The setback comes as Redx prepares to merge with Jounce Therapeutics to secure a Nasdaq listing.
Redx has hit a thorny patch. In the first data from a phase 2 program, Redx’s porcupine inhibitor RXC004 failed to improve progression-free survival in biliary tract cancer (BTC), prompting the British biotech to stop monotherapy development and focus on combinations in the indication.
RXC004 is designed to inhibit the porcupine enzyme, which is involved in the Wnt signaling pathway, and thereby both directly slow tumor growth and address immune resistance. Evidence of the two modes of attack on cancer led Redx to run a phase 2 program featuring monotherapy and checkpoint inhibitor combination cohorts.
The first phase 2 data have dented Redx’s monotherapy ambitions. The results come from PORCUPINE2, one of two midphase trials initiated by the biotech. One of the PORCUPINE2 modules enrolled patients with advanced or metastatic BTC who had progressed after first-line treatment.
After reviewing data on 16 patients in the module, Redx has called time on the monotherapy cohort. The biotech said some patients received durable clinical benefit from RXC004 but overall the results failed to support further monotherapy development in the setting. The setback wiped 26% off Redx’s stock in early trading in London, sinking its share price to 30 pence (35 cents).
“Our primary efficacy hypothesis is that in combination it can overcome immune evasion and anti-PD-1 resistance, which could open new patient segments. While today's results do not support further clinical development of RXC004 as monotherapy in recurrent BTC ... they are nonetheless consistent with the overall hypothesis that RXC004 has potential as an active component of combination therapy,” Jane Robertson, chief medical officer at Redx, said in a statement.