A new study has uncovered an experimental brain cancer treatment that might successfully extend the lives of patients two-fold using a virus. The phase 1 study examined patients with recurrent glioblastoma, which is the most common and aggressive brain tumor. Each patient was treated with an engineered tumor-seeking virus called Toca 511.
The results showed that the 43 patients treated with the unique viral therapy exhibited a survival time of 13.6 months, compared to just 7.1 months for patients that did not undergo the new treatment.
"For the first time, this clinical data shows that this treatment, used in combination with an antifungal drug, kills cancer cells and appears to activate the immune system against them while sparing healthy cells," said Timothy Cloughesy of the University of California, Los Angeles and co-lead author of the study. "This approach also has potential in additional types of the disease, such as metastatic colorectal and breast cancers."
Cloughesy, who is also a consultant for the biopharmaceutical company that developed the treatment and funded the majority of the study, revealed that some patients that received the treatment even lived for more than two years. These patients reported few side effects.
"Brain cancer is a deadly disease, and when it returns there are extremely few treatment options, and survival is usually measured in months," said Michael Vogelbaum of the Cleveland Clinic and co-lead author of the study along with Cloughesy.
The treatment involves injecting Toca 511 into cancer patients, where it then infects actively dividing cancer cells and gives them a gene for an enzyme called cytosine deaminase. Once inside the tumor, Toca 511 genetically programs its cells to create cytosine deaminase, which primes them for step two of the treatment.
The next phase involves patients taking the antifungal drug Toca FC, which is converted by cancer cells into the anticancer drug 5-fluorouracil (5-FU) due to the genetic changes stimulated by Toca 511. Ultimately, infected cancer cells and those that aid them are targeted and killed, while healthy cells remain untouched.
Since the study only covers phase 1 of the new treatment, an additional two phases will likely be needed before the medication is approved by the U.S. Food and Drug Administration.
"The collective results from this virus study, include encouraging survival and excellent safety data, support the ongoing randomized phase 2/3 trial called Toca 5, and offer hope for a new treatment option for patients with brain cancer," Vogelbaum said.
The findings were published in the June 1 issue of the journal Science Translational Medicine.
