Evaluation of the Safety and Biodistribution of M032, an Attenuated HSV-1 Virus Expressing hIL-12, After Intracerebral Administration to Aotus Non-Human Primates.

Herpes simplex virus type 1 (HSV-1) mutants lacking the γ134.5 neurovirulence loci are promising agents for treating malignant glioma. Arming oncolytic HSV-1 (oHSV) to express immunostimulatory genes may potentiate therapeutic efficacy. We have previously demonstrated improved pre-clinical efficacy, biodistribution, and safety of M002, a γ134.5-deleted HSV-1 engineered to express murine IL-12. Herein, we describe the safety and biodistribution of M032, a γ134.5-deleted HSV-1 virus that expresses human IL-12 after intracerebral administration to non-human primates (NHPs), Aotus nancymae. Cohorts were administered vehicle, 106, or 108 pfu of M032 on Day 1 and subjected to detailed clinical observations performed serially over a 92-day trial. Animals were sacrificed on Days 3, 31, and 91 for detailed histopathologic assessments of all organs and to isolate and quantify virus in all organs. With the possible exception of one animal euthanized on Day 16, neither adverse clinical signs nor sex- or dose-related differences were attributed to M032. Elevated white blood cell and neutrophil counts were observed in virus-injected groups on Day 3, but no other significant changes were noted in clinical chemistry or coagulation parameters. Minimal to mild inflammation and fibrosis detected, primarily in meningeal tissues, in M032-injected animals on Days 3 and 31had mostly resolved by Day 91. The highest viral DNA levels were detected at the injection site and motor cortex on Day 3 but decreased in CNS tissues over time. These data demonstrate the requisite safety of intracerebral M032 administration for consideration as a therapeutic for treating malignant brain tumors.