Intratumoral/Peritumoral Herpes Simplex Virus-1 Mutant HSV1716 in Pediatric Patients with Refractory or Recurrent High-Grade Gliomas: A Report of the Pediatric Brain Tumor Consortium

Background/Objectives: Multiple immune-modulatory strategies have been tested in efforts to mitigate the pro-tumor microenvironment in pediatric high-grade glioma. HSV1716 is an oncolytic virus that previously demonstrated evidence of response in adult and pediatric patients. PBTC-037 was a single-center phase I trial developed and performed by the Pediatric Brain Tumor Consortium (PBTC) to estimate the maximum tolerated dose or recommended phase II dose of HSV1716 administered during surgical resection. Methods: Patients aged 12 to 21 years with recurrent or refractory high-grade glioma for whom surgical resection was clinically indicated were eligible. After maximal tumor resection, patients received one intraoperative dose of HSV1716. Results: Two patients were enrolled; one was later deemed ineligible yet was continued in follow up for safety. Both patients underwent complete tumor resection with the administration of HSV1716. Shortly after the enrollment of the two patients, this study was closed to accrual due to a change in the sponsor’s investment focus. One patient completed the 8-week reporting period without toxicity. The second patient who was later deemed ineligible had no evidence of dose-limiting toxicity. The two patients had progressive disease at 1.9 and 2.9 months after enrollment; both eventually died due to progressive disease at 7.5 months. Conclusion: We describe the administration of HSV1716 to two pediatric patients with recurrent high-grade glioma, without evidence of dose-limiting toxicity. Oncolytic viruses are currently being tested in pediatric patients in larger combinatorial trials. Despite the limited numbers, the data presented here will hopefully provide incremental steps toward improved immunovirotherapy of pediatric brain tumors.