First Amendment to Securities Purchase Agreement by and among GT Biopharma, Inc. and Purchasers (including Robert A. Marzilli)

Exhibit 10.1

FIRST AMENDMENT TO SECURITIES PURCHASE AGREEMENT

THIS FIRST AMENDMENT TO SECURITIES PURCHASE AGREEMENT (this “Amendment”), dated as of May 21, 2025, is entered into among GT Biopharma, Inc., a Delaware corporation (the “Company”) and each Person identified on the signature pages hereto (each, including its successors and assigns, a “Purchaser” and collectively, the “Purchasers”). Capitalized terms used herein and not otherwise defined shall have the meanings ascribed thereto in the Purchase Agreement (as defined below).

RECITALS

A. The Company, Five Narrow Lane, L.P. (“Five Narrow”), Bristol Capital LLC (“Bristol Capital”) and certain other purchasers (collectively, the “Initial Purchasers”) are parties to that certain Securities Purchase Agreement, dated as of May 12, 2025 (the “Purchase Agreement”).

B. The Company has requested that the Initial Purchasers agree to amend the Purchase Agreement to add Robert A. Marzilli (“Marzilli”) as a party thereto and approve other related amendments to the Purchase Agreement, and the Purchasers have agreed to such requests, subject to the terms and conditions of this Amendment.

C. Pursuant to Section 5.5 of the Purchase Agreement, the Purchase Agreement may be amended upon the written consent by the Company and such Purchasers which purchased at least 50.1% in interest of the Preferred Stock based on the initial Subscription Amounts thereunder (the “Majority Purchasers”).

D. Five Narrow and Bristol Capital constitute the Majority Purchasers under the Purchased Agreement.

NOW, THEREFORE, in consideration of the agreements contained herein, and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto agree as follows:

AMENDMENTS

1. Amendments.

2.1 Closing. On the Closing Date, upon the terms and subject to the conditions set forth herein, substantially concurrent with the execution and delivery of this Agreement by the parties hereto, the Company agrees to sell, and the Purchasers, severally and not jointly, agree to purchase, up to an aggregate of $6,611,111 of shares of Preferred Stock for an aggregate purchase price equal to $5,950,000. The aggregate number of shares of Preferred Stock sold hereunder on the Closing Date shall be up to 6,612. Each Purchaser shall deliver to the Company, via wire transfer, immediately available funds equal to such Purchasers Subscription Amount and the Company shall deliver to each Purchaser its respective shares of Preferred Stock and Warrants as determined pursuant to Section 2.2(a), and the Company and each Purchaser shall deliver the other items set forth in Section 2.2 deliverable at the Closing. Upon satisfaction of the covenants and conditions set forth in Sections 2.2 and 2.3, the Closing shall occur at the offices of EGS or such other location as the parties shall mutually agree and take place remotely by electronic transfer of the Closing documentation.

2.4 Greenshoe Rights.

(a) From the date hereof until the date that no Greenshoe Securities (as defined herein) remain available for purchase, each Purchaser may, in its sole determination, elect to purchase, severally and not jointly with the other Purchasers and, subject to the proviso below, in one or more closings, shares of Preferred Stock with an aggregate Stated Value thereof of up to $24,018,349 (such securities, the “Greenshoe Securities” and such shares of Common Stock issuable upon conversion of such Greenshoe Securities (the “Greenshoe Conversion Shares”) and such right to receive the Greenshoe Securities pursuant to this Section 2.4, the “Greenshoe Rights”), for an aggregate purchase price equal to $21,616,514, provided the conversion price of the Preferred Stock and Exercise Price of the Vesting Warrants shall be equal to the Conversion Price (as set forth in Section 6(b) of the Certificate of Designation) and the Warrants shall be adjusted pursuant to the adjustment provisions thereunder. Each Purchaser is hereby entitled to exercise its respective Greenshoe Rights for an amount of Greenshoe Securities equal to the ratio of such Purchaser’s original Subscription Amount to the original aggregate Subscription Amount of all Purchasers, provided that, in connection with the exercise of Greenshoe Rights, such Purchaser shall purchase Greenshoe Securities having a Stated Value at least equal to the lesser of (i) $100,000 and (ii) the balance of the Greenshoe Rights attributable to such Purchaser hereunder.

[signature pages follow]

IN WITNESS WHEREOF, each of the parties hereto has caused a counterpart of this Amendment to be duly executed and delivered as of the date first above written.

[Signature Page to Amendment No. 1 to Purchase Agreement]

IN WITNESS WHEREOF, each of the parties hereto has caused a counterpart of this Amendment to be duly executed and delivered as of the date first above written.

[Signature Page to Amendment No. 1 to Purchase Agreement]

IN WITNESS WHEREOF, each of the parties hereto has caused a counterpart of this Amendment to be duly executed and delivered as of the date first above written.

[Signature Page to Amendment No. 1 to Purchase Agreement]

IN WITNESS WHEREOF, each of the parties hereto has caused a counterpart of this Amendment to be duly executed and delivered as of the date first above written.

[Signature Page to Amendment No. 1 to Purchase Agreement]