The online database clinicaltrials.gov lists nearly 360 clinical trials that involve cancer cell vaccines that are or will be recruiting study participants. Several of them are based in Minnesota, but one University of Minnesota study has a unique approach: growing the vaccine in a low-oxygen environment. This approach could be the reason that U researchers are meeting with more success than many other institutions.
This clinical trial is for people with glioma, a particularly deadly brain cancer. First, the tumor is removed surgically, and then physician-researchers create a vaccine from the tumor cells. These cells are trained to find and destroy tumor cells. The vaccine is given several times over time, with the hope that the tumor itself can provide the ammunition to fight cancer.
The first patient who received the vaccine was actually a German Shepard mix, Batman. Because of the success with Batman and other dogs, U of M researchers were able to move the study into people several years after Batman received his vaccine.
So what does oxygen have to do with it? Pediatric neurosurgery researcher John Ohlfest, Ph.D., said growing the tumors in oxygen levels present in the body, as opposed to levels found in the normal atmosphere, appears to be the difference. Oxygen levels change the way cells behave, he explained.
Depending on the tissue type, oxygen levels in the body are approximately 0.5%-8%, while in the air, the levels approach 21%. The lower oxygen levels appear to both make the vaccine more apt to find and destroy the tumor, and make the immune cells that fight the cancer more effective, he said.
The University of Minnesota is the only trial to use this approach, which was published the journal Cancer Research.
“This paper shows that if you take the tumor cells and grow them at a much lower oxygen level, it completely changes everything,” Ohlfest said. “It’s a transformational difference.”
The University of Minnesota used the low-oxygen approach with every patient – animal and human – thus far. Batman lived an additional 18 months beyond his initial diagnosis, when he was given weeks to live, and he did not die from brain cancer. University physicians are hopeful that the human study participants will experience similar or better results. In fact, some of the people who have participated in the trial have stable tumors so far.