Gene Therapy With Herpes Virus Extends Survival in Advanced Brain Cancer Patients

Glioblastoma treatment with surgical resection may benefit patients with worst prognoses.

An experimental gene therapy that uses a mediated herpes simplex virus may improve survival outcomes for glioblastoma patients with the very worst prognoses, according to a recent clinical trial.

Researchers from the Houston Methodist Neurological Institute evaluated the gene therapy, called AdV-Tk therapy, in combination with the traditional treatment of surgical resection.

The action of AdV-Tk falls under the gene-mediated cytotoxic immunotherapy category, which attacks cancer in a variety of ways. The drug directly kills some cancer cells before releasing specific proteins that stimulate the immune system, which activates multiple immune pathways that enable the immune system to kill more cancer cells for months to years later.

The phase 2 trial compared 48 glioblastoma patients who completed AdV-Tk therapy with 134 patients who only received surgical resection. Median survival in the surgical resection alone group was 13.5 months compared with 17.1 months in the AdV-Tk group. The experimental therapy also increased overall survival by 27% at the end of 5 years.

Furthermore, the results showed a significant survival improvement in patients who underwent aggressive surgical excision. Among these patients, survival increased from 57% to 67% at 1 year, from 22% to 35% at 2 years, and from 8% to 19% at 3 years, with an overall improved survival of approximately 8 months.

Patients enrolled in the trial received no prior radiation treatment and were deemed candidates for surgery. During the procedure, surgeons removed as much cancerous tissue as possible before injecting the AdV-Tk mixture 10 times at the site of resection.

Patients were subsequently administered the oral antiviral drug valacylovir for 2 weeks after the surgery, in addition to radiation therapy and chemotherapy.

"These results are far better that what we can now achieve with our present standard of care for treatment of patients with glioblastoma,” said Houston Methodist Neurological Institute neurosurgeon David Baskin, MD, in a press release.