Rilzabrutinib, an oral Bruton’s tyrosine kinase (BTK) inhibitor, has been granted Fast Track designation by the Food and Drug Administration (FDA) for the treatment of immune thrombocytopenia (ITP).

The designation was based on early data that showed the investigational BTK inhibitor has the potential to modulate immune-mediated processes in ITP by blocking inflammatory immune cells, eliminating autoantibody destructive signaling, and preventing autoantibody production without depleting B cells.  Rilzabrutinib is currently being investigated in a double-blind, placebo-controlled phase 3 trial in patients with persistent or chronic ITP (N=194).

Eligible patients include those with an average platelet count of less than 30,000/μL on 2 counts at least 5 days apart in the 14 days before treatment begins. The primary efficacy outcome of the study is the proportion of patients able to achieve platelet counts at or above 50,000/μL for at least 8 out of the last 12 weeks of the 24-week blinded treatment period in the absence of rescue therapy.

“By awarding Fast Track Designation to rilzabrutinib, an investigational candidate for the treatment of ITP, the FDA has recognized rilzabrutinib’s potential to meaningfully improve outcomes for patients with this debilitating disease,” said Dolca Thomas, Chief Medical Officer of Principia, a Sanofi company. “[Fast Track designation] is designed to facilitate the development and expedite the review of investigational treatments that demonstrate the potential to address unmet medical needs in serious or life-threatening conditions.”

In addition to ITP, rilzabrutinib is being investigated for the treatment of pemphigus (phase 3) and IgG4 disease (phase 2).

For more information visit


Rilzabrutinib granted FDA Fast Track Designation for treatment of immune thrombocytopenia. [press release]. November 18, 2020.