FL116

FL116 is an investigational antibody-cytokine fusion protein developed by Suzhou Forlong Biotechnology for the treatment of solid tumors. It consists of a human anti-programmed cell death protein 1 (PD-1) antibody site-specifically fused to an engineered interleukin-18 (IL-18) variant. This variant is designed with minimal binding affinity to the IL-18 binding protein (IL-18BP), an endogenous inhibitor, thereby enhancing its potency and localized activity. FL116 is designed to preferentially activate effector T cells that express both PD-1 and IL-18 receptors within the tumor microenvironment. By simultaneously blocking the PD-1/PD-L1 inhibitory pathway and providing localized IL-18 stimulation, the drug aims to convert 'cold' tumors into 'hot' tumors and overcome resistance to standard immune checkpoint inhibitors. It is currently in the preclinical development candidate stage.