Rigel Initiates Enrollment In Pivotal Blood Disorder Study

 | May 16, 2019 09:05PM ET

Rigel Pharmaceuticals, Inc. (NASDAQ:RIGL) has enrolled the first patient in a pivotal phase III study evaluating Tavalisse (fostamatinib disodium hexahydrate) as a treatment for warm antibody autoimmune hemolytic anemia (“AIHA”). The company expects to complete enrollment in a year.

The study will evaluate the oral spleen tyrosine kinase (“SYK”) inhibitor, Tavalisse, in approximately 80 patients with primary or secondary warm AIHA, who have failed at least one prior treatment, over a period of 24 weeks. Top-line data from the pivotal study is expected in 2021, which will likely form the basis of regulatory application for label expansion of the drug to include AIHA patients.

One of the two primary endpoints of the study is to achieve a durable hemoglobin response measured by hemoglobin levels of more than 10 g/dL and an improvement of 2 g/dL from baseline. Another primary endpoint of the study is the durability of response measure.

The company stated that the rare, serious blood disorder AIHA affects approximately 40,000 patients in the United States. The disorder can become a severe, debilitating disease wherein the patients’ immune system produces antibodies that destroy the body's red blood cells. There are no FDA-approved therapies targeting the disease.

Rigel has completed the phase II study – SOAR – evaluating Tavalisse in similar patient population with AIHA for identical primary endpoints as the phase III study. Data from the study showed that 43% of patients achieved hemoglobin levels of greater than 10 g/dL and at least a 2 g/dl increase from baseline. An open-label extension of the SOAR study is ongoing.

Rigel’s stock has declined 4.7% in the year so far against the industry ’s rise of 6%.