APN411

APN411 is an orally available small molecule inhibitor of **Cbl-b** (Casitas B-lineage lymphoma proto-oncogene b), currently in preclinical development for the treatment of various solid tumors. Developed by **Apeiron Biologics** (now **invIOs**) in collaboration with **Evotec**, APN411 targets Cbl-b, an E3 ubiquitin ligase that acts as a critical intracellular immune checkpoint in T cells and NK cells. By inhibiting Cbl-b, the drug lowers the threshold for immune cell activation and enhances effector functions against tumor cells. This mechanism offers a novel approach to cancer immunotherapy that can be administered systemically as an oral agent, potentially overcoming some of the limitations associated with injectable checkpoint inhibitors.