Cancer vaccines are used to create an immune system response that, in theory, will cause the immune system to create antibodies that will attack and reduce the cancerous tumor.
But Dr. Willem Overwijk in the department of Melanoma Medical Oncology at M.D. Anderson, found that instead of fighting the tumors, the immune system goes back to the injection site and tries to fight the mineral oil used in the vaccine.
"These vaccines worked in the sense that they activated the immune system to become educated and recognize cancer cells as bad and try to kill them. But then as a second step, they attracted so much attention from the immune cells that the immune cells, in a way, got confused and went back to the injection site and these T-cells then never made it to the tumor."
Dr. Overwijk's study, published in Nature Medicine, indicates switching from a mineral oil formula to one based on a saline solution could make the vaccines more effective at targeting cancer. M.D. Anderson will open a clinical trial later this year for melanoma patients to test the efficacy of a water-based vaccine.
"The truth is that we have a very important hunch from this work about what to try next in our clinical trials for our patients. But I really would not want to say that we are going to now change the outcome for patients or anything like that, until we've actually tested it."
However, if Dr. Overwijk's theory holds up in clinical trials, it's likely that oncologists will switch from oil to water-based vaccines for cancer treatment.