Rigel Says Drug for Rare Anemia Meets Endpoint of First Stage of Phase 2 Study

Rare Daily Staff

Rigel Pharmaceuticals said a mid-stage study of its experimental therapy fostamatinib in patients with warm antibody autoimmune hemolytic anemia, a rare disorder where the immune system produces antibodies that destroy the body’s red blood cells, met the endpoint of the first stage of its phase 2 study.

The mid-stage study is evaluating the safety and efficacy of fostamatinib in patients with warm antibody autoimmune hemolytic anemia who have previously received at least one treatment for the disease, but did not have a meaningful benefit and are still anemic. The two-stage design of the study is evaluating fostamatinib at 150 mg twice daily in patients with warm antibody autoimmune hemolytic anemia. There is no available treatment for condition today.

The first stage of the study enrolled 17 patients who have had at least one post-baseline hemoglobin measure. Of the 17 patients, 4 responded during the 12-week evaluation period and an additional 2 patients met the response criteria in the extension study after 12 weeks of dosing, for a response rate of 35 percent on fostamatinib, according to preliminary data.  

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. A comprehensive analysis of the data will continue and will be presented at a future scientific conference.

The safety profile was consistent with the existing fostamatinib safety database, which comprises more than 5,000 patient-years of exposure. Two deaths were reported during the trial due to non-treatment related serious adverse events as determined by the investigators. A third patient experienced a non-treatment related serious adverse event as determined by the investigator, recovered, and continued on treatment.

Rigel said it will begin enrollment for the second stage of the study in which 20 patients will be enrolled under the same protocol.

October 2, 2017