Tyra Biosciences (NASDAQ:TYRA) shares dropped 30% on Wednesday after the biotechnology company released initial results from its Phase 2 SURF302 trial of dabogratinib in patients with FGFR3-altered low-grade intermediate-risk non-muscle invasive bladder cancer.
At the 60 mg once-daily dose, dabogratinib produced a 79% overall response rate and a 64% complete response rate as the best overall response among patients with single and multiple marker lesions combined.
Results were stronger among patients with a single marker lesion, where the 60 mg dose achieved a 100% overall response rate and a 75% complete response rate as the best overall response.
As of the August 31, 2026 data cutoff, SURF302 had enrolled 44 participants across the 60 mg and 50 mg once-daily cohorts. Of the 26 patients evaluable for efficacy, 14 received the 60 mg dose and 12 received 50 mg.
Tyra reports safety data from SURF302
Grade 3 treatment-emergent adverse events were reported in 14% of participants receiving 60 mg and 9% of those receiving 50 mg.
Across both cohorts, Grade 3 treatment-related adverse events occurred in 4.5% of participants, with none reported in the 60 mg group. No Grade 4 or Grade 5 treatment-emergent adverse events were observed.
Tyra also reported no dose reductions or treatment-related discontinuations among participants receiving the 60 mg once-daily dose.
The most frequently reported treatment-emergent adverse events in the 60 mg cohort were fatigue, diarrhoea and dry eye. The company said there were no clinically significant cases of hyperphosphatemia, nail toxicity or ocular toxicity, while transaminase-related treatment-emergent adverse events occurred at a frequency below 10%.
Tyra plans additional dosing cohort and Phase 3 discussions
Tyra intends to complete enrolment in the 60 mg once-daily cohort before beginning a new cohort evaluating a 70 mg daily dose.
The company also plans discussions with health authorities regarding dose selection and the design of a potential Phase 3 study.
Separately, Tyra provided an update from its Phase 2 SURF303 trial of dabogratinib in patients with low-grade upper tract urothelial cancer. The first patient treated with the 60 mg once-daily dose achieved a complete response at the three-month assessment.
Despite the reported response rates and safety profile, Tyra shares fell sharply following the release of the initial clinical data.
Tyra Biosciences stock price
