Efficacy and Safety of a Novel Fusogenic Oncolytic Herpes Simplex Virus
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Date
2023-05
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Publisher
The Ohio State University
Abstract
It is important to develop therapeutics to treat solid tumors because of their prevalence and poor survival rates. Oncolytic herpes simplex viruses (oHSV) are promising therapeutics for solid tumors because they can be engineered to replicate theoretically only in cancer cells. Through directed evolution, Mut-3, a highly potent, wild type-like oHSV was developed. By deleting the UL39 locus that encodes ICP6, Mut-3 was attenuated, resulting in a novel fusogenic oHSV: Mut-3∆6. Mut-3∆6 exhibited reduced potency compared to Mut-3 in differentiated keratinocytes in in vitro MTS cytotoxicity assays, establishing its in vitro safety. In vivo safety was demonstrated when all Balb/c mice intravenously injected with 1e8 pfu of Mut-3∆6 remained healthy for the study duration (85 days), whereas mice injected with 1e6 pfu and 1e7 pfu of wild-type KOS died five to six days after infection. Having established its safety, the focus shifted to evaluating the efficacy of Mut-3∆6. Its potency was investigated through in vitro MTS cytotoxicity assays. In Rh30 (rhabdomyosarcoma), SK-N-AS (neuroblastoma), and CHP-134 (neuroblastoma), Mut-3∆6 exhibited significantly higher potency compared to controls, and its potency occurred at low MOIs, which is desirable because the treatment can be translated more easily to the clinic. These cell lines were selected for in vitro viral replication assays. In CHP-134, Mut-3∆6 replicated more than rRp450 at 24, 48, and 72 hours post infection, and Mut-3∆6 appeared to plateau in replication earlier than the other viruses, indicating CHP-134 cells were lysed more quickly when infected with Mut-3∆6. CHP-134 was therefore identified as a model for an in vivo efficacy study. Novel fusogenic oHSV Mut-3∆6 has demonstrated in vitro and in vivo safety and in vitro cytotoxicity, indicating its potential as a cancer therapeutic. The anti-tumor efficacy of Mut-3∆6 is currently being studied in vivo in the CHP-134 tumor model.
Description
Third Place, Innovations in Medicine Category at the Denman Undergraduate Research Forum
Keywords
oncolytic virotherapy, cancer, directed evolution, solid tumors