Greater China much earlier than we and 3D Medicines had anticipated when we entered into the license agreement in December 2020. An IND application filed by 3D Medicines in March 2022 with China's National Medical Products Administration, or NMPA, to initiate a Phase 1 clinical trial in China for 3D189, also known as GPS, triggered a $1.0 million milestone payment to us. As of December 31, 2022, a total of $191.5 million in potential future development, regulatory and sales milestones, not including future royalties, remains under the License Agreement with 3D Medicines.

In December 2018, pursuant to a Clinical Trial Collaboration and Supply Agreement, we initiated a Phase 1/2 multi-arm "basket" type clinical study of GPS in combination with Merck & Co., Inc.'s anti-PD-1 therapy, pembrolizumab (Keytruda®). In 2020, we, together with Merck, determined to focus on ovarian cancer (second or third line). In November 2022, we reported topline clinical and initial immune response data from this study, which showed that treatment with the combination of GPS and pembrolizumab compared favorably to treatment with anti-PD-1 therapy alone in a similar patient population. We plan to present final data from this study at a medical conference in the first half of 2023.

In February 2020, a Phase 1 open-label investigator-sponsored clinical trial of GPS, in combination with Bristol-Myers Squibb's anti-PD-1 therapy, nivolumab (Opdivo®), in patients with malignant pleural mesothelioma, or MPM, who harbor relapsed or refractory disease after having received frontline standard of care multimodality therapy was commenced at MSK. Enrollment of a target total of 10 evaluable patients was completed at the end of 2022. We expect to report final topline data from this study in the first half of 2023.

GPS was granted Orphan Drug Product Designations from the FDA, as well as Orphan Medicinal Product Designations from the European Medicines Agency, or EMA, for GPS in AML, MPM, and multiple myeloma, or MM, as well as Fast Track Designation for AML, MPM, and MM from the FDA.

***GFH009***

On March 31, 2022, we entered into an exclusive license agreement, or the GFH009 Agreement, with GenFleet Therapeutics (Shanghai), Inc., or GenFleet, a clinical-stage biotechnology company developing cutting-edge therapeutics in oncology and immunology, that grants rights to us for the development and commercialization of GFH009, a highly selective small molecule CDK9 inhibitor, across all therapeutic and diagnostic uses worldwide, except for Greater China.

CDK9 activity has been shown to correlate negatively with overall survival in a number of cancer types, including hematologic cancers, such as AML and lymphomas, as well as solid cancers, such as osteosarcoma, pediatric soft tissue sarcomas, melanoma, endometrial, lung, prostate, breast and ovarian. As demonstrated in preclinical and clinical data, to date, GFH009's high selectivity has the potential to reduce toxicity as compared to older CDK9 inhibitors and other next-generation CDK9 inhibitors currently in clinical development and to potentially be more efficacious.

GFH009 is currently in a Phase 1 dose-escalating clinical trial in the United States and China. We are evaluating both twice-a-week and once-a-week dosing, and the indications are relapsed/refractory AML, chronic lymphocytic leukemia, or CLL, small lymphocytic leukemia, or SLL, and lymphoma. The primary goal of the trial is to establish the recommended Phase 2 dose and to assess safety. We expect enrollment in this study to be completed in the first quarter of 2023 and we expect to determine the recommended Phase 2 dose and report analyzed data from the study early in the second quarter of 2023.

Following completion of the Phase 1 clinical trial and determination of the recommended Phase 2 dose, we intend to commence a Phase 1/2a clinical trial of GFH009 in combination with venetoclax and azacitidine in AML patients who failed or did not respond to treatment with venetoclax and azacitidine. The primary endpoint of the Phase 1/2a clinical trial, which we expect to initiate during the second quarter of 2023, will likely be complete remission (CR) rate and secondary endpoints will likely include progression free survival, OS and proportion of patients proceeding to transplant. We are also planning to potentially commence a Phase 2 clinical trial of GFH009 in certain solid tumors in the third quarter of 2023 and are exploring various options with respect to clinical development for GFH009 in several pediatric indications.

**Recent Developments**

***Cash and Cash Equivalents as of December 31, 2022***

As reported in our Current Report on Form 8-K, filed with the SEC on February 23, 2023, as of December 31, 2022, we estimate that we had cash and cash equivalents of $17.1 million.

The amount presented above is estimated, unaudited and preliminary and is subject to completion. As a result, this estimate may differ from the actual results that will be presented in our consolidated financial statements as of and for the fiscal year ended December 31, 2022 when the consolidated financial statements are completed. The amount presented above is based upon management estimates and is the responsibility of management. Our independent registered public accounting firm has not audited, reviewed, compiled or performed any procedures with respect to this amount and, accordingly, does not express an opinion or any other form of assurance upon it.

**Corporate information**

We were incorporated on April 3, 2006 in Delaware as Argonaut Pharmaceuticals, Inc. On November 28, 2006, we changed our name to RXi Pharmaceuticals Corporation and began operations January 2007. On September 26, 2011, we changed our name to Galena Biopharma, Inc. In December 2017, we completed a business combination with SELLAS Life Sciences Group, Ltd., and changed our name to "SELLAS Life Sciences Group, Inc."

Our principal executive offices are located at 7 Times Square, Suite 2503, New York, NY 10036, and our phone number is (646) 200-5278. Our website address is www.sellaslifesciences.com. The information contained on, or that can be accessed through, our website is not part of, and is not incorporated by reference into, this prospectus and should not be considered to be part of this prospectus.

**Smaller reporting company**

We are a "smaller reporting company" as defined in the Securities Exchange Act of 1934, as amended, or the Exchange Act. We may take advantage of certain of the scaled disclosures available to smaller reporting companies and will be able to take advantage of these scaled disclosures for so long as our voting and non-voting common stock held by non-affiliates is less than $250.0 million measured on the last business day of our second fiscal quarter, or our annual revenue is less than $100.0 million during the most recently completed fiscal year and our voting and non-voting common stock held by non-affiliates is less than $700.0 million measured on the last business day of our second fiscal quarter.

**THE OFFERING**

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| | |
|:---|:---|
| **Common stock offered by us** | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;shares of common stock. |
| **Warrants offered by us** | We are offering warrants to purchase an aggregate of shares of our common stock. Each share of our common stock is being sold together with a warrant to purchase one share of our common stock. Each warrant has an exercise price of $ per share, is immediately exercisable and will expire on the five year anniversary of the date of issuance. This prospectus supplement also relates to the offering of the shares of common stock issuable upon exercise of the warrants. There is no established public trading market for the warrants being offered in this offering, and we do not expect a market to develop. In addition, we do not intend to apply for a listing of the warrants on any securities exchange. Without an active market, the liquidity of the warrants will be limited. For additional information regarding the warrants, see "Description of Capital Stock—Warrants" below. |
| **Common stock to be outstanding immediately after this offering** | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;shares of common stock assuming no exercise of any warrants issued in this offering. |
| **Option to purchase additional shares and warrants** | We have granted the underwriters an option for a period of 30 days to purchase up to additional shares of our common stock and warrants to purchase up to additional shares, in each case at the public offering price, less underwriting discounts and commissions. |
| **Use of proceeds** | We estimate that our net proceeds from this offering will be approximately $ million, after deducting underwriting discounts and commissions and estimated offering expenses payable by us and assuming no exercise of the warrants. |
|  | The principal purposes of this offering are to obtain additional capital to support our operations. We expect to use the net proceeds of this offering, in addition to our existing cash resources, for funding of ongoing operations, including clinical development of the product candidates noted in this prospectus supplement, and for working capital and other general corporate purposes. See "Use of proceeds" for additional information. |
| **Risk factors** | See "Risk factors" beginning on page S-6 of this prospectus supplement and other information included and incorporated by reference in this prospectus supplement and the accompanying prospectus for a discussion of factors that you should carefully consider before deciding to invest in our common stock. |
| **Market symbol** | Our common stock currently is listed on Nasdaq under the symbol "SLS." We do not intend to list the warrants, nor do we expect the warrants to be quoted, on the Nasdaq or any other national securities exchange or any other nationally recognized trading system. |

---

Upon completion of this offering, we will take such steps as are necessary to reduce the exercise price of certain of the warrants that were issued on April 5, 2022, and that remain outstanding, to those investors participating in this offering in an amount not less than $2.0 million, to $, the lower of: (i) the closing price of our common stock, as reported on Nasdaq, on February 23, 2023 or (ii) the average closing price of our common stock, as reported on Nasdaq, for the five immediately preceding trading days.

The number of shares of our common stock to be outstanding after this offering set forth above is based on 20,588,247 shares of our common stock outstanding as of September 30, 2022 and excludes:

&nbsp;&nbsp;&nbsp;&nbsp;· 1,070,520 shares of our common stock issuable upon the exercise of stock
options outstanding as of September 30, 2022, at a weighted-average exercise price of $7.56 per share;

&nbsp;&nbsp;&nbsp;&nbsp;· 648,700 shares of common stock issuable upon the exercise of stock options
issued after September 30, 2022, at a weighted-average exercise price of $3.28 per share

&nbsp;&nbsp;&nbsp;&nbsp;· 297,280 shares of common stock issuable upon the vesting and settlement of
restricted stock units ("RSUs") outstanding as of September 30, 2022;

&nbsp;&nbsp;&nbsp;&nbsp;· 195,700 shares of shares of common stock issuable upon the vesting and settlement
of RSUs issued after September 30, 2022 up to the date of this Prospectus Supplement;

&nbsp;&nbsp;&nbsp;&nbsp;· 5,147,376 shares of our common stock issuable upon the exercise of warrants
outstanding as of September 30, 2022, at a weighted-average exercise price of $5.82 per share;

&nbsp;&nbsp;&nbsp;&nbsp;

&nbsp;&nbsp;&nbsp;&nbsp;· 607,824 shares of our common stock reserved for future issuance under our
2019 Equity Incentive Plan (the "2019 Plan") as of September 30, 2022, as well as any automatic increases in the number of
shares of our common stock reserved for future issuance under our 2019 Plan;

&nbsp;&nbsp;&nbsp;&nbsp;· 274,911 shares of our common stock reserved for future issuance under our
2021 Employee Stock Purchase Plan (the "2021 Employee Plan") as of September 30, 2022;

&nbsp;&nbsp;&nbsp;&nbsp;· 453,996 shares of our common stock issued under our Controlled
Equity Offering <sup>SM</sup>Sales Agreement (the "Sales Agreement") with Cantor Fitzgerald & Co. after September 30,
2022 up to the date of this Prospectus Supplement; and

&nbsp;&nbsp;&nbsp;&nbsp;· 40,044 shares of our common stock issued upon the vesting and settlement
of RSUs under our 2019 Plan after September 30, 2022 up to the date of this Prospectus Supplement.

Unless otherwise indicated, all information in this prospectus supplement assumes no exercise of the outstanding options and warrants described above after September 30, 2022 and no exercise of the warrants issued in this offering.

**RISK FACTORS**

*Investing in our common stock involves a high degree of risk. Before making an investment decision, you should carefully consider the risks described below and in our most recent Annual Report on Form 10-K for the year ended December 31, 2021, as updated or superseded by the risks and uncertainties described in our subsequent filings under the Exchange Act, each of which is incorporated by reference into this prospectus supplement and the accompanying prospectus, and all of the other information in this prospectus supplement and the accompanying prospectus, including our financial statements and related notes incorporated by reference in this prospectus supplement and the accompanying prospectus. If any of these risks is realized, our business, financial condition, results of operations and prospects could be harmed. In that event, the trading price of our common stock could decline and you could lose part or all of your investment. Additional risks and uncertainties that are not yet identified or that we think are immaterial may also harm our business, operating results and financial condition and could result in a complete loss of your investment.*

**Risks related to this offering**

***We have broad discretion in the use of the net proceeds from this offering and may not use them effectively.***

Our management will have broad discretion in the application of the net proceeds from this offering and could spend the net proceeds in ways that do not improve our results of operations or enhance the value of our common stock. Furthermore, you will not have the opportunity as part of your investment decision to assess whether such proceeds are being used appropriately. Because of the number and variability of factors that will determine our use of our cash and cash equivalents, including the net proceeds from this offering, their ultimate use may vary substantially from their currently intended use. The failure by our management to apply these funds effectively could result in financial losses that could have a material adverse effect on our business, cause the price of our common stock to decline and delay the development of our drug candidates. Pending their use, we may invest the net proceeds from this offering in short-term, investment-grade, interest-bearing instruments, which may not yield a favorable return to our stockholders.

***If you purchase securities in this offering, you will suffer immediate dilution of your investment.***

We expect that the combined public offering price of our common stock and the accompanying warrant in this offering will be higher than the net tangible book value per share of our common stock. Therefore, if you purchase shares of our common stock and accompanying warrants in this offering, you will pay a price per share and accompanying warrant that substantially exceeds our net tangible book value per share after this offering. Based on the public offering price of $ per share and accompanying warrant, our as adjusted net tangible book value as of September 30, 2022 would have been $ million, or $ per share, resulting in an immediate increase in the net tangible book value per share of $ to existing stockholders and an immediate dilution of $ in net tangible book value per share to investors purchasing common stock in this offering, representing the difference between our as adjusted net tangible book value per share after giving effect to this offering and the assumed public offering price. To the extent outstanding stock options or warrants are exercised, there will be further dilution to new investors. See "Dilution."

***You may experience future dilution as a result of future equity offerings.***

In order to raise additional capital, we expect to offer additional shares of our common stock or other securities convertible into or exchangeable for our common stock in the future. We cannot assure you that we will be able to sell shares or other securities in any other offering at a price that is equal to or greater than the price per share and accompanying warrant paid by investors in this offering, and investors purchasing shares or other securities in the future could have rights superior to existing stockholders. The price at which we sell additional shares of our common stock or other securities convertible into or exchangeable for our common stock in future transactions may be higher or lower than the price per share and accompanying warrant in this offering.

***We do not intend to pay dividends on our common stock so any returns will be limited to the value of our stock.***

You should not rely on an investment in our common stock to provide dividend income. We do not anticipate that we will pay any cash dividends to holders of our common stock in the foreseeable future. Instead, we plan to retain any earnings to maintain and expand our operations. Accordingly, investors must rely on sales of their common stock after price appreciation, which may never occur, as the only way to realize any return on their investment. As a result, investors seeking cash dividends should not purchase our common stock.

***The market price and trading volume of shares of our common stock may be volatile.***

The market price of shares of our common stock has exhibited substantial volatility. Between January 3, 2022 and December 30, 2022, the daily closing price of shares of our common stock as reported on Nasdaq ranged from a low of $1.80 to a high of $7.18. The market price of shares of our common stock could continue to fluctuate significantly for many reasons, including the following factors:

&nbsp;&nbsp;&nbsp;&nbsp;· reports of the results of our clinical trials regarding the safety or efficacy
of our product candidates and surrogate markers;

&nbsp;&nbsp;&nbsp;&nbsp;· announcements of regulatory developments or technological innovations by
us or our competitors;

&nbsp;&nbsp;&nbsp;&nbsp;· announcements of business or strategic transactions or our success in finalizing
such a transaction;

&nbsp;&nbsp;&nbsp;&nbsp;· announcements of legal or regulatory actions against us or any adverse outcome
of any such actions;

&nbsp;&nbsp;&nbsp;&nbsp;· changes in our relationships with our licensors, licensees and other strategic
partners;

&nbsp;&nbsp;&nbsp;&nbsp;· low volume in the number of shares of our common stock traded on Nasdaq;

&nbsp;&nbsp;&nbsp;&nbsp;· our quarterly or annual operating results;

&nbsp;&nbsp;&nbsp;&nbsp;· announcements of dilutive financing;

&nbsp;&nbsp;&nbsp;&nbsp;· announcements of additional potential reverse stock splits;

&nbsp;&nbsp;&nbsp;&nbsp;· developments in patent or other technology ownership rights;

&nbsp;&nbsp;&nbsp;&nbsp;· additional funds may not be available on terms that are favorable to us and,
in the case of equity financings, may result in dilution to our stockholders;

&nbsp;&nbsp;&nbsp;&nbsp;· government regulation of drug pricing; and

&nbsp;&nbsp;&nbsp;&nbsp;· general changes in the economy, the financial markets or the pharmaceutical
or biotechnology industries.

Factors beyond our control may also have an impact on the market price of shares of our common stock. For example, to the extent that other companies within our industry experience declines in their stock prices, the market price of shares of our common stock may decline as well.

***Sales of a substantial number of shares of our common stock by our existing shareholders in the public market or the exercise of common stock warrants could cause our stock price to fall.***

If our existing shareholders sell, or indicate an intention to sell, substantial amounts of our common stock in the public market or exercise, or indicate an intention to exercise, substantial amounts of warrants of our common stock in the public market, the trading price of our common stock could decline. In addition, a substantial number of shares of common stock are subject to outstanding options or will become eligible for sale in the public market to the extent permitted by the provisions of various vesting schedules. If these additional shares of common stock are sold, or if it is perceived that they will be sold, in the public market, the trading price of our common stock could decline.

We and our executive officers and directors have agreed for a period of 60 days from the date of this prospectus supplement, without the prior written consent of Cantor Fitzgerald & Co., with certain limited exceptions, not to offer, pledge, sell, contract to sell, or otherwise dispose of any shares of our common stock. The lock-up provisions apply to common stock and to securities convertible into or exchangeable or exercisable for common stock. They also apply to common stock owned now or acquired later by the person executing the lock-up agreement or for which the person executing the lock-up agreement later acquires the power of disposition.

***There is no public market for the warrants to purchase shares of our common stock being offered in this offering.***

There is no established public trading market for the warrants being offered in this offering, and we do not expect a market to develop. In addition, we do not intend to apply to list the warrants on any national securities exchange or other nationally recognized trading system, including the Nasdaq. Without an active market, the liquidity of the warrants will be limited.

***Holders of our warrants will have no rights as a common stockholder until they acquire our common stock.***

Until you acquire shares of our common stock upon exercise of the warrants, you will have no rights with respect to shares of our common stock issuable upon exercise of the warrants. Upon exercise of your warrants, you will be entitled to exercise the rights of a common stockholder only as to matters for which the record date occurs after the exercise date.

***The warrants are speculative in nature.***

The warrants offered hereby do not confer any rights of common stock ownership on their holders, such as voting rights or the right to receive dividends, but rather merely represent the right to acquire shares of common stock at a fixed price. Specifically, commencing on the date of issuance, holders of the warrants may acquire the common stock issuable upon exercise of such warrants at an exercise price of $ per share. Moreover, following this offering, the market value of the warrants is uncertain and there can be no assurance that the market value of the warrants will equal or exceed their public offering price. There can be no assurance that the market price of the common stock will ever equal or exceed the exercise price of the warrants and consequently, whether it will ever be profitable for holders of the warrants to exercise the warrants.

**Risks related to our financial position and capital needs**

***Our cash and cash equivalents balance as of December 31, 2022 will fund our operations for less than one year. If we cannot continue as a viable entity, our securityholders may lose some or all of their investment in us.***

As of December 31, 2022, we estimate that we had a cash and cash equivalents balance of approximately $17.1 million. We expect our existing cash and cash equivalents balance will be insufficient to fund current planned operations for at least the next twelve months from December 31, 2022, and that we will need to raise additional capital in order to continue our operations as currently planned. In the event that we are unable to obtain additional financing, we may be unable to continue as a going concern. There is no guarantee that we will be able to secure additional financing. Changes in our operating plans, our existing and anticipated working capital needs, the acceleration or modification of our development activities, any near-term or future expansion plans, increased expenses, potential acquisitions or other events may further affect our ability to continue as a going concern. Similarly, the report of our independent registered public accounting firm on our consolidated financial statements as of and for the year ended December 31, 2021 includes an explanatory paragraph indicating that there is substantial doubt about our ability to continue as a going concern. Our consolidated financial statements do not include any adjustments that might result from the outcome of this uncertainty.

**Tax Risks**

***The Excise Tax included in the Inflation Reduction Act of 2022 may make it more costly for the Company to exercise its call right with respect to the Series A Preferred Stock, and decrease the amount of funds available for distribution in connection with a liquidation of the Company.***

On August 16, 2022, President Biden signed into law the Inflation Reduction Act of 2022, which, among other things, imposes a non-deductible 1% excise tax on the fair market value of stock repurchased by a domestic corporation beginning in 2023, with certain exceptions (the "Excise Tax"). Because we are a corporation and our securities are trading on Nasdaq, we are a "covered corporation" within the meaning of the Inflation Reduction Act, and while not free from doubt, it is possible that the Excise Tax will apply to any redemptions of our common stock, unless an exemption is available. Consequently, the value of your investment in our securities may decrease as a result of the Excise Tax. In addition, the Excise Tax may make a transaction with us less appealing to potential business combination targets, and thus, potentially hinder our ability to enter into and consummate a business combination. Further, the application of the Excise Tax in the event of a liquidation is uncertain, and the proceeds could be subject to the Excise Tax, in which case the per-share amount that would otherwise be received by our stockholders in connection with our liquidation may be reduced.

**Risks related to our dependence on third parties and our license agreements**

***We rely on a license agreement with GenFleet for the development of GFH009, and if this license is breached or otherwise terminated, we could lose the ability to continue the development and potential commercialization of GFH009.***

We have entered into a license agreement with GenFleet under which we have an exclusive license to develop and commercialize GFH009 worldwide, other than in mainland China, Hong Kong, Macau and Taiwan. Under the license agreement, we are subject to various obligations, including diligence obligations with respect to development and commercialization activities, payment obligations upon achievement of certain milestones, and royalties on annual net sales (if the product candidate is ultimately commercialized), as well as other material obligations. If there is any conflict, dispute, disagreement, or issue of nonperformance between us and GenFleet regarding our rights or obligations under the license agreement, including any such conflict, dispute, or disagreement arising from our failure to satisfy diligence or payment obligations under the license agreement, we may be liable to pay damages and GenFleet may have a right to terminate the license. The loss of the license agreement could prevent us from developing, commercializing, or entering into future strategic transactions relating to GFH009.

**SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS**

This prospectus supplement, the accompanying prospectus and the documents incorporated by reference herein and therein contain forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, or the Securities Act, and Section 21E of the Exchange Act, and the Private Securities Litigation Reform Act of 1995. These statements are based on our management's current beliefs, expectations and assumptions about future events, conditions and results and on information currently available to us. All statements other than statements of historical facts contained in this prospectus supplement and the accompanying prospectus, including statements regarding our strategy, future operations, future financial position, future revenue, projected costs, prospects, plan, objectives of management, results of preclinical studies or clinical trials and expected market growth are forward-looking statements. In some cases, forward-looking statements can be identified by terminology such as "plan," "expect," "anticipate," "may," "might," "will," "should," "project," "believe," "estimate," "predict," "potential," "intend," or "continue" and other words or terms of similar meaning.

We have based these forward-looking statements largely on our current expectations and projections about future events and financial trends that we believe may affect our financial condition, results of operations, business strategy and financial needs. These forward-looking statements are subject to a number of known and unknown risks, uncertainties and assumptions, including risks described in the section titled "Risk Factors" contained in our most recent Annual Report on Form 10-K and incorporated by reference in this prospectus, as the same may be amended, supplemented or superseded by the risks and uncertainties described under similar headings in the other documents that are filed after the date hereof and incorporated by reference into this prospectus, regarding, among other things:

&nbsp;&nbsp;&nbsp;&nbsp;· our ability to continue to operate despite incurring
substantial losses since our inception and our expectation that we will continue to incur substantial and increasing losses for the foreseeable
future;

&nbsp;&nbsp;&nbsp;&nbsp;· our ability to continue as a going concern;

&nbsp;&nbsp;&nbsp;&nbsp;· our ability to obtain the substantial additional
financing necessary to achieve our goals;

&nbsp;&nbsp;&nbsp;&nbsp;· whether we will generate revenues and achieve
profitability in the future;

&nbsp;&nbsp;&nbsp;&nbsp;· the ability of investors to evaluate the success
of our business and to assess our future viability given our limited operating history;

&nbsp;&nbsp;&nbsp;&nbsp;· our expectations regarding our continuing to
incur significant operating and non-operating expenses;

&nbsp;&nbsp;&nbsp;&nbsp;· the impact of the COVID-19 pandemic;

&nbsp;&nbsp;&nbsp;&nbsp;· the initiation of legal or administrative actions
against us;

&nbsp;&nbsp;&nbsp;&nbsp;· our ability to use net operating losses to offset
future taxable income;

&nbsp;&nbsp;&nbsp;&nbsp;· our ability to comply with the regulatory and
environmental provisions and laws to which we are subject;

&nbsp;&nbsp;&nbsp;&nbsp;· our ability to develop our product candidates,
including GPS and GFH009;

&nbsp;&nbsp;&nbsp;&nbsp;· our ability to obtain regulatory approval of
our product candidates;

&nbsp;&nbsp;&nbsp;&nbsp;· whether the results of our clinical trials will
be sufficient to support domestic or global regulatory approvals;

&nbsp;&nbsp;&nbsp;&nbsp;· the initiation, timing, progress and results
of our pre-clinical and clinical trials;

&nbsp;&nbsp;&nbsp;&nbsp;· the success of our lead product candidate, GPS,
and our ability to successfully complete clinical trials and obtain regulatory approval for our other product candidates;

&nbsp;&nbsp;&nbsp;&nbsp;· whether our product development program will
uncover all possible adverse events that patients who take our product candidates may experience;

&nbsp;&nbsp;&nbsp;&nbsp;· whether we can maintain orphan drug exclusivity
and Fast Track designation for certain of our product candidates and whether we will receive orphan drug product designation and Fast
Track designation for additional product candidates should we seek such designations;

&nbsp;&nbsp;&nbsp;&nbsp;· our ability to successfully identify, acquire,
develop or commercialize new potential product candidates;

&nbsp;&nbsp;&nbsp;&nbsp;· our ability to realize benefits from strategic
alliances that we may form in the future;

&nbsp;&nbsp;&nbsp;&nbsp;· whether we can continue to rely on third parties
to conduct our preclinical studies and clinical trials;

&nbsp;&nbsp;&nbsp;&nbsp;· whether we can continue to rely on third parties
to manufacture our product candidates;

&nbsp;&nbsp;&nbsp;&nbsp;· whether we can rely on third parties to develop
or potentially commercialize some or all of our product candidates;

&nbsp;&nbsp;&nbsp;&nbsp;· developments or disputes concerning our intellectual
property or other proprietary rights;

&nbsp;&nbsp;&nbsp;&nbsp;· our expectations regarding the potential market
size and the size of the patient populations for our product candidates, if approved, for commercial use;

&nbsp;&nbsp;&nbsp;&nbsp;· the impact of legislation developments regarding
pricing regulations;

&nbsp;&nbsp;&nbsp;&nbsp;· the implementation of our business model and
strategic plans for our business and product candidates;

&nbsp;&nbsp;&nbsp;&nbsp;· our ability to maintain and establish collaborations
or obtain additional funding;

&nbsp;&nbsp;&nbsp;&nbsp;· the market price and value of our common stock;

&nbsp;&nbsp;&nbsp;&nbsp;· our ability to compete in the markets we serve;
and

&nbsp;&nbsp;&nbsp;&nbsp;· other factors that may impact our financial results.

