# EDGAR Filing Document

**Accession Number:** 0001659617
**File Stem:** 0001437749-25-022604
**Filing Date:** 2025-7
**Character Count:** 142773
**Document Hash:** fbc4e894b6fce8b7079487a21033ceb2
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001437749-25-022604.hdr.sgml**: 20250711

**ACCESSION NUMBER**: 0001437749-25-022604

**CONFORMED SUBMISSION TYPE**: 424B5

**PUBLIC DOCUMENT COUNT**: 3

**FILED AS OF DATE**: 20250711

**DATE AS OF CHANGE**: 20250711

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Moleculin Biotech, Inc.
- **CENTRAL INDEX KEY:** 0001659617
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 474671997
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 424B5
- **SEC ACT:** 1933 Act
- **SEC FILE NUMBER:** 333-280064
- **FILM NUMBER:** 251119780

**BUSINESS ADDRESS:**
- **STREET 1:** 5300 MEMORIAL DRIVE
- **STREET 2:** SUITE 950
- **CITY:** HOUSTON
- **STATE:** TX
- **ZIP:** 77007
- **BUSINESS PHONE:** 713-300-5160

**MAIL ADDRESS:**
- **STREET 1:** 5300 MEMORIAL DRIVE
- **STREET 2:** SUITE 950
- **CITY:** HOUSTON
- **STATE:** TX
- **ZIP:** 77007

[**Table of Contents**](#toc)

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

**Registration No. 333-280064**

**Prospectus Supplement**

**(to Prospectus dated July 1, 2024)**

![image1.jpg](image1.jpg)

**Moleculin Biotech, Inc.**

**Up to $6,500,000**

**Common Stock**

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On July 11, 2025, we entered into a certain At The Market Offering Agreement ("ATM Agreement") with Roth Capital Partners, LLC as sales agent ("Roth") relating to the sale of shares of our common stock, par value $0.001 per share, offered by this prospectus supplement and the accompanying prospectus. In accordance with the terms of the ATM Agreement, under this prospectus supplement and the accompanying prospectus, we may offer and sell shares of our common stock having an aggregate offering price of up to $6.5 million from time to time through or to Roth, acting as our sales agent or principal.

Sales of our common stock, if any, under this prospectus supplement and the accompanying prospectus may be made in sales deemed to be "at the market offerings" as defined in Rule 415(a)(4) promulgated under the Securities Act of 1933, as amended (the "Securities Act"). If authorized by us in writing, Roth may also sell shares of our common stock in negotiated transactions at market prices prevailing at the time of sale or at prices related to such prevailing market prices. If we and Roth agree on any method of distribution other than sales of shares of our common stock on or through the Nasdaq Capital Market or another existing trading market in the United States at market prices, we will file a further prospectus supplement providing all information about such offering as required by Rule 424(b) under the Securities Act. Roth is not required to sell any specific number or dollar amount of securities but will act as a sales agent using commercially reasonable efforts consistent with its normal trading and sales practices, on mutually agreed terms between us and Roth. There is no arrangement for funds to be received in any escrow, trust or similar arrangement.

Compensation to Roth for sales of common stock sold pursuant to the ATM Agreement will be equal to up to 3.0% of the gross proceeds of any shares of common stock sold under the ATM Agreement, in addition to the reimbursement of certain expenses. In connection with the sale of our common stock on our behalf, Roth will be deemed to be an "underwriter" within the meaning of the Securities Act and the compensation paid to Roth will be deemed to be underwriting commissions or discounts. We have also agreed to provide indemnification and contribution to Roth with respect to certain liabilities, including liabilities under the Securities Act or the Securities Exchange Act of 1934, as amended (the "Exchange Act"). See "Plan of Distribution" on page S-13.

Our common stock is listed on The Nasdaq Capital Market ("Nasdaq"), under the symbol "MBRX." On July 10, 2025, the last reported sale price of our common stock on Nasdaq was $0.53 per share.

As of July 10, 2025, the aggregate market value of the voting and non-voting common equity held by non-affiliates, our public float, was approximately $31.5 million, , based on 30,207,494 shares of outstanding common stock as of July 10, 2025, of which 29,165,169 shares were held by non-affiliates, and at a price of $1.08 per share, the closing sale price of our common stock on May 12, 2025, which is the highest closing sale price of our common stock on Nasdaq within the prior 60 days of this prospectus supplement. Pursuant to General Instruction I.B.6 of Form S-3, in no event will we sell securities in a public primary offering with a value exceeding more than one-third of our public float in any 12-month period so long as our public float remains below $75.0 million. During the 12 calendar months prior to and including the date of this prospectus supplement, we have sold approximately $3.8 million of securities pursuant to General Instruction I.B.6 of Form S-3.

**Investing in our securities involves a high degree of risk. See** "**Risk Factors**" **beginning on page S-9 of this prospectus supplement and the risk factors incorporated by reference into this prospectus supplement and the accompanying prospectus.**

**Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus supplement or the accompanying prospectus. Any representation to the contrary is a criminal offense.**

**Roth Capital Partners**

The date of this prospectus supplement is July 11, 2025

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[**Table of Contents**](#toc)

**TABLE OF CONTENTS**

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| | |
|:---|:---|
| **PROSPECTUS SUPPLEMENT** |  |
|  | **Page** |
| [<u>ABOUT THIS PROSPECTUS SUPPLEMENT</u>](#about_prosp) | [<u>S-1</u>](#about_prosp) |
| [<u>PROSPECTUS SUPPLEMENT SUMMARY</u>](#prosp_sup) | [<u>S-2</u>](#prosp_sup) |
| [<u>THE OFFERING</u>](#offering) | [<u>S-5</u>](#offering) |
| [<u>RISK FACTORS</u>](#risk) | [<u>S-6</u>](#risk) |
| [<u>FORWARD-LOOKING STATEMENTS</u>](#forward_look) | [<u>S-10</u>](#forward_look) |
| [<u>USE OF PROCEEDS</u>](#use_proce) | [<u>S-11</u>](#use_proce) |
| [<u>DIVIDEND POLICY</u>](#dive_pol) | [<u>S-11</u>](#dive_pol) |
| [<u>DILUTION</u>](#dilut) | [<u>S-11</u>](#dilut) |
| [<u>PLAN OF DISTRIBUTION</u>](#plan_dist) | [S-13](#plan_dist) |
| [<u>LEGAL MATTERS</u>](#legal_mat) | [<u>S-14</u>](#legal_mat) |
| [<u>EXPERTS</u>](#experts) | [<u>S-14</u>](#experts) |
| [<u>INCORPORATION BY REFERENCE</u>](#incorp_ref) | [<u>S-14</u>](#incorp_ref) |
| [<u>WHERE YOU CAN FIND MORE INFORMATION</u>](#more_info) | [<u>S-15</u>](#more_info) |

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| | |
|:---|:---|
| **PROSPECTUS** |  |
|  | **Page** |
| [<u>ABOUT THIS PROSPECTUS</u>](#about_this) | [<u>1</u>](#about_this) |
| [<u>WHERE YOU CAN FIND MORE INFORMATION</u>](#where_more) | [<u>1</u>](#where_more) |
| [<u>INCORPORATION BY REFERENCE</u>](#incorporation) | [<u>2</u>](#incorporation) |
| [<u>ABOUT MOLECULIN BIOTECH, INC.</u>](#about_mole) | [<u>2</u>](#about_mole) |
| [<u>RISK FACTORS</u>](#risk_fact) | [<u>3</u>](#risk_fact) |
| [<u>FORWARD-LOOKING STATEMENTS</u>](#forward_state) | [<u>3</u>](#forward_state) |
| [<u>USE OF PROCEEDS</u>](#use_of) | [<u>3</u>](#use_of) |
| [<u>DESCRIPTION OF COMMON STOCK</u>](#desc_common) | [<u>3</u>](#desc_common) |
| [<u>DESCRIPTION OF PREFERRED STOCK</u>](#desc_pref) | [<u>5</u>](#desc_pref) |
| [<u>DESCRIPTION OF DEBT SECURITIES</u>](#desc_debt) | [<u>5</u>](#desc_debt) |
| [<u>DESCRIPTION OF THE WARRANTS</u>](#desc_warr) | [<u>12</u>](#desc_warr) |
| [<u>DESCRIPTION OF UNITS</u>](#desc_unit) | [<u>13</u>](#desc_unit) |
| [<u>PLAN OF DISTRIBUTION</u>](#plan_distrib) | [<u>14</u>](#plan_distrib) |
| [<u>LEGAL MATTERS</u>](#legal) | [<u>16</u>](#legal) |
| [<u>EXPERTS</u>](#expert) | [<u>16</u>](#expert) |

---

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**ABOUT THIS PROSPECTUS SUPPLEMENT**

This prospectus supplement and the accompanying prospectus are part of a registration statement that we filed with the Securities and Exchange Commission (the "SEC") utilizing a "shelf" registration process. Each time we conduct an offering to sell securities under the accompanying prospectus we will provide a prospectus supplement that will contain specific information about the terms of that offering, including the price, the amount of securities being offered and the plan of distribution. The shelf registration statement was initially filed with the SEC on June 7, 2024, and was declared effective by the SEC on July 1, 2024. This prospectus supplement describes the specific details regarding this offering and may add, update or change information contained in the accompanying prospectus and the documents incorporated by reference herein and therein. The accompanying prospectus provides general information about us and our securities, some of which, such as the section entitled "Plan of Distribution," may not apply to this offering. This prospectus supplement and the accompanying prospectus are an offer to sell only the securities offered hereby, but only under circumstances and in jurisdictions where it is lawful to do so. We are not making offers to sell or solicitations to buy our common stock in any jurisdiction in which an offer or solicitation is not authorized or in which the person making that offer or solicitation is not qualified to do so or to anyone to whom it is unlawful to make an offer or solicitation.

This prospectus supplement relates only to an offering of up to $6.5 million of shares of our common stock made pursuant to the terms of the ATM Agreement entered into between us and Roth on July 11, 2025, a copy of which is incorporated by reference into this prospectus supplement.

If information in this prospectus supplement is inconsistent with the accompanying prospectus or the information incorporated by reference with an earlier date, you should rely on this prospectus supplement. This prospectus supplement, together with the accompanying prospectus, the documents incorporated by reference into this prospectus supplement and the accompanying prospectus and any free writing prospectus we have authorized for use in connection with this offering include all material information relating to this offering. We have not, authorized anyone to provide you with different or additional information and you must not rely on any unauthorized information or representations. We and Roth take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. You should assume that the information appearing in this prospectus supplement, the accompanying prospectus, the documents incorporated by reference in this prospectus supplement and the accompanying prospectus and any free writing prospectus we have authorized for use in connection with this offering is accurate only as of the respective dates of those documents. Our business, financial condition, results of operations and prospects may have changed since those dates. You should carefully read this prospectus supplement, the accompanying prospectus and the information and documents incorporated by reference herein and therein, as well as any free writing prospectus we have authorized for use in connection with this offering, before making an investment decision. See "Incorporation by Reference" and "Where You Can Find More Information" in this prospectus supplement and in the accompanying prospectus.

No action is being taken in any jurisdiction outside the United States to permit a public offering of these securities or possession or distribution of this prospectus supplement or the accompanying prospectus in that jurisdiction. Persons who come into possession of this prospectus supplement and the accompanying prospectus in jurisdictions outside the United States are required to inform themselves about and to observe any restrictions as to this offering and the distribution of this prospectus supplement and the accompanying prospectus applicable to that jurisdiction.

This prospectus supplement and the accompanying prospectus contain summaries of certain provisions contained in some of the documents described herein which are summaries only and are not intended to be complete. Reference is made to the actual documents for complete information. All of the summaries are qualified in their entirety by the full text of the actual documents, some of which have been filed or will be filed and incorporated by reference herein. See "Where You Can Find More Information" in this prospectus supplement. We further note that the representations, warranties and covenants made by us in any agreement that is filed as an exhibit to any document that is incorporated by reference into this prospectus supplement or the accompanying prospectus were made solely for the benefit of the parties to such agreement, including, in some cases, for the purpose of allocating risk among the parties to such agreements, and should not be deemed to be a representation, warranty or covenant to you. Moreover, such representations, warranties or covenants were accurate only as of the date when made. Accordingly, such representations, warranties and covenants should not be relied on as accurately representing the current state of our affairs.

S-i

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This prospectus supplement and the accompanying prospectus contain and incorporate by reference certain market data and industry statistics and forecasts that are based on Company-sponsored studies, independent industry publications and other publicly available information. Although we believe these sources are reliable, estimates as they relate to projections involve numerous assumptions, are subject to risks and uncertainties, and are subject to change based on various factors, including those discussed under "Risk Factors" in this prospectus supplement and the accompanying prospectus and under similar headings in the documents incorporated by reference herein and therein. Accordingly, investors should not place undue reliance on this information.

Unless otherwise stated or the context requires otherwise, all references in this prospectus supplement to the "Company," "we," "us," "our", "Moleculin" refer to Moleculin Biotech, Inc., a Delaware corporation.

S-ii

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**PROSPECTUS SUPPLEMENT SUMMARY**

*This summary highlights information contained elsewhere in this prospectus supplement, the accompanying prospectus and the documents incorporated by reference herein and therein. This summary does not contain all of the information that you should consider before deciding to invest in our securities. You should read this entire prospectus supplement and the accompanying prospectus carefully, including the section entitled* "*Risk Factors*" *beginning on page S-6 and our consolidated financial statements and the related notes and the other information incorporated by reference into this prospectus supplement and the accompanying prospectus, before making an investment decision.*

**Overview**

We are a late-stage pharmaceutical development company currently conducting a pivotal Phase 3 trial evaluating Annamycin (also known by its non-proprietary name "naxtarubicin") in combination with Cytarabine for the treatment of subjects with relapsed/refractory (R/R) acute myeloid leukemia (AML). This Phase 3 trial should have an interim unblinding of data by the end of 2025, less than a year from its commencement, and an additional unblinding in the first half of 2026. We believe such early visibility for a pivotal registration-enabling trial is highly unique in that stakeholders will receive preliminary safety and efficacy data in the "MIRACLE" trial (derived from Moleculin R/R AML AnnAraC Clinical Evaluation) within one year of dosing the first subject. Additionally, we have two portfolios of technologies for hard-to-treat cancers and viruses with clinical and preclinical research funded by investigators at academic institutions.

