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: ~~April~~May 320, 2026

(Date of earliest event reported)

GT Biopharma, Inc.

(Exact name of registrant as specified in its charter)

Delaware

(State or other Jurisdiction of Incorporation)

1-40023

94-1620407

(Commission

File Number)

(IRS Employer

Identification No.)

N/A¹

(Address of Principal Executive Offices and zip code)

(415) 919-4040

(Registrant’s telephone number, including area code)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of 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(b) under the Exchange Act (17 CFR 240.14a-12(b))

☐	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:

Title of each Class		Trading Symbol(s)		Name of each Exchange on which registered
Common stock, $0.001 par value		GTBP		The Nasdaq Stock Market LLC

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. ☐

¹ Effective as of July 1, 2024, the Company became a fully remote company. We do not maintain a principal executive office. For purposes of compliance with applicable requirements of the Securities Act of 1933, as amended, and the Securities Exchange Act of 1934, as amended, any stockholder communication required to be sent to the Company’s principal executive offices may be directed to 505 Montgomery Street, 10th Floor, San Francisco, California 94111, or by email to [email protected].

Item 13.01 ~~Entry~~Notice ~~into~~of Delisting or Failure to Satisfy a ~~Material~~Continued ~~Definitive~~Listing ~~Agreement~~Rule or Standard.

On ~~April~~May 320, 2026, GT Biopharma, Inc., a Delaware corporation (the “Company”), ~~entered~~received ~~into~~a anletter ~~Investigator~~from ~~Initiated Clinical Trial Agreement (~~the ~~“Agreement”)~~Nasdaq ~~with~~Listing ~~the~~Qualifications Staff ~~Regents of the University of Minnesota~~ (the “~~University~~Staff”), ~~pursuant to~~of ~~which,~~The ~~the~~Nasdaq ~~University~~Stock ~~shall~~Market ~~sponsor~~LLC ~~an Investigational New Drug~~ (“~~IND~~Nasdaq”) ~~application~~notifying ~~for~~the ~~IND~~Company ~~169118~~that ~~GTB-5550 (~~the ~~“Research Program”)~~Staff ~~and~~has ~~shall~~granted the ~~serve~~Company asan aadditional ~~sponsor~~compliance ~~investigator~~period ~~for~~of a180 ~~phase~~calendar ~~1a/1b~~days, ~~clinical~~or ~~trial~~until ~~entitled~~November 16, ~~“GTB-5550~~2026, ato ~~Camelid~~regain ~~Nanobody B7-H3~~compliance ~~Tri-Specific~~with ~~Killer~~Nasdaq ~~Engager~~Listing Rule 5550(~~camB7-H3 TriKE®~~a)(2), inwhich ~~Select~~requires ~~Advanced~~listed ~~Solid~~securities ~~Tumors~~to ~~That~~maintain ~~Failed~~a ~~Prior~~minimum ~~Therapy,”~~bid ~~designed~~price ~~by University~~of $1.00 per share (the “~~Study~~Minimum Bid Price Requirement”). If ~~The~~at ~~Research~~any ~~Program~~time isduring ~~being~~this ~~conducted~~additional ~~for~~compliance ~~clinical~~period ~~research~~the ~~use.~~closing ~~The~~bid ~~budget~~price ~~for~~of the ~~Study,~~Company’s ~~including without~~common ~~limitations~~stock, ~~funding and resources, provides for up to approximately~~ $30.8001 ~~million~~par ~~over~~value per share (the ~~course~~“Common ofStock”), ~~three~~is ~~years~~at ~~borne~~least ~~by the Company~~$1.00 ~~The~~per ~~University~~share ~~and~~for ~~the~~a ~~Company~~minimum ~~will~~of ~~each~~10 ~~have~~consecutive ~~the~~business ~~right~~days to(unless ~~publish~~ the ~~Study~~Staff ~~results. The Agreement may be terminated by the~~exercises ~~Company~~its ordiscretion ~~the~~to ~~University~~extend atthis ~~any~~ten ~~time~~business ~~upon~~day ~~thirty~~period ~~days’~~pursuant ~~written notice~~ to ~~the~~Nasdaq ~~other~~Listing ~~party~~Rule 5810(c)(3)(H)), byNasdaq ~~the~~will ~~University~~provide ~~immediately~~the ~~for health,~~Company ~~welfare~~written ~~and~~confirmation ~~safety~~of ~~reasons,~~compliance orwith ~~by either party if~~ the ~~other~~Minimum ~~party~~Bid ~~materially~~Price ~~breaches the Agreement~~Requirement, ~~provided~~and ~~that~~ the ~~breaching~~matter ~~party fails~~will tobe ~~cure such breach within thirty days~~closed.

~~The~~As ~~foregoing~~previously ~~description~~disclosed, ofon ~~the~~November ~~Agreement~~20, ~~does~~2025, ~~not~~the ~~purport~~Company toreceived bea ~~complete~~letter ~~and~~from isthe ~~qualified~~Staff innotifying ~~its~~the ~~entirety~~Company bythat ~~reference to~~ the ~~full~~closing ~~text~~bid price of the ~~Agreement~~Company’s ~~attached~~common tostock ~~this~~had ~~Current~~fallen ~~Report~~below onthe ~~Form~~required ~~8-K~~minimum asbid ~~Exhibit~~price ~~10.~~of $1 per share for 30 consecutive business days and ~~incorporated~~that bythe ~~reference~~Company ~~into~~had ~~this~~been ~~Item~~provided 1an initial 180 calendar day compliance period, or until May 19, 2026, to regain compliance.~~01.~~

Nasdaq determined that the Company is eligible for the additional compliance period because the Company meets the continued listing requirement for the market value of publicly held shares and all other applicable requirements for initial listing on the Nasdaq Capital Market, with the exception of the Minimum Bid Price Requirement.

The Company intends to monitor the closing bid price of the Common Stock and assess its available options to regain compliance with the Minimum Bid Price Requirement and continue listing on The Nasdaq Capital Market. There can be no assurance that the Company will be able to regain compliance with the Minimum Bid Price requirement or will otherwise be in compliance with other applicable Nasdaq listing rules.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits.

Exhibit Number		Description
10.1*		Investigator Initiated Clinical Trial Agreement, dated as of April 3, 2026, by and between GT Biopharma, Inc. and the Regents of the University of Minnesota.
104		Cover Page Interactive Data File, formatted in Inline XBRL

* Certain exhibits and schedules to this exhibit have been omitted pursuant to Item 601(a)(5) of Regulation S-K. The registrant hereby undertakes to furnish copies of any of the omitted schedules and exhibits upon request by the U.S. Securities and Exchange Commission.

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.

	GT BIOPHARMA, INC.
Date: April 7, 2026	By:	/s/ Alan Urban
Date: May 22, 2026	By:	/s/ Alan Urban
		Alan Urban
		Chief Financial Officer

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