REGN4659 + cemiplimab

REGN4659 + cemiplimab is an investigational combination of two monoclonal antibodies developed by Regeneron and Sanofi for oncology. **REGN4659** is a fully human monoclonal antibody targeting glucocorticoid-induced tumor necrosis factor receptor–related protein (GITR), which is expressed on multiple immune cells, especially regulatory T cells (Tregs) and activated NK cells. It is designed to enhance anti-tumor immune responses, primarily by depleting immunosuppressive Tregs and activating NK cells. **Cemiplimab** is a monoclonal antibody targeting programmed cell death protein 1 (PD-1), acting as an immune checkpoint inhibitor to block negative regulation of T-cell activation and promote anti-tumor immune responses. When combined, REGN4659 and cemiplimab aim to provide synergistic immune activation in advanced solid tumors, such as advanced or metastatic non-small cell lung cancer (NSCLC), by simultaneously modulating Treg activity and unleashing T-cell-mediated anti-tumor effects via PD-1 blockade[1][5][6].