Many patients exhibit responses to established therapies, including corticosteroids, IV immunoglobulin, anti-D, splenectomy, and rituximab. However, there are a significant minority of patients who retain persistently low platelet counts despite treatment. These patients are consistently at risk of intracranial hemorrhage and other bleeding complications. Several thrombopoiesis-stimulating therapies including eltrombopag and romiplostim are being investigated to help combat low platelet counts in ITP patients. Rigel reported results from two Phase III clinical trials for fostamatinib as an ITP treatment in August and October 2016. The study is the second Phase 3, multi-center, randomized, double-blind, placebo controlled, study of fostamatinib disodium in the treatment of persistent/chronic immune thrombocytopenic purpura that Rigel has conducted. Primary outcome measures are defined as a stable platelet response by the end of the study (week 24) of at least 50,000/μL on at least 4 of the 6 visits between weeks 14–24. Participants received either a placebo, 100 mg, or 150 mg of the drug in the morning and evening for 24 full weeks. The first study, FIT 1 (047) met the primary endpoint in a statistically significant manner, with 18% of patients hitting the 50,000 platelets/μL of blood and no patients receiving the placebo meeting that criteria. As of June 2016, the open-label, long term extension study (049) is currently tracking 118 patients who opted to receive fostamatinib after completing either study 047 or 048. Autoimmune hemolytic anemia
Approval for treatment of autoimmune hemolytic anemia (AIHA) is in Stage 1 of Phase II trials.
Patients were randomized 2:1 to fostamatinib (100 mg orally twice daily) or placebo twice daily for 24 weeks. Dose could be escalated to 150 mg orally twice daily after one month. The benefit of fostamatinib was assessed based on the percentage of participants who achieved and maintained the pre-determined platelet count between treatment weeks 14 to 24 in fostamatinib and placebo groups respectively. The FIT-1 trial was conducted at 35 sites in Australia, Canada, Denmark, Hungary, Italy, Netherlands, the United Kingdom, and the United States. The FIT-2 trial was conducted at 23 sites in Austria, Bulgaria, Czech Republic, Germany, Norway, Poland, Romania, and Spain.The FDA granted the application for fostamatinib an orphan drug designation and granted the approval of Tavalisse to Rigel Pharmaceuticals.Fostamatinib was approved for medical use in the European Union in January 2020. References
External links
"Fostamatinib". Drug Information Portal. U.S. National Library of Medicine. "Fostamatinib disodium". Drug Information Portal. U.S. National Library of Medicine. Clinical trial number NCT02076399 for "A Efficacy and Safety Study of R935788 in the Treatment of Persistent/Chronic Immune Thrombocytopenic Purpura (ITP) (FIT)" at ClinicalTrials.gov