Presentation Title: Intralesional injection with PV-10 induces a systemic anti-tumor immune response in murine models of breast cancer and melanoma
Abstract Body: PV-10 is a 10% solution of Rose Bengal that is currently being examined as a novel cancer therapeutic. In melanoma patients, intralesional injection (IL) of PV-10 has led to regression of injected lesions as well as distant metastases. In this study, we examined the efficacy and potential immune mechanism of PV-10 treatment in murine models of breast cancer and melanoma. In BALB/c mice bearing MT-901 breast cancer, injection of PV-10 led to regression of injected and untreated contralateral subcutaneous lesions (p<0.05 compared to IL-PBS-treated mice). A significant increase in survival was observed in mice treated with PV-10. To examine immune response, MT901-specific IFN-gamma production and cytotoxicity were measured in splenocytes collected from mice treated with IL-PBS or IL-PV-10. MT901-bearing mice treated with IL-PV-10 demonstrated enhanced IFN-gamma production (992 ± 453 pg/ml) compared to splenocytes from PBS-treated mice (174 ± 105, p<0.05). In addition, a significant increase in lysis of MT-901 cells by T cells after PV-10 treatment was observed (p<0.01 compared to PBS-treated mice). No lysis of irrelevant CT-26 cells was detected. In a murine model of melanoma, B16-F10 cells were injected into C57BL/6 mice to establish one subcutaneous tumor and multiple lung lesions. Treatment of the subcutaneous lesion with a single injection of IL-PV-10 led to regression of the injected lesion as well as distant B16 melanoma lung metastases. In B16-bearing mice, treatment with IL-PV-10 led to the induction of T cells that produced IFN-gamma in response to B16 tumors but not irrelevant tumor (p<0.05) and demonstrated specific lysis of B16 (p<0.01 compared to T cells isolated from PBS-treated mice). In total, these studies support the induction of tumor-specific T cell-mediated immunity after single treatment with IL-PV-10 in multiple histologic subtypes. The immune mechanism of PV-10 ablation in cutaneous melanoma patients is currently under investigation at our institution.