AMG319 is an investigational small molecule inhibitor primarily studied for its potential in cancer immunotherapy. It targets the PI3Kδ (phosphoinositide 3-kinase delta) pathway, which plays a critical role in the activation and function of immune cells, particularly B cells and regulatory T cells (Tregs). By inhibiting PI3Kδ, AMG319 helps reduce the immunosuppressive activity of Tregs within the tumor microenvironment, thereby enhancing the body’s anti-tumor immune response. This compound has been evaluated in clinical trials for the treatment of advanced solid tumors, with a focus on improving the efficacy of other immunotherapies such as checkpoint inhibitors. Its application is especially relevant in cancers where immune evasion is a major barrier to treatment success. Research suggests AMG319 may increase T cell infiltration into tumors and improve immune-mediated tumor cell killing. Due to its mechanism, AMG319 holds promise as a combination therapy agent, particularly with PD-1 or PD-L1 inhibitors, to overcome resistance and boost response rates in patients with difficult-to-treat cancers. Development is ongoing to determine optimal dosing, safety, and long-term clinical benefits.