All of our forward-looking statements are as of the date of this prospectus supplement only. In each case, actual results may differ materially from such forward-looking information. We can give no assurance that such expectations or forward-looking statements will prove to be correct. An occurrence of or any material adverse change in one or more of the risk factors or risks and uncertainties referred to in this prospectus supplement or included in our other public disclosures or our other periodic reports or other documents or filings filed with or furnished to the SEC, could materially and adversely affect our business, prospects, financial condition and results of operations. Except as required by law, we do not undertake or plan to update or revise any such forward-looking statements to reflect actual results, changes in plans, assumptions, estimates or projections or other circumstances affecting such forward-looking statements occurring after the date of this prospectus supplement, even if such results, changes or circumstances make it clear that any forward-looking information will not be realized. Any public statements or disclosures by us following this prospectus supplement that modify or impact any of the forward-looking statements contained herein will be deemed to modify or supersede such statements in this prospectus supplement.

**USE OF PROCEEDS**

We expect that the net proceeds from our issuance and sale of shares of our common stock and accompanying warrants in this offering will be approximately $ million, after deducting underwriting discounts and commissions and estimated offering expenses payable by us and excluding the proceeds, if any, from the exercise of the warrants issued in this offering. If all the warrants are exercised for cash at an exercise price of $ per share, then our net proceeds will be approximately $ million, after deducting underwriting discounts and commissions and estimated offering expenses payable by us. We cannot predict when or if the warrants will be exercised. It is possible that the warrants may expire and may never be exercised. If all the warrants are exercised as described above and the underwriters' option to purchase up to additional shares of common stock and warrants to purchase up to additional shares of common stock is exercised in full, then our net proceeds will be approximately $ million, after deducting underwriting discounts and commissions and estimated offering expenses payable by us.

We expect to use the net proceeds of this offering, in addition to our existing cash resources, for funding of ongoing operations, including clinical development of the product candidates noted in this prospectus supplement, and for working capital and other general corporate purposes.

The amounts and timing of our actual expenditures will depend on numerous factors, including the time and cost necessary to conduct our planned clinical trials, the results of our planned clinical trials and other factors described in the section titled "Risk factors" in this prospectus supplement and the accompanying prospectus, as well as the amount of cash used in our operations and any unforeseen cash needs. Therefore, our actual expenditures may differ materially from the estimates described above. We may find it necessary or advisable to use the net proceeds for other purposes, and we will have broad discretion in the application of the net proceeds from this offering.

**DIVIDEND POLICY**

We have never declared or paid cash dividends on our capital stock. We intend to retain all of our future earnings, if any, to finance the growth and development of our business. We do not intend to pay cash dividends to our stockholders in the foreseeable future. As a result, investors seeking cash dividends should not purchase our common stock.

**DILUTION**

As of September 30, 2022, we had a historical net tangible book value of $10.7 million, or $0.52 per share of common stock, based on 20,588,247 shares of common stock outstanding. Our historical net tangible book value per share represents total tangible assets less total liabilities, divided by the number of shares of common stock outstanding.

After giving effect to the sale by us of shares of common stock and accompanying warrants in this offering at the public offering price of $ per share and accompanying warrant, and after deducting underwriting discounts and commissions and estimated offering expenses payable by us and excluding the proceeds and shares issuable, if any, from the exercise of the warrants issued pursuant to this offering, our as adjusted net tangible book value as of September 30, 2022 would have been $ million, or $ per share. This amount represents an immediate increase in our net tangible book value of $ per share to our existing stockholders and an immediate dilution in our net tangible book value of $ per share to investors purchasing common stock in this offering. We determine dilution by subtracting our as adjusted net tangible book value per share after this offering from the amount of cash paid by an investor for a share of common stock in this offering. The following table illustrates this dilution on a per share basis:

---

| | | |
|:---|:---|:---|
| Public offering price per share and accompanying warrants |  | $|
| Historical net tangible book value per share as of September 30, 2022 | $0.52 |  |
| &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Increase in net tangible book value per share attributable to investors purchasing shares and accompanying warrants in this offering | $— |  |
| As adjusted net tangible book value per share after this offering |  | $|
| Dilution in net tangible book value per share to investors purchasing shares and accompanying warrants in this offering |  | $|

---

The discussion and table above assume no exercise of warrants sold in this offering.

The number of shares of our common stock to be outstanding after this offering set forth above is based on 20,588,247 shares of our common stock outstanding as of September 30, 2022 and excludes:

&nbsp;&nbsp;&nbsp;&nbsp;· 1,070,520 shares of our common stock issuable
upon the exercise of stock options outstanding as of September 30, 2022, at a weighted-average exercise price of $7.56 per share;

&nbsp;&nbsp;&nbsp;&nbsp;· 648,700 shares of common stock issuable upon
the exercise of stock options issued after September 30, 2022, at a weighted-average exercise price of $3.28 per share

&nbsp;&nbsp;&nbsp;&nbsp;· 297,280 shares of common stock issuable upon
the vesting and settlement of RSUs outstanding as of September 30, 2022;

&nbsp;&nbsp;&nbsp;&nbsp;· 195,700 shares of shares of common stock
 issuable upon the vesting and settlement of RSUs issued after September 30, 2022 up to the date of this Prospectus
 Supplement;

&nbsp;&nbsp;&nbsp;&nbsp;· 5,147,376 shares of our common stock issuable
upon the exercise of warrants outstanding as of September 30, 2022, at a weighted-average exercise price of $5.82 per share;

&nbsp;&nbsp;&nbsp;&nbsp;· 607,824 shares of our common stock reserved for
future issuance under our 2019 Plan as of September 30, 2022, as well as any automatic increases in the number of shares of our common
stock reserved for future issuance under our 2019 Plan;

&nbsp;&nbsp;&nbsp;&nbsp;· 274,911 shares of our common stock reserved for
future issuance under our 2021 Employee Plan as of September 30, 2022;

&nbsp;&nbsp;&nbsp;&nbsp;· 453,996 shares of our common stock issued under
the Sales Agreement with Cantor Fitzgerald & Co. after September 30, 2022 up to the date of this Prospectus Supplement; and

&nbsp;&nbsp;&nbsp;&nbsp;· 40,044 shares of our common stock issued upon
the vesting and settlement of RSUs under our 2019 Plan after September 30, 2022 up to the date of this Prospectus Supplement.

**MATERIAL U.S. FEDERAL INCOME TAX CONSIDERATIONS**

The following discussion is a summary of the material U.S. federal income tax considerations of the acquisition, ownership and disposition of shares of our common stock and warrants acquired in this offering by non-U.S. holders (as defined below) and the acquisition, ownership and disposition of warrants acquired in this offering by U.S. holders (as defined below) that, in each case, hold such shares or warrants as a capital asset within the meaning of Section 1221 of the Code (generally, property held for investment).

This section is based on current provisions of the U.S. Internal Revenue Code of 1986, as amended, or the Code, U.S. Treasury Regulations promulgated thereunder, administrative rulings and judicial decisions, all as in effect as of the date of this prospectus supplement and all of which are subject to change or to differing interpretation, possibly with retroactive effect. Any such change or differing interpretation could alter the tax consequences to holders described in this prospectus supplement. There can be no assurance that the U.S. Internal Revenue Service, or the IRS, will not challenge one or more of the tax consequences described herein.

This discussion does not address all aspects of U.S. federal income taxation that may be relevant to a particular holder in light of that holder's individual circumstances nor does it address U.S. state, local or non-U.S. taxes, U.S. federal estate or gift tax laws, any alternative minimum tax levied under the Code, the Medicare tax on net investment income or any other aspect of any U.S. federal tax other than the income tax. This discussion also does not consider any specific facts or circumstances that may apply to a holder and does not address the special tax rules applicable to certain holders, such as:

&nbsp;&nbsp;&nbsp;&nbsp;· insurance companies;

&nbsp;&nbsp;&nbsp;&nbsp;· regulated investment companies and real estate
investment trusts;

&nbsp;&nbsp;&nbsp;&nbsp;· tax-exempt or governmental organizations;

&nbsp;&nbsp;&nbsp;&nbsp;· financial institutions;

&nbsp;&nbsp;&nbsp;&nbsp;· brokers or dealers in securities;

&nbsp;&nbsp;&nbsp;&nbsp;· traders that have elected to mark securities
to market;

&nbsp;&nbsp;&nbsp;&nbsp;· regulated investment companies;

&nbsp;&nbsp;&nbsp;&nbsp;· pension plans;

&nbsp;&nbsp;&nbsp;&nbsp;· corporations that accumulate earnings to avoid
U.S. federal income tax;

&nbsp;&nbsp;&nbsp;&nbsp;· "qualified foreign pension funds"
as defined in Section 897(l)(2) of the Code and entities all of the interests of which are held by qualified foreign pension funds;

&nbsp;&nbsp;&nbsp;&nbsp;· persons deemed to sell our common stock or warrants
under the constructive sale provisions of the Code;

&nbsp;&nbsp;&nbsp;&nbsp;· persons that hold our common stock or warrants as part of a straddle, hedge,
conversion transaction, synthetic security or other integrated investment;

&nbsp;&nbsp;&nbsp;&nbsp;· persons who hold or receive our common stock or warrants pursuant to the
exercise of an yemployee stock option or otherwise as compensation;

&nbsp;&nbsp;&nbsp;&nbsp;· U.S. holders whose functional currency is not the U.S. dollar;

· "Controlled foreign corporations" and "passive foreign investment companies"; and

&nbsp;&nbsp;&nbsp;&nbsp;· certain U.S. expatriates.

This discussion does not address the tax treatment of partnerships (including any entity or arrangements treated as a partnership for U.S. federal income tax purposes) or persons that hold their common stock through such a partnerships. If an entity or arrangement treated as a partnership for U.S. federal income tax purposes holds our common stock or warrants, the tax treatment of a partner in the partnership will depend on the status of the partner, the activities of the partnership and certain determinations made at the partner level. A partner in a partnership or other pass-through entity (including an entity or arrangement that is treated as partnerships for U.S. federal income tax purposes) that will hold our common stock should consult his, her or its tax advisor regarding the tax consequences of acquiring, holding and disposing of our common stock through a partnership or other pass-through entity, as applicable.

This discussion is for general information only and is not intended to be, and may not be construed as, tax advice. Accordingly, all prospective holders of our common stock or warrants should consult their tax advisors with respect to the U.S. federal, state, local and non-U.S. tax consequences of the purchase, ownership and disposition of our common stock or warrants.

**Material U.S. Federal Income Tax Considerations of Owning and Disposing of Warrants for U.S. Holders**

The following discusses the material U.S. federal income tax consideration of owning and disposing of our warrants for a U.S. holder. This section does not address the U.S. federal income tax considerations for U.S. holders of owning or disposing of shares of our common stock or of backup withholding and information reporting.

For purposes of this discussion, a U.S. holder is any beneficial owner of our common stock or warrants that, for U.S. federal income tax purposes, is:

&nbsp;&nbsp;&nbsp;&nbsp;· an individual who is a citizen or resident of
the United States;

&nbsp;&nbsp;&nbsp;&nbsp;· a domestic corporation;

&nbsp;&nbsp;&nbsp;&nbsp;· an estate, the income of which is subject to
U.S. federal income tax regardless of its source; or

&nbsp;&nbsp;&nbsp;&nbsp;· a trust, if (A) a U.S. court is able to exercise
primary supervision over the trust's administration and one or more U.S. persons have authority to control all of the trust's
substantial decisions or (B) the trust has validly elected to be treated as a U.S. person for U.S. federal income tax purposes.

*Allocation of Purchase Price Between Shares and Warrants*

Because our common stock and accompanying warrants are sold together, a purchaser of shares of our common stock and accompanying warrants must allocate its purchase price between each share and the accompanying warrant based on their respective relative fair market values at the time of issuance. This allocation of the purchase price will establish the holder's initial tax basis for U.S. federal income tax purposes for each share and warrant. A holder's allocation of the purchase price among the shares and warrants is not binding on the IRS or the courts, and no assurance can be given that the IRS or the courts will agree with a holder's allocation. Each holder should consult its own tax advisor regarding the allocation of the purchase price among the shares and warrants.

*Exercise of Warrants*

A U.S. holder generally will not recognize gain or loss for U.S. federal income tax purposes on the exercise of a common warrant and the related receipt of common stock. A U.S. holder's tax basis in the common stock received upon exercise of the common warrant generally will equal the sum of the U.S. holder's tax basis in the warrant and the exercise price. It is unclear whether the U.S. holder's holding period for the common stock received upon exercise of the warrants will begin on the date following the date of exercise or on the date of exercise of the warrants; in either case, the holding period will not include the period during which the U.S. holder held the warrants.

In certain circumstances, the warrants may be exercised on a cashless basis. The U.S. federal income tax treatment of an exercise of a warrant on a cashless basis is not clear under current law, and could differ from the consequences described above. It is possible that a cashless exercise is a non-taxable transaction, either because the exercise is not treated as a realization event or because the exercise is treated as a tax-free recapitalization for U.S. federal income tax purposes. Under either characterization, a U.S. holder's tax basis in the common stock received generally would equal the U.S. holder's tax basis in the warrants. If the cashless exercise was not a realization event, it is unclear whether a U.S. holder's holding period for the shares of common stock acquired pursuant to the cashless exercise will commence on the date of exercise of the warrant or the day following the date of exercise of the warrant. If the cashless exercise were treated as a recapitalization, the holding period of the shares of common stock acquired pursuant to it would include the holding period of the warrants.

It is also possible that a cashless exercise is treated as a taxable exchange in which gain or loss would be recognized. In such event, a U.S. holder may be deemed to have surrendered warrants with an aggregate fair market value equal to the exercise price for the total number of warrants to be exercised. The U.S. holder would recognize capital gain or loss in an amount equal to the difference between the fair market value of the warrants deemed surrendered and the U.S. holder's tax basis in such warrants (such gain or loss would be long-term or short-term, depending on the U.S. holder's holding period in the warrants deemed surrendered). In this case, a U.S. holder's tax basis in the shares of common stock received pursuant to the cashless exercise would equal the sum of the U.S. holder's tax basis in the warrants exercised and the exercise price of such warrants. It is unclear whether a U.S. holder's holding period for the common stock would commence on the date of exercise of the warrant or the day following the date of exercise of the warrant.

Due to the absence of authority on the U.S. federal income tax treatment of a cashless exercise, there can be no assurance which, if any, of the alternative tax consequences and holding periods described above would be adopted by the IRS or a court of law. Holders are urged to consult their tax advisors as to the consequences of an exercise of a common warrant on a cashless basis, including with respect to their holding period and tax basis in the common stock received.

*Lapse of Warrants*

If U.S. holder allows a common warrant to expire unexercised, such holder will generally recognize a capital loss for U.S. federal income tax purposes in an amount equal to such holder's tax basis in the common warrant. Any such loss generally will be a capital loss and will be long-term capital loss if the common warrant is held for more than one year. The deductibility of capital losses is subject to limitations.

*Contingent Payments on the Warrants*

The warrants entitle a holder to receive payments upon the occurrence of certain contingencies, including a distribution on shares of our common stock or our failure to deliver shares of common stock upon exercise of a common warrant. The tax treatment of such payments, if made, is subject to substantial uncertainty. Holders should consult their own tax advisors as to the appropriate U.S. federal income tax treatment of any such contingent payments that may be made to them in respect of the warrants.

*Adjustments to Warrant Conversion Ratio*

Under Section 305 of the Code, an adjustment to the number of shares of our common stock that will be issued on exercise of the warrants, or an adjustment to the exercise price of the warrants, may be treated as a constructive distribution to a holder of the warrants if, and to the extent that, such adjustment has the effect for U.S. federal income tax purposes of increasing such U.S. holder's proportionate interest in our earnings and profits or assets, depending on the circumstances of such adjustment. Adjustments made pursuant to a bona fide reasonable adjustment formula which has the effect of preventing the dilution of the interest of the holders of warrants generally will not be deemed to result in a constructive distribution. A constructive distribution under these rules would be subject to tax in the same manner as if the U.S. holders of the warrants received a cash distribution from us equal to the fair market value of such increased interest resulting from the adjustment.

**Material U.S. Federal Income Tax Consequences for Non-U.S. Holders**

The following discusses the material U.S. federal income tax consequences of acquiring, owning and disposing of shares of our common stock and warrants to a non-U.S. holder. For purposes of this discussion, a U.S. holder is any beneficial owner of shares of our common stock or warrants that, for U.S. federal income tax purposes, is:

&nbsp;&nbsp;&nbsp;&nbsp;· a non-resident alien individual;

&nbsp;&nbsp;&nbsp;&nbsp;· a foreign corporation or any other foreign association
taxable as a corporation for U.S. federal income tax purposes; or

&nbsp;&nbsp;&nbsp;&nbsp;· a foreign estate or trust the income of which
is not subject to U.S. federal income tax on a net income basis.

 

*Allocation of Purchase Price Between Shares and Warrants*

If it is relevant for a non-U.S. holder to determine its tax basis in shares of common stock or warrants for U.S. federal income tax purposes, a U.S. holder will determined such tax basis based on the allocation of the purchase price as described above under "*Material U.S. Federal Income Tax Considerations of Owning and Disposing of Warrants to U.S. Holders -- Allocation of Purchase Price Between Shares and Warrants*".

*Warrants*

The U.S. federal income tax treatment of a non-U.S. holder's exercise of a warrant, or the lapse of a warrant held by a non-U.S. holder, generally will correspond to the U.S. federal income tax treatment of the exercise or lapse of a warrant by a U.S. holder, as described under "*Material U.S. Federal Income Tax Considerations of Owning and Disposing of Warrants to U.S. Holders*" above, although to the extent a cashless exercise results in a taxable exchange, the rules described below under "*Material U.S. Federal Income Tax Consequences for Non-U.S. Holders—Gains on Sale or Other Taxable Disposition of Our Common Stock or Warrants*" would apply.

If contingent payments are made with respect to a common warrant, as described above under "*Treatment of Warrants – U.S. Holder s—Contingent Payments on the Warrants*", such payments may be subject to a U.S. withholding tax. Any U.S. federal income tax required to be withheld on any portion of such contingent payment may be withheld from common stock delivered, sales proceeds subsequently paid or credited, or other amounts payable or distributable to a non-U.S. holder.

*Distributions on Our Common Stock and Warrants*

As described in the section titled "Dividend Policy," we do not anticipate paying any future distributions on our shares. However, if we do make distributions on our shares or warrants, such distributions will constitute dividends to the extent paid from our current or accumulated earnings and profits, as determined under U.S. federal income tax principles. If a distribution exceeds our current and accumulated earnings and profits, the excess will be treated as a tax-free return of the non-U.S. holder's investment, up to such holder's adjusted tax basis in the shares. Any remaining excess will be treated as capital gain from the sale or exchange of such shares, subject to the tax treatment described below in "—*Gain on Sale or Other Taxable Disposition of Our Common Stock*." Any such distributions will also be subject to the discussions below in the sections titled "—*Backup Withholding and Information Reporting" and "FATCA*."

Subject to the discussion in the remainder of this section, dividends (including any portion of constructive distributions treated as dividends) paid to a non-U.S. holder generally will be subject to withholding of U.S. federal income tax at a 30% rate or such lower rate as may be specified by an applicable income tax treaty between the United States and such holder's country of residence. Dividends that are treated as effectively connected with a trade or business conducted by a non-U.S. holder within the United States and, if an applicable income tax treaty so provides, that are attributable to a permanent establishment or a fixed base maintained by the non-U.S. holder within the United States, are generally exempt from the 30% withholding tax if that non-U.S. holder has furnished to us or our paying agent an Internal Revenue Service Form W-8ECI (or applicable successor form), certifying under penalties of perjury that the dividend is effectively connected with the non-U.S. holder's conduct of a trade or business in the United States (and, if an applicable income tax treaty so provides, attributable to a permanent establishment or fixed base maintained in the United States). However, such U.S. effectively connected income, net of specified deductions and credits, is generally taxed on a net income basis in the same manner and at the same regular U.S. federal income tax rates applicable to United States persons (as defined in the Code). Any U.S. effectively connected income received by a corporate non-U.S. holder may also, under certain circumstances, be subject to an additional "branch profits tax" at a 30% rate or such lower rate as may be specified by an applicable income tax treaty between the United States and such holder's country of residence.

A non-U.S. holder of our common stock who claims the benefit of an applicable income tax treaty between the United States and such holder's country of residence generally will be required to provide a properly executed IRS Form W-8BEN or W-8BEN-E (or successor form) to the applicable withholding agent and satisfy applicable certification and other requirements. A non-U.S. holder that holds our shares through a financial institution or other agent will be required to provide appropriate documentation to the financial institution or other agent, which then will be required to provide certification to us or our paying agent either directly or through other intermediaries. Non-U.S. holders are urged to consult their tax advisors regarding their entitlement to benefits under a relevant income tax treaty. A non-U.S. holder that is eligible for a reduced rate of U.S. withholding tax under an income tax treaty may obtain a refund or credit of any excess amounts withheld by timely filing a U.S. tax return with the IRS.

*Gains on Sale or Other Taxable Disposition of Our Common Stock or Warrants*

Subject to the discussions below under "—*Backup Withholding and Information Reporting*" and "—*FATCA*," a non-U.S. holder generally will not be subject to any U.S. federal income or withholding tax on any gain realized upon such holder's sale or other taxable disposition of shares of our common stock or warrants unless:

· the gain is effectively connected with the non-U.S. holder's conduct
of a U.S. trade or business and, if an applicable income tax treaty so provides, is attributable to a permanent establishment or a fixed
base maintained by such non-U.S. holder in the United States, in which case the non-U.S. holder generally will be taxed on a net income
basis at the regular U.S. federal income tax rates applicable to United States persons (as defined in the Code) and, if the non-U.S. holder
is a foreign corporation, the branch profits tax described above in "Distributions on Our Common Stock" also may apply;

· the non-U.S. holder is a nonresident alien individual who is present in
the United States for 183 days or more in the taxable year of the disposition and certain other conditions are met, in which case the
non-U.S. holder will be subject to a 30% tax (or such lower rate as may be specified by an applicable income tax treaty between the United
States and such holder's country of residence) on the net gain derived from the sale or other taxable disposition of the shares
of common stock or warrants, as applicable, which may be offset by certain U.S. source capital losses of the non-U.S. holder, if any (even
though the individual is not considered a resident of the United States), provided that the non-U.S. holder has timely filed U.S. federal
income tax returns with respect to such losses; or

· we are, or have been, at any time during the five-year period preceding
such sale or other taxable disposition (or the non-U.S. holder's holding period, if shorter) of such shares of common stock or warrants,
as applicable, a U.S. real property holding corporation, unless our common stock is regularly traded on an established securities market
and the non-U.S. holder holds no more than 5% (by value) of our outstanding common stock or warrants, as applicable, directly or indirectly,
actually or constructively, during the shorter of the 5-year period ending on the date of the disposition or the period that the non-U.S.
holder held our common stock or warrants. If we are or were a U.S. real property holding corporation during the relevant period and the
foregoing exception does not apply, the non-U.S. holder generally will be taxed on its net gain derived from the disposition at the regular
U.S. federal income tax rates applicable to United States persons (as defined in the Code). Generally, a corporation is a U.S. real property
holding corporation only if the fair market value of its U.S. real property interests equals or exceeds 50% of the sum of the fair market
value of its worldwide real property interests plus its other assets used or held for use in a trade or business. Although there can be
no assurance, we do not believe that we are, or have been, a U.S. real property holding corporation, or that we are likely to become one
in the future. No assurance can be provided that our common stock will be regularly traded on an established securities market for purposes
of the rules described above.

*Backup Withholding and Information Reporting*

We must report annually to the IRS and to each non-U.S. holder the gross amount of the distributions on our securities paid to such holder and the tax withheld, if any, with respect to such distributions. A non-U.S. holder may have to comply with specific certification procedures to establish that such holder is not a United States person (as defined in the Code) in order to avoid backup withholding at the applicable rate with respect to dividends on our securities. Dividends paid to non-U.S. holders subject to withholding of U.S. federal income tax, as described above in "—*Distributions on Our Common Stock and Warrants*," generally will be exempt from U.S. backup withholding.

Information reporting and backup withholding will generally apply to the proceeds of a disposition of our securities by a non-U.S. holder effected by or through the U.S. office of any broker, U.S. or foreign, unless the holder certifies its status as a non-U.S. holder and satisfies certain other requirements, or otherwise establishes an exemption. Generally, information reporting and backup withholding will not apply to a payment of disposition proceeds to a non-U.S. holder where the transaction is effected outside the United States through a non-U.S. office of a broker. However, for information reporting purposes, dispositions effected through a non-U.S. office of a broker with substantial U.S. ownership or operations generally will be treated in a manner similar to dispositions effected through a U.S. office of a broker.

Backup withholding is not an additional tax. Any amounts withheld under the backup withholding rules from a payment to a non-U.S. holder can be refunded or credited against the non-U.S. holder's U.S. federal income tax liability, if any, provided that an appropriate claim is filed with the IRS in a timely manner.

Non-U.S. holders should consult their tax advisors regarding the application of the information reporting and backup withholding rules to them. Copies of information returns may be made available to the tax authorities of the country in which the non-U.S. holder resides or is incorporated under the provisions of a specific treaty or agreement.

