Checkpoint inhibitor

Tumors exploit immune “checkpoints” (like PD-1/PD-L1) to switch off attacking T cells. Checkpoint inhibitors block that off-switch. They've transformed oncology but work best when there are tumor-reactive T cells to unleash.

That makes them a natural partner for neoantigen vaccines: the vaccine creates tumor-specific T cells, and the checkpoint inhibitor keeps them active. Many clinical programs test the combination.