Crossing the Divide
Understanding how the immune system controls itself has led to advances in immunotherapy.
View the Immunotherapy Special Issue here
For many years, scientists were able to demonstrate that the immune system was active against cancer, but there was a divide they weren’t able to cross. They couldn’t apply that theory to the treatment of cancer until they learned more about how the immune system controls itself.
Now, that door is open, and a host of new therapies are beginning to pass through it.
Because the immune system is very tightly regulated to prevent it from attacking its host, it tends not to react against a lot of the things that can go wrong within our bodies, including cancer. To create effective immunotherapies, we needed to understand this “tolerance” and figure out how to wipe it away.
Recent insights into that dynamic have resulted in a host of new immunotherapies, including the checkpoint inhibitors Opdivo (nivolumab), Keytruda (pembrolizumab) and Yervoy (ipilimumab). By interfering with the so-called “checkpoint” mechanism that keeps the immune system at bay, these medications free up T cells to attack cancer cells. Other immunotherapy types include vaccines, bispecific monoclonal antibodies and laboratory-engineered T cells that are primed to fight cancer.
Due to these recent advances, we now have approved immunotherapies for melanoma, lung cancer and acute lymphoblastic leukemia, and may soon be able to treat other cancer types, including renal and breast, as well as additional hematologic diseases.
Perhaps the greatest appeal of immunotherapy is its lasting effect. Once the immune system has been programmed to fight cancer, it maintains an active surveillance, just as it does against other infections. Theoretically, after immunotherapy treatment has stopped, a patient’s immune system should remain prepared to fight the disease, even if the illness goes away and then recurs. This would represent a major advance in treatment, since cancers often become resistant to other types of medications, including targeted therapies.
The question we will face in the immediate future is whether we can achieve that lasting effect with the strategies currently available. With that in mind, an important job for researchers will be to determine the ideal length of treatment with some of the new immunotherapies, and whether they may need to be combined with other treatments.
The government, too, will play an important role in immunotherapy development. While pharmaceutical and biotechnology companies don’t often fund basic immunology research, the U.S. government does, and that contribution has been crucial. These recent successes highlight the need for the government to remain an active player in the area of immunotherapy, and to make the long-term investments needed to effectively fight cancer.