Each of our three core technologies is based substantially on discoveries made at and licensed from the University of Texas MD Anderson Cancer Center (MD Anderson) in Houston, Texas, and features one or more drugs that have successfully completed a Phase 1 clinical trial. Three of our six drug candidates have shown human activity in clinical trials and are currently or have been in Phase 1B/2 or Phase 2 clinical trials. One Phase 2B/3 trial is currently underway. Since our inception, our drugs have completed, are currently in, or have been permitted to proceed in, fourteen clinical trials. Annamycin is in a class of drugs referred to as Anthracyclines, which are inhibitors of topoisomerase II, enabling them to cause DNA damage in rapidly replicating tumor cells. Annamycin, in a unique multilamellar lipid formulation, is our lead molecule and we have recently concluded treating subjects in one Phase 1B/2 clinical trial for treating Acute Myeloid Leukemia (AML) and are embarking on a Phase 3 clinical trial for the treatment of AML, which we believe will be pivotal. Annamycin has also been in two Phase 1B/2 clinical trials for treating Soft Tissue Sarcoma metastasized to the lungs (STS lung metastases, STS lung mets, or Advanced STS). Our Phase 1B/2 STS lung mets trial MB-107 is completed, and a clinical study report has been issued. The other trial is an investigator initiated Advanced STS trial which is closed to recruitment.

One of our core management beliefs is that anthracyclines represent one of the most important treatments for AML and Advanced STS, and we believe Annamycin may, for the first time ever, allow a majority of these patients to benefit from this treatment. We believe that such a benefit could be disruptive to the competitive landscape for these markets. This belief, coupled with our limited resources, leads us to currently focus mainly on the development of Annamycin. We intend to advance our other drug candidates via investigator led studies - both clinically and preclinically.

<u>Focus and Core Technologies</u>

Our core technologies consist of the following programs:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;a) Annamycin or L-Annamycin is a "next generation" anthracycline (one of the most widely used classes of chemotherapy), designed to be different than currently approved anthracyclines, which are limited in utility because of cardiotoxicity risks and their susceptibility to multidrug resistance mechanisms. Annamycin was designed to avoid multidrug resistance and to be non-cardiotoxic and, with intensive cardiac monitoring, has shown no cardiotoxicity in subjects treated in our five Annamycin clinical trials to date. Furthermore, we have demonstrated safe dosing significantly beyond the lifetime dose limitations imposed by regulatory authorities upon commonly prescribed anthracyclines due to their inherent cardiotoxicity.

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

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;b) Our WP1066 Portfolio includes WP1066, WP1193 and WP1220, three of several Immune/Transcription Modulators in the portfolio designed to inhibit p-STAT3 (phosphorylated signal transducer and activator of transcription 3) among other transcription factors associated with tumor activity. These also stimulate a natural immune response to tumors by inhibiting the errant activity of Regulatory T-Cells (TRegs).

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;c) Our WP1122 Portfolio contains compounds (including WP1122, WP1096, and WP1097) designed to exploit the potential uses of inhibitors of glycolysis such as 2-deoxy-D-glucose (2-DG). We believe such compounds may provide an opportunity to cut off the energy supply of tumors by taking advantage of their high degree of dependence on glucose in comparison to healthy cells, as well as viruses that also depend upon glycolysis and glycosylation to infect and replicate.

<u>Annamycin and the Lack of Cardiotoxicity</u>

As part of our Annamycin clinical trials, we have engaged an independent expert at the Cleveland Clinic to assess cardiotoxicity associated with chemotherapy (Expert or Independent Expert). The data made available to the Expert include left ventricular ejection fraction (LVEF) as determined by echocardiograms, and ECHO strain imaging, as well as serum Troponin levels (a biochemical marker of acute heart damage). "ECHO strain imaging" is a method in echocardiography (medical ultrasound) for measuring regional or global deformation (contraction or beating) of the myocardium (heart muscle). By strain rate imaging, the simultaneous function of different regions can be displayed and measured. Cardiac health biomarkers such as blood Troponin levels are considered an indicator of potential long-term heart damage. The Expert issued periodic reports during our MB-106 clinical trial and will also issue updated reports after each unblinding in the Phase 2B portions of the MIRACLE trial. Such data from clinical trials where a clinical study report has not yet been issued include some data which are preliminary and subject to change.

We received several independent assessments for the absence of cardiotoxicity in subjects treated with Annamycin. We now have independent assessments covering 84 subjects that have been treated with Annamycin in five different clinical trials in the U.S. and Europe with no evidence of cardiotoxicity. To date of the 77 subjects treated in our internally funded trials, 56 were treated above the FDA's lifetime maximum anthracycline limit of 550 mg/m2, including one subject whose repeated Annamycin treatments took that subject to a total cumulative anthracycline exposure of 3,420 mg/m2 (or roughly five times the FDA approved lifetime anthracycline exposure) and there has been no evidence of cardiotoxicity reported. After review of the data provided, the Independent Expert, in their most recent report and as stated in previous reports, concluded that there was no evidence of drug-related cardiotoxicity in any subjects.

We believe the Expert's reports are particularly relevant in light of a recently published retrospective study showing that the incidence of heart failure more than doubles for cancer patients treated with anthracyclines compared to cancer patients not receiving anthracyclines (C Larson, et al. Anthracycline and Heart Failure in Patients Treated for Breast Cancer or Lymphoma, 1985-2010. JAMA Network Open. 2023;6(2):e2254669. doi:10.1001/jamanetworkopen.2022.54669). Given the heart-damaging impact of prior treatment with currently prescribed anthracyclines, and considering that the subject population that we are enrolling in our Annamycin trials (multiple prior therapies, including anthracyclines known to be cardiotoxic, many elderly, and other comorbidities) we believe that there is a high likelihood that a cardiac event will eventually occur in the future that we will not be able to disassociate from Annamycin. We believe that the potential for such future incidences, however, does not outweigh the significant lack of cardiotoxicity to date as reflected in the Expert's reports.

Although we have not definitively concluded that Annamycin is incapable of cardiotoxicity, we discuss Annamycin's lack of demonstrated cardiotoxicity in this document, corporate presentations and other public communications. Such discussions reflect the information in the preceding paragraphs but in summary are based on the following: 1) Annamycin was initially designed to be non-cardiotoxic; 2) Preclinical studies have demonstrated Annamycin lacks cardiotoxicity as compared to a currently prescribed anthracycline; and, 3) Our Expert's conclusions from analyzing the data from 84 subjects treated with Annamycin in five clinical studies conducted in the US and in Europe. Our discussions will reflect any additional data or analyses as they become available.

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<u>Clinical Trials Summary</u>

We have multiple active INDs/CTAs ("Investigational New Drug" authorization in the US or "Clinical Trial Authorization" in Europe). These INDs/CTAs are under development, approved, in progress, or completed and comprise a total of fourteen clinical trials, internally and externally funded. With Annamycin, we currently have active two AML clinical trials: MB-106 which is a Phase 1B/2 treating AML with AnnAraC (recruitment is closed and this trial is now in subject follow-up) and MB-108 which is a Phase 2B/3 pivotal clinical trial treating R/R AML as 2nd line therapy (recruitment has started and additional sites are being added). Additionally, there is one externally funded Phase 1B/2 trial treating STS Lung Mets with Annamycin as monotherapy. This trial is closed and is in follow-up on the trial's subjects. With WP1066, we have an externally funded Phase 1B/2 trial in combination with radiation treating GBM at Northwestern University that is actively recruiting.

*MIRACLE Trial*

We have a Phase 3 pivotal trial with Annamycin in combination with Cytarabine for the treatment of AML patients who are R/R after induction therapy. This Phase 3 "MIRACLE" trial is a global study. It is an adaptive trial designed with a lead-in Part A portion of the study having three arms (control arm with cytarabine, and two test arms with cytarabine plus two different doses of Annamycin) intended to determine an "optimum dose" to be used in Part B of the study. Once an optimum dose for the Annamycin is determined the study will continue into Part B with two arms (control arm with cytarabine and a test arm with cytarabine plus Annamycin). In some contexts, we refer to Part A as Phase 2B and Part B as Phase 3, however the adaptive design enables the combining of data from Part A (for the optimum dose) with Part B such that data from both parts A and B will comprise Phase 3 data.

**Recent Developments**

*June Offering*

On June 23, 2025, we completed a best efforts public offering (the "June Offering") of (i) 9,972,026 shares (the "June Shares") of the Company's common stock; (ii) pre-funded warrants to purchase up to an aggregate of 6,107,974 shares of common stock (the "June Pre-Funded Warrants"); and (iii) Series E Warrants to purchase up to an aggregate of 48,240,000 shares of common stock (the "Series E Warrants"). The Series E Warrants and June Pre-Funded Warrants are collectively referred to herein as the "June Warrants". The combined purchase price for the securities was $0.37 per share of common stock and accompanying Series E Warrant, and $0.369 per June Pre-Funded Warrant and accompanying Series E Warrant. Roth acted as the exclusive placement agent for the June Offering pursuant to a Placement Agency Agreement, dated June 20, 2025 (the "June Agency Agreement").

Each June Pre-Funded Warrant is exercisable for one share of common stock at an exercise price of $0.001 per share (as adjusted from time to time in accordance with the terms thereof). The June Pre-Funded Warrants are exercisable immediately and may be exercised at any time until all of the June Pre-Funded Warrants are exercised in full, subject to the Beneficial Ownership Limitation described below. Each Series E Warrant has an initial exercise price of $0.37 per share and will be exercisable beginning on the effective date of stockholder approval of the issuance of the shares upon exercise of the Series E Warrants (the "Warrant Stockholder Approval"). The Company agreed to seek Warrant Stockholder Approval no later than 60 days after the consummation of the June Offering.

The Company agreed to seek approval for an amendment to its certificate of incorporation to increase its authorized shares of common stock (the "Amendment") such that it can issue all shares of common stock required under the Series E Warrants upon any future adjustments to the exercise price of the Series E Warrants described below (the "Authorized Share Approval"). If the Company does not obtain Warrant Stockholder Approval and the Authorized Share Approval at the first stockholder meeting for such purpose after the June Offering, the Company agreed to call a stockholder meeting every 60 days thereafter until the earlier of the date it obtains the Warrant Stockholder Approval and the Authorized Share Approval or the date the Series E Warrants are no longer outstanding.

The Company will see the Warrant Stockholder Approval and Authorized Share Approval at its Annual Meeting of Stockholders on August 18, 2025.

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The Series E Warrants provide that if, while the Series E Warrants are outstanding, the Company sells any common stock and/or common stock equivalents other than in connection with certain exempt issuances, at a purchase price per share less than the exercise price of the Series E Warrants in effect immediately prior to such sale, then immediately after such sale the exercise price of the Series E Warrants then in effect will be reduced to an amount equal to the new issuance price, and, following the Authorized Share Increase Date (as defined below), the number of shares issuable upon exercise of the Series E Warrants will be proportionately adjusted such that the aggregate price will remain unchanged, subject to the floor price of $0.12. In addition, the Series E Warrants provide that if at any time on or after the date of issuance there occurs any share split, share dividend, share combination recapitalization or other similar transaction involving the common stock and the lowest daily volume weighted average price during the period commencing five consecutive trading days immediately preceding and the five consecutive trading days commencing on the date of such event is less than the exercise price of the Series E Warrants then in effect, then the exercise price of the Series E Warrants will be reduced to the lowest daily volume weighted average price during such period and, following the Authorized Share Increase Date, the number of shares issuable upon exercise will be proportionately adjusted such that the aggregate price will remain unchanged, subject to the floor price of $0.12. The Series E Warrants will expire five years from the date of the Warrant Stockholder Approval. The date on which the Warrant Stockholder Approval is obtained and deemed effective under Delaware law is referred to herein as the Stockholder Approval Date, and the date on which the Amendment is filed and accepted with the State of Delaware is referred to herein as the Authorized Share Increase Date.

The gross proceeds from the June Offering, before deducting the placement agent fees and other offering expenses payable by the Company, were approximately $5.9 million and up to an additional approximately $17.8 million in gross proceeds if the June Warrants are fully exercised for cash.

In connection with the June Offering, the Company entered into securities purchase agreements (the "Purchase Agreements") with certain institutional investors. Pursuant to the Purchase Agreements, the Company agreed that until sixty days after the later of (1) the Stockholder Approval Date and (2) the Authorized Share Increase Date, that neither the Company nor any of its subsidiaries will (i) issue, enter into any agreement to issue or announce the issuance or proposed issuance of any shares of common stock or any securities convertible into or exercisable or exchangeable for shares of common stock, other than the entering into an "at the market" offering agreement with Roth as placement agent, provided no sales are made during this prohibition period or (ii) file any registration statement or amendment or supplement thereto, other than (A) a registration statement on Form S-8 in connection with any employee benefit plan, or (B) a prospectus supplement for an "at the market" offering with Roth as placement agent as sales agent provided no sales are made pursuant to such prospectus supplement during this prohibition period. In addition, pursuant to the Purchase Agreements, the Company has agreed not to effect or enter into an agreement to effect any issuance of common stock or any securities convertible into or exercisable or exchangeable for shares of common stock involving a variable rate transaction (as defined in the Purchase Agreement) until 180 days following the later of (1) the Stockholder Approval Date and (2) the Authorized Share Increase Date, subject to certain exceptions, including that the Company may enter into an "at the market" offering agreement with Roth and make sales under such agreement 60 days after the later of the (1) Stockholder Approval Date and (2) Authorized Share Increase Date.

Pursuant to the June Agency Agreement, the Company agreed to pay Roth (as placement agent) a total cash fee equal to 7.0% of the aggregate gross proceeds received by the Company from the sale of the securities in the June Offering. The Company also agreed to reimburse Roth for expenses in an amount up to $100,000 and to pay Maxim Group LLC, which acted as financial advisor to the Company for the June Offering, a fee of $50,000.

