GT Biopharma (NASDAQ: GTBP) said it has received FDA clearance for an investigator-sponsored Phase 1a/1b trial of GTB-5550 in patients with multiple myeloma. The program represents the first human study of a B7-H3-targeted TriKE in the indication.
The trial will evaluate up to six dose cohorts in Phase 1a, enrolling patients who have received four or more prior lines of therapy, to identify the maximum tolerated dose. Phase 1b will expand to 25 patients treated at the established dose level to assess safety, tolerability and preliminary anti-tumor activity.
GTB-5550 is administered by subcutaneous injection on three non-consecutive days per week during weeks one and two of each cycle, followed by a two-week rest period. One treatment cycle spans four weeks. Patients with stable disease may continue for up to four cycles, with reassessment on day 28; those achieving a partial response or better can remain on treatment for up to one year.
Trial initiation remains contingent on timing and receipt of non-dilutive grant funding. Unaudited pro forma cash as of September 15, 2026 stands at approximately $11 million, which management expects to sustain operations into the third quarter of 2027.
The company also reported that its ongoing Phase 1 dose-escalation basket trial of GTB-5550 in solid tumor patients continues to actively enroll, with an update anticipated in the fourth quarter of 2026.
GT Biopharma holds an exclusive worldwide license agreement with the University of Minnesota to develop and commercialize therapies based on TriKE technology.
