Enhanced cancer radiotherapy through immunosuppressive stromal cell destruction in tumors
Menée à l'aide de modèles murins, cette étude évalue l'intérêt d'un vaccin, délivré par injection intratumorale, pour favoriser une réponse immunitaire contre les cellules stromales immunosuppressives dont le recrutement est induit par la radiothérapie
Purpose: Radiation therapy (RT) kills cancer cells by causing DNA damage, and stimulates a systemic antitumor immune response by releasing tumor antigen and endogenous adjuvant within the tumor microenvironment. However, RT also induces the recruitment of immunosuppressive myeloid cells, which can interfere with the antitumor immune responses elicited by apoptotic tumor cells. We hypothesized that local delivery of vaccine following RT will lead to the priming of antigen-specific cytotoxic T lymphocyte (CTL) immune responses and render immunosuppressive myeloid cells susceptible to killing by the activated CTLs. Experimental Design : Using several antigenic systems, we tested whether intratumoral injection of antigenic peptide/protein in irradiated tumors would be able to prime CTLs as well as load myeloid cells with antigen, rendering them susceptible to antigen-specific CTL killing. Results : We show that by combining RT and targeted antigenic peptide delivery to the tumor, the adjuvant effect generated by RT itself was sufficient to elicit the priming and expansion of antigen-specific CTLs, through the type I interferon dependent pathway, leading to synergistic therapeutic antitumor effects compared to either treatment alone. In addition, using two different types of transgenic mice, we demonstrated that CTL-mediated killing of stromal cells in tumors by our approach is important for tumor control. Finally, we confirmed the efficacy of this approach in our preclinical model using two clinically tested therapeutic HPV vaccines. Conclusions : These data serve as an important foundation for the future clinical translation of RT combined with a clinically tested therapeutic HPV vaccine for the control of HPV-associated cancers.