Vaccine May Fight Return of Cancer
Treatment moving to large-scale trial
MONDAY, Oct. 4 (HealthSCOUT) -- The results of a small cancer vaccine study have just been published, but the results are so encouraging that a large-scale trial is already in the works.
The vaccine, which uses the patient's own tumor cells to trigger a powerful immune response against the cancer, appears to have a clear anti-tumor effect -- without side effects.
In the current issue of Nature Medicine, researchers from the National Cancer Institute (NCI) in Bethesda, Md., report that in a small group of patients with non-Hodgkin's lymphoma, a common blood-cell cancer, an individually tailored vaccine prevented the cancer from coming back in nearly every patient.
This year, nearly 57,000 Americans will develop non-Hodgkin's lymphoma, and almost 26,000 will die. This study involved 20 recently diagnosed patients with lymphoma who had already received chemotherapy and were in remission.
Using tumor cells taken from each patient before their chemotherapy, the researchers produced large quantities of tumor proteins, then altered them slightly and combined them with an immune-stimulating factor called granuloyte-monocyte colony-stimulating factor (GM-CSF). This mixture, specific to each patient, was injected into each patient, followed by four monthly booster shots.
The researchers found that 18 of the 20 patients vaccinated in this way remained in complete remission for an average of four years after their therapy started, and they have no evidence of the disease.
"Generally, by that time point of four years of follow-up, one would have expected at least half of the patients to have relapsed," says Dr. Larry Kwak, a principal investigator at the NCI's Division of Clinical Sciences and the senior author of the study.
According to Kwak, while the length of remission seen in these patients is encouraging, it isn't the most scientifically important finding in this study. "The first is the achievement of molecular remission," he says, meaning that this is the first study to show that the blood of the patients showed no evidence of cancer even at the molecular level.
At the same time, the vaccine was shown to generate cancer-killing T-cells targeted specifically to the patient's cancer cells. Dr. David Curiel, a professor of pulmonary and critical care medicine at the University of Alabama in Birmingham, says that this is evidence that the immune system had been stimulated to recognize the tumor as foreign.
According to Kwak, "that establishes a scientific proof of principle for other cancer vaccines. That's sort of the Holy Grail of cancer vaccines -- to induce T-cells that actually kill the patient's own tumor." But Curiel, while praising the study, is still waiting for more evidence. "Presumably, what they showed could be extended to the context of other tumors, but I would venture that very cautiously. You need to do it and see," says Curiel.
Curiel also points out that this study confirms that it's important to catch patients at an early stage of lymphoma. "As the disease progresses, there's some concern that there may not be the capacity to stimulate the immune system," he says. "So the fact that earlier-stage patients responded was consistent with the idea that maybe we should be interceding at an earlier stage."
Kwak agrees, noting that extensive chemotherapy and radiation therapy to treat prolonged illness can impair T-cell function, which could make this vaccine therapy less effective.
"The definitive clinical experiment still needs to be done, and that's the Phase III randomized trial that's being developed," says Kwak. This trial hopes to enroll 390 patients with low-grade lymphoma at different medical centers across North America. Two-thirds of the patients will be randomly chosen to take the vaccine, while patients in the control group will still receive the powerful immune booster GM-CSF.
What To Do
A cancer vaccine is still far from being a reality because various cancers have their own peculiarities. Talk to your doctor if you have an early stage of non-Hodgkin's lymphoma; you may be eligible for this trial.
You can find out more about non-Hodgkin's lymphoma from the American Cancer Society or the National Cancer Institute. If you would like information about the upcoming Phase III clinical trial, you can contact the NCI Clinical Studies Support Center toll-free at 1-888-624-1937.