Enrollment for Stage 1 of Rigel Pharmaceuticals’ Phase 2 open-label, multi-center, 2-stage study of fostamatinib has been completed. The study achieved the pre-specified primary endpoint for Stage 1.
The investigational drug is intended for the treatment of patients with warm antibody Autoimmune Hemolytic Anemia (AIHA).
AIHA is a rare, potentially-fatal blood disease in which the immune system produces antibodies that result in permanent damage to the body’s red blood cells. The destruction leads to an insufficient number of oxygen-carrying red blood cells in the circulation, and there are currently no approved therapies to target the disease.
, AIHA affects an estimated 40,000 adult patients in the U.S.
The Phase 2 study, being referred to as the SOAR study, is designed to evaluate the safety and efficacy of fostamatinib in patients with warm antibody AIHA who had received at least one prior treatment, but did not see significant benefit and remain anemic. The drug is a strong and moderately selective spleen tyrosine kinase (SYK) inhibitor, and the safety profile of the study was consistent with fostamatinib’s existing database.
"Many patients with AIHA suffer from severe, debilitating disease that negatively affects their quality of life," said David J. Kuter, M.D., the director for the Center of Hematology at Massachusetts General Hospital and the lead investigator of the SOAR study in a press release
. "There are no FDA-approved medications for the treatment of AIHA, which means that those living with the condition are in need of new and effective therapeutic options."
Of the 17 patients enrolled in Stage 1, 4 responded during the 12-week evaluation period and another 2 patients met the response criteria in the extension study after 12 weeks of dosing, for a response rate of 35% (6/17) on fostamatinib (these data are preliminary and require further verification). During the trial, 2 of the 17 patients withdrew early from the study due to non-safety-related reasons and will be replaced per the study protocol.
After meeting the primary efficacy endpoint in Stage 1, Rigel’s intention is to commence enrollment for Stage 2 of the study as soon as possible. In Stage 2, 20 patients will be enrolled under the same protocol.
Full data from SOAR will be presented at a future scientific conference.
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