Combining Melphalan And Adoptive Transfer Of Tumor-specific Cd4+T Cells Results In Enhanced Anti-tumor Immunity

Objective Chemotherapy is a major treatment modality for many types of cancers. Although chemotherapeutic drugs cause tumor destruction through different mechanisms, they have long been considered immune suppressive. The mounting evidence that many chemotherapeutic agents have immunostimulatory effects has provided a compelling rationale for developing combined chemoimmunotherapy strategy to achieve improved patient outcomes. Immunotherapy has recently become the fourth important treatment modality for malignant tumors, ranked after surgery, radiotherapy, and chemotherapy. There is accumulating evidence that incorporation of chemotherapy with immunologic maneuvers, such as adoptive immunotherapy and therapeutic vaccines, can effectively treat established tumors. Cyclophosphamide (Cy) has been shown to be particularly effective in augmenting the effectiveness of adoptive T-cell therapy (ACT) in various animal models and some clinical studies. We plan to screen some common chemotherapeutic drugs to find the drugs that have the effects similar to Cy, which will provide new ideas for optimal design of chemoimmunotherapies.Methods Flow cytometry analysis (FCM) was used to screen the chemotherapeutic agents including chlorambucil, temozolomide, carmustine, paclitaxel, gemcitabine, doxorubicin and melphalan to evaluate the effect on adoptive transferred CD4+T cells in tumor-bearing mice and find the drugs that can potentiate antitumor CD4+T-cell responses among adoptively transferred tumor-specific CD4+T cells. Animal experiments were used to evaluate the effects of the screened drugs on a variety of immune cells and cytokines in the tumor milieu and on endogenous T lymphocytes. Tumor cells cultured in vitro were used to observe whether the screened drugs can induce CRT membrane translocation and release of HMGB1. Various tumor-bearing mice models were used to observe the effect of combining the screened drugs and tumor-specific CD4+ACT.Results Only melphalan was found to have CD4+T cells-potentiating property similar to CTX. Melphalan can potentiate antitumor CD4+T-cell responses by driving the effector differentiation of adoptively transferred tumor-specific CD4+T cells.Melphalan induced the dynamic changes of immune cells and transient lymphopenia and induced an inflammatory cytokine milieu.It also induced immunogenic tumor cell death by driving CRT translocation and HMGB1release.Moreover, melphalan monotherapy led to activation of endogenous CD8T cells.The combination of melphalan and CD4+T cell adoptive transfer delayed tumor growth and exhibited synergistic antitumor effects.Conclusion melphalan can enhanced antitumor immunity of tumor-specific CD4+T cells. The combination of melphalan and CD4+T cell adoptive transfer exhibits synergistic antitumor effects. Modifying the tumor milieu, activating the endogenous CD8+T cells, and induction of immunogenic cell death maybe contribute to it. These findings suggest a rationale to design and complete more effective combined chemoimmunotherapies.