Cancer treatments have long been limited to things like chemotherapy and radiation therapy, but in recent years more effective methods are emerging. Now, scientists at the University of Konstanz have found that combining two experimental methods – a vaccine and an immunotherapy – helps boost the success rate in mouse models.
The team started with a cancer vaccine, made up of micrometer-sized particles containing a tumor protein and a molecule called a riboxxim. Like any vaccine, the idea is that this will teach the immune system to go on the offensive against the cancer – the riboxxim activates the T cells, and the tumor protein tells them what to attack.
Tests in mice showed a strong anti-tumor response, even at very small doses. But while the response was still detectable eight weeks after vaccination, the tumors began to return after about 30 days. That’s due to a natural process where the body down-regulates the immune system to prevent it going rogue and harming healthy cells.
So the team combined the vaccine with another kind of treatment – an immune checkpoint inhibitor. As the name suggests, these drugs reduce this dampening effect and allow the immune system to continue its crusade against cancer. Alone, this treatment has a success rate of only around 20 percent in humans, but the team found combining the immune checkpoint inhibitor with the vaccine boosted that success rate.
“A major shortcoming of cancer vaccines is the availability of immune stimulants that can be used in humans,” says Marcus Groettrup, senior author of the study. "In combination with the immune checkpoint blockade, our clinically applicable vaccine leads to an increase in the proportion of mice that can be cured of existing tumors to 75 percent.”
The technique showed promise against a range of cancer types too, including prostate cancer, breast cancer and melanoma.
The study adds further evidence to the idea that immunotherapy and vaccines could work well together in the fight against cancer. In one, booster vaccines given a day and a week after CAR-T cell immunotherapy improved outcomes, while in another study checkpoint blockers backed up a drug that converts immune activity-dampening T cells into cancer-fighting ones.
The team says that the new technique is now being tested in a phase 1 trial in humans.
The research was published in the journal Nature Communications.
Source: University of Konstanz