CLN-617 is a single-chain fusion protein comprising human IL-2, human IL-12, leukocyte-associated immunoglobulin-like receptor 2 (LAIR2) and human serum albumin (HSA). It was designed for intratumoral injection to co-deliver IL-2 and IL-12 on a single molecule, with HSA and LAIR2 being used to retain CLN-617 in the tumor by binding collagen and increasing molecular weight.