*FATCA*

Provisions of the Code commonly referred to as the Foreign Account Tax Compliance Act, or FATCA, generally impose a U.S. federal withholding tax at a rate of 30% on payments of dividends on our common stock paid to a foreign entity unless (i) if the foreign entity is a "foreign financial institution," such foreign entity undertakes certain due diligence, reporting, withholding, and certification obligations, (ii) if the foreign entity is not a "foreign financial institution," such foreign entity either certifies it does not have any substantial U.S. owners or furnishes identifying information regarding each substantial U.S. owner and such entity meets certain other specified requirements, or (iii) the foreign entity is otherwise exempt under FATCA. Such withholding may also apply to gross proceeds from the sale or other disposition of our common stock or warrants, although under proposed U.S. Treasury Regulations, no withholding would apply to such gross proceeds. The preamble to the proposed regulations specifies that taxpayers (including withholding agents) are permitted to rely on the proposed regulations pending finalization. Under certain circumstances, a non-U.S. holder may be eligible for refunds or credits of this withholding tax. An intergovernmental agreement between the United States and an applicable foreign country may modify the requirements described in this paragraph. Non-U.S. holders should consult their tax advisors regarding the possible implications of this legislation on their investment in our common stock and the entities through which they hold our common stock, including, without limitation, the process and deadlines for meeting the applicable requirements to prevent the imposition of the 30% withholding tax under FATCA.

The preceding discussion of U.S. federal income tax considerations is for general information only. It is not tax advice. Each prospective investor should consult its tax advisor regarding the particular U.S. federal, state and local and non-U.S. tax consequences of purchasing, holding and disposing of our common stock, including the consequences of any proposed change in applicable laws.

**DESCRIPTION OF CAPITAL STOCK**

We are offering shares of our common stock and accompanying warrants to purchase up to shares of our common stock. Each share of common stock we sell will be accompanied by a warrant to purchase one share of common stock. The shares of common stock and warrants will be issued separately. We are also registering the shares of common stock issuable from time to time upon exercise of the common warrants offered hereby.

As of the date of this prospectus supplement, our amended and restated certificate of incorporation authorizes us to issue up to 350,000,000 shares of common stock, $0.0001 par value per share, and 5,000,000 shares of preferred stock, $0.0001 par value per share.

The following is a summary of the rights of our common and preferred stock and some of the provisions of our amended and restated certificate of incorporation and amended and restated bylaws and Delaware General Corporation Law. This is only a summary, and is qualified in its entirety by reference to our amended and restated certificate of incorporation and our amended and restated bylaws which are incorporated by reference into the registration statement of which this prospectus supplement is a part.

**Common stock**

*Voting*

Each holder of our common stock is entitled to one vote for each share on all matters submitted to a vote of the stockholders, including the election of directors. Our amended and restated certificate of incorporation and amended and restated bylaws do not provide for cumulative voting rights. Because of this absence of cumulative voting, the holders of a majority of the shares of common stock entitled to vote in any election of directors can elect all the directors standing for election, if they should so choose.

*Dividends*

Subject to preferences that may be applicable to any then outstanding shares of preferred stock, holders of common stock are entitled to receive ratably those dividends, if any, as may be declared from time to time by our board of directors out of legally available funds.

*Liquidation*

In the event of our dissolution or liquidation, holders of common stock will be entitled to share ratably in the net assets legally available for distribution to stockholders after the payment of all our debts and other liabilities and the satisfaction of any preferential rights that may be granted to the holders of any then outstanding shares of preferred stock.

*Rights and Preferences*

Holders of common stock have no preemptive, conversion or subscription rights, and there are no redemption or sinking fund provisions applicable to the common stock. The rights, preferences, and privileges of the holders of common stock are subject to, and may be adversely affected by, the rights of the holders of shares of any series of preferred stock.

*Fully-paid*

All of the outstanding shares of our common stock are, and the shares of common stock issued upon the conversion of any securities convertible into our common stock will be, fully paid and non-assessable. The shares of common stock offered by this prospectus or upon the conversion of any preferred stock or debt securities or exercise of any warrants offered pursuant to this prospectus, when issued and paid for, will also be, fully paid and non-assessable.

**Warrants**

The following is a summary of the material terms and provisions of the warrants that are being offered hereby. This summary is subject to and qualified in its entirety by the form of warrant, which will be filed with the SEC as an exhibit to a Current Report on Form 8-K in connection with this offering and incorporated by reference into the registration statement of which this prospectus supplement and the accompanying prospectus form a part. Prospective investors should carefully review the terms and provisions of the form of warrant for a complete description of the terms and conditions of the warrants.

*Duration and Exercise Price*. The warrants offered hereby will have an exercise price of $ per share and will expire on the five-year anniversary of the date of issuance. The exercise price and number of shares of common stock issuable upon exercise of the warrants are subject to appropriate adjustment in the event of stock dividends, stock splits, reorganizations or similar events affecting our common stock.

*Exercisability*. The warrants will be exercisable, at the option of each holder, in whole or in part, by delivering a duly executed exercise notice accompanied by payment in full for the number of shares of our common stock purchased upon such exercise (except in the case of a cashless exercise as discussed below). A holder (together with its affiliates) may not exercise any portion of such holder's common warrants to the extent that the holder would own more than 9.99% of our outstanding common stock immediately after exercise.

*Exercise Limitations*. We may not effect the exercise of any warrant, and a holder will not be entitled to exercise any portion of any common warrant that, upon giving effect to such exercise, would cause the aggregate number of shares of common stock beneficially owned by such holder (together with its affiliates) to exceed 4.99% or 9.99% (at the election of the holder) of the number of shares of common stock outstanding immediately after giving effect to the exercise. However, any holder of a warrant may increase or decrease such percentage upon at least 61 days' prior written notice from the holder to us, provided that such percentage in no event exceeds 9.99%.

*Cashless Exercise*. If, at the time a holder exercises its warrants a registration statement registering the issuance of the shares of common stock underlying such warrants under the Securities Act is not then effective or available for the issuance of such shares, or the prospectus contained therein is not available for the issuance of such shares, then in lieu of making the cash payment to us upon such exercise in payment of the aggregate exercise price, the holder may elect instead to receive upon such exercise (either in whole or in part) the net number of shares of common stock determined according to a formula set forth in the warrant.

*Transferability*. Subject to applicable laws, the warrants may be offered for sale, sold, transferred or assigned without our consent.

*Trading Market*. There is no established trading market for any of the warrants, and we do not expect a market to develop. We do not intend to apply for a listing for any of the warrants on any securities exchange or other nationally recognized trading system. Without an active trading market, the liquidity of the warrants will be limited.

*Rights as a Shareholder*. Except as otherwise provided in the warrants or by virtue of the holders' ownership of shares of our common stock, the holders of warrants do not have the rights or privileges of the holders of our common stock, including any voting rights, until such warrant holders exercise their warrants.

*Fundamental Transaction*. In the event of a fundamental transaction, as described in the common warrants and generally including any reorganization, recapitalization or reclassification of our common stock, the sale, transfer or other disposition of all or substantially all of our properties or assets, our consolidation or merger with or into another person, the acquisition of more than 50% of our outstanding common stock, or any person or group becoming the beneficial owner of 50% of the voting power represented by our outstanding common stock, the holders of the warrants will be entitled to receive, upon exercise of the warrants, the kind and amount of securities, cash or other property that such holders would have received had they exercised the warrants immediately prior to such fundamental transaction, without regard to any limitations on exercise contained in the warrants. In the event of a change of control that is approved by the Company's board of directors, the holders of the warrants shall be entitled to receive from the Company or any successor entity, as of the date of consummation of the change of control the same type or form of consideration (and in the same proportion), at the Black Scholes Value of the unexercised portion of the common warrant, that is being offered and paid to the holders of common stock of the Company in connection with the change of control, whether that consideration be in the form of cash, stock, or any combination thereof, or whether the holders of common stock are given the choice to receive from among alternative forms of consideration in connection with the change of control.

**Preferred stock**

Under our amended and restated certificate of incorporation, our board of directors has the authority, without further action by our stockholders, to issue up to 5,000,000 shares of preferred stock in one or more series and to fix the rights, preferences, privileges and restrictions thereof. These rights, preferences and privileges could include dividend rights, conversion rights, voting rights, terms of redemption, liquidation preferences, sinking fund terms and the number of shares constituting any series or the designation of such series, any or all of which may be greater than the rights of common stock. The issuance of our preferred stock could adversely affect the voting power of holders of common stock and the likelihood that such holders will receive dividend payments and payments upon liquidation. In addition, the issuance of preferred stock could have the effect of delaying, deferring or preventing a change of control of our company or other corporate action.

The following summary of terms of our preferred stock is not complete. You should refer to the provisions of our amended and restated certificate of incorporation and amended and restated bylaws and the resolutions containing the terms of each class or series of the preferred stock which have been or will be filed with the SEC at or prior to the time of issuance of such class or series of preferred stock and described in the applicable prospectus supplement. The applicable prospectus supplement may also state that any of the terms set forth herein are inapplicable to such series of preferred stock, provided that the information set forth in such prospectus supplement does not constitute material changes to the information herein such that it alters the nature of the offering or the securities offered.

Our board of directors will fix the designations, voting powers, preferences and rights of the preferred stock of each series we issue under this prospectus, as well as the qualifications, limitations or restrictions thereof, in the certificate of designation relating to that series. We will file as an exhibit to the registration statement of which this prospectus is a part, or will incorporate by reference from reports that we file with the SEC, the form of any certificate of designation that describes the terms of the series of preferred stock we are offering. We will describe in the applicable prospectus supplement the terms of the series of preferred stock being offered, including, to the extent applicable:

● the title and stated value;

● the number of shares we are offering;

● the liquidation preference per share;

● the purchase price;

● the dividend rate, period and payment date and method of calculation for dividends;

● whether dividends will be cumulative or non-cumulative and, if cumulative, the date from which dividends will accumulate;

● the procedures for any auction and remarketing;

● the provisions for a sinking fund;

● the provisions for redemption or repurchase and any restrictions on our ability to exercise those redemption and repurchase rights;

● any listing of the preferred stock on any securities exchange or market;

● whether the preferred stock will be convertible into our common stock or other securities, and the conversion rate or conversion price, or how they will be calculated, and the conversion period;

● whether the preferred stock will be exchangeable into debt securities, and the exchange rate or exchange price, or how they will be calculated, and the exchange period;

● voting rights of the preferred stock;

● preemptive rights;

● restrictions on transfer, sale or other assignment;

● whether interests in the preferred stock will be represented by depositary shares;

● a discussion of material or special U.S. federal income tax considerations applicable to the preferred stock;

● the relative ranking and preferences of the preferred stock as to dividend rights and rights if we liquidate, dissolve or wind up our affairs;

● any limitations on the issuance of any class or series of preferred stock ranking senior to or on parity with the series of preferred stock as to dividend

● rights and rights if we liquidate, dissolve or wind up our affairs; and

● any other specific terms, preferences, rights or limitations of, or restrictions on, the preferred stock.

If we issue shares of preferred stock under this prospectus, they will be validly issued, fully paid and non-assessable.

The DGCL provides that the holders of preferred stock will have the right to vote separately as a class on any proposal involving fundamental changes in the rights of holders of such preferred stock. This right is in addition to any voting rights that may be provided for in the applicable certificate of designation.

The issuance of our preferred stock could adversely affect the voting power, conversion or other rights of holders of common stock and reduce the likelihood that such holders will receive dividend payments and payments upon liquidation. In addition, the issuance of preferred stock could have the effect of delaying, deferring or preventing a change in control of our company or other corporate action. Additionally, the issuance of preferred stock may have the effect of decreasing the market price of our common stock.

**Possible Anti-Takeover Effects of Delaware Law and Our Certificate of Incorporation and Bylaws**

Provisions of the DGCL and our amended and restated certificate of incorporation and amended and restated bylaws could make it more difficult to acquire our company by means of a tender offer, a proxy contest or otherwise, or to remove incumbent officers and directors. These provisions, summarized below, are expected to discourage certain types of coercive takeover practices and takeover bids that our board of directors may consider inadequate and to encourage persons seeking to acquire control of our company to first negotiate with our board of directors. We believe that the benefits of increased protection of our ability to negotiate with the proponent of an unfriendly or unsolicited proposal to acquire or restructure our company outweigh the disadvantages of discouraging takeover or acquisition proposals because, among other things, negotiation of these proposals could result in an improvement of their terms.

*Classified Board*

Our amended and restated certificate of incorporation and our amended and restated bylaws provide that our board of directors is divided into three classes. The directors designated as Class I directors have terms expiring at the annual meeting of stockholders in 2023. The directors designated as Class II directors will have terms expiring at the annual meeting of stockholders in 2024, and the directors designated as Class III directors will have terms expiring at the annual meeting of stockholders in 2025. Directors for each class will be elected at the annual meeting of stockholders held in the year in which the term for that class expires and thereafter will serve for a term of three years. At any meeting of stockholders for the election of directors at which a quorum is present, the election will be determined by a plurality of the votes cast by the stockholders entitled to vote at the election. Under the classified board provisions, it would take at least two elections of directors for any individual or group to gain control of our board. Accordingly, these provisions could discourage a third party from initiating a proxy contest, making a tender offer or otherwise attempting to gain control of our company.

*Removal of Directors*

Our amended and restated bylaws provide that our stockholders may only remove our directors with cause.

*Amendment*

Our amended and restated certificate of incorporation and our amended and restated bylaws provide that the affirmative vote of the holders of at least 75% of our voting stock then outstanding is required to amend certain provisions relating to the number, term, election and removal of our directors, the filling of our board vacancies, stockholder notice procedures, the calling of special meetings of stockholders and the indemnification of directors. Further, any amendments of our bylaws must be approved by our stockholders as our amended and restated certificate of incorporation does not authorize our board of directors to amend our bylaws.

*Size of Board and Vacancies*

Our amended and restated bylaws provide that the number of directors on our board of directors is fixed exclusively by our board of directors. Newly created directorships resulting from any increase in our authorized number of directors will be filled by a majority of our board of directors then in office, provided that a majority of the entire board of directors, or a quorum, is present and any vacancies in our board of directors resulting from death, resignation, retirement, disqualification, removal from office or other cause will be filled generally by the majority vote of our remaining directors in office, even if less than a quorum is present.

*Special Stockholder Meetings*

Our amended and restated certificate of incorporation provides that only the Chairman of our board of directors, our Chief Executive Officer or our board of directors pursuant to a resolution adopted by a majority of the total number of directors we would have if there were no vacancies may call special meetings of our stockholders.

*Stockholder Action by Unanimous Written Consent*

Our amended and restated certificate of incorporation expressly eliminates the right of our stockholders to act by written consent.

*Requirements for Advance Notification of Stockholder Nominations and Proposals*

Our amended and restated bylaws provide advance notice procedures with respect to stockholder proposals and nomination of candidates for election as directors other than nominations made by or at the direction of board of directors or a committee of our board of directors.

*No Cumulative Voting*

The DGCL provides that stockholders are denied the right to cumulate votes in the election of directors unless our certificate of incorporation provides otherwise. Our amended and restated certificate of incorporation does not provide for cumulative voting.

*Undesignated Preferred Stock*

The authority that is possessed by our board of directors to issue preferred stock could potentially be used to discourage attempts by third parties to obtain control of our company through a merger, tender offer, proxy contest, or otherwise by making it more difficult or costlier to obtain control of our company. Our board of directors may issue preferred stock with voting rights or conversion rights that, if exercised, could adversely affect the voting power of the holders of common stock.

*Authorized but Unissued Shares*

Our authorized but unissued shares of common stock and preferred stock will be available for future issuance without stockholder approval. We may use additional shares for a variety of purposes, including future public offerings to raise additional capital, to fund acquisitions and as employee compensation. The existence of authorized but unissued shares of common stock and preferred stock could render more difficult or discourage an attempt to obtain control of our company by means of a proxy contest, tender offer, merger or otherwise.

The above provisions may deter a hostile takeover or delay a change in control or management of our company.

**Listing on the Nasdaq Capital Market**

Our common stock is listed on the Nasdaq Capital Market under the symbol "SLS". On February 22, 2023, the closing price of our common stock was $3.82 per share. As of February 22, 2023, we had approximately 36 stockholders of record.

**Transfer Agent and Registrar**

The transfer agent and registrar for our capital stock is Computershare Trust Company, N.A. Its address is 250 Royall Street, Canton, MA 02021. Its telephone number is (201) 680-4503.

**UNDERWRITING**

Subject to the terms and conditions set forth in the underwriting agreement, dated February , 2023, between us and Cantor Fitzgerald & Co., 499 Park Avenue, New York, New York 10022, as representative of the underwriters named below (the "Representative") and the sole book-running manager of this offering, we have agreed to sell to the underwriters, and each of the underwriters has agreed, severally and not jointly, to purchase from us, the shares of common stock and accompanying warrants shown opposite its name below:

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| | | |
|:---|:---|:---|
| **Underwriter** | **Number of Shares** | **Number of Warrants** |
| Cantor Fitzgerald & Co. |  |  |
| &nbsp;&nbsp;&nbsp;Total |  |  |

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The underwriting agreement provides that the obligations of the several underwriters are subject to certain conditions precedent such as the receipt by the underwriters of officers' certificates and legal opinions and approval of certain legal matters by their counsel. The underwriting agreement provides that the underwriters will purchase all of the shares of common stock and accompanying warrants if any of them are purchased. We have agreed to indemnify the underwriters and certain of their controlling persons against certain liabilities, including liabilities under the Securities Act, and to contribute to payments that the underwriters may be required to make in respect of those liabilities.

The underwriters are offering the shares of common stock and accompanying warrants subject to their acceptance of the shares of common stock and accompanying warrants from us and subject to prior sale. The underwriters reserve the right to withdraw, cancel or modify offers to the public and to reject orders in whole or in part.

The warrants will be created and issued pursuant to the terms of a warrant (the "Warrant"). The exercise price per whole share purchasable upon the exercise of the warrants is $ per common share, and may be exercised at any time prior to 5:30 p.m. (New York City time), on February , 2028, after which time the warrants will expire and be void and of no value. No fractional common shares will be issued upon the exercise of any warrants. There is no established trading market for the warrants and we do not expect a market to develop. In addition, we do not intend to list the warrants on any national securities exchange or any other nationally recognized trading system. Accordingly, purchasers may not be able to resell the warrants purchased under this prospectus supplement. This may affect the price of the warrants in the secondary market, the transparency and availability of trading prices, the liquidity of the securities and the extent of issuer regulation. See "Risk Factors" on page S-6 of this prospectus supplement.

**Option to Purchase Additional Shares**

We have granted to the underwriters an option, exercisable 30 days from the date of this prospectus supplement, to purchase, from time to time, in whole or in part, (i) up to an aggregate of shares and warrants to purchase up to an aggregate of shares from us at the public offering price set forth on the cover page of this prospectus supplement, less underwriting discounts and commissions. If the underwriters exercise this option, each underwriter will be obligated, subject to certain conditions, to purchase a number of additional shares and accompanying warrants approximately proportionate to that underwriter's initial purchase commitment as indicated in the table above.

**Commission and Expenses**

The underwriters have advised us that they propose to offer the shares of common stock and accompanying warrants to the public at the public offering price set forth on the cover page of this prospectus supplement and to certain dealers, which may include the underwriters, at that price less a concession not in excess of $ per share of common stock and accompanying warrant. The underwriters may allow, and certain dealers may reallow, a discount from the concession not in excess of $ per share of common stock and accompanying warrant to certain brokers and dealers. After the initial offering, the Representative may change the offering price and other selling terms.

The following table shows the public offering price, the underwriting discounts and commissions that we are to pay the underwriters and the proceeds, before expenses, to us in connection with this offering. Such amounts are shown assuming both no exercise and full exercise of the underwriters' option to purchase additional shares and accompanying warrants.

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| | | | | |
|:---|:---|:---|:---|:---|
|  | **Per Share and Accompanying Warrant** | **Per Share and Accompanying Warrant** | **Total** | **Total** |
|  | **Without<br> Option to Purchase<br> Additional Shares and<br> Accompanying Warrants** | **With<br> Option to Purchase<br> Additional Shares and<br> Accompanying Warrants** | **Without<br> Option to Purchase<br> Additional Shares and<br> Accompanying Warrants** | **With<br> Option to Purchase<br> Additional Shares and<br> Accompanying Warrants** |
| Public offering price | $| $| $| $|
| Underwriting discounts and commissions | $| $| $| $|
| Proceeds to us, before expenses | $| $| $| $|

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We estimate expenses payable by us in connection with this offering, other than the underwriting discounts and commissions referred to above, will be approximately $.. We have also agreed to reimburse the underwriters for up to $ of certain of their counsels' fees and expenses, which reimbursed fee is deemed underwriting compensation for this offering by FINRA.

**Listing**

Our common stock is listed on Nasdaq under the trading symbol "SLS." We do not intend to list the warrants on any national securities exchange or any other nationally recognized trading system.

**No Sales of Similar Securities**

We, our officers and our directors have agreed, subject to certain specified exceptions, not to directly or indirectly, for a period of 60 days after the date of the underwriting agreement:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;· sell, offer, contract or grant any option to sell (including any short sale), pledge, transfer, establish an open "put equivalent
position" within the meaning of Rule 16a-l(h) under the Securities Exchange Act of 1934, as amended, or otherwise dispose of, any
shares of common stock, options or warrants to acquire shares of common stock, or securities exchangeable or exercisable for or convertible
into shares of common stock currently or hereafter owned either of record or beneficially,

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;· enter into any swap, hedge or other agreement or transaction that transfers, in whole or in part, the economic consequence of ownership
of common stock, or securities exchangeable or exercisable for or convertible into shares of common stock, or

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;· publicly announce an intention to do any of the foregoing for a period of 60 days after the date of this prospectus supplement without
the prior written consent of Cantor Fitzgerald & Co.

In addition, we and each such person agrees that, without the prior written consent of Cantor Fitzgerald & Co., we or such other person will not, during the restricted period, make any demand for, or exercise any right with respect to, the registration of any shares of common stock or any security convertible into or exercisable or exchangeable for common stock.

The restrictions in the immediately preceding paragraph do not apply in certain circumstances, including transfers by our officers and directors (i) as a bona fide gift or gifts; (ii) to any trust for the direct or indirect benefit of such officer and/or director or the immediate family of such officer and/or director (for purposes of this lock-up agreement, "immediate family" shall mean any relationship by blood, marriage or adoption, not more remote than first cousin); (iii) as a distribution or other transfer by a partnership to its partners or former partners or by a limited liability company to its members or retired members or by a corporation its stockholders or former stockholders or to any wholly-owned subsidiary of such corporation; (iv) to such officer and/or director's affiliates or to any investment fund or other entity controlled or managed by such officer and/or director; (v) pursuant to a qualified domestic order or in connection with a divorce settlement; (vi) or by will or intestate succession to the legal representative, heir, beneficiary or immediate family of such officer and/or director upon the death of such officer and/or director; or (vii) to the Company in satisfaction of any tax withholding obligation, provided that (1) prior to any such transfer, Cantor Fitzgerald & Co. receives a signed lock-up agreement for the balance of the 60-day period from each donee, trustee, distributee or transferee, as the case may be, (2) any such transfer shall not involve a disposition for value, (3) in the case of clauses (i) through (iii), such transfers are not required to be reported with the SEC under the Exchange Act, and (4) such officer and/or director does not otherwise voluntarily effect any public filing or report regarding such transfers.

Cantor Fitzgerald & Co. may, in its sole discretion and at any time or from time to time before the termination of the 60-day period release all or any portion of the securities subject to lock-up agreements.

**Market Making, Stabilization and Other Transactions**

The underwriters may make a market in the common stock as permitted by applicable laws and regulations. However, the underwriters are not obligated to do so, and the underwriters may discontinue any market-making activities at any time without notice in their sole discretion. Accordingly, no assurance can be given as to the liquidity of the trading market for the common stock, that you will be able to sell any of the common stock held by you at a particular time or that the prices that you receive when you sell will be favorable.

The underwriters have advised us that they, pursuant to Regulation M under the Securities Exchange Act of 1934, as amended, and certain persons participating in the offering, may engage in short sale transactions, stabilizing transactions, syndicate covering transactions or the imposition of penalty bids in connection with this offering. These activities may have the effect of stabilizing or maintaining the market price of the common stock at a level above that which might otherwise prevail in the open market. Establishing short sales positions may involve either "covered" short sales or "naked" short sales.

"Covered" short sales are sales made in an amount not greater than the underwriters' option to purchase additional shares of our common stock in this offering. The underwriters may close out any covered short position by either exercising their option to purchase additional shares of our common stock and/or accompanying warrants or purchasing shares of our common stock in the open market. In determining the source of shares to close out the covered short position, the underwriters will consider, among other things, the price of shares available for purchase in the open market as compared to the price at which they may purchase shares through the option to purchase additional shares or warrants.

"Naked" short sales are sales in excess of the option to purchase additional shares of our common stock. The underwriters must close out any naked short position by purchasing shares in the open market. A naked short position is more likely to be created if the underwriters are concerned that there may be downward pressure on the price of the shares of our common stock in the open market after pricing that could adversely affect investors who purchase in this offering.

A stabilizing bid is a bid for the purchase of shares of common stock on behalf of the underwriters for the purpose of fixing or maintaining the price of the common stock. A syndicate covering transaction is the bid for or the purchase of shares of common stock on behalf of the underwriters to reduce a short position incurred by the underwriters in connection with the offering. Similar to other purchase transactions, the underwriters' purchases to cover the syndicate short sales may have the effect of raising or maintaining the market price of our common stock or preventing or retarding a decline in the market price of our common stock. As a result, the price of our common stock may be higher than the price that might otherwise exist in the open market. A penalty bid is an arrangement permitting the underwriters to reclaim the selling concession otherwise accruing to a syndicate member in connection with the offering if the common stock originally sold by such syndicate member are purchased in a syndicate covering transaction and therefore have not been effectively placed by such syndicate member.

Neither we, nor any of the underwriters make any representation or prediction as to the direction or magnitude of any effect that the transactions described above may have on the price of our common stock. The underwriters are not obligated to engage in these activities and, if commenced, may end any of these activities at any time.

