Rigel Pharmaceuticals, Inc., a biotechnology company, discovers and develops small molecule drugs to treat hematologic disorders, cancer, and rare immune diseases. The company offers Tavalisse, an oral spleen tyrosine kinase inhibitor for the treatment of adult patients with chronic immune thrombocytopenia. It also develops Fostamatinib that is in phase III clinical trial for the treatment of warm autoimmune hemolytic anemia; phase III clinical trial for the treatment of hospitalized COVID-19 patients; and phase III clinical trial for the treatment of COVID-19.