Rilzabrutinib Shows Positive Results in People With Immune Thrombocytopenia


The findings, published the New England Journal of Medicine, showed treatment with rilzabrutinib led to a rapid, durable increase in platelet count while supporting an acceptable safety profile.

A phase 1/2 dose-finding study evaluating the safety, pharmacokinetics, and clinical activity of rilzabrutinib showed positive results in adults with heavily pre-treated immune thrombocytopenia (ITP).

The findings, published the New England Journal of Medicine, showed treatment with rilzabrutinib led to a rapid, durable increase in platelet count while supporting an acceptable safety profile.

“Currently, there are no standard treatment recommendations for ITP patients with multiple relapses. Despite advances in treatment options over the years, some patients remain refractory to existing therapies and durable remission remains elusive,” said lead study author David Kuter, MD, director of clinical hematology at Massachusetts General Hospital, in a press release. “The Bruton’s tyrosine kinase is a critical signaling molecule in the immune system that is involved in certain immune-mediated diseases, and our research suggests that targeting BTK may represent a promising approach to addressing the underlying cause of ITP.”

ITP is an acquired autoimmune blood disorder characterized by low platelet count resulting from immune-mediated platelet destruction and impairment of platelet production. A person can be predisposed to a higher risk of bleeding, hospitalization, fatigue, impaired quality of life, and even death if a decrease in platelet counts is temporary or persistent, the study authors noted.

“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 amedian of four prior ITP therapies,” said Dietmar Berger, MD, PhD, global head of clinical development and chief medical officer at Sanofi, in the press release. “Moreover, 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.”

Rilzabrutinib was granted Fast Track Designation by the FDA for treatment of ITP in November 2020 and was previously granted orphan drug designation.

Some highlights of the study results include:

  • In all, 24 of 60 people enrolled in the study at any dose achieved the primary endpoint. Out of the 45 people who initiated rilzabrutinib at 400 mg twice daily, 18 met the primary endpoint.
  • The median time to first platelet count of at least 50×109/L was rapid at 11.5 days, which was maintained in patients with primary platelet response for a mean of 65% of weeks during the 24-week treatment period.
  • In terms of adverse events (AEs), 52% of participants experienced at least 1 treatment-related AE, all of which were grade 1 or 2. The most common AEs were diarrhea, nausea, and fatigue.

The safety and efficacy of rilzabrutinib in ITP are being evaluated in the ongoing randomized, double-blind, phase 3 LUNA 3 study in adults and adolescents with persistent and chronic ITP. Additionally, phase 2 studies are ongoing to evaluate rilzabrutinib as a potential therapy for the autoimmune condition IgG4 disease and immunological diseases, such as asthma, atopic dermatitis, chronic spontaneous urticaria, and warm autoimmune hemolytic anemia.


Positive Phase 1/2 study results of rilzabrutinib in people with immune thrombocytopenia published in The New England Journal of Medicine. April 14, 2022. Accessed April 15, 2022.

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