*Nasdaq Listing Compliance* 

On May 23, 2025, we received a letter (the "Letter") from the staff of the Listing Qualifications Department (the "Staff") of The Nasdaq Stock Market LLC ("Nasdaq"), which notified us that we do not presently comply with Nasdaq's Listing Rule 5550(b)(1) (the "Listing Rule"), which requires that we maintain a minimum of $2.5 million in stockholders' equity, and that we also do not meet the alternatives of market value of listed securities or net income from continuing operations set forth in the Listing Rule.

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The Letter does not have any immediate effect on the listing of our common stock on the Nasdaq Capital Market, and we have 45 calendar days from the date of the letter to submit a plan to regain compliance. If our plan is accepted, the Staff can grant an extension of up to 180 calendar days from May 23, 2025 to evidence compliance. After review of the plan of compliance, the Staff will provide written notification to us whether it accepts the plan, and if the Staff does not accept the plan, we would then be entitled to appeal the Staff's determination to the Nasdaq Hearings Panel. There can be no assurance that, if we do appeal the determination to the Nasdaq Hearings Panel, that such appeal would be successful.

**Corporate Information**

Our principal executive offices are located at 5300 Memorial Drive, Suite 950, Houston, Texas 77007. Our website address is <u>www.moleculin.com</u>. The information on or accessible through our website is not part of this prospectus supplement.

**THE OFFERING**

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| | |
|:---|:---|
| *Common Stock Offered* <br> *by Us* | Shares of our common stock having an aggregate offering price of up to $6.5 million pursuant to the ATM Agreement. |
| *Manner of the Offering* | "At the market offering" as defined in Rule 415(a)(4) promulgated under the Securities Act that may be made from time to time through or to Roth as sales agent or principal. See "Plan of Distribution" on page S-13 of this prospectus supplement. |
| *Common Stock* <br> *Currently Outstanding* | 30207494 |
| *Common Stock to Be*<br> *Outstanding* <br> *Immediately Following* <br> *This Offering* | Up to 11,403,509 shares of our common stock, assuming sales at a price of $0.57 per share, which was the closing price on Nasdaq on July 9, 2025. The actual number of shares issued will vary depending on the price at which shares may be sold from time to time under this offering. Issuances will not exceed our total authorized number of shares of common stock, which is 100,000,000 as of the date of this prospectus supplement. |
| *Use of Proceeds* | We intend to use the net proceeds for working capital and for general corporate purposes. See "Use of Proceeds" on page S-11 of this prospectus supplement for a more complete description of the intended use of proceeds from this offering. |
| *Risk Factors* | Investing in our securities involves a high degree of risk. See "Risk Factors" beginning on page S-9 of this prospectus supplement and the risk factors incorporated by reference into this prospectus supplement and the accompanying prospectus for a discussion of certain factors you should consider before deciding to invest in shares of our common stock. |
| *Nasdaq Capital Market* <br> *Symbol* | MBRX |

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The number of shares of common stock to be outstanding after this offering is based on 30,207,494 shares outstanding as of July 10, 2025, and does not include:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;● 67,963,552 shares of common stock underlying outstanding warrants at a weighted average exercise price of $0.64 per share;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;● 784,250 shares of common stock underlying outstanding options with a weighted average exercise price of $19.57 per share, which options vest over a three to four-year period;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;● 307,684 shares of common stock underlying outstanding restricted stock units, which restricted stock units vest over a four-year period;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;● 73,334 shares of common stock underlying outstanding performance-based restricted stock units, which performance-based restricted stock units vest dependent on specific milestones; and

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;● 119,166 shares available for future issuance under the Moleculin Biotech, Inc. 2024 Stock Plan.

Except as otherwise indicated, the information in this prospectus assumes no exercise of options or exercise of warrants, unless otherwise noted.

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**RISK FACTORS**

*Investing in our securities involves a high degree of risk. Before investing in our securities, you should consider carefully the risks and uncertainties discussed under* "*Risk Factors*" *in our latest annual report on Form 10-K and subsequent quarterly reports on Form 10-Q and current reports on Form 8-K, which are incorporated by reference herein in their entirety. You should carefully consider each of the following risks, together with all other information set forth in or incorporated in this prospectus supplement and accompanying prospectus, including the financial statements and the related notes, before making a decision to buy our securities. If any of the following risks actually occur, our business could be harmed. In that case, the trading price of our common stock could decline, and you may lose all or part of your investment.*

***Risks Related to this Offering***

**We have broad discretion in how we use the proceeds of this offering and may not use these proceeds effectively, which could affect our results of operations and cause our common stock to decline.**

We will have considerable discretion in the application of the net proceeds of this offering. We intend to use the net proceeds for working capital and general corporate purposes. As a result, investors will be relying upon management's judgment with only limited information about our specific intentions for the use of the net proceeds of this offering. We may use the net proceeds for purposes that do not yield a significant return or any return at all for our stockholders. In addition, pending their use, we may invest the net proceeds from this offering in a manner that does not produce income or that loses value.

**If our stock price fluctuates after the offering, you could lose a significant part of your investment.**

The market price of our common stock could be subject to wide fluctuations in response to, among other things, the risk factors described in this prospectus supplement and accompanying prospectus, and other factors beyond our control, such as fluctuations in the valuation of companies perceived by investors to be comparable to us. Furthermore, the stock markets have experienced price and volume fluctuations that have affected and continue to affect the market prices of equity securities of many companies. These fluctuations often have been unrelated or disproportionate to the operating performance of those companies. These broad market and industry fluctuations, as well as general economic, political, and market conditions, such as recessions, interest rate changes or international currency fluctuations, may negatively affect the market price of our common stock. In the past, many companies that have experienced volatility in the market price of their stock have been subject to securities class action litigation. We may be the target of this type of litigation in the future. Securities litigation against us could result in substantial costs and divert our management's attention from other business concerns, which could seriously harm our business.

**We will require additional capital funding, the receipt of which may impair the value of our common stock.**

Our future capital requirements depend on many factors, including our research, development, and clinical trial activities. We will need to raise additional capital through public or private equity or debt offerings or through arrangements with strategic partners or other sources in order to continue to develop our drug candidates. There can be no assurance that additional capital will be available when needed or on terms satisfactory to us, if at all. To the extent we raise additional capital by issuing equity securities, our stockholders may experience substantial dilution and the new equity securities may have greater rights, preferences or privileges than our existing common stock.

**We do not intend to pay dividends in the foreseeable future.**

We have never paid cash dividends on our common stock and currently do not plan to pay any cash dividends in the foreseeable future.

**You will experience immediate and substantial dilution in the book value per share of the common stock you purchase in the offering.**

The shares sold in this offering, if any, will be sold from time to time at various prices. The offering price per share in this offering may exceed the net tangible book value per share of our common stock outstanding prior to this offering, in which case you will experience dilution representing the difference between our net tangible book value per share and the assumed offering price. The future exercise of warrants for shares of our common stock and the exercise of outstanding stock options following the date of this prospectus supplement may result in further dilution of your investment. See the section entitled "Dilution" below for a more detailed illustration of the dilution you may incur if you participate in this offering.

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**The common stock offered hereby will be sold in** "**at the market**" **offerings, and investors who buy shares at different times will likely pay different prices.**

Investors who purchase shares in this offering at different times will likely pay different prices and so may experience different outcomes in their investment results. We will have discretion, subject to market demand, to vary the timing, prices, and numbers of shares sold, and there is no minimum or maximum sales price. Investors may experience a decline in the value of their shares as a result of share sales made at prices lower than the prices they paid.

**The actual number of shares we will issue under the ATM Agreement, at any one time or in total, is uncertain.**

Subject to certain limitations in the ATM Agreement and compliance with applicable law, we have the discretion to deliver placement notices to Roth at any time throughout the term of the ATM Agreement. The number of shares that are sold by Roth after delivering a placement notice will fluctuate based on the market price of the common stock during the sales period and limits we set with Roth. Because the price per share of each share sold will fluctuate based on the market price of shares of our common stock during the sales period, it is not possible at this stage to predict the number of shares of common stock that will or may be ultimately issued.

**Your ownership may be diluted if additional capital stock is issued to raise capital, to finance acquisitions or in connection with strategic transactions.**

We intend to seek to raise additional funds for our operations, to finance acquisitions or to develop strategic relationships by issuing equity or convertible debt securities in addition to the securities issued in this offering, which would reduce the percentage ownership of our existing stockholders. Our board of directors has the authority, without action or vote of the stockholders, to issue all or any part of our authorized but unissued shares of common or preferred stock. Our amended and restated certificate of incorporation authorizes us to issue up to 100,000,000 shares of common stock (which we are seeking to increase to 500,00,000 shares) and 5,000,000 shares of preferred stock. Future issuances of common or preferred stock would reduce your influence over matters on which stockholders vote and would be dilutive to earnings per share. In addition, any newly issued preferred stock could have rights, preferences and privileges senior to those of the common stock. Those rights, preferences and privileges could include, among other things, the establishment of dividends that must be paid prior to declaring or paying dividends or other distributions to holders of our common stock or providing for preferential liquidation rights. These rights, preferences and privileges could negatively affect the rights of holders of our common stock, and the right to convert such preferred stock into shares of our common stock at a rate or price that would have a dilutive effect on the outstanding shares of our common stock.

**We will require additional financing in the near term, which financing may result in the reduction of the exercise price of the Series E warrants and the increase in the number of shares underlying the Series E warrants, which would dilute the ownership interest of our stockholders.**

Developing pharmaceutical products, including conducting preclinical studies and clinical trials, is expensive. We will require substantial additional future capital in order to complete clinical development and commercialize Annamycin

The Series E warrants we issued in the June Offering provide that if, while the Series E warrants are outstanding, we sell any common stock and/or common stock equivalents other than in connection with certain exempt issuances, at a purchase price per share less than the exercise price of the Series E warrants in effect immediately prior to such sale, then immediately after such sale the exercise price of the Series E warrants then in effect will be reduced to an amount equal to the new issuance price, and, following the date that we amend our certificate of incorporation to increase our authorized shares of common stock, the number of shares issuable upon exercise of the Series E warrants will be proportionately adjusted such that the aggregate price will remain unchanged, subject to the floor price. The floor price is $0.12, and the total number of shares potentially issuable under the Series E warrants if the exercise price of the Series E warrants was reduced to the floor price would be 148,740,000 shares of common stock.

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If the exercise price of the Series E warrants decreases, the number of shares underlying the Series E warrants will increase substantially, which would materially dilute the ownership of our stockholders. In addition, after the completion of this offering, the Series E warrant holders are not prohibited from effecting "short sales" of our common stock, which may depress the price of our common stock.

**We are not in compliance with multiple of Nasdaq**'**s continued listing requirements and if we are unable to regain compliance with the listing requirements, our common stock will be delisted from Nasdaq which could have a material adverse effect on our financial condition and could make it more difficult for stockholders to sell their shares.**

Our common stock is listed on Nasdaq, and we are therefore subject to its continued listing requirements, including requirements with respect to the market value of publicly-held shares, market value of listed shares, minimum bid price per share, and minimum stockholder's equity, among others, and requirements relating to board and committee independence. If we fail to satisfy one or more of the requirements, we may be delisted from Nasdaq.

On May 23, 2025, we received a letter from the Staff of the Listing Qualifications Department of Nasdaq notifying us that that we do not presently comply with Nasdaq's Listing Rule 5550(b)(1) (the "Listing Rule"), which requires that we maintain a minimum of $2.5 million in stockholders' equity, and that we also do not meet the alternatives of market value of listed securities or net income from continuing operations set forth in the Listing Rule.

We have submitted a plan to regain compliance. If our plan is accepted, the Staff can grant an extension of up to 180 calendar days from May 23, 2025 to evidence compliance. After review of the plan of compliance, the Staff will provide written notification to us whether it accepts the plan, and if the Staff does not accept the plan, we would then be entitled to appeal the Staff's determination to the Nasdaq Hearings Panel. There can be no assurance that, if we do appeal the determination to the Nasdaq Hearings Panel, that such appeal would be successful.

We expect to account for Series E warrants issued in the June Offering as a warrant liability at fair value as of issuance and any subsequent changes in fair value each reporting period will be reported in earnings, as either a gain or loss. The initial accounting for the warrant liability and the future impact of changes in fair value on earnings may have an adverse effect on our net income and our stockholders' equity. Additionally, such warrant liability may hinder our ability to meet the stockholders' equity required in the Listing Rule.

On June 27, 2025, we received another deficiency letter from the Staff of the Listing Qualifications Department of Nasdaq notifying us that for the last 30 consecutive business days the bid price for our common stock had closed below the minimum $1.00 per share requirement for continued inclusion on the Nasdaq pursuant to Nasdaq Listing Rule 5550(a)(2) (the "Bid Price Rule").

In accordance with Nasdaq Listing Rule 5810(c)(3)(A) (the "Compliance Period Rule"), we have been provided an initial period of 180 calendar days, or until December 24, 2025 (the "Compliance Date"), to regain compliance with the Bid Price Rule. If, at any time before the Compliance Date, the bid price for our common stock closes at $1.00 or more for a minimum of 10 consecutive business days as required under the Compliance Period Rule, the Staff will provide written notification to us that we comply with the Bid Price Rule, unless the Staff exercises its discretion to extend this 10 day period pursuant to Nasdaq Listing Rule 5810(c)(3)(H).

If we are not in compliance with the Bid Price Rule by December 24, 2025, we may be afforded a second 180 calendar day period to regain compliance. To qualify, we would be required to meet the continued listing requirement for market value of publicly held shares and all other initial listing standards for Nasdaq, except for the minimum bid price requirement. In addition, we would be required to notify Nasdaq of our intent to cure the minimum bid price deficiency, which may include, if necessary, implementing a reverse stock split.

If we do not regain compliance with the Bid Price Rule by the Compliance Date and are not eligible for an additional compliance period at that time, the Staff will provide written notification to us that our common stock may be delisted. We would then be entitled to appeal the Staff's determination to a Nasdaq Listing Qualifications Panel and request a hearing. There can be no assurance that, if we do appeal the delisting determination by the Staff to the Nasdaq Listing Qualifications Panel, that such appeal would be successful.

