Sanofi has reported that the Phase III LUNA 3 trial of rilzabrutinib for the treatment of persistent or chronic immune thrombocytopenia (ITP) in the adult population, met its primary endpoint.

The primary endpoint, durable platelet response was observed in 23% of the therapy-treated adults with this rare immune-mediated disease.

This durable platelet response was a platelet count at or above 50,000/µL for a minimum of eight of the last 12 weeks of the 24-week treatment period without rescue therapy.

The randomised, placebo-controlled, double-blind trial assessing the safety and efficacy of rilzabrutinib versus placebo involves the participation of adult and adolescent subjects with persistent or chronic ITP.

Adult patients in the study, who had median platelet counts of 15,000/μL, received rilzabrutinib 400mg twice daily or placebo for up to 24 weeks, followed by a 28-week open-label period.

A 65% platelet response rate was observed in the therapy group, compared to 33% in the placebo group.

Improvements were also noted in secondary endpoints, including decreased bleeding and the need for rescue therapy. The therapy showed a 52% decrease in the need for rescue therapy versus placebo.

The study demonstrated that subjects who received rilzabrutinib were approximately three times more likely to achieve a platelet response than those on placebo.

The median time to first platelet response was 36 days for rilzabrutinib subjects, with a median time to response of 15 days among responders.

Additionally, physical fatigue and quality of life measures improved significantly for subjects on rilzabrutinib. The safety profile was in line with previous studies.

Sanofi development global head and chief medical officer Dietmar Berger said: “These new data support the potential of rilzabrutinib to provide robust and durable platelet response in immune thrombocytopenia, offering hope for patients with limited treatment options.

“Based on its ability to target BTK, an enzyme that plays a critical role in many types of immune cells, we believe rilzabrutinib also has the potential to improve patient outcomes in multiple rare blood and autoimmune disorders.”

The therapy is currently under regulatory review in the European Union (EU) and the US, with a target action date from the Food and Drug Administration (FDA) set for 29 August next year.

In February this year, the company shared positive outcomes from the Phase II trial of rilzabrutinib in subjects with moderate to severe chronic spontaneous urticaria (CSU).