cemiplimab + cyclophosphamide

**Cemiplimab + cyclophosphamide** is an investigational combination therapy studied primarily in advanced or refractory solid tumors, including metastatic or refractory head and neck squamous cell carcinoma. Cemiplimab is a fully human monoclonal antibody that targets the programmed cell death-1 (PD-1) receptor, thereby acting as a checkpoint inhibitor and promoting immune-mediated antitumor activity. Cyclophosphamide is an alkylating agent that, at low doses, can deplete regulatory T cells, potentially reducing immunosuppression in the tumor microenvironment and enhancing the efficacy of immunotherapies. This combination aims to improve clinical outcomes by pairing checkpoint inhibition with immune modulation. Early-phase clinical trials have shown the regimen to be tolerable, but efficacy above cemiplimab or PD-1 inhibitor monotherapy has not been conclusively demonstrated[1][2].