With PhII fail, Redx Pharma stops development of biliary cancer candidate

UK biotech Redx Pharma’s candidate for biliary tract cancer has failed a Phase II study, and the results are “not sufficient” to continue development, the company announced Wednesday.

RXC004, a porcupine inhibitor being developed to treat Wnt-ligand dependent cancers in patients whose disease progressed after other treatments, failed to hit the primary endpoint — progression-free survival at six months.

“Some patients received durable clinical benefit from RXC004 in this cohort, consistent with clinical activity seen in the Phase 1 trial, and the safety profile of RXC004 in this module was also consistent with the safety data previously reported in the Phase 1 trial,” the company said in its press release.

The data announced today are from the monotherapy arm of the study and are the first to be released. The other arm of the study is investigating RXC004 in combination with anti-PD-1 therapy Keytruda.

But the development journey for RXC004 isn’t over. A retrospective analysis of the data will be used to “aid interpretation” of the ongoing combination part of the study. The data from the combination arm are expected in the second half of 2023.

Jane Robertson

“Our primary efficacy hypothesis is that in combination, it can overcome immune evasion and anti-PD-1 resistance, which could open new patient segments,” Jane Robertson, CMO at Redx, said in a statement. “While today’s results do not support further clinical development of RXC004 as monotherapy in recurrent BTC, where very few drugs have received regulatory approval as single agents in this hard-to-treat disease, they are nonetheless consistent with the overall hypothesis that RXC004 has potential as an active component of combination therapy.”

Redx hit another snag last month with a partial clinical hold from the FDA on a study investigating RXC007 in idiopathic pulmonary fibrosis. The company said the hold is not related to clinical data and the FDA wants to look at specific data from a study in dogs. Enrollment for the 12-week cohorts of the Phase IIa study hasn’t been able to get started, although there is an open IND in the US.

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