PTT-3213

PTT-3213 is an orally bioavailable, potent, and selective small molecule inhibitor of G protein-coupled receptor 65 (GPR65), a pH-sensing receptor that functions as a critical innate immune checkpoint within the acidic tumor microenvironment. Developed by Pathios Therapeutics, PTT-3213 is designed to target and reprogram immunosuppressive macrophages, thereby reversing the immune-silent state of tumors. By blocking GPR65 signaling, the drug promotes the infiltration and activity of CD8+ T cells and natural killer (NK) T cells. Preclinical studies have demonstrated that PTT-3213 significantly reduces tumor growth and exhibits synergistic efficacy when used in combination with anti-PD-1 therapies, positioning it as a potential first-in-class treatment for advanced solid tumors.