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Delisting from Nasdaq would adversely affect our ability to raise additional financing through the public or private sale of equity securities, may significantly affect the ability of investors to trade our securities and may negatively affect the value and liquidity of our common stock. Delisting also could have other negative results, including the potential loss of employee confidence, the loss of institutional investors and general investors that will consider investing in our common stock, a reduction in the number of market makers in our common stock, a reduction in the availability of information concerning the trading prices and volume of our common stock, a reduction in the number of broker-dealers willing to execute trades in shares of our common stock or interest in business development opportunities. Further, we would likely become a "penny stock", which would make trading of our common stock more difficult.

**Our ability to regain compliance with Nasdaq**'**s bid price requirements may be hindered by the June Offering and the future exercises of the Series E warrants.**

As discussed in the prior risk factor, on June 27, 2025, we received a deficiency letter from the Staff of the Listing Qualifications Department of Nasdaq notifying us that for the last 30 consecutive business days the bid price for our common stock had closed below the minimum $1.00 per share requirement for continued inclusion on Nasdaq.

The future exercise of the Series E warrants issued in the June Offering may depress our common stock price. In addition, if the exercise price adjustment provisions of the Series E warrants are triggered in the future, which would cause a reduction in the exercise price of the Series E warrants (subject to the floor price) and a proportionate increase in the number of shares underling the Series E warrants, such event may further depress our common stock price.

In order to increase our common stock price, we may in the future complete a reverse stock split. If we complete a reverse stock split and the lowest daily volume weighted average price during the period commencing five consecutive trading days immediately preceding and the five consecutive trading days commencing on the date of such split is less than the exercise price of the Series E warrants then in effect, then the exercise price of the Series E warrants will be reduced to the lowest daily volume weighted average price during such period and, following the Authorized Share Increase Date, the number of shares issuable upon exercise will be proportionately adjusted such that the aggregate price will remain unchanged, subject to the floor price. This future potential adjustment of the Series E warrants may significantly increase the number of shares of common stock underlying the Series E warrants and cause dilution to our shareholders.

At our Annual Meeting of Stockholders to be held on August 18, 2025, we will seek stockholder approval granting our Board of Directors authority to effect a reverse stock split of the outstanding shares of our common stock, at a reverse stock split ratio of between 1-for-2 to 1-for-30 (or any whole number in between), as determined by the Board in its sole discretion, prior to the one-year anniversary of such approval.

**Nasdaq may delist our common stock for public interest concerns as a result of the June offering.**

Because of the dilutive nature of the June Offering, Nasdaq may delist our common stock for public interest concerns. A number of Nasdaq-listed companies have filed public disclosures regarding the receipt of notification letters indicating that Nasdaq made the determination to delist such companies as a result of public interest concerns arising from the issuance of warrants with certain dilutive terms. While we believe that the Series E warrants offered in the June Offering are materially different than the warrants offered by those companies, there can be no assurance that Nasdaq will agree and our common stock may be delisted from Nasdaq as a result.

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**FORWARD-LOOKING STATEMENTS**

Some of the information in this prospectus supplement, and the documents we incorporate by reference herein, contain forward-looking statements within the meaning of the federal securities laws. You should not rely on forward-looking statements in this prospectus supplement, and the documents we incorporate by reference herein. Forward-looking statements typically are identified by use of terms such as "anticipate," "believe," "plan," "expect," "future," "intend," "may," "will," "should," "estimate," "predict," "potential," "continue," and similar words, although some forward-looking statements are expressed differently. This prospectus supplement, and the documents we incorporate by reference, may also contain forward-looking statements attributed to third parties relating to their estimates regarding the markets we may enter in the future. All forward-looking statements address matters that involve risk and uncertainties, and there are many important risks, uncertainties and other factors that could cause our actual results to differ materially from the forward-looking statements contained in this prospectus supplement, and the documents we incorporate by reference.

Forward-looking statements include, but are not limited to, statements about:

● Our ability to continue our relationship with MD Anderson, including, but not limited to, our ability to maintain current licenses and license future intellectual property resulting from our sponsored research agreements with MD Anderson;

● The success or the lack thereof, including the ability to recruit subjects on a timely basis, for a variety of reasons, of our clinical trials through all phases of clinical development;

● Our ability to satisfy any requirements imposed by the United States (US) Food and Drug Administration (FDA) (or its foreign equivalents) as a condition of our clinical trials proceeding or beginning as planned;

● World-wide events including the wars in Ukraine and in the Middle East, and the general supply chain shortages effects on our clinical trials, clinical drug candidate supplies, preclinical activities and our ability to raise future financing;

● Our ability to obtain additional funding on a timely basis to commence or continue our clinical trials, fund operations and develop our product candidates;

● The need to obtain and retain regulatory approval of our drug candidates, both in the United States and in Europe, and in countries deemed necessary for future trials;

● Our ability to complete our clinical trials in a timely fashion in line with our stated milestones and within our expected budget and resources;

● Our ability to regain and then maintain compliance with the continued listing requirements of the Nasdaq Capital Market;

● Our ability to source our drug products at reasonable prices;

● Compliance with obligations under intellectual property licenses with third parties;

● Any delays in regulatory review and approval of drug candidates in clinical development;

● Potential efficacy of our drug candidates;

● Our ability to commercialize our drug candidates;

● Market acceptance of our drug candidates;

● Competition from existing therapies or new therapies that may emerge;

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● Potential product liability claims;

● Our dependency on third-party manufacturers to successfully, and timely, supply or manufacture our drug candidates for our preclinical work and our clinical trials;

● Our ability to establish or maintain collaborations, licensing or other arrangements;

● Our ability and third parties' abilities to protect intellectual property rights;

● Our ability to adequately support future growth; and

● Our ability to attract and retain key personnel to manage our business effectively.

You should also consider carefully the statements under "Risk Factors" and other sections of this prospectus, and the documents we incorporate by reference, which address additional facts that could cause our actual results to differ from those set forth in the forward-looking statements. We caution investors not to place significant reliance on the forward-looking statements contained in this prospectus, and the documents we incorporate by reference. We undertake no obligation to publicly update or review any forward-looking statements, whether as a result of new information, future developments or otherwise.

**USE OF PROCEEDS** 

We may issue and sell shares of common stock having aggregate sales proceeds of up to $6.5 million from time to time, before deducting sales agent commissions and expenses. The amount of proceeds from this offering will depend upon the number of shares of our common stock sold and the market price at which they are sold. There can be no assurance that we will be able to sell any shares under, or fully utilize, the ATM Agreement with Roth.

We intend to use the net proceeds from this offering for working capital and for general corporate purposes. This represents our best estimate of the manner in which we will use the net proceeds we receive from this offering based upon the current status of our business, but we have not reserved or allocated amounts for specific purposes and we cannot specify with certainty how or when we will use any of the net proceeds. Amounts and timing of our actual expenditures will depend on numerous factors. Our management will have broad discretion in applying the net proceeds from this offering.

Pending application of the net proceeds as described above, we intend to invest the proceeds to us in investment-grade, interest-bearing securities such as money market funds, certificates of deposit, or direct or guaranteed obligations of the U.S. government, or hold as cash. We cannot predict whether the proceeds invested will yield a favorable, or any, return.

**DIVIDEND POLICY**

We have never declared or paid any cash dividends on our capital stock, and we do not currently intend to pay any cash dividends on our common stock for the foreseeable future. We expect to retain future earnings, if any, to fund the development and growth of our business. Any future determination to pay dividends on our common stock will be at the discretion of our board of directors and will depend upon, among other factors, our results of operations, financial condition, capital requirements and any contractual restrictions.

**DILUTION**

If you invest in our common stock in this offering, your interest will be diluted immediately to the extent of the difference between the public offering price per share paid by the purchasers of the shares of common stock in this offering and the as adjusted net tangible book value per share of common stock after this offering.

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As of March 31, 2025, our net tangible book value was ($11.1) million, or ($0.79) per share of common stock. Net tangible book value per share represents our total tangible assets, less our total liabilities, divided by the number of outstanding shares of our common stock.

Dilution represents the difference between the price per share of common stock paid by purchasers in this offering and the as adjusted net tangible book value per share of common stock after the offering. After giving effect to: (i) the issuance of 16,080,000 shares of common stock in the June Offering at a price of $0.37 per share, and (ii) the sale of 11,403,509 shares of our common stock, representing net proceeds of $6.2 million after deducting sales agent commissions and estimated offering expenses payable by us, at an assumed offering price of $0.57 per share, the last reported sale price of our common stock on Nasdaq on July 9, 2025, but without adjusting for any other change in our net tangible book value subsequent to March 31, 2025 or any increase in liabilities from the Series E Warrants issued as part of the June Offering, our pro forma as adjusted net tangible book value would have been $0.01 per share. This represents an immediate increase in net tangible book value on a pro forma as adjusted basis of $0.80 per share to our existing stockholders and immediate dilution of $0.56 per share to new investors purchasing common stock at the assumed public offering price.

The following table illustrates the dilution in net tangible book value per share to new investors as of July 9, 2025. The following table illustrates this calculation on a per share basis. The pro forma as adjusted information is illustrative only and will adjust based on the actual price to the public, the actual number of shares sold and other terms of the offering determined at the time shares of our common stock are sold pursuant to this prospectus supplement and accompanying prospectus. The shares sold in this offering, if any, will be sold from time to time at various prices. We will not offer and sell shares in excess of any amount that would cause the number of our outstanding shares to exceed the number of shares then authorized to be issued under our articles of incorporation, which is 100,000,000 shares as of the date of this prospectus supplement (and will increase to 500,000,000 shares if our stockholders approve such increase at our 2025 annual meeting).

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| | |
|:---|:---|
| Assumed offering price per share | $0.57 |
| Historical net tangible book value per share at March 31, 2025 | $(0.79) |
| Increase in net tangible book value per share to the existing stockholders attributable to this offering and the June Offering | $0.80 |
| Pro Forma as adjusted net tangible book value per share after this offering | $0.01 |
| Dilution per share to new investors participating in this offering | $0.56 |

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The number of shares of common stock to be outstanding after this offering is based on 14,127,494 shares outstanding as of March 31, 2025, and includes 16,080,000 shares of common stock issued in the June Offering, but excludes:

● 19,086,641 shares of common stock underlying outstanding warrants at a weighted average exercise price of $1.33 per share;

● 784,528 shares of common stock underlying outstanding options with a weighted average exercise price of $19.60 per share, which options vest over a three to four-year period;

● 334,047 shares of common stock underlying outstanding restricted stock units, which restricted stock units vest over a four-year period;

● 73,334 shares of common stock underlying outstanding performance-based restricted stock units, which performance-based restricted stock units vest dependent on specific milestones; and

● 119,166 shares available for future issuance under the Moleculin Biotech, Inc. 2024 Stock Plan.

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**PLAN OF DISTRIBUTION**

We have entered into the ATM Agreement, dated July 11, 2025 with Roth, under which we may offer and sell up to $6.5 million of shares of our common stock from time to time through Roth acting as agent and/or principal. Sales of shares of our common stock, if any, under this prospectus supplement and accompanying prospectus will be made by any method that is deemed to be an "at-the-market offering" as defined in Rule 415(a)(4) under the Securities Act including sales made directly on or through Nasdaq, the existing trading market for our common stock, sales made to or through a market maker other than on an exchange or otherwise, directly to the Roth as principal, in negotiated transactions at market prices prevailing at the time of sale or at prices related to such prevailing market prices, and/or in any other method permitted by law. As our sales agent, Roth will not engage in any transactions that stabilize the price of our common stock.

Each time we wish to issue and sell shares of common stock under the ATM Agreement, we will notify Roth of the number of shares to be issued, the dates on which such sales may be made, any limitation on the number of shares to be sold in any one day and any minimum price below which sales may not be made. Once we have so instructed Roth, unless Roth declines to accept the terms of such notice, Roth has agreed to use its commercially reasonable efforts consistent with its normal trading and sales practices to sell such shares up to the amount specified on such terms. The obligations of Roth under the ATM Agreement to sell shares of our common stock are subject to a number of conditions that we must meet.

Under the terms of the ATM Agreement, we may also sell shares of our common stock to Roth as principal for its own account at prices agreed upon at the time of sale. If we sell shares of our common stock to Roth as principal, we will enter into a separate terms agreement with Roth.

The settlement of sales of shares between us and Roth is generally anticipated to occur on the first trading day following the date on which the sale was made, or on some other date that is agreed upon by and between us and Roth in connection with a particular transaction, in return for payment of the net proceeds to us. Sales of shares of our common stock as contemplated in this prospectus supplement will be settled through the facilities of The Depository Trust Company or by such other means as we and Roth may agree upon. There is no arrangement for funds to be received in an escrow, trust or similar arrangement.

We will pay Roth a commission in cash of up to 3.0% of the aggregate gross proceeds we receive from each sale of shares of our common stock through Roth as our agent. Because there is no minimum offering amount required as a condition to close this offering, the actual total public offering amount, commissions and proceeds to us, if any, are not determinable at this time. In addition, we have agreed to reimburse Roth for the fees and disbursements of its counsel, payable upon execution of the sales agreement, in an amount not to exceed $50,000, in addition to certain ongoing disbursements not to exceed $5,000 in connection with quarterly diligence bring downs. We estimate that the total expenses for the offering, excluding any commissions or expense reimbursement payable to Roth under the terms of the ATM Agreement, will be approximately $50,000. The remaining sale proceeds, after deducting any other transaction fees, will equal our net proceeds from the sale of such shares.

Roth will provide written confirmation to us following the close of trading on Nasdaq on each day on which shares of common stock are sold under the ATM Agreement. Each confirmation will include the number of shares sold on that day, the aggregate gross proceeds of such sales and the proceeds to us.

Unless otherwise required, we will report at least quarterly the number of shares of common stock sold through Roth under the ATM Agreement, the net proceeds to us and the compensation paid by us to Roth in connection with the sales of common stock.

In connection with the sale of the shares of common stock on our behalf, Roth will be deemed to be an "underwriter" within the meaning of the Securities Act, and the compensation of Roth will be deemed to be underwriting commissions or discounts. We have agreed to indemnify Roth against certain civil liabilities, including liabilities under the Securities Act and/or the Exchange Act. We have also agreed to contribute to payments Roth may be required to make in respect of such liabilities.

