Tyra Biosciences has reported initial data from its Phase II SURF302 clinical trial of the oral drug dabogratinib in FGFR3-altered low-grade intermediate-risk non-muscle invasive bladder cancer (LG IR NMIBC) patients.
The data provided the first clinical evidence supporting selective oral FGFR3 inhibition and indicate that a 60mg once-daily dose may be suitable for further development in the company’s planned registrational adjuvant studies.
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In the trial, the safety profile of dabogratinib was evaluated across two dosing cohorts: 60mg and 50mg once daily, each with 22 participants.
Most treatment-emergent adverse events (TEAEs) were reported as Grade 1 or 2.
Within the 60mg cohort, 14% experienced Grade 3 TEAEs, while in the 50mg group, the figure was 9%. No Grade 4 or 5 TEAEs were reported. Grade 3 treatment-related adverse events were found only in the 50mg group.
At the 60mg dose, there were no reports of treatment-related discontinuations or dose reductions, and no cases assessed as clinically significant hyperphosphatemia, nail toxicity or ocular toxicity.
TEAEs were described as generally manageable, with the most common being fatigue, diarrhoea and dry eye.
For efficacy, 26 participants were evaluable across both dose groups. Objective response rates at three months were 79% (11 of 14) for the 60mg group and 67% (8 of 12) for the 50mg group.
Complete response rates at three months stood at 57% and 33% for 60mg and 50mg groups, respectively. In participants with a single marker lesion, the three-month objective response rate was 100% at the 60mg dose.
Tyra Biosciences CEO Todd Harris said: “We are extremely excited to report initial results from SURF302 today as we work to advance what we believe could become the first once-daily oral therapy for patients with low-grade IR NMIBC.
“These results belong first and foremost to the patients participating in SURF302 and the investigators and study teams who have made this research possible. We’re incredibly grateful for their partnership.”
Further enrolment in the 60mg cohort will continue and a 70mg cohort will be started to investigate dabogratinib in other settings. Tyra Biosciences is also evaluating the therapy in LG upper tract urothelial cancer and achondroplasia across separate Phase II studies.
In August 2025, Tyra Biosciences dosed the first paediatric participant in the dose-escalation/dose-expansion Phase II BEACH301 trial designed to assess the efficacy and safety of dabogratinib, a treatment for children with achondroplasia, which is the most prevalent form of dwarfism.
