Corporate Action (Form 8-K)

Item 3.03 Material Modification to Rights of Security Holders.

As previously disclosed, on each of September 17, 2025, September 18, 2025 and September 23, 2025, certain of the holders of GT Biopharma, Inc.'s Series L 10% Convertible Preferred Stock (the "Series L Preferred Stock") provided a waiver (the "Waiver") to the Certificate of Designation of Preferences, Rights and Limitations of Series L 10% Convertible Preferred Stock (the "Certificate of Designations"). On September 25, 2025, an additional holder of Series L Preferred Stock provided a Waiver. Pursuant to the Waiver, all Series L Preferred Stockholders have agreed to waive the rights to redemption set forth in Section 10 of the Certificate of Designations.

The foregoing description of the Waiver does not purport to be complete and is qualified in its entirety by reference to the full text of the Waiver, which is attached hereto as Exhibit 10.1 and is incorporated herein by reference.