The offering of shares of our common stock pursuant to the ATM Agreement will terminate as permitted therein. We and Roth may each terminate the ATM Agreement as provided therein.

This summary of the material provisions of the ATM Agreement does not purport to be a complete statement of its terms and conditions. A copy of the ATM Agreement will be incorporated by reference into the registration statement of which this prospectus supplement forms a part.

To the extent required by Regulation M, Roth will not engage in any market making activities involving our common stock while the offering is ongoing under this prospectus supplement.

Roth and its affiliates have previously, and may in the future provide, various investment banking, commercial banking, financial advisory and other financial services for us and our affiliates, for which services they have received, and may in the future receive customary fees. In the course of its business, Roth may actively trade our securities for its own account or for the accounts of customers, and, accordingly, Roth may at any time hold long or short positions in such securities.

This prospectus supplement and the accompanying prospectus in electronic format may be made available on a website maintained by Roth, and Roth may distribute this prospectus supplement and the accompanying prospectus electronically.

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**LEGAL MATTERS** 

The validity of the common stock offered hereby will be passed upon for us by ArentFox Schiff LLP, Washington, DC. The sales agent is being represented by Ellenoff Grossman & Schole LLP, New York, NY in connection with this offering.

**EXPERTS**

The audited financial statements incorporated by reference in this prospectus and elsewhere in the registration statement have been so incorporated by reference in reliance upon the report of Grant Thornton LLP, independent registered public accountants, upon the authority of said firm as experts in accounting and auditing.

**INCORPORATION 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. The information incorporated by reference is considered to be part of this prospectus supplement. Information in this prospectus supplement supersedes information incorporated by reference that we filed with the SEC prior to the date of this prospectus supplement. We incorporate by reference in this prospectus supplement the documents listed below and any future filings that we may make with the SEC under Sections 13(a), 13(c), 14, or 15(d) of the Exchange Act prior to the termination of the offering under this prospectus supplement; provided, however, that we are not incorporating, in each case, any documents or information deemed to have been furnished and not filed in accordance with SEC rules:

● [Our Annual Report on Form 10-K for the year ended December 31, 2024 (filed on March 21, 2025)](http://www.sec.gov/ix?doc=/Archives/edgar/data/0001659617/000143774925008751/mbrx20241231_10k.htm) , [as amended on Form 10-K/A (filed April 18, 2025)](http://www.sec.gov/ix?doc=/Archives/edgar/data/0001659617/000143774925012375/mbrx20241231_10ka.htm) , and [as further amended on Form 10-K/A (filed April 30, 2025)](http://www.sec.gov/ix?doc=/Archives/edgar/data/0001659617/000143774925013880/mbrx20241231c_10ka.htm) ;

● [Our Quarterly Report on Form 10-Q for the fiscal quarter ended March 31, 2025 (filed on May 13, 2025)](http://www.sec.gov/ix?doc=/Archives/edgar/data/0001659617/000143774925016466/mbrx20250331_10q.htm) ;

● Our Current Reports on [Form 8-K filed on February 10, 2025](http://www.sec.gov/Archives/edgar/data/1659617/000143774925003211/mbrx20250209_8k.htm) ; [February 13, 2025 (the second Form 8-K filed on such date)](http://www.sec.gov/Archives/edgar/data/1659617/000143774925003760/mbrx20250213c_8k.htm) ; [February 26, 2025;](http://www.sec.gov/Archives/edgar/data/1659617/000143774925005255/mbrx20250225_8k.htm) [April 9, 2025](http://www.sec.gov/Archives/edgar/data/1659617/000143774925011528/mbrx20250408_8k.htm) ; [April 25, 2029](http://www.sec.gov/Archives/edgar/data/1659617/000143774925013163/mbrx20250422_8k.htm) ; [May 9, 2025](http://www.sec.gov/Archives/edgar/data/1659617/000143774925015839/mbrx20250509_8k.htm) ; [May 23, 2025](http://www.sec.gov/Archives/edgar/data/1659617/000143774925018358/mbrx20250523_8k.htm) ; [June 4, 2025](http://www.sec.gov/Archives/edgar/data/1659617/000143774925019375/mbrx20250602_8k.htm) ; [June 18, 2025](http://www.sec.gov/ix?doc=/Archives/edgar/data/0001659617/000143774925020729/mbrx20250617_8k.htm) ; [June 23, 2025](http://www.sec.gov/ix?doc=/Archives/edgar/data/0001659617/000143774925021062/mbrx20250621_8k.htm) ; and [June 27, 2025](http://www.sec.gov/ix?doc=/Archives/edgar/data/0001659617/000143774925021445/mbrx20250627_8k.htm) ;

● [Our Definitive Proxy Statement on Schedule 14A relating to the Company's 2025 Annual Meeting of Stockholders (filed on July 8, 2025)](http://www.sec.gov/Archives/edgar/data/1659617/000143774925022352/mbrx20250630_def14a.htm) ; and,

● [the description of our common stock, par value $0.001 per share contained in our Registration Statement on Form 8-A, dated and filed with the SEC on April 28, 2016](http://www.sec.gov/Archives/edgar/data/1659617/000114420416097020/v438274_8a12b.htm) , and any amendment, exhibit to Form 10-K, or report filed with the SEC for the purpose of updating the description.

All reports and other documents we subsequently file pursuant to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act prior to the termination of this offering will also be incorporated by reference in this prospectus supplement and deemed to be part of this prospectus supplement from the date of the filing of such reports and documents. We are not, however, incorporating by reference any documents or portions thereof, whether specifically listed above or filed in the future, that are not deemed "filed" with the SEC, including any information furnished pursuant to Items 2.02 or 7.01 of Form 8-K or related exhibits furnished pursuant to Item 9.01 of Form 8-K.

We will furnish without charge to you, on written or oral request, a copy of any or all of the documents incorporated by reference in this prospectus supplement, including exhibits to these documents. You should direct any requests for documents to: Moleculin Biotech, Inc., Attn: Corporate Secretary, 5300 Memorial Drive, Suite 950, Houston, TX 77007.

You also may access these filings on our website at www.moleculin.com. We do not incorporate the information on our website into this prospectus supplement and you should not consider any information on, or that can be accessed through, our website as part of this prospectus supplement (other than those filings with the SEC that we specifically incorporate by reference into this prospectus supplement).

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**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 the information set forth or incorporated by reference in the registration statement. 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 into this prospectus supplement or the accompanying prospectus for a copy of such contract, agreement or other document. Because we are subject to the information and reporting requirements of the Exchange Act, we file annual, quarterly and current reports, proxy statements and other information with the SEC. You may read and copy information filed by us with the SEC at the SEC's public reference section, 100 F Street, N.E., Washington, D.C. 20549. Information regarding the operation of the public reference section can be obtained by calling 1-800-SEC-0330.

The SEC also maintains an Internet site at <u>http://www.sec.gov</u> that contains reports, statements and other information about issuers, such as us, who file electronically with the SEC.

We also maintain a website at <u>www.moleculin.com</u> through which you can access our SEC filings free of charge. The information set forth on our website is not part of this prospectus supplement.

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**PROSPECTUS**

**$200,000,000**

![image2.jpg](image2.jpg)

**Common Stock**

**Preferred Stock**

**Debt Securities**

**Warrants**

**Units**

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We may from time to time issue up to $200,000,000 aggregate dollar amount of common stock, preferred stock, debt securities, warrants or units of securities. We will specify in the accompanying prospectus supplement the terms of the securities to be offered and sold. We may sell these securities directly to you, through underwriters, dealers or agents we select, or through a combination of these methods. We will describe the plan of distribution for any particular offering of these securities in the applicable prospectus supplement. This prospectus may not be used to sell our securities unless it is accompanied by a prospectus supplement.

Our common stock is listed on The NASDAQ Capital Market and traded under the symbol "MBRX". On June 6, 2024, the closing price of the common stock, as reported on NASDAQ was $4.46 per share.

**Investing in our securities is highly speculative and involves a high degree of risk. You should purchase these securities only if you can afford a complete loss of your investment. You should carefully consider the risks and uncertainties described under the heading "Risk Factors" beginning on page 3 of this prospectus before making a decision to purchase our securities.** 

**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 July 1, 2024

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**TABLE OF CONTENTS**

---

| | |
|:---|:---|
|  | **Page** |
| [<u>ABOUT THIS PROSPECTUS</u>](#about_this) | [<u>1</u>](#about_this) |
| [<u>WHERE YOU CAN FIND MORE INFORMATION</u>](#where_more) | [<u>1</u>](#where_more) |
| [<u>INCORPORATION BY REFERENCE</u>](#incorporation) | [<u>2</u>](#incorporation) |
| [<u>ABOUT MOLECULIN BIOTECH, INC.</u>](#about_mole) | [<u>2</u>](#about_mole) |
| [<u>RISK FACTORS</u>](#risk_fact) | [<u>3</u>](#risk_fact) |
| [<u>FORWARD-LOOKING STATEMENTS</u>](#forward_state) | [<u>3</u>](#forward_state) |
| [<u>USE OF PROCEEDS</u>](#use_of) | [<u>3</u>](#use_of) |
| [<u>DESCRIPTION OF COMMON STOCK</u>](#desc_common) | [<u>3</u>](#desc_common) |
| [<u>DESCRIPTION OF PREFERRED STOCK</u>](#desc_pref) | [<u>5</u>](#desc_pref) |
| [<u>DESCRIPTION OF DEBT SECURITIES</u>](#desc_debt) | [<u>5</u>](#desc_debt) |
| [<u>DESCRIPTION OF THE WARRANTS</u>](#desc_warr) | [<u>12</u>](#desc_warr) |
| [<u>DESCRIPTION OF UNITS</u>](#desc_unit) | [<u>13</u>](#desc_unit) |
| [<u>PLAN OF DISTRIBUTION</u>](#plan_distrib) | [<u>14</u>](#plan_distrib) |
| [<u>LEGAL MATTERS</u>](#legal) | [<u>16</u>](#legal) |
| [<u>EXPERTS</u>](#expert) | [<u>16</u>](#expert) |

---

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**ABOUT THIS PROSPECTUS**

This prospectus is part of a registration statement that we filed with the Securities and Exchange Commission, or the SEC, utilizing a "shelf" registration process. Under this shelf registration process, we may sell the securities described in this prospectus in one or more offerings up to a total dollar amount of $200,000,000.

We have provided to you in this prospectus a general description of the securities we may offer. Each time we sell securities under this shelf registration process, we will provide a prospectus supplement that will contain specific information about the terms of that offering. That prospectus supplement may include additional risk factors or other special considerations applicable to the securities being offered. We may also add, update or change in the prospectus supplement any of the information contained in this prospectus. To the extent there is a conflict between the information contained in this prospectus and the prospectus supplement, you should rely on the information in the prospectus supplement, provided that if a statement in any document is inconsistent with a statement in another document having a later date - for example, a document incorporated by reference in this prospectus or any prospectus supplement - the statement in the document having the later date modifies or supersedes the earlier statement. You should read both this prospectus and the prospectus supplement together with the additional information described under "Where You Can Find More Information."

The registration statement containing this prospectus, including the exhibits to the registration statement, provides additional information about us and the securities offered under this prospectus. The registration statement, including the exhibits, can be read at the SEC website or at the SEC offices mentioned under the heading "Where You Can Find More Information."

You should rely only on the information incorporated by reference or provided in this prospectus and the accompanying prospectus supplement. We have not authorized anyone to provide you with different information. We are not making an offer to sell or soliciting an offer to buy these securities in any jurisdiction in which the offer or solicitation is not authorized or in which the person making the offer or solicitation is not qualified to do so or to anyone to whom it is unlawful to make the offer or solicitation. You should not assume that the information in this prospectus or the accompanying prospectus supplement is accurate as of any date other than the date on the front of the document.

Unless the context requires otherwise, references to the "Company, " "we," "our," and "us," refer to Moleculin Biotech, Inc. and its subsidiaries, except that such terms refer to only Moleculin Biotech, Inc. and not its subsidiaries in the sections entitled "Description of Common Stock," "Description of Preferred Stock," "Description of Debt Securities," "Description of Warrants," and "Description of Units."

**WHERE YOU CAN FIND MORE INFORMATION**

We have filed with the SEC a registration statement on Form S-3 under the Securities Act with respect to the securities offered in this offering. We file annual, quarterly and current reports, proxy statements and other information with the Securities and Exchange Commission. You may read and copy the registration statement and any other documents we have filed at the Securities and Exchange Commission's Public Reference Room 100 F Street, N.E., Washington, D.C. 20549. Please call the Securities and Exchange Commission at 1-800-SEC-0330 for further information on the Public Reference Room. Our Securities and Exchange Commission filings are also available to the public at the Securities and Exchange Commission's Internet site at <u>www.sec.gov</u>.

This prospectus is part of the registration statement and does not contain all of the information included in the registration statement. Whenever a reference is made in this prospectus to any of our contracts or other documents, the reference may not be complete and, for a copy of the contract or document, you should refer to the exhibits that are a part of the registration statement.

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**INCORPORATION BY REFERENCE**

The SEC allows us to "incorporate by reference" into this prospectus the information we file with it, which means that we can disclose important information to you by referring you to those documents. Later information filed with the SEC will update and supersede this information.

