# EDGAR Filing Document

**Accession Number:** 0001390478
**File Stem:** 0001104659-25-096643
**Filing Date:** 2025-10
**Character Count:** 9139
**Document Hash:** 7c4b08faf3199d4fc9fb447399e624d0
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001104659-25-096643.hdr.sgml**: 20251003

**ACCESSION NUMBER**: 0001104659-25-096643

**CONFORMED SUBMISSION TYPE**: 8-K

**PUBLIC DOCUMENT COUNT**: 13

**CONFORMED PERIOD OF REPORT**: 20251001

**ITEM INFORMATION**: Entry into a Material Definitive Agreement

**ITEM INFORMATION**: Financial Statements and Exhibits

**FILED AS OF DATE**: 20251003

**DATE AS OF CHANGE**: 20251003

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** SELLAS Life Sciences Group, Inc.
- **CENTRAL INDEX KEY:** 0001390478
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 000000000
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 8-K
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-33958
- **FILM NUMBER:** 251373761

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

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

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

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

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

?xml version='1.0' encoding='ASCII'?

**UNITED STATES**

**SECURITIES AND EXCHANGE COMMISSION**

**WASHINGTON, D.C. 20549** 

**FORM 8-K**

**CURRENT REPORT**

**PURSUANT TO SECTION 13 OR 15(d) OF THE**

**SECURITIES EXCHANGE ACT OF 1934** 

Date of report (Date of earliest event reported): **October 1, 2025**

**SELLAS Life Sciences Group, Inc.**

(Exact name of registrant as specified in its charter)

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| | | |
|:---|:---|:---|
| **Delaware** | **001-33958** | **20-8099512** |
| (State or other jurisdiction of<br> incorporation or organization) | (Commission <br> File Number) | (I.R.S. Employer <br> Identification No.) |
|  | **7 Times Square, Suite 2503<br> New York, NY 10036** |  |
|  | (Address of Principal Executive <br> Offices) (Zip Code) |  |
| Registrant's telephone number, including area code: **(646) 200-5278** | Registrant's telephone number, including area code: **(646) 200-5278** | Registrant's telephone number, including area code: **(646) 200-5278** |

---

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligations of the registrant under any of the following provisions:

◻ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

◻ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

◻ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

◻ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

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| | | |
|:---|:---|:---|
| Title of each class | Trading<br> symbol(s) | Name of each exchange on which registered |
| Common Stock, $0.0001 par value per share | SLS | The Nasdaq Stock Market LLC |

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Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company ◻

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ◻

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| | |
|:---|:---|
| **Item 1.01** | **Entry into a Material Definitive Agreement.** |

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On October 1, 2025, SELLAS Life Sciences Group, Inc. (the "Company"), as subtenant, entered into a Letter Agreement with Times Square Tower Associates LLC (the "Sublandlord") relating to a certain sublease (as amended) of certain premises located at Times Square Tower, 7 Times Square, New York, New York (the "Sublease"). The Letter Agreement provides for the extension of the expiration date of the Sublease from September 30, 2026 to September 30, 2027. The annual rent remains unchanged.

The foregoing description of the Letter Agreement is qualified in its entirety by reference to the Letter Agreement, which is filed as Exhibit 10.1 hereto and incorporated herein by reference.

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| | |
|:---|:---|
| **Item 9.01.** | **Financial Statements and Exhibits.** |

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(d)&nbsp;&nbsp;&nbsp;&nbsp; Exhibits

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| | |
|:---|:---|
| **Exhibit Number** | **Description** |
| [10.1](tm2527877d1_ex10-1.htm) | [Letter Agreement by and between SELLAS Life Sciences Group, Inc. and Times Square Tower Associates LLC](tm2527877d1_ex10-1.htm) |
| 104 | Cover Page Interactive Data File (embedded within the Inline XBRL document) |

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**SIGNATURES**

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

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| | | | | |
|:---|:---|:---|:---|:---|
| | | **SELLAS Life Sciences Group, Inc.** | **SELLAS Life Sciences Group, Inc.** | **SELLAS Life Sciences Group, Inc.** |
| Date: | October 3, 2025 | By: | /s/ John T. Burns | /s/ John T. Burns |
|  |  |  | Name: | John T. Burns |
|  |  |  | Title: | Senior Vice President, Chief Financial Officer |

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## Exhibit 10.1

**Exhibit 10.1**

**TIMES SQUARE TOWER ASSOCIATES LLC**

c/o Boston Properties Limited Partnership

599 Lexington Avenue, 16<sup>th</sup> Floor

New York, New York 10022

October 1, 2025

Sellas Life Sciences Group, Inc.

