Phase III Success for Sanofi’s Rilzabrutinib Post $3.7B Principia Acquisition

Sanofi has declared a milestone in its Phase III LUNA 3 trial for rilzabrutinib, an experimental BTK inhibitor, which has shown to effectively manage persistent or chronic immune thrombocytopenia (ITP) in adults. The drug has demonstrated a lasting response in platelet counts, as defined by the study's criteria of maintaining a minimum of 50,000/µL for at least eight of the last twelve weeks, with a notably higher success rate than placebo.

The company has not yet released detailed data but has affirmed that the results are both clinically and statistically significant, with positive outcomes also observed in secondary endpoints. Sanofi's R&D head, Houman Ashrafian, has highlighted the potential of rilzabrutinib as a groundbreaking oral, reversible BTK inhibitor that could significantly improve the health of those suffering from severe immune-mediated conditions, such as ITP.

ITP is an autoimmune disorder characterized by the destruction of platelets by the body's own antibodies, leading to dangerously low platelet counts and an increased risk of severe bleeding events. Patients often experience fatigue, cognitive difficulties, and a diminished quality of life.

Rilzabrutinib, which has a dual mechanism of action, is designed to tackle the root causes of ITP and its associated complications. It was originally developed by Principia Biopharma and works by inhibiting the BTK protein, a key player in inflammatory and immune pathways, thus preventing platelet destruction and reducing the production of harmful autoantibodies. Sanofi acquired Principia Biopharma for $3.68 billion in 2020, securing rilzabrutinib's development.

The announcement follows a series of successes in the BTK inhibitor field, with other companies like Novartis and BeiGene also reporting positive results for their respective BTK blockers in different conditions. Sanofi anticipates submitting rilzabrutinib for regulatory approval in the U.S. and EU by the end of 2024 and is exploring its potential for other indications, including chronic spontaneous urticaria, prurigo nodularis, IgG4-related disease, and warm autoimmune hemolytic anemia.