Tyra Biosciences shares slump 30% after Phase 2 trial data

On Wednesday, shares of Tyra Biosciences, Inc. (NASDAQ:TYRA) dropped 30% after the company unveiled initial Phase 2 SURF302 trial data for dabogratinib in patients with FGFR3-altered low-grade intermediate-risk non-muscle invasive bladder cancer.

Tyra reported a 79% overall response rate (ORR) and a 64% complete response (CR) rate as best overall response with 60 mg once-daily dosing across combined single and multiple marker lesion patients. Among single marker lesion patients, the 60 mg once-daily regimen produced a 100% ORR and a 75% CR rate as best overall response.

As of the August 31, 2026 data cutoff, the trial had enrolled 44 participants across the 60 mg once-daily and 50 mg once-daily dose cohorts. Of the 26 efficacy-evaluable participants, 14 were assigned to 60 mg once-daily and 12 to 50 mg once-daily.

Safety data revealed Grade 3 treatment-emergent adverse events in 14% of participants receiving 60 mg and in 9% receiving 50 mg. Grade 3 treatment-related adverse events were observed in 4.5% of participants overall across both cohorts, with none occurring in the 60 mg once-daily group. No Grade 4 or 5 treatment-emergent adverse events were reported. In the 60 mg once-daily arm, there were no dose reductions or treatment-related discontinuations.

At the 60 mg once-daily dose, the most common treatment-emergent adverse events were fatigue, diarrhea, and dry eye. The company noted no clinically significant hyperphosphatemia, nail toxicity, or ocular toxicity, and transaminase treatment-emergent adverse events occurred at a frequency below 10%.

Tyra intends to finish enrollment in the 60 mg once-daily cohort and to launch a 70 mg once-daily cohort. The company also plans to consult with health authorities regarding Phase 3 study design and dose selection.

In the separate Phase 2 SURF303 trial assessing dabogratinib in low-grade upper tract urothelial cancer, the first treated patient achieved a complete response at the 3-month evaluation on the 60 mg once-daily schedule.

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