In preclinical studies, HF10 replicated efficiently within tumor cells with extensive cytolytic effects and induced increased numbers of activated CD4<sup>+</sup> and CD8<sup>+</sup> T cells and natural killer cells within the tumor, leading to a significant reduction in tumor growth and prolonged survival rates.
We previously demonstrated that HF10, which is a natural, non-engineered HSV-1, has potent oncolytic activity in the treatment of solid malignant tumors in vitro and in vivo [H. Takakuwa, F. Goshima, N. Nozawa, T. Yoshikawa, H. Kimata, A. Nakao, et al., Oncolytic viral therapy using a spontaneously generated herpes simplex virus type 1 variant for disseminated peritoneal tumor in immunocompetent mice, Arch.Virol.