FDA Alert

FDA Approves Rilzabrutinib Tablets for Chronic Immune Thrombocytopenia

Kate Young

Key Highlights

  • Rilzabrutinib is a small-molecule, covalent, reversible kinase inhibitor targeting Bruton tyrosine kinase (BTK).
  • The FDA approved the drug for adults with persistent or chronic immune thrombocytopenia.

On September 2, the FDA announced the approval of rilzabrutinib—a small-molecule, covalent, reversible kinase inhibitor targeting Bruton tyrosine kinase (BTK)—for adults with persistent or chronic immune thrombocytopenia who did not respond to immunoglobulins, anti-D therapy, or corticosteroids.1-2

In a double-blind, parallel-group study evaluating durable platelet response, 202 randomized patients underwent a 24-week treatment period on either rilzabrutinib or placebo. In the treatment group, 23% of patients achieved an increased number of platelets from baseline lasting the majority of the past 12 weeks compared with no patients in the placebo group.1

The FDA warns that rilzabrutinib may increase the risk of bacterial, viral, or fungal infections, and the most common side effects are diarrhea, nausea, headache, abdominal pain, and COVID-19 infection.1 Rilzabrutinib may also cause fetal harm when administered to pregnant people and may result in severe hepatotoxicity in patients taking BTK inhibitors.2

Rilzabrutinib is recommended as a 400 mg dose taken twice daily with a whole glass of water and should be stored at room temperature.2  

References:

  1. FDA approves drug to treat adults with persistent or chronic immune thrombocytopenia. https://www.fda.gov/drugs/news-events-human-drugs/fda-approves-drug-treat-adults-persistent-or-chronic-immune-thrombocytopenia. Published Sept. 2, 2025. Accessed Sept. 8, 2025.
  2. Full prescribing information. https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/219685s000lbl.pdf. Published Sept. 2, 2025. Accessed Sept. 8, 2025.