 SOUTH SAN FRANCISCO, Calif., June 29, 2021 PRNewswire -- Rigel Pharmaceuticals, Inc. Nasdaq: RIGL, today announced that fostamatinib, the Companys novel oral spleen tyrosine kinase SYK inhibitor, has been selected for a National Institutes of Health NIH ACTIV-4 Accelerating COVID-19 Therapeutic Interventions and Vaccines trial in hospitalized patients with COVID-19. 