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ASCO 2015: Gene Therapy Paired With Traditional Surgical Resection Benefits Patients With Glioblastoma

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Key Points

  • Median survival for those using the experimental treatment increased 3.6 months (13.5 to 17.1 months), and there was a 27% increase in overall survival at the end of 5 years.
  • Patients who had aggressive surgical excision combined with gene therapy experienced an overall improved survival period of about 8 months.
  • After initial treatment, patients were orally administered the antiviral drug valacyclovir for 2 weeks and received radiation therapy and subsequent chemotherapy as tolerated.

Houston Methodist Neurological Institute neurosurgeon David Baskin, MD, presented preliminary data from a phase II clinical trial that suggests gene therapy  (AdV-Tk therapy), which uses a mediated herpes simplex virus, combined with a traditional treatment—surgical resection—could benefit patients with glioblastoma who have the worst prognoses. These findings were presented at the 2015 ASCO Annual Meeting in Chicago (Abstract 2010).

As the most aggressive of primary brain cancers, glioblastomas are difficult to treat. Median survival is around 15 months for patients with this tumor, and the quality of life in the last 5 months is often poor.

Study Findings

From 2006 to 2010, 48 patients completed this experimental therapy. Their outcomes were compared with those of 134 patients who received surgical resection but no AdV-Tk therapy. While median survival increased 3.6 months (13.5 to 17.1 months), there was a 27% increase in overall survival at the end of 5 years. Dr. Baskin said the data showed a dramatic improvement in survival for patients who underwent aggressive surgical excision, improving from 57% to 67% survival at 1 year, 22% to 35% at 2 years, and 8% to 19% at 3 years, with an overall improved survival of about 8 months. “These results are far better than what we can now achieve with our present standard of care for treatment of patients with glioblastoma,” Dr. Baskin remarked.

Patients participating in the multicenter, open-label phase II study had no prior radiation treatment and were deemed to be candidates for surgery. During resection, neurosurgeons removed as much cancerous tissue as possible and then injected the AdV-Tk mixture 10 times at the site of resection. Patients were orally administered the antiviral drug valacyclovir for 2 weeks following the procedure and received radiation therapy and subsequent chemotherapy as tolerated.

Because of AdV-Tk's action, it is also called gene-mediated cytotoxic immunotherapy (GMCI). AdV-Tk first kills a number of cancer cells directly. It then releases specific proteins, causing superstimulation of the body’s own immune system. This action activates a number of immune pathways—much like a vaccine does—so that the immune system can then go on to kill many more cancer cells, for months to years later.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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