**Passive Market Making**

The underwriters may also engage in passive market making transactions in our common stock on the NASDAQ in accordance with Rule 103 of Regulation M during a period before the commencement of offers or sales of shares of our common stock in this offering and extending through the completion of distribution. A passive market maker must display its bid at a price not in excess of the highest independent bid of that security. However, if all independent bids are lowered below the passive market maker's bid, that bid must then be lowered when specified purchase limits are exceeded. Passive market making may cause the price of our common stock to be higher than the price that otherwise would exist in the open market in the absence of those transactions. The underwriters are not required to engage in passive market making and, if commenced, may end passive market making activities at any time.

**Electronic Distribution**

A prospectus in electronic format may be made available by e-mail or on the web sites or through online services maintained by one or more of the underwriters, selling group members (if any) or their affiliates. The underwriters may agree with us to allocate a specific number of shares of common stock for sale to online brokerage account holders. Any such allocation for online distributions will be made by the underwriters on the same basis as other allocations. Other than the prospectus in electronic format, the information on the underwriters' web sites and any information contained in any other web site maintained by any of the underwriters is not part of this prospectus supplement, has not been approved and/or endorsed by us or the underwriters and should not be relied upon by investors.

**Other Activities and Relationships** 

The underwriters and certain of their respective affiliates are full service financial institutions engaged in a wide range of activities for their own accounts and the accounts of customers, which may include, among other things, corporate finance, mergers and acquisitions, merchant banking, equity and fixed income sales, trading and research, derivatives, foreign exchange, futures, asset management, custody, clearance and securities lending. The underwriters and certain of their affiliates have, from time to time, performed, and may in the future perform, various investment banking and financial advisory services for us and our affiliates, for which they received or will receive customary fees and expenses.

In addition, in the ordinary course of its business, the underwriters and their respective affiliates may, directly or indirectly, hold long or short positions, trade and otherwise conduct such activities in or with respect to debt or equity securities and/or bank debt of, and/or derivative products. Such investment and securities activities may involve our securities and instruments. The underwriters and their respective affiliates may also make investment recommendations or publish or express independent research views in respect of such securities or instruments and may at any time hold, or recommend to clients that they acquire, long or short positions in such securities and instruments.

Cantor Fitzgerald & Co. acts as our sales agent under the Controlled Equity Offering<sup>SM</sup> Sales Agreement dated April 16, 2021. between us and Cantor.

**Stamp Taxes**

If you purchase shares of common stock offered in this prospectus supplement, you may be required to pay stamp taxes and other charges under the laws and practices of the country of purchase, in addition to the offering price listed on the cover page of this prospectus supplement.

**NOTICE TO INVESTORS**

**Canada**

This prospectus supplement constitutes an "exempt offering document" as defined in and for the purposes of applicable Canadian securities laws. No prospectus has been filed with any securities commission or similar regulatory authority in Canada in connection with the offer and sale of the securities. No securities commission or similar regulatory authority in Canada has reviewed or in any way passed upon this prospectus supplement or on the merits of the securities and any representation to the contrary is an offence.

**Canadian investors are advised that this prospectus supplement has been prepared in reliance on section 3A.3 of National Instrument 33-105 *Underwriting Conflicts* ("NI 33-105"). Pursuant to section 3A.3 of NI 33-105, this prospectus supplement is exempt from the requirement that the issuer and the underwriter(s) provide investors with certain conflicts of interest disclosure pertaining to "connected issuer" and/or "related issuer" relationships that may exist between the issuer and the underwriter(s) as would otherwise be required pursuant to subsection 2.1(1) of NI 33-105.**

*Resale Restrictions*

The offer and sale of the securities in Canada is being made on a private placement basis only and is exempt from the requirement that the issuer prepares and files a prospectus under applicable Canadian securities laws. Any resale of the securities acquired by a Canadian investor in this offering must be made in accordance with applicable Canadian securities laws, which may vary depending on the relevant jurisdiction, and which may require resales to be made in accordance with Canadian prospectus requirements, pursuant to a statutory exemption from the prospectus requirements, in a transaction exempt from the prospectus requirements or otherwise under a discretionary exemption from the prospectus requirements granted by the applicable local Canadian securities regulatory authority. These resale restrictions may under certain circumstances apply to resales of the securities outside of Canada.

 

*Representations of Purchasers*

Each Canadian investor who purchases the securities will be deemed to have represented to the issuer and the underwriter(s) that the investor (i) is purchasing the securities as principal, or is deemed to be purchasing as principal in accordance with applicable Canadian securities laws, for investment only and not with a view to resale or redistribution; (ii) is an "accredited investor" as such term is defined in section 1.1 of National Instrument 45-106 *Prospectus Exemptions* ("NI 45-106") or, in Ontario, as such term is defined in section 73.3(1) of the *Securities Act* (Ontario); and (iii) is a "permitted client" as such term is defined in section 1.1 of National Instrument 31-103 *Registration Requirements, Exemptions and Ongoing Registrant Obligations*.

 

*Taxation and Eligibility for Investment*

Any discussion of taxation and related matters contained in this prospectus supplement does not purport to be a comprehensive description of all of the tax considerations that may be relevant to a Canadian investor when deciding to purchase the securities and, in particular, does not address any Canadian tax considerations. No representation or warranty is hereby made as to the tax consequences to a resident, or deemed resident, of Canada of an investment in the securities or with respect to the eligibility of the securities for investment by such investor under relevant Canadian federal and provincial legislation and regulations.

*Rights of Action for Damages or Rescission*

Securities legislation in certain of the Canadian jurisdictions provides certain purchasers of securities pursuant to an offering memorandum (such as this prospectus supplement), including where the distribution involves an "eligible foreign security" as such term is defined in Ontario Securities Commission Rule 45-501 *Ontario Prospectus and Registration Exemptions* and in Multilateral Instrument 45-107 *Listing Representation and Statutory Rights of Action Disclosure Exemptions*, as applicable, with a remedy for damages or rescission, or both, in addition to any other rights they may have at law, where the offering memorandum, or other offering document that constitutes an offering memorandum, and any amendment thereto, contains a "misrepresentation" as defined under applicable Canadian securities laws. These remedies, or notice with respect to these remedies, must be exercised or delivered, as the case may be, by the purchaser within the time limits prescribed under, and are subject to limitations and defences under, applicable Canadian securities legislation. In addition, these remedies are in addition to and without derogation from any other right or remedy available at law to the investor.

*Language of Documents*

Upon receipt of this document, each Canadian investor hereby confirms that it has expressly requested that all documents evidencing or relating in any way to the sale of the securities described herein (including for greater certainty any purchase confirmation or any notice) be drawn up in the English language only. *Par la réception de ce document, chaque investisseur Canadien confirme par les présentes qu'il a expressément exigé que tous les documents faisant foi ou se rapportant de quelque manière que ce soit à la vente des valeurs mobilières décrites aux présentes (incluant, pour plus de certitude, toute confirmation d'achat ou tout avis) soient rédigés en anglais seulement.*

**Australia**

This document does not constitute a prospectus, product disclosure statement or other disclosure document under the Australia's Corporations Act 2001 (Cth) (the "Corporations Act") of Australia. This document has not been lodged with the Australian Securities & Investments Commission and is only directed to the categories of exempt persons set out below. Accordingly, if you receive this document in Australia:

You confirm and warrant that you are either:

&nbsp;&nbsp;&nbsp;&nbsp;· a "sophisticated investor" under section 708(8)(a) or (b) of the Corporations Act;

&nbsp;&nbsp;&nbsp;&nbsp;· a "sophisticated investor" under section 708(8)(c) or (d) of the Corporations Act and that you have provided an accountant's
certificate to the company which complies with the requirements of section 708(8)(c)(i) or (ii) of the Corporations Act and related regulations
before the offer has been made; or

&nbsp;&nbsp;&nbsp;&nbsp;· a "professional investor" within the meaning of section 708(11)(a) or (b) of the Corporations Act.

To the extent that you are unable to confirm or warrant that you are an exempt sophisticated investor or professional investor under the Corporations Act any offer made to you under this document is void and incapable of acceptance.

You warrant and agree that you will not offer any of the shares issued to you pursuant to this document for resale in Australia within 12 months of those securities being issued unless any such resale offer is exempt from the requirement to issue a disclosure document under section 708 of the Corporations Act.

**European Economic Area**

In relation to each member state of the European Economic Area (each a "Member State"), no securities have been offered or will be offered pursuant to the offer described herein in that Member State prior to the publication of a prospectus in relation to the securities which has been approved by the competent authority in that Member State or, where appropriate, approved in another Member State and notified to the competent authority in that Member State, all in accordance with the Prospectus Regulation, except that the securities may be offered to the public in that Member State at any time:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(i) to any legal entity which is a qualified investor as defined under Article 2 of the Prospectus Regulation;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(ii) to fewer than 150 natural or legal persons (other than qualified investors as defined under Article 2 of the Prospectus Regulation), subject to obtaining the prior consent of the underwriters for any such offer; or

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(iii) in any other circumstances falling within Article 1(4) of the Prospectus Regulation,

provided that no such offer of securities shall require the issuer or any underwriter to publish a prospectus pursuant to Article 3 of the Prospectus Regulation or supplement a prospectus pursuant to Article 23 of the Prospectus Regulation.

Each person in a Member State who acquires any securities in the offer or to whom any offer is made will be deemed to have represented, acknowledged and agreed to and with the issuer and the underwriters that it is a qualified investor within the meaning of the Prospectus Regulation.

In the case of any securities being offered to a financial intermediary as that term is used in Article 5(1) of the Prospectus Regulation, each such financial intermediary will be deemed to have represented, acknowledged and agreed to and with the issuer and the underwriters that the securities acquired by it in the offer have not been acquired on a non-discretionary basis on behalf of, nor have they been acquired with a view to their offer or resale to, persons in circumstances which may give rise to an offer to the public other than their offer or resale in a Member State to qualified investors, in circumstances in which the prior consent of the underwriters has been obtained to each such proposed offer or resale. Neither the issuer nor the underwriters have authorised, nor do they authorise, the making of any offer of securities through any financial intermediary, other than offers made by the underwriters which constitute the final placement of securities contemplated in this document.

The issuer and the underwriters and their affiliates will rely upon the truth and accuracy of the foregoing representations, acknowledgements and agreements.

For the purposes of this provision, the expression an "offer to the public" in relation to any securities in any Member State means the communication in any form and by any means of sufficient information on the terms of the offer and any securities to be offered so as to enable an investor to decide to purchase, or subscribe for, any securities and the expression "Prospectus Regulation" means Regulation (EU) 2017/1129.

In Member States, this document is being distributed only to, and is directed only at, persons who are "qualified investors" within the meaning of Article 2(e) of the Prospectus Regulation ("Qualified Investors"). This document must not be acted on or relied on in any Member State by persons who are not Qualified Investors. Any investment or investment activity to which this document relates is available in any Member State only to Qualified Investors and will be engaged in only with such persons.

**Hong Kong**

No securities have been, may be or will be offered or sold in Hong Kong, by means of any document, other than to persons whose ordinary business is to buy or sell shares or debentures, whether as principal or agent; or to "professional investors" as defined in the Securities and Futures Ordinance (Cap. 571) of Hong Kong (the "SFO") and any rules made thereunder; or in other circumstances which do not result in the document being a "prospectus" as defined in the Companies (Winding UP and Miscellaneous Provisions) Ordinance (Cap. 32) of Hong Kong (the "C(WUMP)O"), or which do not constitute an offer to the public within the meaning of the C(WUMP)O. No document, invitation or advertisement relating to the securities has been issued or may be issued or will be issued or may be in the possession of any person for the purpose of issue (in each case whether in Hong Kong or elsewhere), which is directed at, or the contents of which are likely to be accessed or read by, the public of Hong Kong (except if permitted under the securities laws of Hong Kong) other than with respect to securities which are or are intended to be disposed of only to persons outside Hong Kong or only to "professional investors" as defined in the SFO and any rules made thereunder.

This document has not been and will not be registered with the Registrar of Companies in Hong Kong. Accordingly, this document may not be issued, circulated or distributed in Hong Kong, and the securities may not be offered for subscription to members of the public in Hong Kong. Each person acquiring the securities will be required, and is deemed by the acquisition of the securities, to confirm that he is aware of the restriction on offers of the securities described in this document and the relevant offering documents and that he is not acquiring, and has not been offered any securities in circumstances that contravene any such restrictions.

**Japan**

The offering has not been and will not be registered under the Financial Instruments and Exchange Act of Japan (Act No. 25 of 1948 of Japan, as amended) (the "FIEA"), and the Initial Purchaser will not offer or sell any securities, directly or indirectly, in Japan or to, or for the benefit of, any resident of Japan (which term as used herein means, unless otherwise provided herein, any person resident in Japan, including any corporation or other entity organized under the laws of Japan), or to others for re-offering or resale, directly or indirectly, in Japan or to a resident of Japan, except pursuant to an exemption from the registration requirements of, and otherwise in compliance with, the FIEA and any other applicable laws, regulations and ministerial guidelines of Japan.

**Singapore**

This document has not been and will not be lodged or registered with the Monetary Authority of Singapore. Accordingly, this document and any other document or material in connection with the offer or sale, or the invitation for subscription or purchase of the securities may not be issued, circulated or distributed, nor may the securities be offered or sold, or be made the subject of an invitation for subscription or purchase, whether directly or indirectly, to any person in Singapore other than (i) to an institutional investor under Section 274 of the Securities and Futures Act, Chapter 289 of Singapore (the "SFA"), (ii) to a relevant person as defined under Section 275(2) of the SFA, or any person pursuant to Section 275(1A) of the SFA, and in accordance with the conditions, specified in Section 275 of the SFA and where (where applicable) Regulation 3 of the Securities and Futures (Classes of Investors) Regulations 2018, or (iii) otherwise pursuant to, and in accordance with the conditions of any other applicable provision of the SFA. **In the event that you are not an investor falling within any of the categories set out above, please return this document immediately. You may not forward or circulate this document to any other person in Singapore.**

No offer is made to you with a view to the securities being subsequently offered for sale to any other party. There are on-sale restrictions that may be applicable to investors who acquire securities. As such, investors are advised to acquaint themselves with the provisions of the SFA relating to resale restrictions and comply accordingly.

Where the securities are subscribed or purchased under Section 275 of the SFA by a relevant person which is:

&nbsp;&nbsp;&nbsp;&nbsp;· a corporation (which is not an accredited investor as defined under Section 4A of the SFA) the sole business of which is to hold investments
and the entire share capital of which is owned by one or more individuals, each of whom is an accredited investor; or

&nbsp;&nbsp;&nbsp;&nbsp;· a trust (where the trustee is not an accredited investor) whose sole purpose is to hold investments and each beneficiary is an accredited
investor,

securities or securities-based derivatives contracts (each term as defined in Section 2(1) of the SFA) of that corporation or the beneficiaries' rights and interest (howsoever described) in that trust shall not be transferable within six months after that corporation or that trust has acquired the securities under Section 275 of the SFA except:

&nbsp;&nbsp;&nbsp;&nbsp;· to an institutional investor under Section 274 of the SFA or to a relevant person defined in Section 275(2) of the SFA, or to any
person pursuant to an offer referred to in Section 275(1A) or Section 276(4)(i)(B) of the SFA;

&nbsp;&nbsp;&nbsp;&nbsp;· where no consideration is given for the transfer;

&nbsp;&nbsp;&nbsp;&nbsp;· where the transfer is by operation of law;

&nbsp;&nbsp;&nbsp;&nbsp;· as specified in Section 276(7) of the SFA; or

&nbsp;&nbsp;&nbsp;&nbsp;· as specified in Regulation 37A of the Securities and Futures (Offers of Investments) (Securities and Securities-based Derivatives
Contracts) Regulations 2018 of Singapore.

**Switzerland**

The securities may not be publicly offered in Switzerland and will not be listed on the SIX Swiss Exchange, or SIX, or on any other stock exchange or regulated trading facility in Switzerland. This document has been prepared without regard to the disclosure standards for issuance prospectuses under art. 652a or art. 1156 of the Swiss Code of Obligations or the disclosure standards for listing prospectuses under art. 27 ff. of the SIX Listing Rules or the listing rules of any other stock exchange or regulated trading facility in Switzerland. Neither this document nor any other offering or marketing material relating to the securities or the offering may be publicly distributed or otherwise made publicly available in Switzerland.

Neither this document nor any other offering or marketing material relating to the offering, the issuer or the securities have been or will be filed with or approved by any Swiss regulatory authority. In particular, this document will not be filed with, and the offer of securities will not be supervised by, the Swiss Financial Market Supervisory Authority FINMA, or FINMA, and the offer of securities has not been and will not be authorized under the Swiss Federal Act on Collective Investment Schemes, or CISA. The investor protection afforded to acquirers of interests in collective investment schemes under the CISA does not extend to acquirers of securities.

**Israel**

This document does not constitute a prospectus under the Israeli Securities Law, 5728-1968, or the Securities Law, and has not been filed with or approved by the Israel Securities Authority. In the State of Israel, this document is being distributed only to, and is directed only at, and any offer of the shares is directed only at, investors listed in the first addendum, or the Addendum, to the Israeli Securities Law, consisting primarily of joint investment in trust funds, provident funds, insurance companies, banks, portfolio managers, investment advisors, members of the Tel Aviv Stock Exchange, underwriters, venture capital funds, entities with equity in excess of NIS 50 million and "qualified individuals", each as defined in the Addendum (as it may be amended from time to time), collectively referred to as qualified investors (in each case purchasing for their own account or, where permitted under the Addendum, for the accounts of their clients who are investors listed in the Addendum). Qualified investors will be required to submit written confirmation that they fall within the scope of the Addendum, are aware of the meaning of same and agree to it.

**United Kingdom**

In relation to the United Kingdom, no securities have been offered or will be offered pursuant to the offer described herein to the public in the United Kingdom prior to the publication of a prospectus in relation to the securities which has been approved by the UK Financial Conduct Authority, except that the securities may be offered to the public in the United Kingdom at any time:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(i) to any legal entity which is a qualified investor as defined under Article 2 of the UK Prospectus Regulation;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(ii) to fewer than 150 natural or legal persons (other than qualified investors as defined under Article 2 of the UK Prospectus Regulation), subject to obtaining the prior consent of the underwriters for any such offer; or

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(iii) in any other circumstances falling within Section 86 of the Financial Services and Markets Act 2000 (as amended) (the "FSMA"),

provided that no such offer of the securities shall require the issuer or any underwriter to publish a prospectus pursuant to Section 85 of the FSMA or supplement a prospectus pursuant to Article 23 of the UK Prospectus Regulation.

Each person in the United Kingdom who acquires any securities in the offer or to whom any offer is made will be deemed to have represented, acknowledged and agreed to and with the issuer and the underwriters that it is a qualified investor within the meaning of the UK Prospectus Regulation.

In the case of any securities being offered to a financial intermediary as that term is used in Article 5(1) of the UK Prospectus Regulation, each such financial intermediary will be deemed to have represented, acknowledged and agreed to and with the issuer and the underwriters that the securities acquired by it in the offer have not been acquired on a non-discretionary basis on behalf of, nor have they been acquired with a view to their offer or resale to, persons in circumstances which may give rise to an offer to the public other than their offer or resale in the United Kingdom to qualified investors, in circumstances in which the prior consent of the underwriters has been obtained to each such proposed offer or resale. Neither the issuer nor the underwriters have authorised, nor do they authorise, the making of any offer of securities through any financial intermediary, other than offers made by the underwriters which constitute the final placement of securities contemplated in this document.

The issuer and the underwriters and their affiliates will rely upon the truth and accuracy of the foregoing representations, acknowledgements and agreements.

For the purposes of this provision, the expression an "offer to the public" in relation to the securities in the United Kingdom means the communication in any form and by any means of sufficient information on the terms of the offer and any securities to be offered so as to enable an investor to decide to purchase or subscribe for any securities and the expression "UK Prospectus Regulation" means Regulation (EU) 2017/1129 as it forms part of United Kingdom law by virtue of the European Union (Withdrawal) Act 2018.

In the United Kingdom, this document is being distributed only to, and is directed only at, persons who are "qualified investors" within the meaning of Article 2(e) of the UK Prospectus Regulation who are also: (i) persons who fall within the definition of "investment professionals" in Article 19(5) of the Financial Services and Markets Act 2000 (Financial Promotion) Order 2005, as amended (the "Order"); (ii) persons falling within Article 49(2) of the Order; or (iii) persons to whom it may otherwise lawfully be communicated (all such persons together being referred to as "relevant persons"). This document must not be acted on or relied on in the United Kingdom by persons who are not relevant persons. Any investment or investment activity to which this document relates is available in the United Kingdom only to relevant persons and will be engaged in only with such persons.

Any invitation or inducement to engage in investment activity (within the meaning of Section 21 of the FSMA) may only be communicated or caused to be communicated in connection with the issue or sale of the securities in circumstances in which Section 21(1) of the FSMA does not apply. All applicable provisions of the FSMA and the Order must be complied with in respect of anything done by any person in relation to the securities in, from or otherwise involving the United Kingdom.

**LEGAL MATTERS**

Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C., New York, New York, which has acted as our counsel in connection with this offering, will pass upon the validity of the securities offered hereby. Duane Morris LLP, New York, New York, is counsel to the underwriters in connection with this offering.

**EXPERTS**

The consolidated financial statements incorporated in this Prospectus Supplement to the Registration Statement on Form S-3 by reference from SELLAS Life Sciences Group, Inc.'s Annual Report on Form 10-K for the year ended December 31, 2021 have been audited by Moss Adams LLP, an independent registered public accounting firm, as stated in their report (which report expresses an unqualified opinion and includes an explanatory paragraph related to a going concern uncertainty), which is incorporated herein by reference. Such consolidated financial statements have been so incorporated in reliance upon the report of such firm given upon their authority as experts in accounting and auditing.

**WHERE YOU CAN FIND MORE INFORMATION**

This prospectus supplement and the accompanying prospectus are part of a registration statement on Form S-3 we filed with the SEC under the Securities Act and do not contain all of the information set forth in the registration statement and the exhibits thereto. Whenever a reference is made in this prospectus supplement or the accompanying prospectus to any of our contracts, agreements or other documents, the reference may not be complete and you should refer to the exhibits that are a part of the registration statement or the exhibits to the reports or other documents incorporated by reference therein. For further information with respect to us and the common stock we are offering under this prospectus supplement, we refer you to the registration statement and the exhibits and schedules filed as a part of the registration statement.

We file annual, quarterly and current reports, proxy statements and other information with the SEC. The SEC maintains a website that contains reports, proxy statements and other information regarding issuers that file electronically with the SEC, including us. The address of the SEC website is www.sec.gov.

Copies of certain information filed by us with the SEC are also available on our website at www.sellaslifesciences.com. Information contained in or accessible through our website does not constitute a part of this prospectus supplement or the accompanying prospectus and is not incorporated by reference into this prospectus supplement or the accompanying prospectus.

**INCORPORATION OF CERTAIN INFORMATION BY REFERENCE**

The SEC allows us to "incorporate by reference" information from other documents that we file with it, which means that we can disclose important information to you by referring you to those documents instead of having to repeat the information in this prospectus supplement or the accompanying prospectus. The information incorporated by reference is considered to be part of this prospectus supplement and the accompanying prospectus, and later information that we file with the SEC will automatically update and supersede this information. We incorporate by reference the documents listed below and any future filings made by us with the SEC (other than Current Reports or portions thereof furnished under Item 2.02 or Item 7.01 of Form 8-K and exhibits filed on such form that are related to such items and other portions of documents that are furnished, but not filed, pursuant to applicable rules promulgated by the SEC) that are filed by us with the SEC pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act after the filing and concurrent effectiveness of the registration statement but prior to the termination of all offerings covered by this prospectus supplement:

&nbsp;&nbsp;&nbsp;&nbsp;· [our Annual Report on Form 10-K for the fiscal year ended December 31, 2021, filed with the SEC on March 31, 2022](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001390478/000139047822000006/sls-20211231.htm) ;

&nbsp;&nbsp;&nbsp;&nbsp;· [the portions of our definitive proxy statement on Schedule 14A, as filed with the SEC on April 25, 2022 that are deemed "filed" with the SEC under the Exchange Act;](https://www.sec.gov/Archives/edgar/data/1390478/000110465922049655/tm223704-1_def14a.htm)

&nbsp;&nbsp;&nbsp;&nbsp;· our Quarterly Reports on Form 10-Q for the quarters ended [March 31, 2022, filed with the SEC on May 12, 2022](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001390478/000139047822000012/sls-20220331.htm) , [June 30, 2022, filed with the SEC on August 11, 2022](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001390478/000139047822000020/sls-20220630.htm) , and [September 30, 2022, filed with the SEC on November 14, 2022](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001390478/000139047822000028/sls-20220930.htm) ;

&nbsp;&nbsp;&nbsp;&nbsp;· our Current Reports on Form 8-K filed with the SEC on [March 31, 2022](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001390478/000110465922041033/tm2210758d1_8k.htm) , [April 1, 2022](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001390478/000110465922041807/tm2211208d1_8k.htm) , [June 9, 2022](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001390478/000139047822000016/sls-20220608.htm) , [August 16, 2022](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001390478/000110465922091744/tm2223534d1_8k.htm) , [November 14, 2022](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001390478/000139047822000030/sls-20221114.htm) , [December 13, 2022](http://www.sec.gov/ix?doc=/Archives/edgar/data/1390478/000110465922126475/tm2232491d1_8k.htm) , [February 6, 2023](http://www.sec.gov/ix?doc=/Archives/edgar/data/1390478/000110465923011193/tm235617d1_8k.htm) and February 23, 2023 (except for any information furnished under Items 2.02 or 7.01 and exhibits furnished thereto);
 and

&nbsp;&nbsp;&nbsp;&nbsp;· [the description of our common stock set forth in our registration statement on Form 8-A, filed with the SEC on February 8, 2008,](https://www.sec.gov/Archives/edgar/data/1390478/000095013508000652/b684708ae8va12b.htm) as amended on [February 12, 2008,](https://www.sec.gov/Archives/edgar/data/1390478/000095013508000827/b68470aae8va12bza.htm) including any further amendments thereto or reports filed for the purposes of updating this description.

