A recent study published in Nature Medicine showed that a new method of immunotherapy has been effective at destroying lymphoma. The protocol involves injecting a cancer vaccine inside a patient’s tumor in order to trigger the immune system to attack the disease. 73% of patients in the clinical trial saw either a portion or the entire tumor destroyed.
The study was led by Dr. Joshua Brody, senior researcher at Icahn School of Medicine in New York City. Brody also directs the Lymphoma Immunotherapy Program there. According to Brody, the researchers are “injecting two immune stimulants right into one single tumor.” This approach allows “all of the other tumors [to] just melt away.” The immune stimulants that are introduced into the tumor help alert the immune system to detect and destroy any similar cancer cells in the body.
Along with the patients who experienced tumor shrinkage, six patients also saw a stop in cancer progression for 3-18 months. Three patients saw either a significant regression or full remission. The results of the study are so promising that in March, the team moved on to an expanded clinical trial testing the protocol with lymphoma, breast, and head and neck cancers.
This approach is different than other immunotherapy approaches because it doesn’t focus on T-cells. Most immunotherapy treatments are concerned with T-cells, or what Brody names the “soldiers” of the immune system. Those T-cells are responsible for directly fighting foreign invaders in the body, and new therapies called checkpoint inhibitors help the T-cells to be aware of cancerous cells.
Many people know these drugs as the “Jimmy Carter” drugs since that’s what the former president used to treat his late-stage melanoma. While checkpoint inhibitor drugs have been very effective against several kinds of cancers, it really is case-by-case, and many cancer patients don’t benefit from them. Researchers are constantly working to improve the efficacy of these drugs.
The approach being studied by Brody and his team focuses not on T-cells, but on dendritic cells, or what Brody names the “generals” of the immune system. Dendritic cells help to guide T-cells to attack foreign cells. The goal of Brody’s team is to “mobilize these immune generals to tell the soldiers what to do.”
During the trial, patients received nine daily injections of the immune stimulant which aimed to help dendritic cells to detect cancerous cells and then group together. The patients later received eight injections of a different stimulant that actually “activates” the dendritic cells, which ultimately tells T-cells to begin destroying the visible cancer cells in the body.
Although the method is named a “vaccine,” the injections don’t work like a typical vaccine for the measles or flu. While those vaccines are preventative, teaching the immune system how to later ward off a disease, these vaccines are therapeutic. As Brody said, “We’re trying to teach the immune system to get rid of the thing even after you’ve already got the problem.”
According to lab tests with mice, this approach may be more powerful when its combined with checkpoint inhibitor drugs. The new trial is thus giving patients the vaccine and the checkpoint inhibitors.
The results of this study show great promise as another way to treat cancer with the immune system. Susanna Greer, director of clinical cancer research and immunology for the American Cancer Society, believes the method to be promising, but adds that more human studies are needed to confirm the findings.