vaccine + cyclophosphamide

This is a combination therapy consisting of a vaccine (type varies by indication, often cancer vaccines such as peptide-based or dendritic cell-derived exosome vaccines) and cyclophosphamide, an alkylating agent. The rationale for this combination is that low-dose cyclophosphamide can selectively deplete regulatory T cells (Tregs), which are known to suppress anti-tumor immune responses, thereby enhancing the efficacy of therapeutic vaccination. Cyclophosphamide's immunomodulatory effect potentiates the induction of tumor-specific T cell responses by the vaccine, leading to improved tumor control compared to either agent alone. This approach has been studied in preclinical models and early-phase clinical trials for various cancers including pancreatic cancer[1][2][3][6]. The specific mechanism involves both direct cytotoxic effects on tumors at higher doses and immune potentiation at lower doses through Treg depletion.