GT生物制药公司美股招股说明书(2025-12-02版)

14,589,546 Shares of Common Stock This prospectus relates to the offering from time to time by the selling stockholders named in this prospectus (the “SellingStockholders”) of up to an aggregate 14,589,546 shares of common stock, par value $0.001 per share (the “Common Stock”), of GTBiopharma, Inc., a Delaware corporation (the “Company”), consisting of (i) 7,219,771 shares of Common Stock issuable upon theconversion of 3,277.78 shares of Series L 10% Convertible Preferred Stock, par value $0.001 per share (the “Series L Preferred Stock”or the “Preferred Shares,” and the shares of Common Stock issuable upon conversion of the Preferred Shares, the “ConversionShares”) issued upon the exercise of certain of the Greenshoe Rights (as defined below) issued in connection with our privateplacement in May 2025, (ii) 7,219,775 shares of Common Stock issuable upon the exercise of vested warrants (the “Vesting Warrants,”and the shares of Common Stock issuable upon the exercise of the Vesting Warrants, the “Vesting Warrant Shares”) issued inconnection with our private placement in May 2025, and (iii) 150,000 shares of Common Stock issuable upon the exercise of the pre- We have agreed to bear all of the expenses incurred in connection with the registration of the Shares. The SellingStockholders will pay or assume discounts, commissions, fees of underwriters, selling brokers or dealer managers and similar The Selling Stockholders, or their respective donees, pledgees, transferees or other successors-in-interest, may sell orotherwise dispose of the Shares covered by this prospectus in a number of different ways. We provide more information about how the Our Common Stock is presently listed on the Nasdaq Capital Market (“Nasdaq”) under the trading symbol “GTBP.” OnDecember 1, 2025, the closing sale price for our Common Stock was $0.78 per share. Investing in our securities involves a high degree of risk. See the section entitled “Risk Factors” beginning on page 6 ofthis prospectus and in the documents incorporated by reference into this prospectus for a discussion of risks that should be Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved ofthese securities or passed upon the adequacy or accuracy of this prospectus. Any representation to the contrary is a criminaloffense. The date of this prospectus is December 2, 2025. TABLE OF CONTENTS ABOUT THIS PROSPECTUS This prospectus is part of a registration statement filed with the U.S. Securities and Exchange Commission (the “SEC”) usinga “shelf” registration process. By using a shelf registration statement, the Selling Stockholders may sell up to 14,589,546 shares ofCommon Stock from time to time in one or more offerings as described in this prospectus. We will not receive any proceeds from the We may also file a prospectus supplement or post-effective amendment to the registration statement of which this prospectusforms a part that may contain material information relating to these offerings. The prospectus supplement or post-effective amendmentmay also add, update or change information contained in this prospectus with respect to that offering. If there is any inconsistencybetween the information in this prospectus and the applicable prospectus supplement or post-effective amendment, you should rely onthe prospectus supplement or post-effective amendment, as applicable. Before purchasing any securities, you should carefully read this Neither we, nor the Selling Stockholders, have authorized anyone to provide you with any information or to make anyrepresentations other than those contained or incorporated by reference in this prospectus, any post-effective amendment, or anyapplicable prospectus supplement prepared by or on behalf of us or to which we have referred you. We and the Selling Stockholderstake no responsibility for and can provide no assurance as to the reliability of any other information that others may give you. TheSelling Stockholders will not make an offer to sell these securities in any jurisdiction where the offer or sale is not permitted. Youshould assume that the information appearing in this prospectus, any post-effective amendment and any applicable prospectus Although we believe these sources are reliable, we do not guarantee the accuracy or completeness of this information and wehave not independently verified this information. In addition, the market and industry data and forecasts that may be incorporated byreference in this prospectus, any post-effective amendment or any prospectus supplement may involve estimates, assumptions and other risks and uncertainties and are subject to change based on various factors, including those discussed under the heading “Risk The information appearing in this prospectus, any applicable prospectus supplement or any related free writing prospectus isaccurate only as of the date on the front of the document and any information we have incorporated