A personalized vaccine still in clinical trials may be helping some people with glioblastoma live longer.
Glioblastoma is a highly aggressive form of cancer that can spread quickly throughout the brain.
According to researchers, the five-year survival rate with standard treatment is less than 5 percent. Median survival stands at 15 to 17 months.
In the largest glioblastoma vaccine study to date, median survival is currently at 23 months.
Among those who were enrolled in the trial for more than three years, 30 percent survived more than 30 months.
The phase III trial enrolled 331 patients at more than 80 sites in the United States, Canada, the United Kingdom, and Germany.
How the vaccine works
The vaccine is called DCVax-L.
This is combined with dendritic immune cells from the person’s blood. In the lab, these cells are primed to attack tumor cells. When the vaccine is injected into the patient, it prompts the immune system to fight the cancer.
“What’s particularly impressive about immunotherapy trials is that there seems to be a population of about 20 to 30 percent of patients who are living significantly longer than expected — the long tail of the survival curve,” she continued.
How the ongoing trial works
To be eligible for the trial, participants had to be between the ages of 18 and 70 and newly diagnosed with glioblastoma.
All participants received standard care for glioblastoma. That includes surgery, plus a combination of chemotherapy and radiotherapy (chemoradiotherapy). The participants were divided into two groups. One group of 232 patients had standard care plus DCVax-L. The other group of 99 patients had standard care and a placebo treatment.
All patients who progressed or experienced a recurrence during the trial were given the vaccine. Almost 90 percent of the study participants ended up receiving the vaccine.
At the time of the interim analysis, 108 of the 331 participants were still alive. The researchers continue to monitor patients.
Dr. Santosh Kesari is a neurologist and neuro-oncologist and chair of the Department of Translational Neurosciences and Neurotherapeutics at the John Wayne Cancer Institute at Providence Saint John’s Health Center in California.
Kesari, one of the study’s authors, told Healthline that this trial has the potential to be a breakthrough. In addition to a positive improvement in survival, Kesari said the vaccine is safe. It doesn’t have the negative impact on quality of life that some other cancer treatments can.
Patients receive the DCVax-L six times during the first year. After that, they get it twice a year.
In the trial, only 7 people (2 percent) had serious adverse events that may have been related to the vaccine. These included cerebral edema, seizures, nausea, and lymph gland infection. Total adverse events in patients taking the vaccine and those receiving standard care alone are comparable.
“The vaccine is given subcutaneously. There can be an injection site reaction, chills, or fever. Compared with chemotherapy and radiation, the vaccine has very low toxicity,” explained Kesari.
“Survival looks really good. But the real question is: Can we do a study in the future and really randomize patients so the control arm doesn’t get the vaccine? That’s what’s really needed,” said Kesari.
Dr. Timothy Byun is a medical oncologist with St. Joseph Hospital’s Center for Cancer Prevention and Treatment in California, a facility that participated in the study.
Byun told Healthline that the study outcome is interesting. But, like Kesari, he suspects the crossover of patients from the placebo arm to DCVax-L on progression may impact the analysis of overall survival. “It is a well-tolerated therapy, so from [a] safety perspective, I don’t worry much. Since we are still waiting for final data, I don’t know if and when the FDA would approve this therapy,” he said.
The future of personalized medicine
Byun noted that dendritic vaccine therapy (Provenge) is already in use in metastatic castrate-resistant prostate cancer.
“However, it is not as widely adopted due to limited efficacy and cost,” he said.
“There have been many studies involving dendritic vaccines in different types of cancer and most were not very successful. But with improved understanding of the immune system, more personalized cancer vaccine studies are underway either as monotherapy or in combination immunotherapy,” said Byun.
The researchers involved in the DCVax-L study hope new clinical trials of combination therapies can begin soon.
Personalized medicine — immunotherapy, targeted therapy, and vaccines — is the wave of the future, according to Kesari.