Something old, something new: The marriage of PD-1 and IL-2.

IL-2 remains a promising candidate for immunotherapy of cancer, but its use is hampered by systemic toxicities. In this issue of Immunity, Tichet, Hanahan, and colleagues demonstrate that an IL-2 variant fused to an anti-PD-1 antibody overcomes these limitations to promote impressive tumor control. This approach may be a path to treat tumors that do not respond to anti-PD-1 monotherapy.