FDA approves Tavalisse for chronic immune thrombocytopenia

The FDA approved fostamatinib disodium hexahydrate for the treatment of adults with chronic immune thrombocytopenia who had insufficient response to a previous treatment.

Fostamatinib disodium hexahydrate (Tavalisse, Rigel Pharmaceuticals) — an oral spleen tyrosine kinase inhibitor — targets the underlying autoimmune cause of chronic immune thrombocytopenia (ITP) by impeding platelet destruction.

The approval is based on data from the FIT clinical program, which included two randomized placebo-controlled phase 3 trials, an open-label extension and an initial proof-of-concept study. The drug’s application included data on 163 patients with ITP and safety data from 4,600 individuals across other indications for which fostamatinib has been evaluated.

Common adverse events associated with fostamatinib included diarrhea, hypertension, nausea, dizziness, elevated liver enzymes, respiratory infection, rash, abdominal pain, fatigue, chest pain and neutropenia. Serious adverse events observed in the ITP double-blind studies included febrile neutropenia, diarrhea, pneumonia and hypertensive crisis, which occurred among 1% of treated patients.

“Chronic ITP is challenging to treat because the heterogeneity of the disease makes it difficult to predict how an individual patient will respond to available treatments and not all patients can find a treatment that works well for them,” James Bussel, MD, professor emeritus of pediatrics at Weill Cornell Medicine and the principal study investigator on the FIT phase 3 program, said in a press release. “The FDA approval of fostamatinib arms physicians with a new treatment option, which works via a novel mechanism.”

Disclosure: Bussel reports consultant and paid advisory board roles with Rigel Pharmaceuticals.