Principia Updates PRN1008 Pemphigus Clinical Program

Accelerated enrollment of company’s Phase 3 pivotal trial anticipating final results in second half of 2021

SOUTH SAN FRANCISCO, Calif., Dec. 30, 2019 (GLOBE NEWSWIRE) -- Principia Biopharma Inc. (Nasdaq: PRNB), a late-stage biopharmaceutical company dedicated to bringing transformative oral therapies to patients with significant unmet medical needs in immune-mediated diseases, today announced updated anticipated timing for final results in its ongoing pivotal Phase 3 clinical trial of PRN1008 data in patients with pemphigus, as well as complete response rates from its Phase 2 Part B open-label trial.

“We are delighted to see the interest in our Phase 3 PEGASUS trial and through the hard work of our investigators, study coordinators and our own clinical team, we believe the accelerated enrollment timelines now project us to have final data in the second half of 2021 as opposed to the first half of 2022,” said Dolca Thomas, MD, Principia’s chief medical officer. “And we are pleased to see that the complete response (CR) rate in the Phase 2 Part B trial was 40 percent (six patients) despite most patients being initially treated at a sub-therapeutic dose 400 mg once daily.”

Among the 15 patients dosed in Part B of the Phase 2 trial, nine (60 percent) achieved the primary endpoint of control of disease activity (CDA) by week four on low dose corticosteroids (less than or equal to 0.5 mg/kg per day). 12 of 15 (80 percent) patients achieved CDA by week 12. Nine (60 percent) of the 15 patients have achieved a PDAI score (a scoring system to indicate disease severity) of 1 or 0. Safety of PRN1008 is consistent with Phase 2 Part A trial and has been well-tolerated in Part B with no treatment related serious adverse event reported.

Final data from the Phase 2 Part B trial will be submitted for presentation at an upcoming medical conference.

About PEGASUS -- the Phase 3 Trial of PRN1008
Principia is currently enrolling patients in a global, randomized, double-blind, placebo-controlled, pivotal, Phase 3 clinical trial, the PEGASUS study, in approximately 120 patients to evaluate PRN1008 versus placebo using a background treatment of tapering doses of CS. The trial entry criteria include patients with moderate to severe pemphigus who are either newly diagnosed or relapsing with chronic disease. This demographic will potentially represent three quarters of the pemphigus patient population. The primary efficacy endpoint is the ability of PRN1008 to achieve durable CR on very low-dose CS (5 mg/day) at 37 weeks of treatment. Durable CR is defined as a state in which all lesions have healed, and no new lesions have appeared for a period of at least eight weeks. Key secondary endpoints include cumulative CS use and time to CR. After 37 weeks, all patients will have the option to be treated with active PRN1008 therapy in an open-label extension period of 24 weeks. PRN1008 has been granted orphan drug designation by the U.S. Food and Drug Administration for the treatment of patients with PV and by the European Commission for treatment of patients with pemphigus.