The therapeutic effect of fostamatinib in the treatment of ITP

On April 17, 2018, the U.S. Food and Drug Administration approved fostatinib (TAVALISSE, Rigel Pharmaceuticals) for the treatment of thrombocytopenia in adult patients with chronic immune thrombocytopenia (ITP) who have had an inadequate response to prior therapy.

Approval was based on two identical double-blind placebo-controlled trials FIT-1 (NCT02076399) and FIT-2 (NCT02076412), which enrolled a total of 150 patients with persistent or chronic ITP who had an inadequate response to prior treatments, including corticosteroids, immunoglobulins, splenectomy, and/or thrombopoietin receptor agonists. Patients were randomly assigned in a 2:1 ratio to fostatinib (100 mg orally twice daily) or placebo for 24 weeks. After one month, the dose may be increased to 150 mg orally twice daily.

Efficacy is based on stable platelet responses (platelet responses of at least 50 x109/L on at least 4 of 6 visits between Weeks 14 to 24). In FIT-1, 18% (n=9) of patients treated with fostatinib demonstrated stable platelet responses compared with 0% (n=0) of patients treated with placebo (p=0.03). In FIT-2, stable platelet responses were seen in 16% (n=8) and 4% (n=1) of patients, respectively (p=0.26). In the FIT-3 (NCT 02077192) extension study, stable responses were observed in 23% (n=10) of patients new to fostatinib. Durable platelet responses were observed in the FIT-1, FIT-2 trials, and FIT-3 extension studies.

At least The most common adverse reactions reported in at least 5% of patients treated with fostatinib were diarrhea, hypertension, nausea, dizziness, increased alanine aminotransferase/aspartate aminotransferase (ALT/AST), respiratory tract infection, rash, abdominal pain, fatigue, chest pain, and neutropenia. In the ITP double-blind study, serious adverse drug reactions included febrile neutropenia, diarrhea, pneumonia, and hypertensive crisis, all of which occurred in patients treated with fostatinib.1%.

The initial recommended dose of fostatinib is 100 mg taken orally twice daily. After one month, if the platelet count has not increased to at least 50x10⁹/L, increase the dose to 150 mg twice daily.

Fostatinib is not currently on the market in China. Domestic patients who need this drug can only purchase it from overseas or contact regular overseas medical consulting companies. It is understood that there is a version of fostatinib available overseas, with a price of around 24,000 yuan. If the patient still needs fostatinib, please consult a regular overseas medical consulting company for more information.