Any statement contained in a document incorporated by reference herein shall be deemed to be modified or superseded for all purposes to the extent that a statement contained in this prospectus or in any other subsequently filed document which is also incorporated or deemed to be incorporated by reference, modifies or supersedes such statement. Any statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this prospectus. You may request a copy of these filings (other than an exhibit to a filing unless that exhibit is specifically incorporated by reference into that filing) at no cost by writing, telephoning or e-mailing us at the following address or telephone number:

SELLAS Life Sciences Group, Inc.,

Attention: Corporate Secretary

7 Times Square

Suite 2503

New York, New York 10036

(646) 200-5278

You may also access these documents, free of charge on the SEC's website at www.sec.gov or on our website at www.sellaslifesciences.com. Information contained on our website is not incorporated by reference into this prospectus, and you should not consider any information on, or that can be accessed from, our website as part of this prospectus or any accompanying prospectus supplement.

**PROSPECTUS**

![](tm237388d1_424b5img002.jpg)

**$150,000,000**

**Common Stock**

**Preferred Stock**

**Debt Securities**

**Warrants**

**Rights**

**Units**

From time to time, we may offer and sell up to an aggregate amount of $150,000,000 of any combination of the securities described in this prospectus in one or more offerings. We may also offer such securities as may be issuable upon conversion, redemption, repurchase, exchange or exercise of any securities registered hereunder, including any applicable anti-dilution provisions.

This prospectus provides a general description of the securities we may offer. Each time we sell securities pursuant to this prospectus, we will provide the specific terms of these offerings in one or more supplements to this prospectus. We may also authorize one or more free writing prospectuses to be provided to you in connection with these offerings. The prospectus supplement and any related free writing prospectus may also add, update or change information contained in this prospectus. You should carefully read this prospectus, the applicable prospectus supplement and any related free writing prospectus, as well as any documents incorporated by reference, before buying any of the securities being offered.

**This prospectus may not be used to consummate a sale of securities unless it is accompanied by the applicable prospectus supplement.**

Our common stock is traded on the Nasdaq Capital Market under the symbol "SLS." On April 15, 2021, the closing price of our common stock, as reported on the Nasdaq Capital Market, was $7.89 per share. The applicable prospectus supplement will contain information, where applicable, as to any other listings on the Nasdaq Capital Market or any securities market or other exchange of the securities, if any, covered by the prospectus supplement.

**Investing in our securities involves a high degree of risk. You should review carefully the risks and uncertainties described under the heading "Risk Factors" contained in this prospectus beginning on page 7 and any applicable prospectus supplement and in any free writing prospectuses we have authorized for use in connection with a specific offering, and under similar headings in the other documents that are incorporated by reference into this prospectus.**

The securities may be sold directly by us to investors, through agents designated from time to time or to or through underwriters or dealers, on a continuous or delayed basis. For additional information on the methods of sale, you should refer to the section titled "Plan of Distribution" in this prospectus. If any agents or underwriters are involved in the sale of any securities with respect to which this prospectus is being delivered, the names of such agents or underwriters and any applicable fees, commissions, discounts and over-allotment options will be set forth in a prospectus supplement. The price to the public of such securities and the net proceeds we expect to receive from such sale will also be set forth in a prospectus supplement.

**Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.**

The date of this prospectus is April 29, 2021.

**TABLE OF CONTENTS**

---

| | |
|:---|:---|
| [ABOUT THIS PROSPECTUS](#a_001) | [ii](#a_001) |
| [PROSPECTUS SUMMARY](#a_002) | [1](#a_002) |
| [RISK FACTORS](#a_003) | [7](#a_003) |
| [SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS](#a_004) | [7](#a_004) |
| [USE OF PROCEEDS](#a_005) | [9](#a_005) |
| [DILUTION](#a_006) | [9](#a_006) |
| [DESCRIPTION OF CAPITAL STOCK](#a_007) | [9](#a_007) |
| [DESCRIPTION OF DEBT SECURITIES](#a_008) | [13](#a_008) |
| [DESCRIPTION OF WARRANTS](#a_009) | [19](#a_009) |
| [DESCRIPTION OF RIGHTS](#a_010) | [21](#a_010) |
| [DESCRIPTION OF UNITS](#a_011) | [23](#a_011) |
| [LEGAL OWNERSHIP OF SECURITIES](#a_012) | [24](#a_012) |
| [PLAN OF DISTRIBUTION](#a_013) | [27](#a_013) |
| [LEGAL MATTERS](#a_014) | [29](#a_014) |
| [EXPERTS](#a_015) | [29](#a_015) |
| [WHERE YOU CAN FIND MORE INFORMATION](#a_016) | [29](#a_016) |
| [INCORPORATION BY REFERENCE](#a_017) | [30](#a_017) |

---

i

**ABOUT THIS PROSPECTUS**

This prospectus is part of a registration statement that we filed with the Securities and Exchange Commission, or the SEC, using a "shelf" registration process. Under this shelf registration process, we may, from time to time, offer and sell, either individually or in combination, in one or more offerings, up to a total dollar amount of $150,000,000 of any combination of the securities described in this prospectus. This prospectus provides you with a general description of the securities we may offer.

Each time we offer securities under this prospectus, we will provide a prospectus supplement that will contain more specific information about the terms of that offering. We may also authorize one or more free writing prospectuses to be provided to you that may contain material information relating to these offerings. The prospectus supplement and any related free writing prospectus that we may authorize to be provided to you may also add, update or change any of the information contained in this prospectus or in the documents that we have incorporated by reference into this prospectus. We urge you to carefully read this prospectus, any applicable prospectus supplement and any related free writing prospectuses we have authorized for use in connection with a specific offering, together with the information incorporated herein by reference as described under the heading "Incorporation By Reference," before buying any of the securities being offered.

**This prospectus may not be used to consummate a sale of securities unless it is accompanied by a prospectus supplement.**

You should rely only on the information contained in, or incorporated by reference into, this prospectus and any applicable prospectus supplement, along with the information contained in any free writing prospectuses we have authorized for use in connection with a specific offering. We have not authorized anyone to provide you with information in addition to or different from that contained in this prospectus, any applicable prospectus supplement and any related free writing prospectus. We take no responsibility for, and can provide no assurances as to the reliability of, any information not contained in this prospectus, any applicable prospectus supplement or any related free writing prospectus that we may authorize to be provided to you. This prospectus is an offer to sell only the securities offered hereby, but only under circumstances and in jurisdictions where it is lawful to do so.

You should assume that the information in this prospectus, any applicable prospectus supplement or any related free writing prospectus, is accurate only as of the date on the front of the document and that any information incorporated by reference is accurate only as of the date of the document incorporated by reference, regardless of the time of delivery of this prospectus, any applicable prospectus supplement or any related free writing prospectus, or any sale of a security. Our business, financial condition, results of operations and prospects may have changed since those dates.

To the extent there is a conflict between the information contained in this prospectus, on the one hand, and the information contained in any document incorporated by reference filed with the SEC before the date of this prospectus, on the other hand, you should rely on the information in this prospectus. If any statement in a document incorporated by reference is inconsistent with a statement in another document incorporated by reference having a later date, the statement in the document having the later date modifies or supersedes the earlier statement.

This prospectus contains summaries of certain provisions contained in some of the documents described herein, but reference is made to the actual documents for complete information. All of the summaries are qualified in their entirety by the actual documents. Copies of some of the documents referred to herein have been filed, will be filed or will be incorporated by reference as exhibits to the registration statement of which this prospectus is a part, and you may obtain copies of those documents as described below in the section titled "Where You Can Find More Information."

The names "SELLAS Life Sciences Group, Inc.," "SELLAS," the SELLAS logo, and other trademarks or service marks of SELLAS Life Sciences Group, Inc. appearing in this prospectus are the property of SELLAS Life Sciences Group, Inc. Other trademarks, service marks or trade names appearing in this prospectus are the property of their respective owners. We do not intend the use or display of other companies' trade names, trademarks or service marks to imply a relationship with, or endorsement or sponsorship of or by either, of these other companies.

ii

**PROSPECTUS SUMMARY**

*This summary highlights information contained elsewhere in this prospectus or incorporated by reference in this prospectus. This summary provides an overview of selected information and does not contain all of the information you should consider before investing in our securities. You should read this entire prospectus and the applicable prospectus supplement carefully, especially the sections titled "Risk Factors" and our consolidated financial statements and related notes included elsewhere in this prospectus, the applicable prospectus supplement and the documents incorporated by reference therein before making an investment decision. Except as otherwise indicated or unless the context otherwise requires, references to "company," "we," "us," "our" or "SELLAS," refer to SELLAS Life Sciences Group, Inc. and its consolidated subsidiaries.*

**Overview**

We are a late-stage clinical biopharmaceutical company focused on developing novel cancer immunotherapeutics for a broad range of cancer indications. Our product candidates currently include galinpepimut-S and nelipepimut-S.

 

*Galinpepimut-S, or GPS*

Our lead product candidate, galinpepimut-S, or GPS, is a cancer immunotherapeutic agent licensed from Memorial Sloan Kettering Cancer Center, or MSK, that targets the Wilms tumor 1, or WT1, protein, which is present in 20 or more cancer types. Based on its mechanism of action as a directly immunizing agent, GPS has potential as a monotherapy or in combination with other immunotherapeutic agents to address a broad spectrum of hematologic, or blood, cancers and solid tumor indications.

In January 2020, we commenced in the United States a Phase 3 clinical trial, the REGAL study, for GPS monotherapy in patients with acute myeloid leukemia, or AML, in the maintenance setting after achievement of second complete remission, or CRem2, following successful completion of second-line antileukemic therapy. We expect this study will be used as the basis for submission of a Biologics License Application, or BLA, subject to a statistically significant and clinically meaningful data outcome and agreement with the U.S. Food & Drug Administration, or the FDA. In the second half of 2020, we received approval from each of the French and German regulatory authorities to advance the REGAL study in France and Germany, respectively. We expect approvals from additional European health authorities in early 2021 which will allow us to expand AML patient enrollment for the REGAL study in Europe. We plan to enroll approximately 116 patients at up to approximately 135 clinical sites primarily in the United States and Europe with a planned interim safety and futility analysis after 80 events (deaths) which we anticipate will take place in the first half of 2022, provided that the ongoing COVID-19 pandemic does not significantly adversely impact our projected timeline for enrollment.

In December 2020, we entered into an exclusive license agreement with 3D Medicines Inc., a China-based biopharmaceutical company developing next-generation immuno-oncology drugs, for the development and commercialization of GPS, as well as the Company's next generation heptavalent immunotherapeutic GPS+, which is at preclinical stage, across all therapeutic and diagnostic uses in the Greater China territory (mainland China, Hong Kong, Macau and Taiwan). We have retained sole rights to GPS and GPS+ outside of the Greater China area.

In December 2018, pursuant to a Clinical Trial Collaboration and Supply Agreement, we initiated a Phase 1/2 multi-arm "basket" type clinical study of GPS in combination with Merck & Co., Inc.'s anti-PD-1 therapy, Keytruda® (pembrolizumab). The tumor type currently being studied is ovarian cancer (second or third line). We reported initial data from this study in December 2020 and we expect to report further clinical and immunobiological data by the end of the first half of 2021. We, together with Merck, have determined not to pursue the following indications as part of the basket study: colorectal cancer, triple negative breast cancer, small cell lung cancer, or SCLC, or AML, and we are exploring other additional potential indications to investigate in the study.

In February 2020, a Phase I open-label investigator-sponsored clinical trial of GPS, in combination with Bristol-Myers Squibb's anti-PD-1 therapy, nivolumab (Opdivo®), in patients with malignant pleural mesothelioma, or MPM, who harbor relapsed or refractory disease after having received frontline standard of care multimodality therapy was commenced at MSK. In December 2020, we announced initial data from this study and we expect to report further clinical and immunobiological data by the end of the first half of 2021.

GPS was granted Orphan Drug Product Designations from the FDA, as well as Orphan Medicinal Product Designations from the European Medicines Agency, or EMA, for GPS in AML, MPM, and multiple myeloma, or MM, as well as Fast Track Designation for AML, MPM, and MM from the FDA.

*Nelipepimut-S, or NPS*

Nelipepimut-S, or NPS, is a cancer immunotherapy targeting the human epidermal growth factor receptor 2, or HER2, expressing cancers. Data presented in 2018 from a Phase 2b clinical trial of the combination of trastuzumab (Herceptin®) plus NPS in HER2 low expressing (1+ or 2+ per immunohistochemistry, or IHC) breast cancer patients in the adjuvant setting to prevent recurrences showed a clinically and statistically significant improvement in the disease-free survival, or DFS, rate for the TNBC cohort at 24 months for patients treated with NPS plus trastuzumab of 92.6% compared to 70.2% for those treated with trastuzumab alone. Following discussions with the FDA and based upon written feedback from the FDA and on the totality of clinical, safety and translational NPS data to date, we have finalized the design and plan for a Phase 3 registration-enabling study of NPS in combination with trastuzumab for the treatment of patients with TNBC in the adjuvant setting after standard treatment. If successful, we believe this study may be considered as the basis for a BLA submission to the FDA. We are seeking out-licensing opportunities to fund and conduct the future clinical development of NPS in order to maximize the potential of the program and we do not plan to conduct and fund a Phase 3 program for NPS on our own.

*FBP-targeting bivalent vaccine (GALE-301/-302)*

In order to prioritize development of our core assets, we determined to cease development of GALE-301 and GALE-302, cancer immunotherapies that target the E39 peptide derived from the folate binding protein, or FBP, which were licensed in from The Henry M. Jackson Foundation, or HJF, and the MD Anderson Cancer Center, or MDACC. We entered into a Termination Agreement with HJF and MDACC in February 2021.

The chart below summarizes the current status of our clinical development pipeline:

![](tm237388d1_424b5img003.jpg)

 ****

***Impact of COVID-19***

On March 11, 2020, the World Health Organization declared the outbreak of a new coronavirus to be a "pandemic". The COVID-19 pandemic continues to present substantial public health and economic challenges around the world which have impacted, and will continue to impact, millions of individuals and business worldwide. Efforts to contain the spread of the coronavirus since March 2020 have led to travel bans and restrictions, quarantines, shelter-in-place orders and shutdowns. As we have historically functioned operationally as a semi-virtual company, the transition to "work-from-home" for our employees has not materially altered our business operations. We have implemented a return-to-work policy in compliance with federal, state and local requirements and guidance which provides for a hybrid of remote and in-office work, and we expect to operate on such a semi-virtual basis for at least the first half of 2021. We are continuously monitoring the impact of the pandemic on our clinical development programs. Our Phase 3 REGAL study is progressing, with the necessary work to activate additional sites in the United States and Europe continuing. Throughout 2020 and early 2021, we initiated additional sites as planned. However, we have observed that clinical site initiations and patient enrollment may be delayed due to prioritization of hospital resources towards the COVID-19 pandemic. Clinicians and patients may not be able to comply with clinical trial protocols if quarantines impede patient movement or interrupt operations at sites. Accordingly, we are uncertain at this time the extent to which these newly initiated sites will be fully operational, which we believe could have an impact on the projected timing of the REGAL study. Additionally, several European Union countries in which we plan to initiate clinical sites, including Germany, France, and Italy, continue to impose restrictions in response to the continued surge in coronavirus cases throughout the European Union. We believe that the COVID-19 pandemic has not materially impacted our efforts to out-license NPS. The full extent to which the COVID-19 pandemic directly or indirectly impacts our business, results of operations and financial condition will depend on future developments that are highly uncertain, subject to change and cannot be predicted with confidence, including the actions taken to contain or treat COVID-19, the overall duration of the outbreak, the availability, effectiveness and uptake of vaccines for COVID-19, the emergence of new variants of COVID-19 and whether existing vaccines are effective with respect to such variants, and the emergence of new geographic hotspots where the coronavirus is spreading more rapidly. In particular, the continued spread of the coronavirus globally could adversely impact our clinical trial operations and could have an adverse impact on our business and the financial results.

***Recent Developments***

*Proceeds from Warrant Exercises*

Subsequent to December 31, 2020, we received $3.0 million of gross proceeds from the exercise of 830,200 warrants to acquire shares of common stock at a weighted average exercise price of $3.61.

*3D Medicines Milestone Payment*

In February 2021, we triggered a milestone in the amount of $1.0 million related to the completion of a technology transfer plan under our license agreement with 3D Medicines, Inc. We received payment of this milestone during the first quarter of 2021.

**Corporate Information**

We were incorporated on April 3, 2006 in Delaware as Argonaut Pharmaceuticals, Inc. On November 28, 2006, we changed our name to RXi Pharmaceuticals Corporation and began operations January 2007. On September 26, 2011, we changed our name to Galena Biopharma, Inc. In December 2017, we completed the Merger with Private SELLAS, and changed our name to "SELLAS Life Sciences Group, Inc."

Our principal executive offices are located at 7 Times Square, Suite 2503, New York, NY 10036, and our phone number is (646) 200-5278. Our website address is www.sellaslife.com. The information contained on, or that can be accessed through, our website is not part of, and is not incorporated by reference into this prospectus and should not be considered to be part of this prospectus.

**The Securities We May Offer**

We may offer shares of our common stock and preferred stock, various series of debt securities and/or warrants, rights or units to purchase any such securities, either individually or in combination, up to a total dollar amount of $150,000,000, from time to time under this prospectus, together with any applicable prospectus supplement and any related free writing prospectuses, at prices and on terms to be determined by market conditions at the time of any offering. We may also offer common stock, preferred stock and/or debt securities upon the exercise of warrants, rights or units. This prospectus provides you with a general description of the securities we may offer. Each time we offer a type or series of securities under this prospectus, we will provide a prospectus supplement that will describe the specific amounts, prices and other important terms of the securities, including, to the extent applicable:

&nbsp;&nbsp;&nbsp;&nbsp;· designation or classification;

&nbsp;&nbsp;&nbsp;&nbsp;· aggregate principal amount or aggregate offering price;

&nbsp;&nbsp;&nbsp;&nbsp;· maturity date, if applicable;

&nbsp;&nbsp;&nbsp;&nbsp;· original issue discount, if any;

&nbsp;&nbsp;&nbsp;&nbsp;· rates and times of payment of interest or dividends, if any;

&nbsp;&nbsp;&nbsp;&nbsp;· redemption, conversion, exercise, exchange or sinking fund terms, if any;

&nbsp;&nbsp;&nbsp;&nbsp;· conversion or exchange prices or rates, if any, and, if applicable, any provisions for changes to or adjustments in the conversion
or exchange prices or rates and in the securities or other property receivable upon conversion or exchange;

&nbsp;&nbsp;&nbsp;&nbsp;· ranking, if applicable;

&nbsp;&nbsp;&nbsp;&nbsp;· restrictive covenants, if any;

&nbsp;&nbsp;&nbsp;&nbsp;· voting or other rights, if any; and

&nbsp;&nbsp;&nbsp;&nbsp;· material or special U.S. federal income tax considerations, if any.

Any applicable prospectus supplement and any related free writing prospectus that we may authorize to be provided to you may also add, update or change any of the information contained in this prospectus or in the documents we have incorporated by reference. However, no prospectus supplement or free writing prospectus will offer any security that is not registered and described in this prospectus at the time of the effectiveness of the registration statement of which this prospectus is a part.

**This prospectus may not be used to consummate a sale of our securities unless it is accompanied by a prospectus supplement.**

We may sell the securities directly to investors or to or through agents, underwriters or dealers. We, and our agents or underwriters, reserve the right to accept or reject all or part of any proposed purchase of securities. If we do offer securities to or through agents or underwriters, we will include in the applicable prospectus supplement:

&nbsp;&nbsp;&nbsp;&nbsp;· the names of those agents or underwriters;

&nbsp;&nbsp;&nbsp;&nbsp;· applicable fees, discounts and commissions to be paid to them;

&nbsp;&nbsp;&nbsp;&nbsp;· details regarding over-allotment options, if any; and

&nbsp;&nbsp;&nbsp;&nbsp;· the estimated net proceeds to us.

*Common Stock*

We may issue shares of our common stock from time to time. The holders of our common stock are entitled to one vote for each share held of record on all matters submitted to a vote of stockholders. Subject to preferences that may be applicable to any then outstanding shares of preferred stock, the holders of common stock are entitled to receive ratably such dividends as may be declared by our board of directors out of legally available funds. Upon our liquidation, dissolution or winding up, holders of our common stock are entitled to share ratably in all assets legally available for distribution to stockholders remaining after payment of liabilities and the liquidation preferences of any outstanding shares of preferred stock. Holders of common stock have no preemptive rights and no right to convert their common stock into any other securities. There are no redemption or sinking fund provisions applicable to our common stock. When we issue shares of common stock under this prospectus, the shares will be fully paid and non-assessable. The rights, preferences and privileges of the holders of common stock are subject to, and may be adversely affected by, the rights of the holders of shares of any series of preferred stock that we may designate in the future. In this prospectus, we have summarized certain general features of the common stock under "Description of Capital Stock—Common Stock." We urge you, however, to read the applicable prospectus supplement (and any related free writing prospectus that we may authorize to be provided to you) related to any common stock being offered.

*Preferred Stock*

We may issue shares of our preferred stock from time to time, in one or more series. If we sell any series of preferred stock under this prospectus and any applicable prospectus supplement, our board of directors will determine the designations, voting powers, preferences and rights of the preferred stock being offered, as well as the qualifications, limitations or restrictions thereof, including dividend rights, conversion rights, preemptive rights, terms of redemption or repurchase, liquidation preferences, sinking fund terms and the number of shares constituting any series or the designation of any series. Convertible preferred stock may be convertible into our common stock or exchangeable for our other securities. Conversion may be mandatory or at the holder's option and would be at prescribed conversion rates.

We will file as an exhibit to the registration statement of which this prospectus is a part, or will incorporate by reference from reports that we file with the SEC, the form of the certificate of designation that describes the terms of the series of preferred stock that we are offering before the issuance of the related series of preferred stock. We urge you to read the applicable prospectus supplement (and any free writing prospectus that we may authorize to be provided to you) related to the series of preferred stock being offered, as well as the complete certificate of designation that contains the terms of the applicable series of preferred stock.

*Debt Securities*

We may issue debt securities from time to time, in one or more series, as either senior or subordinated debt or as senior or subordinated convertible debt. The senior debt securities will rank equally with any other unsecured and unsubordinated debt. The subordinated debt securities will be subordinate and junior in right of payment, to the extent and in the manner described in the instrument governing the debt, to all of our senior indebtedness. Convertible debt securities will be convertible into our common stock or other securities. Conversion may be mandatory or at the holder's option and would be at prescribed conversion rates.

Any debt securities issued under this prospectus will be issued under one or more documents called indentures, which are contracts between us and a national banking association or other eligible party, as trustee. Forms of senior and subordinated indentures have been filed as exhibits to the registration statement of which this prospectus is a part, and supplemental indentures and forms of debt securities containing the terms of the debt securities being offered will be filed as exhibits to the registration statement of which this prospectus is a part or will be incorporated by reference from reports that we file with the SEC. In this prospectus, we have summarized certain general features of the debt securities under "Description of Debt Securities." We urge you, however, to read the applicable prospectus supplement (and any related free writing prospectus that we may authorize to be provided to you) related to the series of debt securities being offered, as well as the complete indentures that contain the terms of the debt securities.

*Warrants*

We may issue warrants for the purchase of common stock, preferred stock and/or debt securities in one or more series. We may issue warrants independently or together with common stock, preferred stock and/or debt securities, and the warrants may be attached to or separate from these securities. Forms of the warrant agreements and forms of warrant certificates containing the terms of the warrants being offered have been filed as exhibits to the registration statement of which this prospectus is a part, and supplemental warrant agreements and forms of warrant certificates will be filed as exhibits to the registration statement of which this prospectus is a part or will be incorporated by reference from reports that we file with the SEC. We urge you to read the applicable prospectus supplement (and any free writing prospectus that we may authorize to be provided to you) related to the particular series of warrants being offered, as well as the complete warrant agreements and warrant certificates that contain the terms of the warrants.

Any warrants issued under this prospectus may be evidenced by warrant certificates. Warrants may also be issued under an applicable warrant agreement that we enter into with a warrant agent. We will indicate the name and address of the warrant agent, if applicable, in the prospectus supplement relating to the particular series of warrants being offered.

*Rights*

We may issue rights for the purchase of common stock, preferred stock or debt securities. We may issue subscription rights independently or together with common stock, preferred stock and/or debt securities, and the rights may be attached to or separate from these securities. Each series of rights will be issued under a separate rights agreement to be entered into between us and a bank or trust company, as rights agent. The rights agent will act solely as our agent in connection with the certificates relating to the rights of the series of certificates and will not assume any obligation or relationship of agency or trust for or with any holders of rights certificates or beneficial owners of rights. We urge you to read the applicable prospectus supplement (and any free writing prospectus that we may authorize to be provided to you) related to the particular series of rights being offered, as well as the complete rights agreements that contain the terms of the rights.

*Units*

We may issue units consisting of common stock, preferred stock, one or more debt securities, warrants or rights for the purchase of common stock, preferred stock and/or debt securities in one or more series, in any combination. Each unit will be issued so that the holder of the unit is also the holder of each security included in the unit. Thus, the holder of a unit will have the rights and obligations of a holder of each security included in the unit. The unit agreement under which a unit is issued may provide that the securities included in the unit may not be held or transferred separately, at any time or at any time before a specified date. We urge you to read the applicable prospectus supplement (and any free writing prospectus that we may authorize to be provided to you) related to the particular series of units being offered, as well as the complete unit agreements that contain the terms of the units.

**Use of Proceeds**

Except as described in any applicable prospectus supplement or in any free writing prospectuses we have authorized for use in connection with a specific offering, we currently intend to use the net proceeds from the sale of the securities offered by us hereunder, if any, for working capital and general corporate purposes, including research and development of our product candidates (including clinical trial activities), and general and administrative expenses. See "Use of Proceeds" in this prospectus.

**Nasdaq Capital Market Listing**

Our common stock is listed on the Nasdaq Capital Market under the symbol "SLS." The applicable prospectus supplement will contain information, where applicable, as to other listings, if any, on the Nasdaq Capital Market or other securities exchange of the securities covered by the applicable prospectus supplement.