We incorporate by reference the documents listed below, all filings filed by us pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act after the date of the initial registration statement of which this prospectus forms a part prior to effectiveness of such registration statement, and any future filings we make with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act prior to the time that all securities covered by this prospectus have been sold or the offering is otherwise terminated; provided, however, that we are not incorporating any information furnished under either Item 2.02 or Item 7.01 of any current report on Form 8-K:

&nbsp;&nbsp;&nbsp;&nbsp;• <u>[Our Annual Report on Form 10-K for the year ended December 31, 2023 (filed on March 22, 2024)](http://www.sec.gov/ix?doc=/Archives/edgar/data/0001659617/000143774924009044/mbrx20231231_10k.htm) , [as amended on Form 10-K/A (filed April 26, 2024)](http://www.sec.gov/ix?doc=/Archives/edgar/data/0001659617/000143774924013444/mbrx20240417_10ka.htm) ;</u> 

&nbsp;&nbsp;&nbsp;&nbsp;• [<u>Our Quarterly Report on Form 10-Q for the fiscal quarter ended March 31, 2024 (filed on May 10, 2024)</u>](http://www.sec.gov/ix?doc=/Archives/edgar/data/0001659617/000143774924016031/mbrx20240331_10q.htm) ;

&nbsp;&nbsp;&nbsp;&nbsp;• Our Current Reports on Form 8-K filed on [<u>January 5, 2024</u>](http://www.sec.gov/ix?doc=/Archives/edgar/data/0001659617/000143774924000758/mbrx20240104c_8k.htm) ; [<u>February 14, 2024</u>](http://www.sec.gov/ix?doc=/Archives/edgar/data/0001659617/000143774924004172/mbrx20240214_8k.htm) ; [<u>March 19, 2024</u>](http://www.sec.gov/ix?doc=/Archives/edgar/data/0001659617/000143774924008537/mbrx20240318_8k.htm) ; and [<u>April 8, 2024</u>](http://www.sec.gov/ix?doc=/Archives/edgar/data/0001659617/000143774924011423/mbrx20240404_8k.htm) ; and

&nbsp;&nbsp;&nbsp;&nbsp;• the description of our common stock, par value $0.001 per share contained in our [<u>Registration Statement on Form 8-A, dated and filed with the SEC on April 28, 2016</u>](http://www.sec.gov/Archives/edgar/data/1659617/000114420416097020/v438274_8a12b.htm) , and any amendment, exhibit to Form 10-K, or report filed with the SEC for the purpose of updating the description.

An updated description of our capital stock is included in this prospectus under "Description of Common Stock" and "Description of Preferred Stock".

We will provide to each person, including any beneficial owner, to whom this prospectus is delivered, upon written or oral request, at no cost to the requester, a copy of any and all of the information that is incorporated by reference in this prospectus. You may request a copy of these filings, at no cost, by contacting us at:

Moleculin Biotech, Inc.

Attn: Corporate Secretary

5300 Memorial Drive, Suite 950

Houston, TX 77007

Phone: 713-300-5160

**ABOUT MOLECULIN BIOTECH, INC.**

**Our Company**

We are a clinical stage pharmaceutical company with a growing pipeline, including Phase 2 clinical programs for hard-to-treat cancers and viruses. We have three core technologies, each of which have had one or more drugs successfully complete a Phase 1 clinical trial, based substantially on discoveries made at and licensed from the University of Texas MD Anderson Cancer Center (MD Anderson) in Houston, Texas. Three of our six drug candidates have shown human activity in clinical trials and are currently or have been in Phase 1B/2 or Phase 2 clinical trials. Since our inception and as of March 2024, our drugs have completed, are currently in, or have been permitted to proceed in, thirteen clinical trials. Annamycin is our lead molecule and is in three Phase 1B/2 clinical trials - one for treating Acute Myeloid Leukemia (AML) and two for treating Soft Tissue Sarcoma metastasized to the lungs (STS lung metastases, STS lung mets, or Advanced STS).

One of our core management beliefs is that anthracyclines represent the most important treatment for AML and Advanced STS, and we believe Annamycin may, for the first time ever, allow a majority of these patients to benefit from this treatment. This belief leads us to currently focus mainly on the development of Annamycin.

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**Corporate Information**

Our principal executive office is located at 5300 Memorial Drive, Suite 950, Houston, Texas 77007. Our website address is www.moleculin.com. Information contained in, or accessible through, our website does not constitute part of this prospectus and inclusions of our website address in this prospectus are inactive textual references only.

**RISK FACTORS**

Before making an investment decision, you should consider the "Risk Factors" included under Item 1A. of our most recent Annual Report on Form 10-K and in our updates to those Risk Factors in our Quarterly Reports on Form 10-Q, all of which are incorporated by reference in this prospectus, as updated by our future filings with the SEC. The market or trading price of our common stock could decline due to any of these risks. In addition, please read "Forward-Looking Statements" in this prospectus, where we describe additional uncertainties associated with our business and the forward-looking statements included or incorporated by reference in this prospectus. Please note that additional risks not currently known to us or that we currently deem immaterial may also impair our business and operations. The accompanying prospectus supplement may contain a discussion of additional risks applicable to an investment in us and the particular type of securities we are offering under that prospectus supplement.

**FORWARD-LOOKING STATEMENTS**

Some of the information in this prospectus, and the documents we incorporate by reference, contain forward-looking statements within the meaning of the federal securities laws. You should not rely on forward-looking statements in this prospectus, and the documents we incorporate by reference. Forward-looking statements typically are identified by use of terms such as "anticipate," "believe," "plan," "expect," "future," "intend," "may," "will," "should," "estimate," "predict," "potential," "continue," and similar words, although some forward-looking statements are expressed differently. This prospectus, and the documents we incorporate by reference, may also contain forward-looking statements attributed to third parties relating to their estimates regarding the markets we may enter in the future. All forward-looking statements address matters that involve risk and uncertainties, and there are many important risks, uncertainties and other factors that could cause our actual results to differ materially from the forward-looking statements contained in this prospectus, and the documents we incorporate by reference.

You should also consider carefully the statements under "Risk Factors" and other sections of this prospectus, and the documents we incorporate by reference, which address additional facts that could cause our actual results to differ from those set forth in the forward-looking statements. We caution investors not to place significant reliance on the forward-looking statements contained in this prospectus, and the documents we incorporate by reference. We undertake no obligation to publicly update or review any forward-looking statements, whether as a result of new information, future developments or otherwise.

**USE OF PROCEEDS** 

We expect to use the net proceeds from the sale of securities offered by this prospectus and the prospectus supplement for our clinical trials and preclinical programs, for other research and development activities and for general corporate purposes. These may include additions to working capital, repayment of existing indebtedness and acquisitions. If we decide to use the net proceeds of any offering of securities other than for our clinical trials, if any, and preclinical programs, for other research and development activities and for general corporate purposes, we will describe the use of the net proceeds in the prospectus supplement for that offering.

**DESCRIPTION OF COMMON STOCK**

**General** 

We are currently authorized to issue 100,000,000 shares of common stock, par value $0.001.

Subject to preferences that may be applicable to any preferred stock outstanding at the time, the holders of our common stock are entitled to receive dividends out of legally available assets at such times and in such amounts as our Board of Directors may from time to time determine. Each stockholder is entitled to one vote for each share of common stock held on all matters submitted to a vote of stockholders. Cumulative voting is not allowed.

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Our common stock is not subject to conversion or redemption and holders of our common stock are not entitled to preemptive rights. Upon the liquidation, dissolution or winding up of our company, the remaining assets legally available for distribution to stockholders, after payment of claims or creditors and payment of liquidation preferences, if any, on outstanding preferred stock, are distributable ratably among the holders of our common stock and any participating preferred stock outstanding at that time. Each outstanding share of common stock is fully paid and nonassessable.

**Anti-Takeover Effects of Provisions of Delaware Law and our Charter Documents** 

Provisions of Delaware law and our Amended and Restated Certificate of Incorporation, as amended ("Certificate of Incorporation") and our Fourth Amended and Restated Bylaws, as amended ("Bylaws"), could make the acquisition of our company through a tender offer, a proxy contest or other means more difficult and could make the removal of incumbent officers and directors more difficult. We expect these provisions to discourage coercive takeover practices and inadequate takeover bids and to encourage persons seeking to acquire control of our company to first negotiate with our Board of Directors. We believe that the benefits provided by our ability to negotiate with the proponent of an unfriendly or unsolicited proposal outweigh the disadvantages of discouraging these proposals. We believe the negotiation of an unfriendly or unsolicited proposal could result in an improvement of its terms.

Our Bylaws do not permit stockholders to call a special meeting of stockholders. Our Bylaws provide that special meetings of the stockholders may be called by the Chairman of the Board of Directors, our Chief Executive Officer, our President, or the Board of Directors. Our Bylaws require that all stockholder actions be taken by a vote of the stockholders at an annual or special meeting, and do not permit our stockholders to act by written consent without a meeting. Our Bylaws provide for an advance notice procedure for stockholder proposals to be brought before an annual meeting of our stockholders, including proposed nominations of persons for election to the Board of Directors. At an annual meeting, stockholders may only consider proposals or nominations specified in the notice of meeting or brought before the meeting by or at the direction of the Board of Directors. The Bylaws do not give our Board of Directors the power to approve or disapprove stockholder nominations of candidates or proposals regarding other business to be conducted at a special or annual meeting of the stockholders. However, our Bylaws may have the effect of precluding the conduct of business at a meeting if the proper procedures are not followed. These provisions may also discourage or deter a potential acquirer from conducting a solicitation of proxies to elect the acquirer's own slate of directors or otherwise attempting to obtain control of our company.

**Exclusive Forum Provision.**

This choice of forum provision may limit a stockholder's ability to bring a claim in a judicial forum that it finds favorable for disputes with us or our directors, officers or other employees, which may discourage such lawsuits against us and our directors, officers and employees. In addition, these provisions could increase the costs to stockholders in bringing such claims. Alternatively, a court could find these provisions of our certificate of incorporation to be inapplicable or unenforceable in respect of one or more of the specified types of actions or proceedings, which may require us to incur additional costs associated with resolving such matters in other jurisdictions, which could adversely affect our business and financial condition.

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**Quotation**

Our common stock is listed on The NASDAQ Capital Market and traded under the symbol "MBRX".

**Transfer Agent**

The transfer agent for our common stock is VStock Transfer, LLC located at 18 Lafayette Place, Woodmere, New York 11598.

**DESCRIPTION OF PREFERRED STOCK**

**General**

We are currently authorized to issue 5,000,000 shares of preferred stock, par value $0.001. As of the date of this prospectus, we have no shares of preferred stock outstanding.

Our Board of Directors has the authority, without action by our stockholders, to designate and issue preferred stock in one or more series. Our Board of Directors may also designate the rights, preferences and privileges of each series of preferred stock, any or all of which may be greater than the rights of the common stock. It is not possible to state the actual effect of the issuance of any shares of preferred stock on the rights of holders of the common stock until our Board of Directors determines the specific rights of the holders of the preferred stock. However, these effects might include: (a) restricting dividends on the common stock; (b) diluting the voting power of the common stock; (c) impairing the liquidation rights of the common stock; and (d) delaying or preventing a change in control of our company without further action by our stockholders.

**DESCRIPTION OF DEBT SECURITIES**

**General** 

The following description sets forth general terms that will apply to the debt securities. We will describe the particular terms of any debt securities that we offer in the prospectus supplement relating to those debt securities.

The debt securities will be either our senior debt securities or our subordinated debt securities. The senior debt securities will be issued under an indenture between us and the trustee named in the indenture. We refer to this indenture as the "senior indenture." The subordinated debt securities will be issued under a separate Subordinated Indenture between us and the trustee named in the indenture. We refer to this indenture as the "subordinated indenture" and, together with the senior indenture, as the "indentures." Except as permitted by applicable law, the indentures have been or will be qualified under the Trust Indenture Act of 1939.

We have filed the forms of the indentures as exhibits to the registration statement. For your convenience, we have included references to specific sections of the indentures in the descriptions below. Capitalized terms not otherwise defined in this prospectus will have the meanings given in the indenture to which they relate.

The following summaries of provisions of the debt securities and the indentures are not complete and are qualified in their entirety by reference to the provisions of the indentures and the debt securities.

Neither of the indentures limits the principal amount of debt securities that we may issue. Each indenture provides that debt securities may be issued in one or more series up to the principal amount that we may authorize from time to time. Each indenture also provides that the debt securities may be denominated in any currency or currency unit that we designate. In addition, each series of debt securities may be reopened in order to issue additional debt securities of that series in the future without the consent of the holders of debt securities of that series. Unless otherwise described in the prospectus supplement relating to a particular offering, neither the indentures nor the debt securities will contain any provisions to afford holders of any debt securities protection in the event of a takeover, recapitalization or similar restructuring of our business.

Unless otherwise described in the prospectus supplement relating to a particular offering, the senior debt securities will rank equally with all of our other unsecured and unsubordinated debt. The subordinated debt securities will be subordinated to the prior payment in full of our senior debt securities. We will describe the particular terms of the subordinated debt securities that we offer in the prospectus supplement relating to those subordinated debt securities.

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We will describe the specific terms relating to each particular series of debt securities in the prospectus supplement relating to the offering of those debt securities. The terms we will describe in the prospectus supplement will include some or all of the following:

&nbsp;&nbsp;&nbsp;&nbsp;• the title and type of the debt securities;

&nbsp;&nbsp;&nbsp;&nbsp;• the total principal amount or initial offering price of the debt securities;

&nbsp;&nbsp;&nbsp;&nbsp;• the date or dates when the principal of the debt securities will be payable;

&nbsp;&nbsp;&nbsp;&nbsp;• whether we will have the right to extend the stated maturity of the debt securities;

&nbsp;&nbsp;&nbsp;&nbsp;• whether the debt securities will bear interest and, if so, the rate or rates, or the method for calculating the rate or rates, of interest;

&nbsp;&nbsp;&nbsp;&nbsp;• if the debt securities will bear interest, the date from which interest will accrue, the dates when interest will be payable and the regular record dates for these interest payment dates;

&nbsp;&nbsp;&nbsp;&nbsp;• the place where the principal, premium, if any, and interest, if any, on the debt securities will be paid, registered debt securities may be surrendered for registration of transfer, and debt securities may be surrendered for exchange;

&nbsp;&nbsp;&nbsp;&nbsp;• any sinking fund or other provisions that would obligate us to repurchase or otherwise redeem the debt securities;

&nbsp;&nbsp;&nbsp;&nbsp;• the terms and conditions upon which we will have the option or the obligation to redeem the debt securities;

&nbsp;&nbsp;&nbsp;&nbsp;• the denominations in which any registered debt securities will be issuable;

&nbsp;&nbsp;&nbsp;&nbsp;• the identity of each security registrar and paying agent, and the designation of the exchange rate agent, if any, if other than the trustee;

&nbsp;&nbsp;&nbsp;&nbsp;• the portion of the principal amount of debt securities that will be payable upon acceleration of the maturity of the debt securities;

&nbsp;&nbsp;&nbsp;&nbsp;• the currency used to pay principal, premium, if any, and interest, if any, on the debt securities, if other than U.S. dollars, and whether you or we may elect to have principal, premium and interest paid in a currency other than the currency in which the debt securities are denominated;

&nbsp;&nbsp;&nbsp;&nbsp;• any index, formula or other method used to determine the amount of principal, premium or interest on the debt securities;

&nbsp;&nbsp;&nbsp;&nbsp;• any changes or additions to the events of default, defaults or our covenants made in the applicable indenture;

&nbsp;&nbsp;&nbsp;&nbsp;• whether the debt securities are issuable as registered debt securities or bearer debt securities, whether there are any restrictions relating to the form in which they are issued and whether bearer and registered debt securities may be exchanged for each other;

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&nbsp;&nbsp;&nbsp;&nbsp;• to whom interest will be payable

&nbsp;&nbsp;&nbsp;&nbsp;• if other than the registered holder (for registered debt securities),

&nbsp;&nbsp;&nbsp;&nbsp;• if other than upon presentation and surrender of the related coupons (for bearer debt securities), or

&nbsp;&nbsp;&nbsp;&nbsp;• if other than as specified in the indentures (for global debt securities);

&nbsp;&nbsp;&nbsp;&nbsp;• whether the debt securities are to be convertible or exchangeable for other securities and, if so, the terms of conversion or exchange;

&nbsp;&nbsp;&nbsp;&nbsp;• particular terms of subordination with respect to subordinated debt securities; and

&nbsp;&nbsp;&nbsp;&nbsp;• any other terms of the debt securities consistent with the provisions of the applicable indenture.

