CD39: A complementary target to immune checkpoints to counteract tumor-mediated immunosuppression.

We report that CD39-expressing-melanoma cells inhibited both T-cell proliferation and the generation of cytotoxic effectors in an adenosine-dependent manner, and that treatment with a CD39-blocking antibody alleviated tumor-mediated immunosuppression. Thus, blocking CD39 ectonucleotidase may represent a novel immunotherapeutic strategy to restore antitumor immunity.