Patient Enrollment Concluded Early in PEGASUS Phase 3 Pemphigus Trial for RilzabrutinibTrial enrolled patients ahead of originally anticipated timeline despite COVID-19 pandemic

SOUTH SAN FRANCISCO, Calif., Nov. 24, 2020 (GLOBE NEWSWIRE) -- Principia Biopharma Inc., a Sanofi company, focused on developing treatments for immune mediated diseases, today announced it has completed patient enrollment into the global Phase 3 PEGASUS trial for rilzabrutinib, an oral investigational Bruton tyrosine kinase (BTK) inhibitor. 

“We are pleased with the speed of recruitment and would like to thank investigators and study coordinators, and most importantly the patients who are volunteering to be part of a potential groundbreaking clinical trial,” said Dolca Thomas, MD, chief medical officer at Principia.  “Since there continues to be a significant need for treatment options among pemphigus patients, we are very encouraged by the interest in the trial.”

About PEGASUS -- the Phase 3 Trial of Rilzabrutinib

PEGASUS is a global, randomized, double-blind, placebo-controlled, pivotal, Phase 3 clinical trial enrolling approximately 120 participants to evaluate rilzabrutinib versus placebo, using a background treatment of tapering doses of corticosteroids (CS). The trial entry criteria include participants 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 rilzabrutinib to achieve durable complete remission (CR) at 37 weeks of treatment. Durable CR is defined as a state in which all lesions have healed on very low dose CS (5mg/day), 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. At 37 weeks, all patients will have the option to be treated with active rilzabrutinib therapy in an open-label extension period of 24 weeks. Rilzabrutinib has been granted orphan drug designation by the U.S. Food and Drug Administration and the European Commission for the treatment of patients with pemphigus.

About rilzabrutinib

Rilzabrutinib is an oral, reversible covalent, Bruton tyrosine kinase (BTK) inhibitor being investigated for the treatment of immune mediated diseases. BTK is involved in innate and adaptive immune responses and is a signaling molecule in immune mediated diseases. Rilzabrutinib data demonstrates an ability to block inflammatory immune cells, eliminate autoantibody destructive signaling, and prevent new autoantibody production without depleting B cells. Rilzabrutinib is currently under clinical development, and its safety and efficacy have not been reviewed by any regulatory authority.

About Pemphigus

According to the International Pemphigus and Pemphigoid Foundation, pemphigus is a group of potentially life-threatening disorders characterized by blisters in mucous membranes and skin. The blistering in pemphigus happens because of an immune response resulting in autoantibodies attacking the “glue” that holds mucous membranes or skin cells together. This process is called “acantholysis” and is not fully understood. Pemphigus patients develop mucosal erosions and/or blisters, erosions, or small bumps that fill with pus or fluid. The four major types of pemphigus include pemphigus vulgarispemphigus foliaceusIgA pemphigus, and paraneoplastic pemphigus. The most common form of pemphigus is pemphigus vulgaris; however, in some areas of the world, pemphigus foliaceus is more prevalent. Pemphigus vulgaris is generally more severe than pemphigus foliaceus. Pemphigus vulgaris usually involves a lot of blisters and erosions. In pemphigus foliaceus, blistering is more superficial than pemphigus vulgaris.

About Principia Biopharma

Principia, a Sanofi company, is dedicated to bringing transformative therapies to patients with significant unmet medical needs in immune mediated diseases. Through Principia’s proprietary Tailored Covalency® platform, our strategy is to build and advance a pipeline of drug candidates with significant therapeutic benefits, limit unintended side effects, improve quality of life and over time modify the course of disease. The company is pursuing three drug candidates. Rilzabrutinib, a reversible covalent BTK inhibitor, is being evaluated in a global Phase 3 clinical trial in pemphigus, a Phase 1/2 and Phase 3 clinical trial in immune thrombocytopenia (ITP), and a Phase 2A clinical trial in IgG4-RD. Tolebrutinib (SAR442168) is a covalent BTK inhibitor which crosses the blood-brain barrier and has entered Phase 3 clinical trials in multiple sclerosis. PRN473 Topical, a topical reversible covalent BTK inhibitor is being evaluated in Phase 1 trials. For more information, please visit

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