We may issue debt securities as original issue discount securities to be sold at a substantial discount below their principal amount. If we issue original issue discount securities, then we will describe the material U.S. federal income tax consequences that apply to those debt securities in the applicable prospectus supplement.

**Registration and Transfer** 

We presently plan to issue each series of debt securities only as registered securities. However, we may issue a series of debt securities as bearer securities, or a combination of both registered securities and bearer securities. If we issue senior debt securities as bearer securities, they will have interest coupons attached unless we elect to issue them as zero coupon securities. If we issue bearer securities, we may describe material U.S. federal income tax consequences and other material considerations, procedures and limitations in the applicable prospectus supplement.

Holders of registered debt securities may present the debt securities for exchange for different authorized amounts of other debt securities of the same series and in the same aggregate principal amount at the corporate trust office of the trustee or at the office of any other transfer agent we may designate for the purpose and describe in the applicable prospectus supplement. The registered securities must be duly endorsed or accompanied by a written instrument of transfer. The agent will not impose a service charge on you for the transfer or exchange. We may, however, require that you pay any applicable tax or other governmental charge. If we issue bearer securities, we will describe any procedures for exchanging those bearer securities for other senior debt securities of the same series in the applicable prospectus supplement. Generally, we will not allow you to exchange registered securities for bearer securities.

In general, unless otherwise specified in the applicable prospectus supplement, we will issue registered securities without coupons and in denominations of $1,000 or integral multiples, and bearer securities in denominations of $5,000. We may issue both registered and bearer securities in global form.

**Conversion and Exchange** 

If any debt securities will be convertible into or exchangeable for our common stock, preferred stock or other securities, the applicable prospectus supplement will set forth the terms and conditions of the conversion or exchange, including:

&nbsp;&nbsp;&nbsp;&nbsp;• the conversion price or exchange ratio;

&nbsp;&nbsp;&nbsp;&nbsp;• the conversion or exchange period;

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&nbsp;&nbsp;&nbsp;&nbsp;• whether the conversion or exchange will be mandatory or at the option of the holder or us;

&nbsp;&nbsp;&nbsp;&nbsp;• provisions for adjustment of the conversion price or exchange ratio; and

&nbsp;&nbsp;&nbsp;&nbsp;• provisions that may affect the conversion or exchange if the debt securities are redeemed.

**Redemption** 

Unless otherwise indicated in the applicable prospectus supplement, we may, at our option, redeem any series of debt securities in whole at any time or in part from time to time. If any series of debt securities are redeemable only on or after a certain date or only upon satisfaction of additional conditions, the applicable prospectus supplement will specify the date or the additional conditions. Unless otherwise specified in the applicable prospectus supplement, the redemption price for debt securities will equal 100% of the principal amount plus any accrued and unpaid interest on those debt securities.

The applicable prospectus supplement will contain the specific terms on which we may redeem a series of debt securities prior to its stated maturity. Unless otherwise described in the prospectus supplement relating to a particular offering, we will send a notice of redemption to holders at least 30 days but not more than 60 days prior to the redemption date. The notice will state:

&nbsp;&nbsp;&nbsp;&nbsp;• the redemption date;

&nbsp;&nbsp;&nbsp;&nbsp;• the redemption price;

&nbsp;&nbsp;&nbsp;&nbsp;• if less than all of the debt securities of the series are being redeemed, the particular debt securities to be redeemed (and the principal amounts, in the case of a partial redemption);

&nbsp;&nbsp;&nbsp;&nbsp;• that on the redemption date, the redemption price will become due and payable and any applicable interest will cease to accrue on and after that date;

&nbsp;&nbsp;&nbsp;&nbsp;• the place or places of payment;

&nbsp;&nbsp;&nbsp;&nbsp;• whether the redemption is for a sinking fund; and

&nbsp;&nbsp;&nbsp;&nbsp;• any other provisions required by the terms of the debt securities of the series that are being redeemed.

On or before any redemption date, we will deposit an amount of money with the trustee or with a paying agent sufficient to pay the redemption price.

Unless otherwise described in the prospectus supplement relating to a particular offering, if we are redeeming less than all the debt securities, the trustee will select the debt securities to be redeemed using a method it considers fair and appropriate. After the redemption date, holders of redeemed debt securities will have no rights with respect to the debt securities except the right to receive the redemption price and any unpaid interest to the redemption date.

**Events of Default** 

Unless otherwise described in the prospectus supplement relating to a particular offering, an "event of default" regarding any series of debt securities is any one of the following events:

&nbsp;&nbsp;&nbsp;&nbsp;• default for 30 days in the payment of any interest installment when due and payable;

&nbsp;&nbsp;&nbsp;&nbsp;• default in the making of any sinking fund payment when due;

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&nbsp;&nbsp;&nbsp;&nbsp;• default in the payment of principal or premium (if any) when due at its stated maturity, by declaration, when called for redemption or otherwise;

&nbsp;&nbsp;&nbsp;&nbsp;• default in the performance of any covenant in the debt securities of that series or in the applicable indenture for 60 days after notice to us by the trustee or by the holders of 25% in principal amount of the outstanding debt securities of that series;

&nbsp;&nbsp;&nbsp;&nbsp;• certain events of bankruptcy, insolvency and reorganization; and

&nbsp;&nbsp;&nbsp;&nbsp;• any other event of default provided with respect to that series of debt securities.

We are required to file every year with each trustee an officers' certificate stating whether any default exists and specifying any default that exists.

**Acceleration of Maturity** 

Unless otherwise described in the prospectus supplement relating to a particular offering, if an event of default has occurred and is continuing with respect to debt securities of a particular series (except, in the case of subordinated debt securities, defaults relating to bankruptcy events), the trustee or the holders of not less than 25% in principal amount of outstanding debt securities of that series may declare the principal amount of outstanding debt securities of that series due and payable immediately.

Unless otherwise described in the prospectus supplement relating to a particular offering, at any time after a declaration of acceleration of maturity with respect to debt securities of any series has been made and before a judgment or decree for payment of the money due has been obtained by the trustee, the holders of a majority in principal amount of the outstanding debt securities of that series by written notice to us and the trustee, may rescind and annul the declaration and its consequences if:

&nbsp;&nbsp;&nbsp;&nbsp;• we have paid or deposited with the trustee a sum sufficient to pay:

&nbsp;&nbsp;&nbsp;&nbsp;• all overdue interest on all outstanding debt securities of that series and any related coupons,

&nbsp;&nbsp;&nbsp;&nbsp;• all unpaid principal of and premium, if any, on any of the debt securities which has become due otherwise than by the declaration of acceleration, and interest on the unpaid principal at the rate or rates prescribed in the debt securities,

&nbsp;&nbsp;&nbsp;&nbsp;• to the extent lawful, interest on overdue interest at the rate or rates prescribed in the debt securities, and

&nbsp;&nbsp;&nbsp;&nbsp;• all sums paid or advanced by the trustee and the reasonable compensation, expenses, disbursements and advances of the trustee, its agents and counsel; and

&nbsp;&nbsp;&nbsp;&nbsp;• all events of default with respect to debt securities of that series, other than the non-payment of amounts of principal, interest or any premium on the debt securities which have become due solely by the declaration of acceleration, have been cured or waived.

No rescission will affect any subsequent default or impair any right consequent thereon.

**Waiver of Defaults** 

Unless otherwise described in the prospectus supplement relating to a particular offering, the holders of not less than a majority in principal amount of the outstanding debt securities of any series may, on behalf of the holders of all the debt securities of the series and any related coupons, waive any past default under the applicable indenture with respect to the series and its consequences, except a default:

&nbsp;&nbsp;&nbsp;&nbsp;• in the payment of the principal of or premium, if any, or interest on any debt security of the series or any related coupon, or

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&nbsp;&nbsp;&nbsp;&nbsp;• in respect of a covenant or provision that cannot be modified or amended without the consent of the holder of each outstanding debt security of the series affected thereby.

If an event of default with respect to debt securities of a particular series occurs and is continuing, the trustee will not be obligated to exercise any of its rights or powers under the applicable indenture at the request or direction of any of the holders of debt securities of the series, unless the holders have offered to the trustee reasonable indemnity and security against the costs, expenses and liabilities that might be incurred by it in compliance with the request.

The holders of a majority in principal amount of the outstanding debt securities of any series have the right to direct the time, method and place of conducting any proceeding for any remedy available to the trustee under the applicable indenture, or exercising any trust or power conferred on the trustee with respect to the debt securities of that series. The trustee may refuse to follow directions in conflict with law or the indenture that may expose the trustee to personal liability or may be unduly prejudicial to the other, non-directing holders. Additionally, the trustee may take any other action the trustee deems proper which is not inconsistent with the direction.

**Modification of Indenture** 

We and the trustee may, without the consent of any holders of debt securities, enter into supplemental indentures for various purposes, including:

&nbsp;&nbsp;&nbsp;&nbsp;• to evidence the succession of another entity to us and the assumption by the successor of our covenants and obligations under the debt securities and the indenture;

&nbsp;&nbsp;&nbsp;&nbsp;• establishing the form or terms of any series of debt securities issued under the supplemental indentures;

&nbsp;&nbsp;&nbsp;&nbsp;• adding to our covenants for the benefit of the holders or to surrender any of our rights or powers under the indenture;

&nbsp;&nbsp;&nbsp;&nbsp;• adding additional events of default for the benefit of the holders;

&nbsp;&nbsp;&nbsp;&nbsp;• to change or eliminate any provisions of the indenture provided that the change or elimination becomes effective only when there is no debt security outstanding entitled to the benefit of any changed or eliminated provision;

&nbsp;&nbsp;&nbsp;&nbsp;• to secure the debt securities;

&nbsp;&nbsp;&nbsp;&nbsp;• to cure any ambiguities or correct defective or inconsistent provisions of the indenture, provided that holders of debt securities are not materially affected by the change;

&nbsp;&nbsp;&nbsp;&nbsp;• to evidence and provide for acceptance of a successor trustee; and

&nbsp;&nbsp;&nbsp;&nbsp;• to comply with the requirements of the Trust Indenture Act.

We and the trustee may, with the consent of the holders of not less than a majority in principal amount of the outstanding debt securities of all affected series acting as one class, execute supplemental indentures adding any provisions to or changing or eliminating any of the provisions of the indenture or modifying the rights of the holders of the debt securities of the series. Without the consent of the holders of all the outstanding debt securities affected thereby, no supplemental indenture may:

&nbsp;&nbsp;&nbsp;&nbsp;• change the stated maturity of the principal of, or any installment of principal of or interest on, any debt security;

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&nbsp;&nbsp;&nbsp;&nbsp;• reduce the principal amount of, the rate of interest on or any premium payable upon the redemption of, or change the manner of calculating the rate of interest on, any debt security;

&nbsp;&nbsp;&nbsp;&nbsp;• reduce the amount of the principal of any original issue discount security that would be due and payable upon acceleration of the maturity of the debt security;

&nbsp;&nbsp;&nbsp;&nbsp;• change the place of payment where, or the currency in which, principal or interest on any debt security is payable;

&nbsp;&nbsp;&nbsp;&nbsp;• impair the right to institute suit for enforcement of payments;

&nbsp;&nbsp;&nbsp;&nbsp;• reduce the percentage in principal amount of the outstanding debt securities of any series, the holders of which must consent to a supplemental indenture or any waiver of compliance with various provisions of, or defaults and covenants under, the indenture; or

&nbsp;&nbsp;&nbsp;&nbsp;• modify any of the provisions described in this section

**Consolidation, Merger and Sale of Assets** 

Unless otherwise described in the prospectus supplement relating to a particular offering, as provided in the indentures, we may not consolidate with or merge into any other person, or convey, transfer or lease all or substantially all of our assets to any other person, unless:

&nbsp;&nbsp;&nbsp;&nbsp;• the person surviving or formed by the transaction is organized and validly existing under the laws of any United States jurisdiction and expressly assumes our obligations under the debt securities and the indentures;

&nbsp;&nbsp;&nbsp;&nbsp;• immediately after giving effect to the transaction, no event of default will have occurred and be continuing under the indentures; and

&nbsp;&nbsp;&nbsp;&nbsp;• the trustees under the indentures receive certain officers' certificates and opinions of counsel.

