BS008

A novel therapeutic regimen showed that the oncolytic type II herpes simplex virus (oHSV2) was able to prevent colorectal cancer growth, recurrence, and metastasis. However, no study has yet explored whether oHSV2 has an impact on the development of diffuse large B-cell lymphoma (DLBCL). We chose the clinical chemotherapeutic drug doxorubicin (DOX) as a positive control to evaluate the effect of oHSV2 infection on the apoptotic, invasive, and proliferative capacity of DLBCL cells. We next further explored the therapeutic efficacy of oncolytic virus oHSV2 or DOX in DLBCL tumor bearing BALB/c mice, and evaluated the infiltration of CD8 + T cells and CD4 + T cells in tumor tissues. A pathological approach was used to explore the effects of oHSV2 on various organs of tumor bearing mice, including the heart, liver, and kidney. Next, SU-DHL-4 cells were co-cultured with cytotoxic T lymphocytes (CTLs) to mimic the tumor immune microenvironment (TME), to explore the impact of oHSV2 on the immune environment at the cellular level, and then analyzed the relationship between oHSV2 and the PD-1/PD-L1 immune-checkpoint. Subsequently, we further validated the efficacy of combined oHSV2 and PD-L1 treatment on transplanted tumor growth in mice at the in vivo level. DLBCL cells were sensitive to the action of the oncolytic virus oHSV2, and the decline in their proliferative activity showed a time-and dose-dependent manner. oHSV2 and DOX intervention preeminently increased the cell apoptosis, restrained cell proliferation and invasion, with the greatest changes occurring in response to oHSV2 infection. oHSV2 application effectively improved the immune status of the tumor microenvironment, favoring the invasion of CD8 + T and CD4 + T cells, thereby enhancing their antitumor effects. Besides, oHSV2 treatment has a safety profile in the organs of tumor bearing mice and indeed inhibits the PD-1/PD-L1 immune checkpoint in DLBCL. Interestingly, the combination of oHSV2 and PD-L1 antibodies results in more profound killing of DLBCL cells than oHSV2 infection alone, with a significant increase in the proportion of CD4 + T cells and CD8 + T cells. The antitumor effect was the best after combining oHSV2 and PD-L1 antibodies, suggesting that the combination therapy of oHSV2 and PD-L1 would have a better prospect for clinical application.

Selectively replicating herpes simplex virus-2 (HSV-2) vector is a promising treatment for cancer therapy. The insertion of multiple transgenes into the viral genome has been performed to improve its oncolytic activity.

Herein, we simultaneously constructed five “armed” oncolytic viruses (OVs), designated oHSV2-IL12, -IL15, GM-CSF, -PD1v, and IL7 × CCL19. These OVs delete theICP34.5andICP47genes with the insertion of transgenes into the deletedICP34.5locus. The anti-tumor efficacy in vivo was tested in the syngeneic 4T1 and CT26 tumor-bearing mice model.

The OVs showed comparable oncolytic capability in vitro. The combination therapy of oHSV2-IL12, -IL15, GM-CSF, -PD1v, and IL7 × CCL19 exhibited the highest tumor inhibition efficacy compared with the treatment of single OV or two OVs combination.

The OVs armed with different transgenes combination therapy also named 5-valent oHSV2 (also called cocktail therapy) might be an effective therapeutic strategy for solid tumors.