Synergistic antitumor effect on cervical cancer by rational combination of PD1 blockade and CRISPR-Cas9-mediated HPV knockout

Targeted therapy results in objective responses in cervical cancer. However, the responses are short. In contrast, treatment with immune checkpoint inhibitors results in a lower responses rate, but the responses tend to be more durable. Based on these findings, we hypothesized that HPV16 E6/E7-targeted therapy may synergize with the PD-1 pathway blockade to enhance antitumor activity. To test hypothesis, we described for the first time the effects of the CRISPR/Cas9 that was targeted to the HPV and PD1 in vitro and in vivo. Our data showed that gRNA/cas9 targeted HPV16 E6/E7 induced cervical cancer cell SiHa apoptosis, and suggested that overexpression of PD-L1, induced by HPV16 E6/E7, may be responsible for lymphocyte dysfunction. In established SiHa cell- xenografted humanized SCID mice, Administration of gRNA-PD-1 together with gRNA-HPV16 E6/E7 treatment improved the survival and suppressed the tumor growth obviously. In addition, combination treatment increased the population of dendritic cells, CD8+ and CD4+ T lymphocyte cells. According, it enhanced the expression of Th1-associated immune-stimulating genes while reducing the transcription of regulatory/suppressive immune genes, reshaping tumor microenvironment from an immunosuppressive to a stimulatory state. These results demonstrate potent synergistic effects of combination therapy using HPV16 E6/E7-targeted therapy and immune checkpoint blockade PD1, supporting a direct translation of this combination strategy in clinic for the treatment of cervical cancer.