Vaccine delivers a boost to T cell therapy.

As the CAR-T cells killed tumor cells expressing the target antigen, host T cells (not the engineered CAR-T cells) encountered other antigens from those tumor cells, stimulating those host T cells to target those antigens and help destroy tumor cells. They found that even in tumors where only 50 percent of the tumor cells expressed the target antigen, about 25 percent of the tumors could still be eradicated, by a combination of CAR-T cells and host T-cells. "That would be exactly the kind of thing that could help you deal with the antigen heterogeneity of solid tumors, because if you primed host T-cells to attack other antigens, they may be able to come in and kill the tumor cells that your CAR-T cells cannot", Irvine says. [Extracted from the article]