Anti-tumor effects of inactivated Sendai virus particles with an IL-2 gene on angiosarcoma

•Cutaneous angiosarcoma is a tumor resistant to conventional therapies.•Sendai virus particles (HVJ-E) with IL-2 gene inhibited the mouse angiosarcoma.•HVJ-E/IL-2 stimulated local accumulation of CD8 (+) T and NK cells.•HVJ-E/IL-2 reduced regulatory T cells and myeloid-derived suppressor cells.•Co-administration of sunitinib with HVJ-E/IL-2 greatly improved tumor-free rates.

Cutaneous angiosarcoma is a life-threatening tumor that is resistant to conventional therapies. The therapeutic effects of Sendai virus particles (hemagglutinating virus of Japan envelope: HVJ-E) carrying IL-2 gene (HVJ-E/IL-2) were examined in a mouse model of angiosarcoma. Intra-tumoral injection of HVJ-E/IL-2 effectively inhibited the growth of angiosarcoma cells (ISOS-1) inoculated in mice and improved tumor-free rates. HVJ-E/IL-2 stimulated local accumulation of CD8 (+) T cells and NK cells and reduced regulatory T cells in regional lymph nodes. Notably, the prevalence of myeloid-derived suppressor cells was lower in HVJ-E/IL-2-treated mice than in HVJ-E-treated mice. HVJ-E/IL-2 treatment promoted IFN-γ production from CD8 (+) T cells in response to tumor cells, more significantly than HVJ-E treatment. Greatly improved tumor-free rates were obtained when sunitinib, a tyrosine kinase inhibitor, was administered in combination with HVJ-E/IL-2. Immunogene therapy with HVJ-E/IL-2 with or without sunitinib could be a promising therapeutic option for cutaneous angiosarcoma.