After two chimeric antigen receptor (CAR) T-cell therapies won FDA approval in 2017 to treat children and young adults with acute lymphoblastic leukemia (ALL) and adults with diffuse large B-cell lymphoma, the American Society of Clinical Oncology hailed CAR T-Cell Immunotherapy as the Advance of the Year. More than 100 companies are now working on CAR T-cell therapies—primarily for hematologic cancers, but also for certain solid tumors—and there has been an explosion in the number of clinical trials registered each year. However, few companies possess all the necessary in-house skills to develop CAR T-cell products.