Tyra Biosciences unveiled early trial results on its FGFR3-specific inhibitor in advanced bladder cancer patients on Friday, the public company’s first presentation of human data since its inception in 2018.
The biotech’s data were highly anticipated: Its shares $TYRA were up over 100% ahead of the readout, but they fell 18% Friday morning on the update.
While the company tested a range of doses in the Phase 1 portion of its SURF301 study in metastatic urothelial carcinoma, its efficacy results focused on the patients who received at least 90 mg, where it believes the drug achieved “adequate target coverage.” Five of the 10 patients who received a 90 mg daily dose of TYRA-300 achieved a partial response, as did one patient who received a 120 mg dose. According to Tyra, three of those six responses are still ongoing.
The company said 41 patients with FGFR3+ cancer have enrolled as of Aug. 15, including those who were previously treated with Johnson & Johnson’s Balversa.
Tyra’s ultimate goal is to develop a safer treatment than Balversa, which in 2019 became the first FGFR-targeted drug to receive FDA accelerated approval for bladder cancer and earlier this year was granted full approval in advanced FGFR3+ urothelial carcinoma.
In its confirmatory trial, Balversa resulted in a response rate of 35% in FGFR3+ advanced bladder cancers.
TYRA-300, which goes only after FGFR3 while sparing other isoforms (FGFR1/2/4), aims to evade or lessen certain side effects including eye problems, mouth sores and inflammation, and increased phosphate levels.
“As we started to see a profile and hear from investigators that this was a really well-tolerated drug, we got really excited that the sparing of FGFR1 and 2 thesis could play out,” CEO Todd Harris said of the safety data in an interview with Endpoints News.
Todd HarrisThe biotech said in a release that SURF301 patients experienced “infrequent FGFR2- and FGFR1-associated toxicities.” TD Cowen analyst Tyler Van Buren wrote in a note Friday that “TYRA-300 boasts a superior tolerability profile compared to pan-FGFR inhibitors,” like Balversa.
In 15 patients at the 90 mg dose, the most common adverse events were liver enzyme increases and dry mouth, which six trial participants experienced. One grade 3 case of elevated liver enzyme levels resulted in treatment discontinuation and one grade 3 case of diarrhea was reported as a dose-limiting toxicity at 90 mg.
“These data give us confidence to advance TYRA-300 through Part B in SURF301 and explore larger opportunities with Phase 2 studies in metastatic urothelial cancer, non-muscle invasive bladder cancer and achondroplasia,” Harris said in a statement.
Harris told Endpoints that for both non-muscle invasive bladder cancer and achondroplasia, a form of dwarfism, Tyra expects to test lower doses of TYRA-300 than the 90 mg it highlighted in urothelial carcinoma.