Tyra Biosciences shares dropped 30% on Wednesday, even though the company’s first Phase 2 bladder cancer results showed a 79% overall response rate.
The data came from SURF302, a trial of dabogratinib in patients with FGFR3-altered, low-grade, intermediate-risk non-muscle invasive bladder cancer. At the 60 mg once-daily dose, 64% of patients reached a complete response as their best overall response, with single and multiple marker lesions combined.
Patients with a single marker lesion did better. In that group the 60 mg dose produced a 100% overall response rate and a 75% complete response rate.
The numbers behind the trial
As of the August 31, 2026 data cutoff, SURF302 had enrolled 44 participants across the 60 mg and 50 mg cohorts. Efficacy could be evaluated in 26 of them: 14 on the 60 mg dose and 12 on 50 mg.
Grade 3 treatment-emergent adverse events were reported in 14% of participants on 60 mg and 9% of those on 50 mg. Across both cohorts, Grade 3 treatment-related events occurred in 4.5% of participants, and none appeared in the 60 mg group. There were no Grade 4 or Grade 5 events.
Nobody on the 60 mg dose had a dose reduction or stopped treatment because of side effects. Fatigue, diarrhoea and dry eye were the most common events in that cohort. Tyra said it saw no clinically significant hyperphosphatemia, nail toxicity or ocular toxicity, and transaminase-related events occurred in fewer than 10% of patients.
Next, the company plans to finish enrolling the 60 mg cohort and then open a new cohort testing 70 mg daily. It also intends to talk with health authorities about dose selection and the design of a possible Phase 3 study.
Tyra gave an update on a second trial as well. In SURF303, which tests dabogratinib in low-grade upper tract urothelial cancer, the first patient treated at 60 mg once daily had a complete response at the three-month assessment.
Where the stock stood before
Expectations had been building. On June 17, TheFly reported, Oppenheimer started coverage of Tyra (NASDAQ:TYRA) with an Outperform rating and a $50 price target. The firm pointed to the three-month complete response data expected from SURF302, and cited a cash position of $383.5 million that it expected to fund operations into the second half of 2028.
The company’s first-quarter results, released May 13, showed spending rising. Research and development costs reached $33.5 million for the quarter ended March 31, up from $25.0 million a year earlier, and the net loss was $39.3 million against $28.1 million.
Sources
- Tyra Biosciences shares plunge 30% after Phase 2 dabogratinib data
- Is Tyra Biosciences, Inc. (TYRA) Stock a Biotech Opportunity Ahead of Key SURF302 Trial Data?
