Two recent articles summarize the promise that immunotherapy provides for the future of cancer treatment. Immunotherapy refers to treatments that aid your own immune system in fighting cancer cells.
The first, from U.S. News and World Report, reports on several of the new drugs that have recently shown promise in treating lung cancer and advanced melanoma, specifically Opdivo, Keytruda and Yervoy.
Cancer cells have the ability to avoid the attack of the immune system’s defenses by “tricking” T-cells, the powerful agents that fight any invaders, into not attacking the cancer cells. The new immunotherapy treatments, called checkpoint inhibitors, don’t allow this to happen. They essentially block the action of proteins which cause the “off switch” that blocks T-cells, and turn the switch back on, so that the T-cells can recognize and attack the cancer cells.
Keytruda and Opdivo target proteins on the surface of the T-cells called PD-1 (Programmed Cell Death 1). Certain cancer cells produce proteins which latch onto PD-1, disarming the T-cells. The drugs prevent this action, allowing the immune system to respond. There have been some promising studies indicating that blocking PD-1 and PD-L1 in GIST may help to increase the efficacy of imatinib in treatment for GIST.1
Although these treatments hold great promise, they are still in the early stages of development, and so far have only been effective in about 20 percent of people. The drugs are also staggeringly expensive with costs often hitting $150,000 per year. Also, there can be serious side effects, and amping up the immune system can cause it to attack normal cells as well.
There is also the fact that most people will not respond. Scientists at Memorial Sloan Kettering Cancer Center discovered that tumors with the most mutations were most likely to respond to this type of treatment, which is logical since the immune system would have an easier time recognizing that these cells are abnormal. More research needs to be done before this type of treatment is applicable for a greater number of cancer cell types.
Interview Sheds Light on Trends in Immunotherapy
The second article, from Forbes, is an in-depth interview with Jill O’Donnell-Tormey, CEO and director of scientific affairs at the nonprofit Cancer Research Institute about the future of immunotherapy.
Ms. O’Donnell-Tormey discussed the most promising trends in immunotherapy, including the promise of combination therapies, utilizing immunotherapy with currently standard-of-care drugs. She also mentions the promise of vaccine therapies, and the fact that combining them with checkpoint inhibitors may be more effective.
She also describes the challenges in finding new epitopes in cancer vaccine therapy. Epitopes are the targets the immune system sees. Scientists were initially trying to find an antigen or marker expressed by all cancer types, or at least by all within one particular type of cancer, but that has proved elusive.
The other treatments mentioned in the article is CAR T cells, which are proving highly effective in acute lymphoblastic leukemia.
- Seifert et. Al, Pd-1/PDL1 Blockade Enhances the Efficacy of Imatinib in Gastrointestinal Stromal Tumor (GIST), Journal of the American College of Surgeons, September, 2014, Volume 219, Issue 3, Supplement, Page S129.http://www.journalacs.org/article/S1072-7515(14)00844-8/abstract