Sanofi's BTK Inhibitor Effective in Immune Thrombocytopenia Patients

Sanofi recently announced positive results from the Phase 1/2 clinical trial evaluating its Bruton's tyrosine kinase (BTK) inhibitor, rilzabrutinib, in adults with heavily pre-treated immune thrombocytopenia (ITP).  

The global trial studied rilzabrutinib in 60 individuals between 19 and 74 years old who previously received four different ITP therapies. Initial doses were 200 mg once daily, 400 mg once daily, 300 mg twice daily, or 400 mg twice daily.  

The trial's primary endpoint measured the number of participants who achieved at least two consecutive platelet counts and an overall platelet count increase from the start of treatment without requiring rescue medication.  

Trial results, published in the New England Journal of Medicine, found that treatment with rilzabrutinib led to a rapid and durable increase in platelet count and supported an acceptable safety profile.  

Specifically, 24 of the 60 people enrolled in the study achieved the primary endpoint with any dosing regimen. Of the 45 people who took 400 mg of rilzabrutinib twice daily, 18 met the primary endpoint. 

Additionally, the median time to first platelet count was 11.5 days, which was maintained in patients with primary platelet response for 65% of weeks during the treatment period.  

Over half (52%) of patients experienced at least one minor treatment-related adverse event. But researchers noted no Grade 3 or higher adverse events or serious events.  

"We are pleased to share these encouraging early clinical results through this publication. These findings demonstrate a clinically meaningful response in difficult-to-treat ITP patients who received a  median of four prior ITP therapies," Dietmar Berger, MD, PhD, said in the announcement.  

"The overall study population, which also included less refractory patients, showed a numerically higher response. Rilzabrutinib could become a first-in-class BTK inhibitor therapy with the potential to increase platelet counts quickly and durably for people with ITP," Berger continued.  

In October 2018, FDA granted rilzabrutinib orphan drug designation to treat ITP. And then, iIn November 2020, FDA granted fast track designation to the drug following positive Phase 1/2 study results.  

Researchers are currently evaluating the safety and efficacy of rilzabrutinib in the ongoing, randomized Phase 3 LUNA study in adults and adolescents under 12 years of age with persistent/ chronic ITP. 

And Phase 2 studies are ongoing to evaluate the drug as a potential therapy for the autoimmune condition IgG4 disease and immunological disease, including asthma, atopic dermatitis, chronic spontaneous urticaria, and warm autoimmune hemolytic anemia.