CAR-T cells are highly effective in treating selected blood cancers. However, challenges remain with this new therapy, which was first approved in 2017 in the U.S. and a year later in Europe for treating acute lymphoblastic leukemia (ALL). For instance, no effective CAR-T cell therapies for solid tumors exist. Furthermore, CAR-T-induced remissions are not always durable, and the production of CAR-T cells is slow and laborious.