Gilead Sciences‘ (NASDAQ: GILD) recently approved Yescarta could be a billion-dollar blockbuster cancer-cell therapy, but the company could face stiff competition from Celgene (NASDAQ: CELG) someday. Celgene has successfully used research and development (R&D), acquisitions, and partnerships to become one of the world’s biggest oncology biotech companies, and the use of this strategy could catapult it ahead of Gilead Sciences in chimeric antigen receptor T-cell therapy (CAR-T).