FDA New Drug and Biologic Approvals, 2018 Midyear Review

Mary L Windle, PharmD


August 01, 2018

In This Article

Thrombocytopenia in Chronic Immune Thrombocytopenia: Tavalisse (fostamatinib)

Indication: Indicated for thrombocytopenia in patients with chronic immune thrombocytopenia (ITP) who have had an insufficient response to a previous treatment.

Mechanism: Tyrosine kinase inhibitor with demonstrated activity against spleen tyrosine kinase (SYK). R406, a major fostamatinib metabolite, inhibits signal transduction of Fc-activating receptors and B-cell receptor. R406 reduces antibody-mediated destruction of platelets.

Dosage: Initial dose is 100 mg PO BID. After a month, if platelet count has not increased to at least 50 x 109/L, increase dose to 150 mg PO BID.

Approval was based on the FIT clinical program (N=163), which included 2 randomized placebo-controlled phase 3 trials and an open-label extension trial. Results from the randomized trials showed more patients experienced a platelet response with fostamatinib than with placebo (18% vs 0% and 16% vs 4%). In the open-label expansion trial, 23% of patients who had received placebo in the previous randomized trials experienced a platelet response. Fewer bleeding episodes were observed in patients in the fostamatinib arm compared with placebo (29% vs 37%).


  • Bussel JB, Arnold DM, Grossbard E, et al. Fostamatinib for the treatment of adult persistent and chronic immune thrombocytopenia: Results of two phase 3, randomized, placebo-controlled trials. Am J Hematol. 2018 Apr 26. https://www.ncbi.nlm.nih.gov/pubmed/29696684


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