 FOSTER CITY, Calif. EMERYVILLE, Calif.--BUSINESS WIRE--Gilead Sciences, Inc. Nasdaq: GILD and Gritstone Oncology, Inc. Nasdaq: GRTS, a clinical-stage biotechnology company developing next generation cancer and infectious disease immunotherapies, today announced that the companies have entered into a collaboration, option and license agreement to research and develop a vaccine-based immunotherapy as part of Gileads efforts to find a curative treatment for human immunodeficiency virus H 