Attacking glioblastoma brain tumor cells with a modified poliovirus is showing encouraging early results in an ongoing study. The phase I study is seeking to establish the proper dose, and its interim results were reported at the 2013 annual meeting of the American Society of Clinical Oncology in early June in Chicago, Illinois.

The treatment capitalizes on the discovery that cancer cells have an abundance of receptors that work like magnets in drawing the poliovirus, which then infects and kills the cells. The investigational therapy is known as PVSRIPO. It uses an engineered form of the virus that is lethal to cancer cells, while harmless to normal cells. The therapy is infused directly into a patient’s tumor. The virus-based therapy also triggers the body’s immune system to attack the infected tumor cells.

Preliminary data previewed the results of seven participants enrolled in the study, whose tumors recurred despite traditional treatments for glioblastoma multiforme, which is the most common and aggressive brain tumor.

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Of the individuals enrolled in the study, three have responded well to the drug. One patient remains disease-free 12 months after treatment, another 11 months posttreatment and the third is disease-free after five months. With traditional treatment, about half of glioblastoma patients see recurrent tumor growth within 8 weeks.

Two participants in the study did not fare as well; one had recurrent tumor growth after 2 months, and another’s condition declined after 4 months. The remaining two patients have been treated in the last 3 and 2 months, respectively, and currently remain disease-free.

“These early results are intriguing,” said principal investigator Annick Desjardins, MD, FRCPC, of Duke University School of Medicine in Durham, North Carolina. “Current therapies for glioblastoma are limited because they cannot cross the blood-brain barrier and often do not specifically attack the tumor. This treatment appears to overcome those problems. We are eager to see additional results as we move forward with our study.”