**RISK FACTORS**

*Investing in our securities involves a high degree of risk. Before deciding whether to invest in our securities, you should carefully consider the risks described in the documents incorporated by reference in this prospectus and any applicable prospectus supplement, as well as other information we include or incorporate by reference into this prospectus and any applicable prospectus supplement, before making an investment decision. Our business, financial condition or results of operations could be materially adversely affected by any of these risks. The trading price of our securities could decline due to the occurrence of any of these risks, and you may lose all or part of your investment. This prospectus and the documents incorporated herein by reference also contain forward-looking statements that involve risks and uncertainties. Actual results could differ materially from those anticipated in these forward-looking statements as a result of certain factors, including the risks described in the documents incorporated herein by reference, including in (1) our most recent Annual Report on Form 10-K on file with the SEC, (2) our most recent Quarterly Reports on Form 10-Q on file with the SEC and (3) any amendments thereto reflected in subsequent filings with the SEC, all of which are incorporated by reference into this prospectus in their entirety, together with other information in this prospectus, the applicable prospectus supplement and the documents incorporated by reference that we may authorize for use in connection with a specific offering. Please also read carefully the section below entitled "Special Note Regarding Forward-Looking Statements."*

**SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS**

This prospectus, the applicable prospectus supplement, and the documents incorporated by reference contain forward-looking statements about us and our industry that involve substantial risks and uncertainties. All statements other than statements of historical facts contained in this prospectus, the applicable prospectus supplement, and the documented incorporated by reference, including statements regarding our future financial condition, business strategy and plans, and objectives of management for future operations, are forward-looking statements. In some cases, you can identify forward-looking statements by terminology such as "aim," "anticipate," "assume," "believe," "contemplate," "continue," "could," "design," "due," "estimate," "expect," "goal," "intend," "may," "objective," "plan," "predict," "positioned," "potential," "seek," "should," "target," "will," "would" and other similar expressions that are predictions of or indicate future events and future trends, or the negative of these terms or other comparable terminology.

We have based these forward-looking statements largely on our current expectations and projections about future events and financial trends that we believe may affect our financial condition, results of operations, business strategy and financial needs. These forward-looking statements are subject to a number of known and unknown risks, uncertainties and assumptions, including risks described in the section titled "Risk Factors" contained in our most recent Annual Report on Form 10-K and Quarterly Reports on Form 10-Q and incorporated by reference in this prospectus, as the same may be amended, supplemented or superseded by the risks and uncertainties described under similar headings in the other documents that are filed after the date hereof and incorporated by reference into this prospectus, regarding, among other things:

&nbsp;&nbsp;&nbsp;&nbsp;· our ability to continue to operate despite incurring substantial losses since our inception and our expectation that we will continue
to incur substantial and increasing losses for the foreseeable future;

&nbsp;&nbsp;&nbsp;&nbsp;· our ability to continue as a going concern;

&nbsp;&nbsp;&nbsp;&nbsp;· our ability to obtain the substantial additional financing necessary to achieve our goals;

&nbsp;&nbsp;&nbsp;&nbsp;· whether we will generate revenues and achieve profitability in the future;

&nbsp;&nbsp;&nbsp;&nbsp;· the ability of investors to evaluate the success of our business and to assess our future viability given our limited operating history;

&nbsp;&nbsp;&nbsp;&nbsp;· our expectations regarding our continuing to incur significant operating and non-operating expenses;

&nbsp;&nbsp;&nbsp;&nbsp;· the impact of the COVID-19 pandemic;

&nbsp;&nbsp;&nbsp;&nbsp;· the initiation of legal or administrative actions against us;

&nbsp;&nbsp;&nbsp;&nbsp;· our ability to use net operating losses to offset future taxable income;

&nbsp;&nbsp;&nbsp;&nbsp;· our ability to comply with the regulatory and environmental provisions and laws to which we are subject;

&nbsp;&nbsp;&nbsp;&nbsp;· our ability to obtain regulatory approval of our product candidates;

&nbsp;&nbsp;&nbsp;&nbsp;· whether the results of our clinical trials will be sufficient to support domestic or global regulatory approvals;

&nbsp;&nbsp;&nbsp;&nbsp;· the initiation, timing, progress and results of our pre-clinical and clinical trials;

&nbsp;&nbsp;&nbsp;&nbsp;· the success of our lead product candidate, GPS, and our ability to successfully complete clinical trials and obtain regulatory approval
for our other product candidates;

&nbsp;&nbsp;&nbsp;&nbsp;· whether our product development program will uncover all possible adverse events that patients who take our product candidates may
experience;

&nbsp;&nbsp;&nbsp;&nbsp;· whether we can maintain Orphan Drug exclusivity and Fast Track designation for certain of our product candidates and whether we will
receive orphan drug product designation and fast track designation for additional product candidates should we seek such designations;

&nbsp;&nbsp;&nbsp;&nbsp;· our ability to successfully identify, acquire, develop or commercialize new potential product candidates;

&nbsp;&nbsp;&nbsp;&nbsp;· our ability to realize benefits from strategic alliances that we may form in the future;

&nbsp;&nbsp;&nbsp;&nbsp;· whether we can continue to rely on third parties to conduct our preclinical studies and clinical trials;

&nbsp;&nbsp;&nbsp;&nbsp;· whether we can continue to rely on third parties to manufacture our product candidates;

&nbsp;&nbsp;&nbsp;&nbsp;· whether we can rely on third parties to develop or potentially commercialize some or all of our product candidates;

&nbsp;&nbsp;&nbsp;&nbsp;· developments or disputes concerning our intellectual property or other proprietary rights;

&nbsp;&nbsp;&nbsp;&nbsp;· our expectations regarding the potential market size and the size of the patient populations for our product candidates, if approved,
for commercial use;

&nbsp;&nbsp;&nbsp;&nbsp;· the impact of legislation developments regarding pricing regulations;

&nbsp;&nbsp;&nbsp;&nbsp;· the implementation of our business model and strategic plans for our business and product candidates;

&nbsp;&nbsp;&nbsp;&nbsp;· our ability to maintain and establish collaborations or obtain additional funding;

&nbsp;&nbsp;&nbsp;&nbsp;· the market price and value of our common stock;

&nbsp;&nbsp;&nbsp;&nbsp;· our ability to compete in the markets we serve; and

&nbsp;&nbsp;&nbsp;&nbsp;· other factors that may impact our financial results.

These risks are not exhaustive. Other sections of this prospectus, the applicable prospectus supplement, or the documents incorporated herein by reference may include additional factors that could harm our business and financial performance. Moreover, we operate in a very competitive and rapidly changing environment. New risk factors emerge from time to time, and it is not possible for our management to predict all risk factors, nor can we assess the impact of all factors on our business or the extent to which any factor, or combination of factors, may cause actual results to differ materially from those contained in, or implied by, any forward-looking statements.

You should not rely upon forward-looking statements as predictions of future events. We cannot assure you that the events and circumstances reflected in the forward-looking statements will be achieved or occur. Although we believe that the expectations reflected in the forward-looking statements are reasonable, we cannot guarantee future results, levels of activity, performance or achievements. Except as required by law, we undertake no obligation to update publicly any forward-looking statements for any reason after the date of this prospectus or to conform these statements to actual results or to changes in our expectations.

You should carefully read this prospectus, and the applicable prospectus supplement, together with the information incorporated herein by reference as described under the heading "Incorporation by Reference," as well as the documents filed as exhibits to the registration statement of which this prospectus is a part with the understanding that our actual future results, levels of activity, performance and achievements may be materially different from what we expect. We qualify all of our forward-looking statements by these cautionary statements.

Except as required by law, we assume no obligation to update these forward-looking statements publicly, or to update the reasons actual results could differ materially from those anticipated in these forward-looking statements, even if new information becomes available in the future.

**USE OF PROCEEDS**

Except as described in any applicable prospectus supplement or in any related free writing prospectuses we may authorize for use in connection with a specific offering, we currently intend to use the net proceeds from the sale of the securities offered by us hereunder, if any, for working capital, capital expenditures and other general corporate purposes including research and development of our product candidates (including clinical trial activities), and general and administrative expenses. In addition, we may use a portion of the proceeds for the acquisition of, or investment in, technologies, solutions or businesses that complement our business, although we have no present commitments or agreements to enter into any such acquisitions or investments. As of the date of this prospectus, we cannot specify with certainty all of the particular uses for the net proceeds to us from the sale of the securities offered by us hereunder. We will set forth in the applicable prospectus supplement or free writing prospectus our intended use for the net proceeds received from the sale of any securities sold pursuant to the prospectus supplement or free writing prospectus.

**DILUTION**

We will set forth in a prospectus supplement the following information regarding any material dilution of the equity interests of investors purchasing securities in an offering under this prospectus:

&nbsp;&nbsp;&nbsp;&nbsp;· the net tangible book value per share of our equity securities before and after the offering;

&nbsp;&nbsp;&nbsp;&nbsp;· the amount of the increase in such net tangible book value per share attributable to the cash payments made by purchasers in the offering;
and

&nbsp;&nbsp;&nbsp;&nbsp;· the amount of the immediate dilution from the public offering price which will be absorbed by such purchasers.

**DESCRIPTION OF CAPITAL STOCK**

The following description of our capital stock summarizes the material terms and provisions of our common stock and our preferred stock. For the complete terms of our common stock, please refer to our amended and restated certificate of incorporation and our amended and restated bylaws, each as amended to date, that are incorporated by reference into the registration statement of which this prospectus is a part or may be incorporated by reference into this prospectus. The terms of these securities may also be affected by the Delaware General Corporation Law. The summary below is qualified in its entirety by reference to our amended and restated certificate of incorporation and amended and restated bylaws, which are filed as exhibits to the registration statement of which this prospectus is a part.

**General**

Our amended and restated certificate of incorporation authorizes us to issue up to 350,000,000 shares of common stock, $0.0001 par value per share, and 5,000,000 shares of preferred stock, $0.0001 par value per share.

As of December 31, 2020, there were:

&nbsp;&nbsp;&nbsp;&nbsp;· 14,254,554 shares of common stock outstanding;

&nbsp;&nbsp;&nbsp;&nbsp;· 0 shares of preferred stock outstanding;

&nbsp;&nbsp;&nbsp;&nbsp;· 207,520 shares of common stock issuable upon exercise of outstanding options;

&nbsp;&nbsp;&nbsp;&nbsp;· 170,000 shares of common stock issuable upon vesting of outstanding restricted stock units; and

&nbsp;&nbsp;&nbsp;&nbsp;· warrants outstanding for the purchase of an aggregate of 1,391,650 shares of common stock.

**Common stock**

*Voting*

Each holder of our common stock is entitled to one vote for each share on all matters submitted to a vote of the stockholders, including the election of directors. Our amended and restated certificate of incorporation and amended and restated bylaws do not provide for cumulative voting rights. Because of this absence of cumulative voting, the holders of a majority of the shares of common stock entitled to vote in any election of directors can elect all the directors standing for election, if they should so choose.

*Dividends*

Subject to preferences that may be applicable to any then outstanding shares of preferred stock, holders of common stock are entitled to receive ratably those dividends, if any, as may be declared from time to time by our board of directors out of legally available funds.

*Liquidation*

In the event of our dissolution or liquidation, holders of common stock will be entitled to share ratably in the net assets legally available for distribution to stockholders after the payment of all our debts and other liabilities and the satisfaction of any preferential rights that may be granted to the holders of any then outstanding shares of preferred stock.

*Rights and Preferences*

Holders of common stock have no preemptive, conversion or subscription rights, and there are no redemption or sinking fund provisions applicable to the common stock. The rights, preferences, and privileges of the holders of common stock are subject to, and may be adversely affected by, the rights of the holders of shares of any series of preferred stock.

*Fully-paid*

All of the outstanding shares of our common stock are, and the shares of common stock issued upon the conversion of any securities convertible into our common stock will be, fully paid and non-assessable. The shares of common stock offered by this prospectus or upon the conversion of any preferred stock or debt securities or exercise of any warrants offered pursuant to this prospectus, when issued and paid for, will also be, fully paid and non-assessable.

**Preferred stock**

Under our amended and restated certificate of incorporation, our board of directors has the authority, without further action by our stockholders, to issue up to 5,000,000 shares of preferred stock in one or more series and to fix the rights, preferences, privileges and restrictions thereof. These rights, preferences and privileges could include dividend rights, conversion rights, voting rights, terms of redemption, liquidation preferences, sinking fund terms and the number of shares constituting any series or the designation of such series, any or all of which may be greater than the rights of common stock. The issuance of our preferred stock could adversely affect the voting power of holders of common stock and the likelihood that such holders will receive dividend payments and payments upon liquidation. In addition, the issuance of preferred stock could have the effect of delaying, deferring or preventing a change of control of our company or other corporate action.

The following summary of terms of our preferred stock is not complete. You should refer to the provisions of our amended and restated certificate of incorporation and amended and restated bylaws and the resolutions containing the terms of each class or series of the preferred stock which have been or will be filed with the SEC at or prior to the time of issuance of such class or series of preferred stock and described in the applicable prospectus supplement. The applicable prospectus supplement may also state that any of the terms set forth herein are inapplicable to such series of preferred stock, provided that the information set forth in such prospectus supplement does not constitute material changes to the information herein such that it alters the nature of the offering or the securities offered.

Our board of directors will fix the designations, voting powers, preferences and rights of the preferred stock of each series we issue under this prospectus, as well as the qualifications, limitations or restrictions thereof, in the certificate of designation relating to that series. We will file as an exhibit to the registration statement of which this prospectus is a part, or will incorporate by reference from reports that we file with the SEC, the form of any certificate of designation that describes the terms of the series of preferred stock we are offering. We will describe in the applicable prospectus supplement the terms of the series of preferred stock being offered, including, to the extent applicable:

&nbsp;&nbsp;&nbsp;&nbsp;· the title and stated value;

&nbsp;&nbsp;&nbsp;&nbsp;· the number of shares we are offering;

&nbsp;&nbsp;&nbsp;&nbsp;· the liquidation preference per share;

&nbsp;&nbsp;&nbsp;&nbsp;· the purchase price;

&nbsp;&nbsp;&nbsp;&nbsp;· the dividend rate, period and payment date and method of calculation for dividends;

&nbsp;&nbsp;&nbsp;&nbsp;· whether dividends will be cumulative or non-cumulative and, if cumulative, the date from which dividends will accumulate;

&nbsp;&nbsp;&nbsp;&nbsp;· the procedures for any auction and remarketing;

&nbsp;&nbsp;&nbsp;&nbsp;· the provisions for a sinking fund;

&nbsp;&nbsp;&nbsp;&nbsp;· the provisions for redemption or repurchase and any restrictions on our ability to exercise those redemption and repurchase rights;

&nbsp;&nbsp;&nbsp;&nbsp;· any listing of the preferred stock on any securities exchange or market;

&nbsp;&nbsp;&nbsp;&nbsp;· whether the preferred stock will be convertible into our common stock or other securities, and the conversion rate or conversion price,
or how they will be calculated, and the conversion period;

&nbsp;&nbsp;&nbsp;&nbsp;· whether the preferred stock will be exchangeable into debt securities, and the exchange rate or exchange price, or how they will be
calculated, and the exchange period;

&nbsp;&nbsp;&nbsp;&nbsp;· voting rights of the preferred stock;

&nbsp;&nbsp;&nbsp;&nbsp;· preemptive rights;

&nbsp;&nbsp;&nbsp;&nbsp;· restrictions on transfer, sale or other assignment;

&nbsp;&nbsp;&nbsp;&nbsp;· whether interests in the preferred stock will be represented by depositary shares;

&nbsp;&nbsp;&nbsp;&nbsp;· a discussion of material or special U.S. federal income tax considerations applicable to the preferred stock;

&nbsp;&nbsp;&nbsp;&nbsp;· the relative ranking and preferences of the preferred stock as to dividend rights and rights if we liquidate, dissolve or wind up
our affairs;

&nbsp;&nbsp;&nbsp;&nbsp;· any limitations on the issuance of any class or series of preferred stock ranking senior to or on parity with the series of preferred
stock as to dividend rights and rights if we liquidate, dissolve or wind up our affairs; and

&nbsp;&nbsp;&nbsp;&nbsp;· any other specific terms, preferences, rights or limitations of, or restrictions on, the preferred stock.

If we issue shares of preferred stock under this prospectus, they will be validly issued, fully paid and non-assessable.

The DGCL provides that the holders of preferred stock will have the right to vote separately as a class on any proposal involving fundamental changes in the rights of holders of such preferred stock. This right is in addition to any voting rights that may be provided for in the applicable certificate of designation.

The issuance of our preferred stock could adversely affect the voting power, conversion or other rights of holders of common stock and reduce the likelihood that such holders will receive dividend payments and payments upon liquidation. In addition, the issuance of preferred stock could have the effect of delaying, deferring or preventing a change in control of our company or other corporate action. Additionally, the issuance of preferred stock may have the effect of decreasing the market price of our common stock.

**Possible Anti-Takeover Effects of Delaware Law and Our Certificate of Incorporation and Bylaws**

Provisions of the DGCL and our amended and restated certificate of incorporation and amended and restated bylaws could make it more difficult to acquire our company by means of a tender offer, a proxy contest or otherwise, or to remove incumbent officers and directors. These provisions, summarized below, are expected to discourage certain types of coercive takeover practices and takeover bids that our board of directors may consider inadequate and to encourage persons seeking to acquire control of our company to first negotiate with our board of directors. We believe that the benefits of increased protection of our ability to negotiate with the proponent of an unfriendly or unsolicited proposal to acquire or restructure our company outweigh the disadvantages of discouraging takeover or acquisition proposals because, among other things, negotiation of these proposals could result in an improvement of their terms.

*Classified Board*

Our amended and restated certificate of incorporation and our amended and restated bylaws provide that our board of directors is divided into three classes. The directors designated as Class I directors have terms expiring at the annual meeting of stockholders in 2023. The directors designated as Class II directors will have terms expiring at the annual meeting of stockholders in 2021, and the directors designated as Class III directors will have terms expiring at the annual meeting of stockholders in 2022. Directors for each class will be elected at the annual meeting of stockholders held in the year in which the term for that class expires and thereafter will serve for a term of three years. At any meeting of stockholders for the election of directors at which a quorum is present, the election will be determined by a plurality of the votes cast by the stockholders entitled to vote at the election. Under the classified board provisions, it would take at least two elections of directors for any individual or group to gain control of our board. Accordingly, these provisions could discourage a third party from initiating a proxy contest, making a tender offer or otherwise attempting to gain control of our company.

*Removal of Directors*

Our amended and restated bylaws provide that our stockholders may only remove our directors with cause.

*Amendment*

Our amended and restated certificate of incorporation and our amended and restated bylaws provide that the affirmative vote of the holders of at least 75% of our voting stock then outstanding is required to amend certain provisions relating to the number, term, election and removal of our directors, the filling of our board vacancies, stockholder notice procedures, the calling of special meetings of stockholders and the indemnification of directors. Further, any amendments of our bylaws must be approved by our stockholders as our amended and restated certificate of incorporation does not authorize our board of directors to amend our bylaws.

*Size of Board and Vacancies*

Our amended and restated bylaws provide that the number of directors on our board of directors is fixed exclusively by our board of directors. Newly created directorships resulting from any increase in our authorized number of directors will be filled by a majority of our board of directors then in office, provided that a majority of the entire board of directors, or a quorum, is present and any vacancies in our board of directors resulting from death, resignation, retirement, disqualification, removal from office or other cause will be filled generally by the majority vote of our remaining directors in office, even if less than a quorum is present.

*Special Stockholder Meetings*

Our amended and restated certificate of incorporation provides that only the Chairman of our board of directors, our Chief Executive Officer or our board of directors pursuant to a resolution adopted by a majority of the total number of directors we would have if there were no vacancies may call special meetings of our stockholders.

*Stockholder Action by Unanimous Written Consent*

Our amended and restated certificate of incorporation expressly eliminates the right of our stockholders to act by written consent.

*Requirements for Advance Notification of Stockholder Nominations and Proposals*

Our amended and restated bylaws provide advance notice procedures with respect to stockholder proposals and nomination of candidates for election as directors other than nominations made by or at the direction of board of directors or a committee of our board of directors.

*No Cumulative Voting*

The DGCL provides that stockholders are denied the right to cumulate votes in the election of directors unless our certificate of incorporation provides otherwise. Our amended and restated certificate of incorporation does not provide for cumulative voting.

*Undesignated Preferred Stock*

The authority that is possessed by our board of directors to issue preferred stock could potentially be used to discourage attempts by third parties to obtain control of our company through a merger, tender offer, proxy contest, or otherwise by making it more difficult or costlier to obtain control of our company. Our board of directors may issue preferred stock with voting rights or conversion rights that, if exercised, could adversely affect the voting power of the holders of common stock.

*Authorized but Unissued Shares*

Our authorized but unissued shares of common stock and preferred stock will be available for future issuance without stockholder approval. We may use additional shares for a variety of purposes, including future public offerings to raise additional capital, to fund acquisitions and as employee compensation. The existence of authorized but unissued shares of common stock and preferred stock could render more difficult or discourage an attempt to obtain control of our company by means of a proxy contest, tender offer, merger or otherwise.

The above provisions may deter a hostile takeover or delay a change in control or management of our company.

**Listing on the Nasdaq Capital Market**

Our common stock is listed on the Nasdaq Capital Market under the symbol "SLS". On April 15, 2021, the closing price of our common stock was $7.89 per share. As of April 13, 2021, we had approximately 17 stockholders of record.

The applicable prospectus supplement will contain information, where applicable, as to other listing, if any, on the Nasdaq Capital Market or other securities exchange of the preferred stock covered by such prospectus supplement.

**Transfer Agent and Registrar**

The transfer agent and registrar for our capital stock is Computershare Trust Company, N.A. Its address is 250 Royall Street, Canton, MA 02021. Its telephone number is (201) 680-4503.

**DESCRIPTION OF DEBT SECURITIES**

We may issue debt securities from time to time, in one or more series, as either senior or subordinated debt or as senior or subordinated convertible debt. While the terms we have summarized below will apply generally to any debt securities that we may offer under this prospectus, we will describe the particular terms of any debt securities that we may offer in more detail in the applicable prospectus supplement. The terms of any debt securities offered under a prospectus supplement may differ from the terms described below. Unless the context requires otherwise, whenever we refer to the indenture, we also are referring to any supplemental indentures that specify the terms of a particular series of debt securities.

We will issue the debt securities under the indenture that we will enter into with the trustee named in the indenture. The indenture will be qualified under the Trust Indenture Act of 1939, as amended, or the Trust Indenture Act. We have filed forms of senior and subordinated indentures as exhibits to the registration statement of which this prospectus is a part, and supplemental indentures and forms of debt securities containing the terms of the debt securities being offered will be filed as exhibits to the registration statement of which this prospectus is a part or will be incorporated by reference from reports that we file with the SEC.

The following summary of material provisions of the debt securities and the indenture is subject to, and qualified in its entirety by reference to, all of the provisions of the indenture applicable to a particular series of debt securities. We urge you to read the applicable prospectus supplements and any related free writing prospectuses related to the debt securities that we may offer under this prospectus, as well as the complete indenture that contains the terms of the debt securities.

**General**

The indenture does not limit the amount of debt securities that we may issue. It provides that we may issue debt securities up to the principal amount that we may authorize and may be in any currency or currency unit that we may designate. Except for the limitations on consolidation, merger and sale of all or substantially all of our assets contained in the indenture, the terms of the indenture do not contain any covenants or other provisions designed to give holders of any debt securities protection against changes in our operations, financial condition or transactions involving us.

We may issue the debt securities issued under the indenture as "discount securities," which means they may be sold at a discount below their stated principal amount. These debt securities, as well as other debt securities that are not issued at a discount, may be issued with "original issue discount," or OID, for U.S. federal income tax purposes because of interest payment and other characteristics or terms of the debt securities. Material U.S. federal income tax considerations applicable to debt securities issued with OID will be described in more detail in any applicable prospectus supplement.

