FDA approved Tavalisse (fostamatinib disodium hexahydrate tablets) for the treatment of thrombocytopenia in adult patients with chronic immune thrombocytopenia who have had an insufficient response to a previous treatment.
The agent is sponsored by Rigel Pharmaceuticals Inc.
Approval was based on two identical, double-blind, placebo-controlled trials, FIT-1 (NCT02076399) and FIT-2 (NCT02076412) that enrolled a total of 150 patients with persistent or chronic ITP who had an insufficient response to previous treatment, which included corticosteroids, immunoglobulins, splenectomy, and/or a thrombopoietin receptor agonist.
Patients were randomized 2:1 to fostamatinib (100 mg orally twice daily) or placebo for 24 weeks. Dose could be escalated to 150 mg orally twice daily after one month.
Efficacy was based on stable platelet response (at least 50 x109/L on at least 4 of the 6 visits between Weeks 14 to 24). In FIT-1, stable platelet response was demonstrated in 18% (n=9) of patients receiving fostamatinib compared with 0% (n=0) of patients receiving placebo (p=0.03). In FIT-2, stable platelet response was seen in 16% (n=8) and 4% (n=1) of patients, respectively (p=0.26).
In the FIT-3 (NCT 02077192) extension study, a stable response was observed in 23% (n=10) of patients newly exposed to fostamatinib. Durable platelet responses were seen in the FIT-1, FIT-2 trials and the FIT-3 extension study.
The recommended dose initially is 100 mg administered orally twice daily. After a month, if platelet count has not increased to at least 50×109/L, increase dose to 150 mg twice a day.
Full prescribing information is available here.
