Researchers at The University of Texas MD Anderson Cancer Center report that a follicular lymphoma vaccine uniquely tailored for each patient extended disease-free survival by 14 months. The results were recently published online in the Journal of Clinical Oncology. Click here to read the published abstract.
To make the vaccine, unique proteins from each patient’s tumor were isolated and combined with a delivery agent and a growth factor. This mixture was then injected back into the patient.
Earlier studies have shown that lymphoma vaccines are able to induce anti-tumor immune responses in some patients. Importantly, patients that produced an immune response seemed to have longer remissions than those that did not. However, when the vaccines were tested in phase 3 studies, the results were not as impressive. Two phase 3 studies comparing vaccines vs no vaccine in patients with follicular lymphoma have been reported. The MD Anderson study is the first phase 3 study to demonstrate a benefit for patients receiving vaccine.
Notably, there were a few important differences between the most recent study and the two prior studies. First, the vaccine in the recently published study, though very similar, was produced in a slightly different way. Second, patients received an uncommon chemotherapy regimen called PACE. In one of the other studies patients received CVP chemotherapy (a less aggressive treatment regimen compared to PACE) prior to vaccine, while in the other prior study, patients received rituximab prior to vaccine. Third, and perhaps most importantly, in the most recent study, only those patients with a complete response lasting several months following PACE were eligible to be randomized to vaccine or no vaccine.
The results of the MD Anderson study are important because they validate the concept that vaccines may have the potential to induce an immune response that is capable of preventing lymphoma from relapsing. Also, the study results suggest that vaccines are likely to be most effective when there is as little lymphoma as possible (i.e., the presence of lymphoma inhibits the vaccine from inducing an anti-tumor immune response). Finally, and somewhat unexpectedly, the MD Anderson study found that those patients who had a vaccine directed against tumor IgM appeared to benefit more than patients who had a vaccine directed against tumor IgG (IgM and IgG are proteins present on the surface of some lymphomas). These results will help direct future research.
The study, however, has some limitations. First, the method of vaccine production is extremely lengthy and may not be practical for many patients. Second, many patients will not achieve a durable complete remission following chemotherapy and therefore may not be likely to be benefit from the vaccine. Third, none of the patients in the recent study received rituximab prior to vaccine. Although it was not known at the time the investigators designed the MD Anderson study, we know now that rituximab is able to prolong survival in patients with follicular lymphoma. It may be unethical to withhold rituximab from patients unless there is a suggestion that the alternative therapy is also going to prolong survival.
Despite these limitations, these exciting new results are likely to stimulate a new wave of research, building on the recent findings, and helping us move one day towards better treatments (and maybe a cure).