**Satisfaction and Discharge** 

We may terminate our obligations with respect to debt securities of any series not previously delivered to the trustee for cancellation when those debt securities:

&nbsp;&nbsp;&nbsp;&nbsp;• have become due and payable;

&nbsp;&nbsp;&nbsp;&nbsp;• will become due and payable at their stated maturity within one year; or

&nbsp;&nbsp;&nbsp;&nbsp;• are to be called for redemption within one year under arrangements satisfactory to the indenture trustee for giving notice of redemption.

We may terminate our obligations with respect to the debt securities of a series by depositing with the trustee, as trust funds in trust dedicated solely for that purpose, an amount sufficient to pay and discharge the entire indebtedness on the debt securities of that series. In that case, the applicable indenture will cease to be of further effect, and our obligations will be satisfied and discharged with respect to that series (except our obligations to pay all other amounts due under the indenture and to provide certain officers' certificates and opinions of counsel to the trustee). At our expense, the trustee will execute proper instruments acknowledging the satisfaction and discharge.

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**The Trustees** 

Any trustee may be deemed to have a conflicting interest for purposes of the Trust Indenture Act and may be required to resign as trustee if there is an event of default under the applicable indenture and, as more fully described in Section 310(b) of the Trust Indenture Act, one or more of the following occurs:

&nbsp;&nbsp;&nbsp;&nbsp;• the trustee is a trustee under another indenture under which our securities are outstanding;

&nbsp;&nbsp;&nbsp;&nbsp;• the trustee is a trustee for more than one outstanding series of debt securities under a single indenture;

&nbsp;&nbsp;&nbsp;&nbsp;• we or our affiliates or underwriters hold certain threshold ownership beneficial ownership interest in the trustee;

&nbsp;&nbsp;&nbsp;&nbsp;• the trustee holds certain threshold beneficial ownership interests in us or in securities of ours that are in default;

&nbsp;&nbsp;&nbsp;&nbsp;• the trustee is one of our creditors; or

&nbsp;&nbsp;&nbsp;&nbsp;• the trustee or one of its affiliates acts as an underwriter or agent for us.

We may appoint an alternative trustee for any series of debt securities. The appointment of an alternative trustee would be described in the applicable prospectus supplement.

We and our affiliates may engage in transactions with the trustee and its affiliates in the ordinary course of business.

**Governing Law** 

Each of the indentures are, and the related senior debt securities and subordinated debt securities will be, governed by and construed under the internal laws of the State of New York.

**DESCRIPTION OF THE WARRANTS**

We may issue warrants to purchase debt securities, preferred stock or common stock. We may offer warrants separately or together with one or more additional warrants, debt securities, shares of preferred stock or common stock, or any combination of those securities in the form of units, as described in the applicable prospectus supplement. If we issue warrants as part of a unit, the prospectus supplement will specify whether those warrants may be separated from the other securities in the unit prior to the warrants' expiration date. We may issue the warrants under warrant agreements to be entered into between us and a bank or trust company, as warrant agent, all as described in the prospectus supplement. If we issue the warrants under warrant agreements, the warrant agent will act solely as our agent in connection with the warrants and will not assume any obligation or relationship of agency or trust for or with any holders or beneficial owners of warrants.

We will describe the particular terms of any warrants that we offer in the prospectus supplement relating to those warrants. Those terms may include the following:

&nbsp;&nbsp;&nbsp;&nbsp;• the specific designation and aggregate number of warrants, and the price at which we will issue the warrants;

&nbsp;&nbsp;&nbsp;&nbsp;• the currency or currency units in which the offering price, if any, and the exercise price are payable;

&nbsp;&nbsp;&nbsp;&nbsp;• the date on which the right to exercise the warrants will begin and the date on which the right will expire or, if the warrants are not continuously exercisable throughout that period, the specific date or dates on which they are exercisable;

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&nbsp;&nbsp;&nbsp;&nbsp;• whether the warrants will be issued in fully registered form or bearer form, in definitive or global form or in any combination of these forms;

&nbsp;&nbsp;&nbsp;&nbsp;• any applicable material United States federal income tax considerations;

&nbsp;&nbsp;&nbsp;&nbsp;• the identity of the warrant agent, if any, for the warrants and of any other depositaries, execution or paying agents, transfer agents, registrars or other agents;

&nbsp;&nbsp;&nbsp;&nbsp;• the designation, aggregate principal amount, currency, denomination and terms of any debt securities that may be purchased upon exercise of the warrants;

&nbsp;&nbsp;&nbsp;&nbsp;• the designation, amount, currency, denominations and terms of any preferred stock or common stock purchasable upon exercise of the warrants;

&nbsp;&nbsp;&nbsp;&nbsp;• if applicable, the designation and terms of the debt securities, preferred stock or common stock with which the warrants are issued and the number of warrants issued with each security;

&nbsp;&nbsp;&nbsp;&nbsp;• if applicable, the date from and after which the warrants and the related debt securities, preferred stock or common stock will be separately transferable;

&nbsp;&nbsp;&nbsp;&nbsp;• the principal amount of debt securities or the number of shares of preferred stock or common stock purchasable upon exercise of any warrant and the price at which those shares may be purchased;

&nbsp;&nbsp;&nbsp;&nbsp;• provisions for changes to or adjustments in the exercise price;

&nbsp;&nbsp;&nbsp;&nbsp;• if applicable, the minimum or maximum number of warrants that may be exercised at any one time;

&nbsp;&nbsp;&nbsp;&nbsp;• information with respect to any book-entry procedures;

&nbsp;&nbsp;&nbsp;&nbsp;• any antidilution provision of the warrants;

&nbsp;&nbsp;&nbsp;&nbsp;• any redemption or call provisions; and

&nbsp;&nbsp;&nbsp;&nbsp;• any additional terms of the warrants, including terms, procedures and limitations relating to the exchange and exercise of the warrants.

Each warrant will entitle the holder thereof to purchase such number of shares of common stock or preferred stock or other securities at the exercise price as will in each case be set forth in, or be determinable as set forth in, the applicable prospectus supplement. Warrants may be exercised at any time up to the close of business on the expiration date set forth in the applicable prospectus supplement. After the close of business on the expiration date, unexercised warrants will become void. Warrants may be exercised as set forth in the applicable prospectus supplement relating to the warrants offered thereby. Upon receipt of payment and the warrant certificate properly completed and duly executed at the corporate trust office of the warrant agent or any other office indicated in the applicable prospectus supplement, we will, as soon as practicable, forward the purchased securities. If less than all of the warrants represented by the warrant certificate are exercised, a new warrant certificate will be issued for the remaining warrants.

**DESCRIPTION OF UNITS**

We may issue, in one or more series, units comprised of shares of our common stock or preferred stock, warrants to purchase common stock or preferred stock, debt securities or any combination of those securities. 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 included security.

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We may evidence units by unit certificates that we issue under a separate agreement. We may issue the units under a unit agreement between us and one or more unit agents. If we elect to enter into a unit agreement with a unit agent, the unit agent will act solely as our agent in connection with the units and will not assume any obligation or relationship of agency or trust for or with any registered holders of units or beneficial owners of units. We will indicate the name and address and other information regarding the unit agent in the applicable prospectus supplement relating to a particular series of units if we elect to use a unit agent.

We will describe in the applicable prospectus supplement the terms of the series of units being offered, including: (i) 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; (ii) any provisions of the governing unit agreement that differ from those described herein; and (iii) any provisions for the issuance, payment, settlement, transfer or exchange of the units or of the securities comprising the units.

The other provisions regarding our common stock, preferred stock, warrants and debt securities as described in this section will apply to each unit to the extent such unit consists of shares of our common stock, preferred stock, warrants and/or debt securities.

**PLAN OF DISTRIBUTION**

We may sell the securities covered by this prospectus in one or more of the following ways from time to time:

&nbsp;&nbsp;&nbsp;&nbsp;• to or through underwriters or dealers for resale to the purchasers;

&nbsp;&nbsp;&nbsp;&nbsp;• directly to purchasers;

&nbsp;&nbsp;&nbsp;&nbsp;• through agents or dealers to the purchasers; or

&nbsp;&nbsp;&nbsp;&nbsp;• through a combination of any of these methods of sale.

In addition, we may enter into derivative or other hedging transactions with third parties, or sell securities not covered by this prospectus to third parties in privately negotiated transactions. The applicable prospectus supplement may indicate that third parties may sell securities covered by this prospectus and the prospectus supplement, including in short sale transactions, in connection with those derivatives. If so, the third party may use securities we pledge or that are borrowed from us or others to settle those sales or to close out any related open borrowings of stock, and may use securities received from us in settlement of those derivatives to close out any related open borrowings of stock. The third party in those sale transactions will be an underwriter and, if applicable, will be identified in the prospectus supplement (or a post-effective amendment thereto).

A prospectus supplement with respect to each series of securities will include, to the extent applicable:

&nbsp;&nbsp;&nbsp;&nbsp;• the terms of the offering;

&nbsp;&nbsp;&nbsp;&nbsp;• the name or names of any underwriters, dealers, remarketing firms, or agents and the terms of any agreement with those parties, including the compensation, fees, or commissions received by, and the amount of securities underwritten, purchased, or remarketed by, each of them, if any;

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&nbsp;&nbsp;&nbsp;&nbsp;• the public offering price or purchase price of the securities and an estimate of the net proceeds to be received by us from any such sale, as applicable;

&nbsp;&nbsp;&nbsp;&nbsp;• any underwriting discounts or agency fees and other items constituting underwriters' or agents' compensation;

&nbsp;&nbsp;&nbsp;&nbsp;• the anticipated delivery date of the securities, including any delayed delivery arrangements, and any commissions we may pay for solicitation of any such delayed delivery contracts;

&nbsp;&nbsp;&nbsp;&nbsp;• that the securities are being solicited and offered directly to institutional investors or others;

&nbsp;&nbsp;&nbsp;&nbsp;• any discounts or concessions to be allowed or reallowed or to be paid to agents or dealers; and

&nbsp;&nbsp;&nbsp;&nbsp;• any securities exchange on which the securities may be listed.

Any offer and sale of the securities described in this prospectus by us, any underwriters, or other third parties described above may be effected from time to time in one or more transactions, including, without limitation, privately negotiated transactions, either:

&nbsp;&nbsp;&nbsp;&nbsp;• at a fixed public offering price or prices, which may be changed;

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

&nbsp;&nbsp;&nbsp;&nbsp;• at prices related to prevailing market prices at the time of sale; or

&nbsp;&nbsp;&nbsp;&nbsp;• at negotiated prices.

Offerings of securities covered by this prospectus also may be made into an existing trading market for those securities in transactions at other than a fixed price, either:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• on or through the facilities of the NASDAQ Capital Market or any other securities exchange or quotation or trading service on which those securities may be listed, quoted, or traded at the time of sale; and/or

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• to or through a market maker otherwise than on the NASDAQ Capital Market or those other securities exchanges or quotation or trading services.

Those at-the-market offerings, if any, will be conducted by underwriters acting as our principal or agent, who may also be third-party sellers of securities as described above.

In addition, we may sell some or all of the securities covered by this prospectus through:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• purchases by a dealer, as principal, who may then resell those securities to the public for its account at varying prices determined by the dealer at the time of resale or at a fixed price agreed to with us at the time of sale;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• block trades in which a dealer will attempt to sell as agent, but may position or resell a portion of the block as principal in order to facilitate the transaction; and/or

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&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;• ordinary brokerage transactions and transactions in which a broker-dealer solicits purchasers.

Any dealer may be deemed to be an underwriter, as that term is defined in the Securities Act of 1933 of the securities so offered and sold.

In connection with offerings made through underwriters or agents, we may enter into agreements with those underwriters or agents pursuant to which we receive our outstanding securities in consideration for the securities being offered to the public for cash. In connection with these arrangements, the underwriters or agents also may sell securities covered by this prospectus to hedge their positions in any such outstanding securities, including in short sale transactions. If so, the underwriters or agents may use the securities received from us under those arrangements to close out any related open borrowings of securities.

We may loan or pledge securities to a financial institution or other third party that in turn may sell the loaned securities or, in any event of default in the case of a pledge, sell the pledged securities using this prospectus and the applicable prospectus supplement. That financial institution or third party may transfer its short position to investors in our securities or in connection with a simultaneous offering of other securities covered by this prospectus.

We may solicit offers to purchase the securities covered by this prospectus directly from, and we may make sales of such securities directly to, institutional investors or others, who may be deemed to be underwriters within the meaning of the Securities Act with respect to any resale of such securities.

The securities may also be offered and sold, if so indicated in a 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.

If indicated in the applicable prospectus supplement, we may sell the securities through agents from time to time. We generally expect that any agent will be acting on a "best efforts" basis for the period of its appointment.

If underwriters are used in any sale of any securities, the securities may be either offered to the public through underwriting syndicates represented by managing underwriters, or directly by underwriters. Unless otherwise stated in a prospectus supplement, the obligations of the underwriters to purchase any securities will be conditioned on customary closing conditions, and the underwriters will be obligated to purchase all of that series of securities, if any are purchased.

Underwriters, dealers, agents, and remarketing firms may at the time of any offering of securities be entitled under agreements entered into with us to indemnification by us against certain civil liabilities, including liabilities under the Securities Act, or to contribution with respect to payments that the underwriters, dealers, agents, and remarketing firms may be required to make. Underwriters, dealers, agents, and remarketing agents may be customers of, engage in transactions with, or perform services in the ordinary course of business for us and/or our affiliates.

Any underwriters to whom securities covered by this prospectus are sold by us for public offering and sale, if any, may make a market in the securities, but those underwriters will not be obligated to do so and may discontinue any market making at any time without notice.

**LEGAL MATTERS** 

ArentFox Schiff LLP, Washington, DC, will pass upon the validity of the securities offered by this prospectus for us. Legal matters will be passed upon for any underwriters, dealers or agents by counsel named in the applicable prospectus supplement.

**EXPERTS**

The audited financial statements incorporated by reference in this prospectus and elsewhere in the registration statement have been so incorporated by reference in reliance upon the report of Grant Thornton LLP, independent registered public accountants, upon the authority of said firm as experts in accounting and auditing.

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![image2.jpg](image2.jpg)

**Moleculin Biotech, Inc.**

**Up to $6,500,000**

**Common Stock**

**Roth Capital Partners**

**July 11, 2025**