We will describe in the applicable prospectus supplement the terms of the series of debt securities being offered, including:

&nbsp;&nbsp;&nbsp;&nbsp;· the title of the series of debt securities;

&nbsp;&nbsp;&nbsp;&nbsp;· any limit upon the aggregate principal amount that may be issued;

&nbsp;&nbsp;&nbsp;&nbsp;· the maturity date or dates;

&nbsp;&nbsp;&nbsp;&nbsp;· the form of the debt securities of the series;

&nbsp;&nbsp;&nbsp;&nbsp;· the applicability of any guarantees;

&nbsp;&nbsp;&nbsp;&nbsp;· whether or not the debt securities will be secured or unsecured, and the terms of any secured debt;

&nbsp;&nbsp;&nbsp;&nbsp;· whether the debt securities rank as senior debt, senior subordinated debt, subordinated debt or any combination thereof, and the terms
of any subordination;

&nbsp;&nbsp;&nbsp;&nbsp;· if the price (expressed as a percentage of the aggregate principal amount thereof) at which such debt securities will be issued is
a price other than the principal amount thereof, the portion of the principal amount thereof payable upon declaration of acceleration
of the maturity thereof, or if applicable, the portion of the principal amount of such debt securities that is convertible into another
security or the method by which any such portion shall be determined;

&nbsp;&nbsp;&nbsp;&nbsp;· the interest rate or rates, which may be fixed or variable, or the method for determining the rate and the date interest will begin
to accrue, the dates interest will be payable and the regular record dates for interest payment dates or the method for determining such
dates;

&nbsp;&nbsp;&nbsp;&nbsp;· our right, if any, to defer payment of interest and the maximum length of any such deferral period;

&nbsp;&nbsp;&nbsp;&nbsp;· if applicable, the date or dates after which, or the period or periods during which, and the price or prices at which, we may, at
our option, redeem the series of debt securities pursuant to any optional or provisional redemption provisions and the terms of those
redemption provisions;

&nbsp;&nbsp;&nbsp;&nbsp;· the date or dates, if any, on which, and the price or prices at which we are obligated, pursuant to any mandatory sinking fund or
analogous fund provisions or otherwise, to redeem, or at the holder's option to purchase, the series of debt securities and the
currency or currency unit in which the debt securities are payable;

&nbsp;&nbsp;&nbsp;&nbsp;· the denominations in which we will issue the series of debt securities, if other than denominations of $1,000 and any integral multiple
thereof;

&nbsp;&nbsp;&nbsp;&nbsp;· any and all terms, if applicable, relating to any auction or remarketing of the debt securities of that series and any security for
our obligations with respect to such debt securities and any other terms which may be advisable in connection with the marketing of debt
securities of that series;

&nbsp;&nbsp;&nbsp;&nbsp;· whether the debt securities of the series shall be issued in whole or in part in the form of a global security or securities; the
terms and conditions, if any, upon which such global security or securities may be exchanged in whole or in part for other individual securities;
and the depositary for such global security or securities;

&nbsp;&nbsp;&nbsp;&nbsp;· if applicable, the provisions relating to conversion or exchange of any debt securities of the series and the terms and conditions
upon which such debt securities will be so convertible or exchangeable, including the conversion or exchange price, as applicable, or
how it will be calculated and may be adjusted, any mandatory or optional (at our option or the holders' option) conversion or exchange
features, the applicable conversion or exchange period and the manner of settlement for any conversion or exchange;

&nbsp;&nbsp;&nbsp;&nbsp;· if other than the full principal amount thereof, the portion of the principal amount of debt securities of the series which shall
be payable upon declaration of acceleration of the maturity thereof;

&nbsp;&nbsp;&nbsp;&nbsp;· additions to or changes in the covenants applicable to the particular debt securities being issued, including, among others, the consolidation,
merger or sale covenant;

&nbsp;&nbsp;&nbsp;&nbsp;· additions to or changes in the events of default with respect to the securities and any change in the right of the trustee or the
holders to declare the principal, premium, if any, and interest, if any, with respect to such securities to be due and payable;

&nbsp;&nbsp;&nbsp;&nbsp;· additions to or changes in or deletions of the provisions relating to covenant defeasance and legal defeasance;

&nbsp;&nbsp;&nbsp;&nbsp;· additions to or changes in the provisions relating to satisfaction and discharge of the indenture;

&nbsp;&nbsp;&nbsp;&nbsp;· additions to or changes in the provisions relating to the modification of the indenture both with and without the consent of holders
of debt securities issued under the indenture;

&nbsp;&nbsp;&nbsp;&nbsp;· the currency of payment of debt securities if other than U.S. dollars and the manner of determining the equivalent amount in U.S.
dollars;

&nbsp;&nbsp;&nbsp;&nbsp;· whether interest will be payable in cash or additional debt securities at our or the holders' option and the terms and conditions
upon which the election may be made;

&nbsp;&nbsp;&nbsp;&nbsp;· the terms and conditions, if any, upon which we will pay amounts in addition to the stated interest, premium, if any and principal
amounts of the debt securities of the series to any holder that is not a "United States person" for federal tax purposes;

&nbsp;&nbsp;&nbsp;&nbsp;· any restrictions on transfer, sale or assignment of the debt securities of the series; and

&nbsp;&nbsp;&nbsp;&nbsp;· any other specific terms, preferences, rights or limitations of, or restrictions on, the debt securities, any other additions or changes
in the provisions of the indenture, and any terms that may be required by us or advisable under applicable laws or regulations.

**Conversion or Exchange Rights**

We will set forth in the applicable prospectus supplement the terms on which a series of debt securities may be convertible into or exchangeable for our common stock or our other securities. We will include provisions as to settlement upon conversion or exchange and whether conversion or exchange is mandatory, at the option of the holder or at our option. We may include provisions pursuant to which the number of shares of our common stock or our other securities that the holders of the series of debt securities receive would be subject to adjustment.

**Consolidation, Merger or Sale**

Unless we provide otherwise in the prospectus supplement applicable to a particular series of debt securities, the indenture will not contain any covenant that restricts our ability to merge or consolidate, or sell, convey, transfer or otherwise dispose of our assets as an entirety or substantially as an entirety. However, any successor to or acquirer of such assets (other than a subsidiary of ours) must assume all of our obligations under the indenture or the debt securities, as appropriate.

**Events of Default under the Indenture**

Unless we provide otherwise in the prospectus supplement applicable to a particular series of debt securities, the following are events of default under the indenture with respect to any series of debt securities that we may issue:

&nbsp;&nbsp;&nbsp;&nbsp;· if we fail to pay any installment of interest on any series of debt securities, as and when the same shall become due and payable,
and such default continues for a period of 90 days; provided, however, that a valid extension of an interest payment period by us in accordance
with the terms of any indenture supplemental thereto shall not constitute a default in the payment of interest for this purpose;

&nbsp;&nbsp;&nbsp;&nbsp;· if we fail to pay the principal of, or premium, if any, on any series of debt securities as and when the same shall become due and
payable whether at maturity, upon redemption, by declaration or otherwise, or in any payment required by any sinking or analogous fund
established with respect to such series; provided, however, that a valid extension of the maturity of such debt securities in accordance
with the terms of any indenture supplemental thereto shall not constitute a default in the payment of principal or premium, if any;

&nbsp;&nbsp;&nbsp;&nbsp;· if we fail to observe or perform any other covenant or agreement contained in the debt securities or the indenture, other than a covenant
specifically relating to another series of debt securities, and our failure continues for 90 days after we receive written notice of such
failure, requiring the same to be remedied and stating that such is a notice of default thereunder, from the trustee or holders of at
least 25% in aggregate principal amount of the outstanding debt securities of the applicable series; and

&nbsp;&nbsp;&nbsp;&nbsp;· if specified events of bankruptcy, insolvency or reorganization occur.

If an event of default with respect to debt securities of any series occurs and is continuing, other than an event of default specified in the last bullet point above, the trustee or the holders of at least 25% in aggregate principal amount of the outstanding debt securities of that series, by notice to us in writing, and to the trustee if notice is given by such holders, may declare the unpaid principal of, premium, if any, and accrued interest, if any, due and payable immediately. If an event of default specified in the last bullet point above occurs with respect to us, the principal amount of and accrued interest, if any, of each issue of debt securities then outstanding shall be due and payable without any notice or other action on the part of the trustee or any holder.

The holders of a majority in principal amount of the outstanding debt securities of an affected series may waive any default or event of default with respect to the series and its consequences, except defaults or events of default regarding payment of principal, premium, if any, or interest, unless we have cured the default or event of default in accordance with the indenture. Any waiver shall cure the default or event of default.

Subject to the terms of the indenture, if an event of default under an indenture shall occur and be continuing, the trustee will be under no obligation to exercise any of its rights or powers under such indenture at the request or direction of any of the holders of the applicable series of debt securities, unless such holders have offered the trustee reasonable indemnity. The holders of a majority in principal amount of the outstanding debt securities of any series will have the right to direct the time, method and place of conducting any proceeding for any remedy available to the trustee, or exercising any trust or power conferred on the trustee, with respect to the debt securities of that series, provided that:

&nbsp;&nbsp;&nbsp;&nbsp;· the direction so given by the holder is not in conflict with any law or the applicable indenture; and

&nbsp;&nbsp;&nbsp;&nbsp;· subject to its duties under the Trust Indenture Act, the trustee need not take any action that might involve it in personal liability
or might be unduly prejudicial to the holders not involved in the proceeding.

A holder of the debt securities of any series will have the right to institute a proceeding under the indenture or to appoint a receiver or trustee, or to seek other remedies only if:

&nbsp;&nbsp;&nbsp;&nbsp;· the holder has given written notice to the trustee of a continuing event of default with respect to that series;

&nbsp;&nbsp;&nbsp;&nbsp;· the holders of at least 25% in aggregate principal amount of the outstanding debt securities of that series have made written request,

&nbsp;&nbsp;&nbsp;&nbsp;· such holders have offered to the trustee indemnity satisfactory to it against the costs, expenses and liabilities to be incurred by
the trustee in compliance with the request; and

&nbsp;&nbsp;&nbsp;&nbsp;· the trustee does not institute the proceeding and does not receive from the holders of a majority in aggregate principal amount of
the outstanding debt securities of that series other conflicting directions within 90 days after the notice, request and offer.

These limitations do not apply to a suit instituted by a holder of debt securities if we default in the payment of the principal, premium, if any, or interest on, the debt securities.

We will periodically file statements with the trustee regarding our compliance with specified covenants in the indenture.

**Modification of Indenture; Waiver**

We and the trustee may change an indenture without the consent of any holders with respect to specific matters:

&nbsp;&nbsp;&nbsp;&nbsp;· to cure any ambiguity, defect or inconsistency in the indenture or in the debt securities of any series;

&nbsp;&nbsp;&nbsp;&nbsp;· to comply with the provisions described above under "Description of Debt Securities—Consolidation, Merger or Sale;"

&nbsp;&nbsp;&nbsp;&nbsp;· to provide for uncertificated debt securities in addition to or in place of certificated debt securities;

&nbsp;&nbsp;&nbsp;&nbsp;· to add to our covenants, restrictions, conditions or provisions such new covenants, restrictions, conditions or provisions for the
benefit of the holders of all or any series of debt securities, to make the occurrence, or the occurrence and the continuance, of a default
in any such additional covenants, restrictions, conditions or provisions an event of default or to surrender any right or power conferred
upon us in the indenture;

&nbsp;&nbsp;&nbsp;&nbsp;· to add to, delete from or revise the conditions, limitations, and restrictions on the authorized amount, terms, or purposes of issue,
authentication and delivery of debt securities, as set forth in the indenture;

&nbsp;&nbsp;&nbsp;&nbsp;· to make any change that does not adversely affect the interests of any holder of debt securities of any series in any material respect;

&nbsp;&nbsp;&nbsp;&nbsp;· to provide for the issuance of and establish the form and terms and conditions of the debt securities of any series as provided above
under "Description of Debt Securities—General" to establish the form of any certifications required to be furnished
pursuant to the terms of the indenture or any series of debt securities, or to add to the rights of the holders of any series of debt
securities;

&nbsp;&nbsp;&nbsp;&nbsp;· to evidence and provide for the acceptance of appointment under any indenture by a successor trustee; or

&nbsp;&nbsp;&nbsp;&nbsp;· to comply with any requirements of the SEC in connection with the qualification of any indenture under the Trust Indenture Act.

In addition, under the indenture, the rights of holders of a series of debt securities may be changed by us and the trustee with the written consent of the holders of at least a majority in aggregate principal amount of the outstanding debt securities of each series that is affected. However, unless we provide otherwise in the prospectus supplement applicable to a particular series of debt securities, we and the trustee may make the following changes only with the consent of each holder of any outstanding debt securities affected:

&nbsp;&nbsp;&nbsp;&nbsp;· extending the fixed maturity of any debt securities of any series;

&nbsp;&nbsp;&nbsp;&nbsp;· reducing the principal amount, reducing the rate of or extending the time of payment of interest, or reducing any premium payable
upon the redemption of any series of any debt securities; or

&nbsp;&nbsp;&nbsp;&nbsp;· reducing the percentage of debt securities, the holders of which are required to consent to any amendment, supplement, modification
or waiver.

**Discharge**

Each indenture provides that we can elect to be discharged from our obligations with respect to one or more series of debt securities, except for specified obligations, including obligations to:

&nbsp;&nbsp;&nbsp;&nbsp;· provide for payment;

&nbsp;&nbsp;&nbsp;&nbsp;· register the transfer or exchange of debt securities of the series;

&nbsp;&nbsp;&nbsp;&nbsp;· replace stolen, lost or mutilated debt securities of the series;

&nbsp;&nbsp;&nbsp;&nbsp;· pay principal of and premium and interest on any debt securities of the series;

&nbsp;&nbsp;&nbsp;&nbsp;· maintain paying agencies;

&nbsp;&nbsp;&nbsp;&nbsp;· hold monies for payment in trust;

&nbsp;&nbsp;&nbsp;&nbsp;· recover excess money held by the trustee;

&nbsp;&nbsp;&nbsp;&nbsp;· compensate and indemnify the trustee; and

&nbsp;&nbsp;&nbsp;&nbsp;· appoint any successor trustee.

In order to exercise our rights to be discharged, we must deposit with the trustee money or government obligations sufficient to pay all the principal of, any premium, if any, and interest on, the debt securities of the series on the dates payments are due.

**Form, Exchange and Transfer**

We will issue the debt securities of each series only in fully registered form without coupons and, unless we provide otherwise in the applicable prospectus supplement, in denominations of $1,000 and any integral multiple thereof. The indenture provides that we may issue debt securities of a series in temporary or permanent global form and as book-entry securities that will be deposited with, or on behalf of, The Depository Trust Company, or DTC, or another depositary named by us and identified in the applicable prospectus supplement with respect to that series. To the extent the debt securities of a series are issued in global form and as book-entry, a description of terms relating to any book-entry securities will be set forth in the applicable prospectus supplement.

At the option of the holder, subject to the terms of the indenture and the limitations applicable to global securities described in the applicable prospectus supplement, the holder of the debt securities of any series can exchange the debt securities for other debt securities of the same series, in any authorized denomination and of like tenor and aggregate principal amount.

Subject to the terms of the indenture and the limitations applicable to global securities set forth in the applicable prospectus supplement, holders of the debt securities may present the debt securities for exchange or for registration of transfer, duly endorsed or with the form of transfer endorsed thereon duly executed if so required by us or the security registrar, at the office of the security registrar or at the office of any transfer agent designated by us for this purpose. Unless otherwise provided in the debt securities that the holder presents for transfer or exchange, we will impose no service charge for any registration of transfer or exchange, but we may require payment of any taxes or other governmental charges.

We will name in the applicable prospectus supplement the security registrar, and any transfer agent in addition to the security registrar, that we initially designate for any debt securities. We may at any time designate additional transfer agents or rescind the designation of any transfer agent or approve a change in the office through which any transfer agent acts, except that we will be required to maintain a transfer agent in each place of payment for the debt securities of each series.

If we elect to redeem the debt securities of any series, we will not be required to:

&nbsp;&nbsp;&nbsp;&nbsp;· issue, register the transfer of, or exchange any debt securities of that series during a period beginning at the opening of business
15 days before the day of mailing of a notice of redemption of any debt securities that may be selected for redemption and ending at the
close of business on the day of the mailing; or

&nbsp;&nbsp;&nbsp;&nbsp;· register the transfer of or exchange any debt securities so selected for redemption, in whole or in part, except the unredeemed portion
of any debt securities we are redeeming in part.

**Information Concerning the Trustee**

The trustee, other than during the occurrence and continuance of an event of default under an indenture, undertakes to perform only those duties as are specifically set forth in the applicable indenture. Upon an event of default under an indenture, the trustee must use the same degree of care as a prudent person would exercise or use in the conduct of his or her own affairs. Subject to this provision, the trustee is under no obligation to exercise any of the powers given it by the indenture at the request of any holder of debt securities unless it is offered reasonable security and indemnity against the costs, expenses and liabilities that it might incur.

**Payment and Paying Agents**

Unless we otherwise indicate in the applicable prospectus supplement, we will make payment of the interest on any debt securities on any interest payment date to the person in whose name the debt securities, or one or more predecessor securities, are registered at the close of business on the regular record date for the interest.

We will pay principal of and any premium and interest on the debt securities of a particular series at the office of the paying agents designated by us, except that unless we otherwise indicate in the applicable prospectus supplement, we will make interest payments by check that we will mail to the holder or by wire transfer to certain holders. Unless we otherwise indicate in the applicable prospectus supplement, we will designate the corporate trust office of the trustee as our sole paying agent for payments with respect to debt securities of each series. We will name in the applicable prospectus supplement any other paying agents that we initially designate for the debt securities of a particular series. We will maintain a paying agent in each place of payment for the debt securities of a particular series.

All money we pay to a paying agent or the trustee for the payment of the principal of or any premium or interest on any debt securities that remains unclaimed at the end of two years after such principal, premium or interest has become due and payable will be repaid to us, and the holder of the debt security thereafter may look only to us for payment thereof.

**Governing Law**

The indenture and the debt securities will be governed by and construed in accordance with the internal laws of the State of New York, except to the extent that the Trust Indenture Act of 1939 is applicable.

**DESCRIPTION OF WARRANTS**

The following description, together with the additional information we may include in any applicable prospectus supplement and in any related free writing prospectus that we may authorize to be distributed to you, summarizes the material terms and provisions of the warrants that we may offer under this prospectus, which may consist of warrants to purchase common stock, preferred stock and/or debt securities and may be issued in one or more series. Warrants may be offered independently or in combination with common stock, preferred stock or debt securities offered by any prospectus supplement, and may be attached to or separate from those securities. While the terms we have summarized below will apply generally to any warrants that we may offer under this prospectus, we will describe the particular terms of any series of warrants that we may offer in more detail in the applicable prospectus supplement. The following description of warrants will apply to the warrants offered by this prospectus unless we provide otherwise in the applicable prospectus supplement. The applicable prospectus supplement for a particular series of warrants may specify different or additional terms.

We have filed forms of the warrant agreements and forms of warrant certificates containing the terms of the warrants that may be offered as exhibits to the registration statement of which this prospectus is a part. We will file as exhibits to the registration statement of which this prospectus is a part, or will incorporate by reference from reports that we file with the SEC, the form of warrant and/or the warrant agreement and warrant certificate, as applicable, that contain the terms of the particular series of warrants we are offering, and any supplemental agreements, before the issuance of such warrants. The following summaries of material terms and provisions of the warrants are subject to, and qualified in their entirety by reference to, all the provisions of the form of warrant and/or the warrant agreement and warrant certificate, as applicable, and any supplemental agreements applicable to a particular series of warrants that we may offer under this prospectus. We urge you to read the applicable prospectus supplement related to the particular series of warrants that we may offer under this prospectus, as well as any related free writing prospectus, and the complete form of warrant and/or the warrant agreement and warrant certificate, as applicable, and any supplemental agreements, that contain the terms of the warrants.

**General**

We will describe in the applicable prospectus supplement the terms of the series of warrants being offered, including, to the extent applicable:

&nbsp;&nbsp;&nbsp;&nbsp;· the offering price and aggregate number of warrants offered;

&nbsp;&nbsp;&nbsp;&nbsp;· the currency for which the warrants may be purchased;

&nbsp;&nbsp;&nbsp;&nbsp;· the designation and terms of the securities with which the warrants are issued and the number of warrants issued with each such security
or each principal amount of such security;

&nbsp;&nbsp;&nbsp;&nbsp;· the date on and after which the warrants and the related securities will be separately transferable;

&nbsp;&nbsp;&nbsp;&nbsp;· in the case of warrants to purchase debt securities, the principal amount of debt securities purchasable upon exercise of one warrant
and the price at, and currency in which, this principal amount of debt securities may be purchased upon such exercise;

&nbsp;&nbsp;&nbsp;&nbsp;· in the case of warrants to purchase common stock or preferred stock, the number of shares of common stock or preferred stock, as the
case may be, purchasable upon the exercise of one warrant and the price at which these shares may be purchased upon such exercise;

&nbsp;&nbsp;&nbsp;&nbsp;· the amount of warrants or rights outstanding;

&nbsp;&nbsp;&nbsp;&nbsp;· the effect of any merger, consolidation, sale or other disposition of our business on the warrant agreements and the warrants;

&nbsp;&nbsp;&nbsp;&nbsp;· the terms of any rights to redeem or call the warrants;

&nbsp;&nbsp;&nbsp;&nbsp;· the terms of any rights to force the exercise of the warrants;

&nbsp;&nbsp;&nbsp;&nbsp;· any provisions for changes to or adjustments in the exercise price or number of securities issuable upon exercise of the warrants;

&nbsp;&nbsp;&nbsp;&nbsp;· the dates on which the right to exercise the warrants will commence and expire;

&nbsp;&nbsp;&nbsp;&nbsp;· the manner in which the warrant agreements and warrants may be modified;

&nbsp;&nbsp;&nbsp;&nbsp;· a discussion of material or special U.S. federal income tax considerations of holding or exercising the warrants;

&nbsp;&nbsp;&nbsp;&nbsp;· the terms of the securities issuable upon exercise of the warrants; and

&nbsp;&nbsp;&nbsp;&nbsp;· any other specific terms, preferences, rights or limitations of or restrictions on the warrants.

Before exercising their warrants, holders of warrants will not have any of the rights of holders of the securities purchasable upon such exercise, including:

&nbsp;&nbsp;&nbsp;&nbsp;· in the case of warrants to purchase debt securities, the right to receive payments of principal of, or premium, if any, or interest
on, the debt securities purchasable upon exercise or to enforce covenants in the applicable indenture; or

&nbsp;&nbsp;&nbsp;&nbsp;· in the case of warrants to purchase common stock or preferred stock, the right to receive dividends, if any, or, payments upon our
liquidation, dissolution or winding up or to exercise voting rights, if any.

**Exercise of Warrants**

Each warrant will entitle the holder to purchase the securities that we specify in the applicable prospectus supplement at the exercise price that we describe in the applicable prospectus supplement. The warrants may be exercised as set forth in the prospectus supplement relating to the warrants offered. Unless we otherwise specify in the applicable prospectus supplement, warrants may be exercised at any time up to the specified time on the expiration date that we set forth in the applicable prospectus supplement. After the close of business on the expiration date, unexercised warrants will become void.

Unless we otherwise specify in the applicable prospectus supplement, holders of the warrants may exercise the warrants by delivering the warrant or warrant certificate, as applicable, representing the warrants to be exercised together with specified information, and paying the required amount to the warrant agent in immediately available funds, as provided in the applicable prospectus supplement. We will set forth in the applicable warrant or warrant certificate and in the applicable prospectus supplement the information that the holder of the warrant will be required to deliver to the warrant agent in connection with the exercise of the warrant.

Upon receipt of the required payment and the warrant or warrant certificate, as applicable, properly completed and duly executed at the corporate trust office of the warrant agent, if any, or any other office, including ours, indicated in the prospectus supplement, we will, as soon as practicable, issue and deliver the securities purchasable upon such exercise. If less than all of the warrants (or the warrants represented by such warrant certificate) are exercised, a new warrant or a new warrant certificate, as applicable, will be issued for the remaining warrants. If we so indicate in the applicable prospectus supplement, holders of the warrants may surrender securities as all or part of the exercise price for warrants.

**Governing Law**

Unless we provide otherwise in the applicable prospectus supplement, the warrants, warrant agreements, and any claim, controversy or dispute arising under or related to the warrants or warrant agreements will be governed by and construed in accordance with the laws of the State of New York.

**Enforceability of Rights by Holders of Warrants**

Each warrant agent, if any, will act solely as our agent under the applicable warrant agreement and will not assume any obligation or relationship of agency or trust with any holder of any warrant. A single bank or trust company may act as warrant agent for more than one issue of warrants. A warrant agent will have no duty or responsibility in case of any default by us under the applicable warrant agreement or warrant, including any duty or responsibility to initiate any proceedings at law or otherwise, or to make any demand upon us. Any holder of a warrant may, without the consent of the related warrant agent or the holder of any other warrant, enforce by appropriate legal action its right to exercise, and receive the securities purchasable upon exercise of, its warrants.

**Outstanding Warrants**

Certain of our outstanding warrants contain customary net exercise provisions and provisions for the adjustment of the exercise price and the number of shares issuable upon the exercise of the warrant in the event of certain stock dividends, stock splits, recapitalizations, reclassifications, consolidations and other fundamental transactions.

**DESCRIPTION OF RIGHTS**

**General**

We may issue rights to our stockholders to purchase shares of our common stock, preferred stock or the other securities described in this prospectus. We may offer rights separately or together with one or more additional rights, debt securities, preferred stock, common stock, warrants or any combination of those securities in the form of units, as described in the applicable prospectus supplement. Each series of rights will be issued under a separate rights agreement to be entered into between us and a bank or trust company, as rights agent. The rights agent will act solely as our agent in connection with the certificates relating to the rights of the series of certificates and will not assume any obligation or relationship of agency or trust for or with any holders of rights certificates or beneficial owners of rights. The following description sets forth certain general terms and provisions of the rights to which any prospectus supplement may relate. The particular terms of the rights to which any prospectus supplement may relate and the extent, if any, to which the general provisions may apply to the rights so offered will be described in the applicable prospectus supplement. To the extent that any particular terms of the rights, rights agreement or rights certificates described in a prospectus supplement differ from any of the terms described below, then the terms described below will be deemed to have been superseded by that prospectus supplement. We encourage you to read the applicable rights agreement and rights certificate for additional information before you decide whether to purchase any of our rights. We will provide in a prospectus supplement the following terms of the rights being issued:

&nbsp;&nbsp;&nbsp;&nbsp;· the date of determining the stockholders entitled to the rights distribution;

&nbsp;&nbsp;&nbsp;&nbsp;· the aggregate number of shares of common stock, preferred stock or other securities purchasable upon exercise of the rights;

&nbsp;&nbsp;&nbsp;&nbsp;· the exercise price;

&nbsp;&nbsp;&nbsp;&nbsp;· the aggregate number of rights issued;

&nbsp;&nbsp;&nbsp;&nbsp;· whether the rights are transferrable and the date, if any, on and after which the rights may be separately transferred;

&nbsp;&nbsp;&nbsp;&nbsp;· the date on which the right to exercise the rights will commence, and the date on which the right to exercise the rights will expire;

&nbsp;&nbsp;&nbsp;&nbsp;· the method by which holders of rights will be entitled to exercise;

&nbsp;&nbsp;&nbsp;&nbsp;· the conditions to the completion of the offering, if any;

&nbsp;&nbsp;&nbsp;&nbsp;· the withdrawal, termination and cancellation rights, if any;

&nbsp;&nbsp;&nbsp;&nbsp;· whether there are any backstop or standby purchaser or purchasers and the terms of their commitment, if any;

&nbsp;&nbsp;&nbsp;&nbsp;· whether stockholders are entitled to oversubscription rights, if any;

&nbsp;&nbsp;&nbsp;&nbsp;· any applicable material U.S. federal income tax considerations; and

&nbsp;&nbsp;&nbsp;&nbsp;· any other terms of the rights, including terms, procedures and limitations relating to the distribution, exchange and exercise of
the rights, as applicable.

Each right will entitle the holder of rights to purchase for cash the principal amount of shares of common stock, preferred stock or other securities at the exercise price provided in the applicable prospectus supplement. Rights may be exercised at any time up to the close of business on the expiration date for the rights provided in the applicable prospectus supplement.

