Rigel Pharmaceuticals is a biotech company that develops small molecule drugs for hematologic disorders, cancer, and rare immune diseases. Its products include Tavalisse, an oral spleen tyrosine kinase inhibitor for chronic immune thrombocytopenia, and Fostamatinib, in phase III clinical trials for autoimmune hemolytic anemia and COVID-19. The company is also developing R289 and R552 for autoimmune and inflammatory diseases. Rigel has research and license agreements with AstraZeneca, BerGenBio, Daiichi Sankyo, Kissei Pharmaceutical, and Eli Lilly. It was founded in 1996 and is based in South San Francisco, California.