Oncolytic viruses are viruses that infect and kill cancer cells. As the cell dies it releases more virus particles that proceed to infect and kill other cancer cells until a tumor is destroyed. Oncolytic variants of the herpes simplex virus (HSV)-1 have been used successfully to treat melanoma, glioma, and other cancers in adults. Results of the first study to test the effectiveness of an oncolytic HSV-1 in pediatric patients was published in the journal Clinical Cancer Research.

“The virus we tested — HSV1716 — is similar to talimogene laherparepvec, the HSV-1 recently FDA-approved for melanoma by intralesional injection,” says Timothy Cripe, MD, PhD, division chief of Hematology/Oncology & BMT, principal investigator in the Center for Childhood Cancer and Blood Diseases in The Research Institute at Nationwide Children’s, and senior investigator on the study. “Oncolytic viruses have a high potential for therapeutic performance with limited toxic effects due to their tumor-selective attributes.”

The study was comprised of pediatric and young adult patients aged 8 to 30 years with refractory incurable non-CNS solid tumors. The patients’ diagnoses included clival chordoma, malignant peripheral nerve sheath tumor, and renal cell carcinoma. A single dose of HSV1716 was delivered using tomography-guided intratumoral injection to 8 patients and 2 doses to 1 patient who achieved a stable disease state. No dose limiting toxicities were observed. Adverse reactions were mild and included a low-grade fever, chills, and mild cytopenias. No clinical responses were observed during the trial.

“We observed that intratumoral HSV1716 is safe and well-tolerated without shedding in children and young adults with late-stage, aggressive cancer,” said Dr Cripe, who is also professor of Pediatrics at The Ohio State University College of Medicine. “We also observed viremia consistent with viral replication and transient inflammatory reactions, both of which indicate promise for future studies.”

Reference

1. Streby KA, Geller JI, Currier MA, et al. Intratumoral injection of HSV1716, an oncolytic herpes virus, is safe and shows evidence of immune response and viral replication in young cancer patients [published online May 11, 2017].Clin Cancer Res. doi: 10.1158/1078-0432.CCR-16-2900