Holders may exercise rights as described in the applicable prospectus supplement. Upon receipt of payment and the rights certificate properly completed and duly executed at the corporate trust office of the rights agent or any other office indicated in the prospectus supplement, we will, as soon as practicable, forward the shares of common stock, preferred stock or other securities, as applicable, purchasable upon exercise of the rights. If less than all of the rights issued in any rights offering are exercised, we may offer any unsubscribed securities directly to persons other than stockholders, to or through agents, underwriters or dealers or through a combination of such methods, including pursuant to standby arrangements, as described in the applicable prospectus supplement.

**Rights Agent**

The rights agent for any rights we offer will be set forth in the applicable prospectus supplement.

**DESCRIPTION OF UNITS**

The following description, together with the additional information that we include in any applicable prospectus supplement and in any free writing prospectus that we may authorize to be distributed to you, summarizes the material terms and provisions of the units that we may offer under this prospectus. While the terms we have summarized below will apply generally to any units that we may offer under this prospectus, we will describe the particular terms of any series of units in more detail in the applicable prospectus supplement. The terms of any units offered under a prospectus supplement may differ from the terms described below.

We will incorporate by reference from reports that we file with the SEC, the form of unit agreement that describes the terms of the series of units we are offering, and any supplemental agreements, before the issuance of the related series of units. The following summaries of material terms and provisions of the units are subject to, and qualified in their entirety by reference to, all the provisions of the unit agreement and any supplemental agreements applicable to a particular series of units. We urge you to read the applicable prospectus supplements related to the particular series of units that we may offer under this prospectus, as well as any related free writing prospectuses and the complete unit agreement and any supplemental agreements that contain the terms of the units.

**General**

We may issue units consisting of common stock, preferred stock, one or more debt securities, warrants or rights for the purchase of common stock, preferred stock and/or debt securities in one or more series in any combination. Each unit will be issued so that the holder of the unit is also the holder of each security included in the unit. Thus, the holder of a unit will have the rights and obligations of a holder of each security included in the unit. The unit agreement under which a unit is issued may provide that the securities included in the unit may not be held or transferred separately, at any time or at any time before a specified date.

We will describe in the applicable prospectus supplement the terms of the series of units being offered, including:

&nbsp;&nbsp;&nbsp;&nbsp;· the designation and terms of the units and of the securities comprising the units, including whether and under what circumstances
those securities may be held or transferred separately;

&nbsp;&nbsp;&nbsp;&nbsp;· any provisions of the governing unit agreement that differ from those described below; and

&nbsp;&nbsp;&nbsp;&nbsp;· any provisions for the issuance, payment, settlement, transfer or exchange of the units or of the securities comprising the units.

The provisions described in this section, as well as those set forth in any prospectus supplement or as described under "Description of Common Stock," "Description of Preferred Stock," "Description of Debt Securities," "Description of Warrants" and "Description of Rights" will apply to each unit, as applicable, and to any common stock, preferred stock, debt security, warrant or right included in each unit, as applicable.

**Unit Agent**

The name and address of the unit agent, if any, for any units we offer will be set forth in the applicable prospectus supplement.

**Issuance in Series**

We may issue units in such amounts and in such numerous distinct series as we determine.

**Enforceability of Rights by Holders of Units**

Each unit agent will act solely as our agent under the applicable unit agreement and will not assume any obligation or relationship of agency or trust with any holder of any unit. A single bank or trust company may act as unit agent for more than one series of units. A unit agent will have no duty or responsibility in case of any default by us under the applicable unit agreement or unit, including any duty or responsibility to initiate any proceedings at law or otherwise, or to make any demand upon us. Any holder of a unit may, without the consent of the related unit agent or the holder of any other unit, enforce by appropriate legal action its rights as holder under any security included in the unit.

**LEGAL OWNERSHIP OF SECURITIES**

We can issue securities in registered form or in the form of one or more global securities. We describe global securities in greater detail below. We refer to those persons who have securities registered in their own names on the books that we or any applicable trustee, depositary or warrant agent maintain for this purpose as the "holders" of those securities. These persons are the legal holders of the securities. We refer to those persons who, indirectly through others, own beneficial interests in securities that are not registered in their own names, as "indirect holders" of those securities. As we discuss below, indirect holders are not legal holders, and investors in securities issued in book-entry form or in street name will be indirect holders.

**Book-Entry Holders**

We may issue securities in book-entry form only, as we will specify in the applicable prospectus supplement. This means securities may be represented by one or more global securities registered in the name of a financial institution that holds them as depositary on behalf of other financial institutions that participate in the depositary's book-entry system. These participating institutions, which are referred to as participants, in turn, hold beneficial interests in the securities on behalf of themselves or their customers.

Only the person in whose name a security is registered is recognized as the holder of that security. Securities issued in global form will be registered in the name of the depositary or its participants. Consequently, for securities issued in global form, we will recognize only the depositary as the holder of the securities, and we will make all payments on the securities to the depositary. The depositary passes along the payments it receives to its participants, which in turn pass the payments along to their customers who are the beneficial owners. The depositary and its participants do so under agreements they have made with one another or with their customers; they are not obligated to do so under the terms of the securities.

As a result, investors in a global security will not own securities directly. Instead, they will own beneficial interests in a global security, through a bank, broker or other financial institution that participates in the depositary's book-entry system or holds an interest through a participant. As long as the securities are issued in global form, investors will be indirect holders, and not legal holders, of the securities.

**Street Name Holders**

We may terminate a global security or issue securities in non-global form. In these cases, investors may choose to hold their securities in their own names or in "street name." Securities held by an investor in street name would be registered in the name of a bank, broker or other financial institution that the investor chooses, and the investor would hold only a beneficial interest in those securities through an account he or she maintains at that institution.

For securities held in street name, we or any applicable trustee or depositary will recognize only the intermediary banks, brokers and other financial institutions in whose names the securities are registered as the holders of those securities, and we or any applicable trustee or depositary will make all payments on those securities to them. These institutions pass along the payments they receive to their customers who are the beneficial owners, but only because they agree to do so in their customer agreements or because they are legally required to do so. Investors who hold securities in street name will be indirect holders, not holders, of those securities.

**Legal Holders**

Our obligations, as well as the obligations of any applicable trustee and of any third parties employed by us or a trustee, run only to the legal holders of the securities. We do not have obligations to investors who hold beneficial interests in global securities, in street name or by any other indirect means. This will be the case whether an investor chooses to be an indirect holder of a security or has no choice because we are issuing the securities only in global form.

For example, once we make a payment or give a notice to the legal holder, we have no further responsibility for the payment or notice even if that legal holder is required, under agreements with its participants or customers or by law, to pass it along to the indirect holders but does not do so. Similarly, we may want to obtain the approval of the legal holders to amend an indenture, to relieve us of the consequences of a default or of our obligation to comply with a particular provision of the indenture or for other purposes. In such an event, we would seek approval only from the legal holders, and not the indirect holders, of the securities. Whether and how the legal holders contact the indirect holders is up to the legal holders.

**Special Considerations for Indirect Holders**

If you hold securities through a bank, broker or other financial institution, either in book-entry form or in street name, you should check with your own institution to find out:

&nbsp;&nbsp;&nbsp;&nbsp;· how it handles securities payments and notices;

&nbsp;&nbsp;&nbsp;&nbsp;· whether it imposes fees or charges;

&nbsp;&nbsp;&nbsp;&nbsp;· how it would handle a request for the holders' consent, if ever required;

&nbsp;&nbsp;&nbsp;&nbsp;· whether and how you can instruct it to send you securities registered in your own name so you can be a holder, if that is permitted
in the future;

&nbsp;&nbsp;&nbsp;&nbsp;· how it would exercise rights under the securities if there were a default or other event triggering the need for holders to act to
protect their interests; and

&nbsp;&nbsp;&nbsp;&nbsp;· if the securities are in book-entry form, how the depositary's rules and procedures will affect these matters.

**Global Securities**

A global security is a security that represents one or any other number of individual securities held by a depositary. Generally, all securities represented by the same global securities will have the same terms.

Each security issued in book-entry form will be represented by a global security that we issue to, deposit with and register in the name of a financial institution or its nominee that we select. The financial institution that we select for this purpose is called the depositary. Unless we specify otherwise in the applicable prospectus supplement, DTC will be the depositary for all securities issued in book-entry form.

A global security may not be transferred to or registered in the name of anyone other than the depositary, its nominee or a successor depositary, unless special termination situations arise. We describe those situations below under "Special Situations When a Global Security Will Be Terminated." As a result of these arrangements, the depositary, or its nominee, will be the sole registered owner and legal holder of all securities represented by a global security, and investors will be permitted to own only beneficial interests in a global security. Beneficial interests must be held by means of an account with a broker, bank or other financial institution that in turn has an account with the depositary or with another institution that does. Thus, an investor whose security is represented by a global security will not be a legal holder of the security, but only an indirect holder of a beneficial interest in the global security.

If the prospectus supplement for a particular security indicates that the security will be issued in global form only, then the security will be represented by a global security at all times unless and until the global security is terminated. If termination occurs, we may issue the securities through another book-entry clearing system or decide that the securities may no longer be held through any book-entry clearing system.

**Special Considerations for Global Securities**

The rights of an indirect holder relating to a global security will be governed by the account rules of the investor's financial institution and of the depositary, as well as general laws relating to securities transfers. We do not recognize an indirect holder as a holder of securities and instead deal only with the depositary that holds the global security.

If securities are issued only in the form of a global security, an investor should be aware of the following:

&nbsp;&nbsp;&nbsp;&nbsp;· an investor cannot cause the securities to be registered in his or her name, and cannot obtain non-global certificates for his or
her interest in the securities, except in the special situations we describe below;

&nbsp;&nbsp;&nbsp;&nbsp;· an investor will be an indirect holder and must look to his or her own bank, broker or other financial institution for payments on
the securities and protection of his or her legal rights relating to the securities, as we describe above;

&nbsp;&nbsp;&nbsp;&nbsp;· an investor may not be able to sell interests in the securities to some insurance companies and to other institutions that are required
by law to own their securities in non-book-entry form;

&nbsp;&nbsp;&nbsp;&nbsp;· an investor may not be able to pledge his or her interest in a global security in circumstances where certificates representing the
securities must be delivered to the lender or other beneficiary of the pledge in order for the pledge to be effective;

&nbsp;&nbsp;&nbsp;&nbsp;· the depositary's policies, which may change from time to time, will govern payments, transfers, exchanges and other matters
relating to an investor's interest in a global security;

&nbsp;&nbsp;&nbsp;&nbsp;· we and any applicable trustee have no responsibility for any aspect of the depositary's actions or for its records of ownership
interests in a global security, nor do we or any applicable trustee supervise the depositary in any way;

&nbsp;&nbsp;&nbsp;&nbsp;· the depositary may, and we understand that DTC will, require that those who purchase and sell interests in a global security within
its book-entry system use immediately available funds, and your bank, broker or other financial institution may require you to do so as
well; and

&nbsp;&nbsp;&nbsp;&nbsp;· financial institutions that participate in the depositary's book-entry system, and through which an investor holds its interest
in a global security, may also have their own policies affecting payments, notices and other matters relating to the securities.

&nbsp;&nbsp;&nbsp;&nbsp;· There may be more than one financial intermediary in the chain of ownership for an investor. We do not monitor and are not responsible
for the actions of any of those intermediaries.

**Special Situations When a Global Security Will Be Terminated**

In a few special situations described below, the global security will terminate and interests in it will be exchanged for physical certificates representing those interests. After that exchange, the choice of whether to hold securities directly or in street name will be up to the investor. Investors must consult their own banks, brokers or other financial institutions to find out how to have their interests in securities transferred to their own name, so that they will be direct holders. We have described the rights of holders and street name investors above.

Unless we provide otherwise in the applicable prospectus supplement, the global security will terminate when the following special situations occur:

&nbsp;&nbsp;&nbsp;&nbsp;· if the depositary notifies us that it is unwilling, unable or no longer qualified to continue as depositary for that global security
and we do not appoint another institution to act as depositary within 90 days;

&nbsp;&nbsp;&nbsp;&nbsp;· if we notify any applicable trustee that we wish to terminate that global security; or

&nbsp;&nbsp;&nbsp;&nbsp;· if an event of default has occurred with regard to securities represented by that global security and has not been cured or waived.

The applicable prospectus supplement may also list additional situations for terminating a global security that would apply only to the particular series of securities covered by the applicable prospectus supplement. When a global security terminates, the depositary, and not we or any applicable trustee, is responsible for deciding the names of the institutions that will be the initial direct holders.

**PLAN OF DISTRIBUTION**

We may sell our securities from time to time:

&nbsp;&nbsp;&nbsp;&nbsp;· to or through underwriters;

&nbsp;&nbsp;&nbsp;&nbsp;· through dealers;

&nbsp;&nbsp;&nbsp;&nbsp;· through agents;

&nbsp;&nbsp;&nbsp;&nbsp;· directly to one or more purchasers;

&nbsp;&nbsp;&nbsp;&nbsp;· ordinary brokerage transactions and transactions in which the broker-dealer solicits purchasers;

&nbsp;&nbsp;&nbsp;&nbsp;· block trades in which the broker-dealer will attempt to sell the shares as agent but may position and resell a portion of the block
as principal to facilitate the transaction;

&nbsp;&nbsp;&nbsp;&nbsp;· purchases by a broker-dealer as principal and resale by the broker-dealer for its account;

&nbsp;&nbsp;&nbsp;&nbsp;· an exchange distribution in accordance with the rules of the applicable exchange; or

&nbsp;&nbsp;&nbsp;&nbsp;· through a combination of any of these methods or any other method permitted by law.

We may directly solicit offers to purchase securities, or agents may be designated to solicit such offers. In any applicable prospectus supplement relating to such offering, we will name any agent that could be viewed as an underwriter under the Securities Act and describe any commissions that we must pay to any such agent. Any such agent will be acting on a best efforts basis for the period of its appointment or, if indicated in the applicable prospectus supplement, on a firm commitment basis. This prospectus may be used in connection with any offering of our securities through any of these methods or other methods described in the applicable prospectus supplement.

The distribution of our securities may be effected from time to time in one or more transactions:

&nbsp;&nbsp;&nbsp;&nbsp;· at a fixed price, or prices, which may be changed from time to time;

&nbsp;&nbsp;&nbsp;&nbsp;· at market prices prevailing at the time of sale;

&nbsp;&nbsp;&nbsp;&nbsp;· at prices related to such prevailing market prices; or

&nbsp;&nbsp;&nbsp;&nbsp;· at negotiated prices.

Each prospectus supplement will describe the method of distribution of the securities and any applicable restrictions.

A prospectus supplement or supplements (and any related free writing prospectus that we may authorize to be provided to you with respect to a particular offering) will describe the terms of the offering of our securities, including the following:

&nbsp;&nbsp;&nbsp;&nbsp;· the name or names of the agent or any underwriters;

&nbsp;&nbsp;&nbsp;&nbsp;· the public offering or purchase price of the securities or other consideration therefor, and the proceeds, if any, we will receive
from the sale;

&nbsp;&nbsp;&nbsp;&nbsp;· any over-allotment options under which underwriters may purchase additional securities from us;

&nbsp;&nbsp;&nbsp;&nbsp;· any agency fees or underwriting discounts and commissions to be allowed or paid to the agent or underwriters;

&nbsp;&nbsp;&nbsp;&nbsp;· all other items constituting underwriting compensation;

&nbsp;&nbsp;&nbsp;&nbsp;· any discounts and commissions to be allowed or paid to dealers; and

&nbsp;&nbsp;&nbsp;&nbsp;· any securities exchange or market on which the securities will be listed.

If any underwriters or agents are used in the sale of our securities in respect of which this prospectus is delivered, we will enter into an underwriting agreement, sales agreement or other agreement with them at the time of sale to them, and we will set forth in the applicable prospectus supplement relating to such offering the names of the underwriters or agents and the terms of the related agreement with them.

In connection with the offering of securities, we may grant to the underwriters an option to purchase additional securities with an additional underwriting commission, as may be set forth in the applicable prospectus supplement.

If a dealer is used in the sale of the securities in respect of which the prospectus is delivered, we will sell such securities to the dealer, as principal. The dealer, who may be deemed to be an "underwriter" as that term is defined in the Securities Act, may then resell such securities to the public at varying prices to be determined by such dealer at the time of resale.

We may provide agents and underwriters with indemnification against civil liabilities, including liabilities under the Securities Act, or contribution with respect to payments that the agents or underwriters may make with respect to those liabilities.

If so indicated in the applicable prospectus supplement, we will authorize underwriters or other persons acting as agents to solicit offers by certain institutions to purchase securities from us pursuant to delayed delivery contracts providing for payment and delivery on the date stated in the applicable prospectus supplement. Each contract will be for an amount not less than, and the aggregate amount of securities sold pursuant to such contracts shall not be less nor more than, the respective amounts stated in the applicable prospectus supplement. Institutions with whom the contracts, when authorized, may be made include commercial and savings banks, insurance companies, pension funds, investment companies, educational and charitable institutions and other institutions. Delayed delivery contracts will not be subject to any conditions except that:

&nbsp;&nbsp;&nbsp;&nbsp;· the purchase by an institution of the securities covered under that contract shall not at the time of delivery be prohibited under
the laws of the jurisdiction to which that institution is subject; and

&nbsp;&nbsp;&nbsp;&nbsp;· if the securities are also being sold to underwriters acting as principals for their own account, the underwriters shall have purchased
such securities not sold for delayed delivery.

Offered securities may also be offered and sold, if so indicated in the applicable prospectus supplement, in connection with a remarketing upon their purchase, in accordance with a redemption or repayment pursuant to their terms, or otherwise, by one or more remarketing firms, acting as principals for their own accounts or as agents for us. Any remarketing firm will be identified and the terms of its agreement, if any, with us and its compensation will be described in the applicable prospectus supplement. Remarketing firms may be deemed to be underwriters in connection with their remarketing of offered securities.

Certain agents, underwriters and dealers, and their associates and affiliates, may be customers of, have borrowing relationships with, engage in other transactions with, or perform services, including investment banking services, for us or one or more of our respective affiliates in the ordinary course of business for which they receive compensation.

In order to facilitate the offering of our securities, any underwriters may engage in transactions that stabilize, maintain or otherwise affect the price of the securities or any other securities the prices of which may be used to determine payments on such securities. Specifically, any underwriters may overallot in connection with the offering, creating a short position for their own accounts. In addition, to cover overallotments or to stabilize the price of the securities or of any such other securities, the underwriters may bid for, and purchase, the securities or any such other securities in the open market. Finally, in any offering of our securities through a syndicate of underwriters, the underwriting syndicate may reclaim selling concessions allowed to an underwriter or a dealer for distributing the securities in the offering if the syndicate repurchases previously distributed securities in transactions to cover syndicate short positions, in stabilization transactions or otherwise. Any of these activities may stabilize or maintain the market price of the securities above independent market levels. Any such underwriters are not required to engage in these activities and may end any of these activities at any time.

We may engage in at the market offerings into an existing trading market in accordance with Rule 415(a)(4) under the Securities Act. In addition, we may enter into derivative transactions with third parties, or sell securities not covered by this prospectus to third parties in privately negotiated transactions. If the applicable prospectus supplement so indicates, in connection with those derivatives, the third parties may sell securities covered by this prospectus and the applicable prospectus supplement, including in short sale transactions. If so, the third party may use securities pledged by us or borrowed from us or others to settle those sales or to close out any related open borrowings of stock, and may use securities received in settlement of those derivatives to close out any related open borrowings of stock. The third party in such sale transactions will be an underwriter and, if not identified in this prospectus, will be named in the applicable prospectus supplement (or a post-effective amendment). In addition, we may otherwise loan or pledge securities to a financial institution or other third party that in turn may sell the securities short using this prospectus and an applicable prospectus supplement. Such financial institution or other third party may transfer its economic short position to investors in our securities or in connection with a concurrent offering of other securities.

Under Rule 15c6-1 of the Exchange Act, trades in the secondary market generally are required to settle in two business days, unless the parties to any such trade expressly agree otherwise. The applicable prospectus supplement may provide that the original issue date for your securities may be more than two scheduled business days after the trade date for your securities. Accordingly, in such a case, if you wish to trade securities on any date prior to the second business day before the original issue date for your securities, you will be required, by virtue of the fact that your securities initially are expected to settle in more than two scheduled business days after the trade date for your securities, to make alternative settlement arrangements to prevent a failed settlement.

The specific terms of any lock-up provisions in respect of any given offering will be described in the applicable prospectus supplement. The anticipated date of delivery of offered securities will be set forth in the applicable prospectus supplement relating to each offer.

**LEGAL MATTERS**

Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C., New York, New York, will pass upon the validity of the securities offered hereby unless otherwise indicated in the applicable prospectus supplement. Any underwriters will also be advised about the validity of the securities and other legal matters by their own counsel, which will be named in the applicable prospectus supplement.

**EXPERTS**

Our consolidated financial statements appearing in our Annual Report on Form 10-K for the year ended December 31, 2020, have been audited by Moss Adams LLP, an independent registered public accounting firm, as stated in their report, which is incorporated herein by reference. Such consolidated financial statements have been so incorporated in reliance upon the report of such firm given upon their authority as experts in auditing and accounting.

**WHERE YOU CAN FIND MORE INFORMATION**

We are a reporting company and file annual, quarterly and current reports, proxy statements and other information with the SEC. This prospectus is part of the registration statement on Form S-3 we filed with the SEC under the Securities Act and does not contain all the information set forth or incorporated by reference in the registration statement. Whenever a reference is made in this prospectus to any of our contracts, agreements or other documents, the reference may not be complete and you should refer to the exhibits that are a part of the registration statement or the exhibits to the reports or other documents incorporated by reference into this prospectus for a copy of such contract, agreement or other document. You may read and copy the registration statement, as well as our reports, proxy statements and other information, at the SEC's Public Reference Room at 100 F Street, N.E., Washington, D.C. 20549. Please call the SEC at 1-800-SEC-0330 for more information about the operation of the public reference room. The SEC also maintains an Internet site that contains reports, proxy and information statements and other information regarding issuers that file electronically with the SEC, including SELLAS Life Sciences Group, Inc. The SEC's Internet site can be found at www.sec.gov. We maintain a website at www.sellaslife.com. Information found on, or accessible through, our website is not a part of, and is not incorporated into, this prospectus, or any prospectus supplement, and you should not consider it part of this prospectus or any prospectus supplement.

**INCORPORATION BY REFERENCE**

The SEC allows us to incorporate by reference the information we file with it, which means that we can disclose important information to you by referring you to another document that we have filed separately with the SEC. You should read the information incorporated by reference because it is an important part of this prospectus and the applicable prospectus supplement. Information in this prospectus supersedes information incorporated by reference that we filed with the SEC prior to the date of this prospectus, while information that we file later with the SEC will automatically update and supersede the information in this prospectus and the applicable prospectus supplement. We incorporate by reference into this prospectus and the registration statement of which this prospectus is a part the information or documents listed below that we have filed with the SEC (Commission File No. 001-33958):

&nbsp;&nbsp;&nbsp;&nbsp;· [our Annual Report on Form 10-K for the year ended December 31, 2020, filed with the SEC on March 23, 2021;](https://www.sec.gov/ix?doc=/Archives/edgar/data/1390478/000139047821000007/sls-20201231.htm)

&nbsp;&nbsp;&nbsp;&nbsp;· our Current Reports on Form 8-K, filed with the SEC on [January 14, 2021](https://www.sec.gov/Archives/edgar/data/1390478/000110465921004248/tm213149d1_8k.htm) , [January 28, 2021](https://www.sec.gov/Archives/edgar/data/1390478/000110465921008294/tm214421d1_8ka.htm) , [February 4, 2021](https://www.sec.gov/Archives/edgar/data/1390478/000110465921011694/tm215305d1_8k.htm) , and [March 23, 2021](https://www.sec.gov/Archives/edgar/data/1390478/000139047821000009/sls-20210323x8xk.htm) (except for the information furnished under Items 2.02 or 7.01 and the exhibits furnished
 thereto); and

&nbsp;&nbsp;&nbsp;&nbsp;· [the description of our common stock set forth in our registration statement on Form 8-A, filed with the SEC on February 8, 2008,](https://www.sec.gov/Archives/edgar/data/1390478/000095013508000652/b684708ae8va12b.htm) as
amended on [February 12, 2008](https://www.sec.gov/Archives/edgar/data/1390478/000095013508000827/b68470aae8va12bza.htm) , including any further amendments thereto or reports filed for the purposes of updating this description.

We also incorporate by reference any future filings (other than the portions of current reports furnished under Item 2.02 or Item 7.01 of Form 8-K and exhibits filed on such form that are related to such items unless such Form 8-K expressly provides to the contrary) made with the SEC pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act, including those made after the date of the initial filing of the registration statement of which this prospectus is a part and prior to effectiveness of such registration statement, until we file a post-effective amendment that indicates the termination of the offering of the common stock made by this prospectus and will become a part of this prospectus from the date that such documents are filed with the SEC. Information in such future filings updates and supplements the information provided in this prospectus and any applicable prospectus supplement. Any statements in any such future filings will automatically be deemed to modify and supersede any information in any document we previously filed with the SEC that is incorporated or deemed to be incorporated herein by reference to the extent that statements in the later filed document modify or replace such earlier statements.

We will furnish without charge to each person, including any beneficial owner, to whom a prospectus and applicable prospectus supplement is delivered, upon written or oral request, a copy of any or all of the documents incorporated by reference into this prospectus but not delivered with the prospectus and applicable prospectus supplement, including exhibits that are specifically incorporated by reference into such documents. You should direct any requests for documents to SELLAS Life Sciences Group, Inc., Attention: Corporate Secretary, 7 Times Square, Suite 2503, New York, NY 10036. Our phone number is (646) 200-5278.

**Shares**

**Warrants to Purchase up to Shares**

![](tm237388d1_424b5img001.jpg)

**Common Stock**

&nbsp;&nbsp;**PRELIMINARY PROSPECTUS SUPPLEMENT**

***Sole Book-Running Manager***

**Cantor**

, 2023