Antiviral Drug May Extend Brain Cancer Survival
But further studies needed before recommending Valcyte for treating glioblastoma
Instead, it seems that CMV "cooperates with human cancer gene alterations to accelerate development and growth of the cancer," said Kwon, of the Ohio State University Comprehensive Cancer Center in Columbus.
As Reardon put it, "For some reason, these [glioblastoma] cells are a place where CMV likes to proliferate."
That has been known for several years, he said. The news here is that an anti-CMV drug might extend people's survival.
Still, there are questions, he said. The study, which was funded partly by Valcyte maker Hoffman-La Roche, included 50 patients from a single hospital. Many were given the antiviral drug as part of a "compassionate use" program at the hospital.
The researchers then compared them with 137 patients who were treated for glioblastoma at the same hospital around the same time, but were not given Valcyte. All patients in both groups received standard treatment, which typically meant surgery, chemotherapy and, in many cases, radiation.
Reardon said the problem with that type of study is that there's a risk of bias. Patients who were chosen to receive Valcyte may have been younger, in better overall health and more likely to respond to treatment.
On the other hand, he said, the survival figures for the Valcyte patients were "so far above average, it's hard to imagine they're just the result of cherry-picking the patients."
Reardon said more work is needed to see what drug dose is optimal, and whether patients have to take it indefinitely.
Another question, Kwon said, is whether the drug treatment actually reduced CMV levels in the patients' tumors, or if the virus was still lurking.
Plus, there's a risk of side effects with Valcyte, Kwon said, including diarrhea, vomiting and upset stomach. It can also harm kidney or liver function.
Despite all that, Kwon said, given the poor prognosis with glioblastoma, "anti-CMV treatment should be seriously considered."
Doctors could prescribe Valcyte for glioblastoma patients, Reardon said. But since it's not specifically approved for the cancer, insurers may not pay -- a big obstacle, since the drug costs a couple thousand dollars a month.
Glioblastoma is diagnosed in two or three people per 100,000 in the United States and Europe, according to the National Brain Tumor Society. No one is sure what causes the cancer, but it is more common in men and in people older than 50.