Control of aggressive 4T1-luc metastatic breast cancer using immunogenic cell lysates generated with methotrexate.

This study investigated a novel immunization therapy for pre-clinical aggressive metastatic breast cancer using immunogenic cell lysates derived from 4T1-luc cells treated with cisplatin and methotrexate, addressing the critical need for improved treatments given the poor prognosis associated with breast cancer metastasis and its significant mortality rate. Methotrexate, a conventional cytotoxic agent, demonstrated a previously unrecognized capacity to induce immunogenic cell lysates, presenting a potential drug repositioning opportunity. In a murine model of stage IV metastatic breast cancer, immunization with these lysates significantly reduced primary tumor growth and lung metastasis, as assessed by bioluminescence imaging. Immunization also modulated immune cell populations, reducing splenomegaly and hepatomegaly, and partially reversing the immunosuppressive phenotype associated with 4T1-luc tumor growth, as evidenced by cytokine profiling (IL-6 and IFN-γ) and flow cytometry analysis of CD4 + and CD8 + T cell subpopulations. Specifically, methotrexate-treated lysates induced a significant shift in CD4 + T cells towards an effector phenotype. These findings highlight the potential of this immunotherapy approach to improve breast cancer treatment outcomes and warrant further investigation.