7 Times Square, 25<sup>th</sup> Floor,

New York NY 10036

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| | |
|:---|:---|
| **Re:** | **Time Square Tower, 7 Time Square, New York, NY (the "Building")** |

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Ladies and Gentlemen:

Reference is hereby made to that certain Sublease dated June 5, 2020, a Confirmation of Sublease Terms and Dates dated July 16, 2020, a First Amendment to Sublease dated December 6, 2021, a Second Amendment to Sublease dated December 11, 2023 and a Letter Agreement dated October 2, 2024 (collectively, the "***Sublease***") between Times Square Tower Associates LLC, successor-in-interest to Reimer & Braunstein LLP, as sublandlord, and Sellas Life Sciences Group, Inc., as subtenant, relating to a portion of the twenty-fifth (25<sup>th</sup>) floor of the Building. All capitalized terms used but not otherwise defined herein shall have the respective meanings given thereto in the Sublease.

In consideration of Ten Dollars ($10.00) and other good and valuable consideration the receipt and sufficiency of which are hereby acknowledged, Landlord and Tenant confirm and agree that the New Term Expiration Date is hereby modified to be September 30, 2027.

Except as otherwise expressly modified herein, the Sublease remains unmodified and in full force and effect.

Tenant represents to Landlord that it has dealt solely with CBRE, Inc. ("***Broker***") in connection with this letter agreement. Broker shall be compensated by Landlord pursuant to a separate agreement. Tenant shall indemnify, defend, protect and hold Landlord harmless from and against any and all losses, liabilities, damages, claims, judgments, fines, suits, demands, costs, interest and expenses of any kind of nature, including reasonable attorneys' fees and disbursements, which the Landlord may incur by reason of any claim of or liability to any broker, finder or like agent (other than Broker) arising out of any dealings claimed to have occurred between Tenant and the claimant in connection with this letter agreement.

Kindly indicate your agreement to the foregoing by signing this letter agreement below. This letter agreement may be signed in counterparts and may be transmitted electronically via a mutually acceptable digital signature service provider, email and in .pdf form, and all such counterparts shall, when combined, constitute a fully executed original.

[rest of page left intentionally blank]

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| | |
|:---|:---|
| Very truly yours, | Very truly yours, |
| **TIMES SQUARE TOWER ASSOCIATES LLC** | **TIMES SQUARE TOWER ASSOCIATES LLC** |
| BY: BP TIMES SQUARE TOWER MEZZANINE LLC | BY: BP TIMES SQUARE TOWER MEZZANINE LLC |
| BY: NO. 1 TIMES SQUARE DEVELOPMENT LLC | BY: NO. 1 TIMES SQUARE DEVELOPMENT LLC |
| BY: BOSTON PROPERTIES LIMITED PARTNERSHIP | BY: BOSTON PROPERTIES LIMITED PARTNERSHIP |
| BY: BXP, INC. | BY: BXP, INC. |
| By: | /s/ Heather Kahn |
| Name: | Heather Kahn |
| Title: | Senior Vice President |

---

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| | |
|:---|:---|
| **AGREED TO AND ACCEPTED BY:** | **AGREED TO AND ACCEPTED BY:** |
| **TENANT:** | **TENANT:** |
| **SELLAS LIFE SCIENCES GROUP, INC.** | **SELLAS LIFE SCIENCES GROUP, INC.** |
| /s/ John T. Burns | /s/ John T. Burns |
| Name: | John T. Burns |
| Title: | SVP & Chief Financial Officer |

---