Exhibit 10.1

Execution Version

EIGHTH AMENDMENT TO NOTE PURCHASE AGREEMENT

AND FOURTH AMENDMENT TO DISCLOSURE LETTER

This EIGHTH AMENDMENT TO NOTE PURCHASE AGREEMENT AND FOURTH AMENDMENT TO DISCLOSURE LETTER (this “Agreement”), dated as of October 6, 2025, is entered into by and among PUMA BIOTECHNOLOGY, INC., a Delaware corporation (the “Issuer”), the Guarantors party hereto, the Purchasers party hereto and ATHYRIUM OPPORTUNITIES IV CO-INVEST 1 LP, as the Administrative Agent. All capitalized terms used herein and not otherwise defined herein shall have the meanings given to such terms in the Note Purchase Agreement (as defined below).

RECITALS

WHEREAS, the Issuer, the Guarantors, the Purchasers and the Administrative Agent entered into that certain Note Purchase Agreement dated as of July 23, 2021 (as amended or modified from time to time, the “Note Purchase Agreement”);

WHEREAS, the Credit Parties have requested that the Note Purchase Agreement and the Disclosure Letter be amended as set forth below, subject to the terms and conditions specified in this Agreement; and

WHEREAS, the parties hereto are willing to amend the Note Purchase Agreement and the Disclosure Letter, subject to the terms and conditions specified in this Agreement.

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

1.           Amendments. The Note Purchase Agreement and the Disclosure Letter are hereby amended as follows:

(a)    The definition of “Qualified Equity Issuance” in Section 1.01 of the Note Purchase Agreement is hereby amended by replacing the text “November 1, 2025” with the text “April 30, 2026”.

(b)    Section 7.23 of the Note Purchase Agreement is hereby amended by replacing each occurrence of the text “November 1, 2025” with the text “April 30, 2026”.

(c)    Schedule 1.01(c) to the Disclosure Letter is hereby amended by replacing the text “November 1, 2025” with the text “April 30, 2026”.

2.           Condition Precedent. This Agreement shall be effective as of the date hereof upon satisfaction of each of the following conditions:

(a)    the Administrative Agent shall have received counterparts of this Agreement duly executed by the Issuer, the Guarantors, the Purchasers and the Administrative Agent; and

(b)    the Issuer shall have paid all reasonable and documented out-of-pocket expenses incurred by the Administrative Agent and its Affiliates prior to the date hereof (including the reasonable fees, charges and disbursements of outside counsel for the Administrative Agent), in each case, to the extent required under Section 11.04 of the Note Purchase Agreement and invoiced at least three Business Days prior to the date hereof.

3.          Reaffirmation of Representations and Warranties; No Default. The Issuer and each other Credit Party represents and warrants to the Administrative Agent and each Purchaser that after giving effect to this Agreement (a) the representations and warranties of the Issuer and each other Credit Party contained in Article VI of the Note Purchase Agreement or any other Note Document, or which are contained in any document furnished at any time under or in connection therewith, are true and correct in all material respects (and in all respects if any such representation or warranty is already qualified by materiality or reference to Material Adverse Effect) on and as of the date hereof, except to the extent that such representations and warranties specifically refer to an earlier date, in which case they shall be true and correct in all material respects (and in all respects if any such representation or warranty is already qualified by materiality or reference to Material Adverse Effect) as of such earlier date, and except that for purposes of this Section 3, the representations and warranties contained in clauses (a) and (b) of Section 6.05 of the Note Purchase Agreement shall be deemed to refer to the most recent statements furnished pursuant to clauses (a) and (b) of Section 7.01 of the Note Purchase Agreement, respectively, and (b) no Default or Event of Default exists.

4.            Miscellaneous.

(a)         The Note Purchase Agreement and the obligations of the Credit Parties thereunder and under the other Note Documents, are hereby ratified and confirmed and shall remain in full force and effect according to their terms.

(b)         Sections 11.14 and 11.15 of the Note Purchase Agreement are incorporated herein by reference and shall apply, mutatis mutandis, to this Agreement as if fully set forth herein.

(c)         As a material part of the consideration for the Administrative Agent and the Purchasers entering into this Agreement, the Credit Parties agree that the Administrative Agent, the Purchasers, each of their respective Affiliates and each of the foregoing Persons’ respective officers, managers, members, directors, advisors, sub-advisors, partners, agents and employees, and their respective successors and assigns (hereinafter all of the above collectively referred to as the “Purchaser Group”), are irrevocably and unconditionally released, discharged and acquitted from any and all actions, causes of action, claims, demands, damages and liabilities of whatever kind or nature, in law or in equity, now known or unknown, suspected or unsuspected to the extent that any of the foregoing arises from any action or failure to act under or otherwise arising in connection with the Note Documents, in each case arising on or prior to the date hereof, except to the extent such actions, causes of action, claims, demands, damages and liabilities result from the gross negligence or willful misconduct of any of the Purchaser Group as determined by a court of competent jurisdiction in a final and nonappealable judgment.

(d)         This Agreement may be executed in any number of counterparts, each of which when so executed and delivered shall be an original, but all of which shall constitute one and the same instrument. Delivery of an executed counterpart of a signature page of this Agreement by facsimile or other electronic imaging means (e.g. “pdf” or “tif”) shall be effective as delivery of a manually executed counterpart of this Agreement.

(e)      THIS AGREEMENT AND THE RIGHTS AND OBLIGATIONS OF THE PARTIES HEREUNDER SHALL BE GOVERNED BY AND CONSTRUED AND INTERPRETED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK.

[Signature pages follow]

IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be duly executed as of the date first above written.

EIGHTH AMENDMENT TO NOTE PURCHASE AGREEMENT

AND FOURTH AMENDMENT TO DISCLOSURE LETTER (SEPTEMBER 2025)

PUMA BIOTECHNOLOGY, INC.

EIGHTH AMENDMENT TO NOTE PURCHASE AGREEMENT

AND FOURTH AMENDMENT TO DISCLOSURE LETTER (SEPTEMBER 2025)

PUMA BIOTECHNOLOGY, INC

EIGHTH AMENDMENT TO NOTE PURCHASE AGREEMENT

AND FOURTH AMENDMENT TO DISCLOSURE LETTER (SEPTEMBER 2025)

PUMA BIOTECHNOLOGY, INC