Most types of prostate cancers don’t respond well to immunotherapy. However, genetic screening efforts can help identify which immunotherapy treatment options will work with specific patients.
Checkpoint Mismatch Repair
Checkpoint inhibitors are a type of immunotherapy drug that can be highly effective in treating prostate cancer. Unfortunately, very few men respond to checkpoint inhibitors. This has led researchers to identify the specific circumstances in which checkpoint inhibitors work, with research revealing that men who have cancer tumors that have mismatch repair (MMR) deficiency, a type of DNA-repair process, are particularly responsive to treatment.
MMR-deficient cancer cells are usually highly mutated, much more than a typical cancer cell. These cells often possess high levels of microsatellite instability, which causes DNA sequences to repeat themselves — something that is evidence of an MMR deficiency. New research into developing tests for microsatellite instability has demonstrated that genetic screening for MMR deficiency can be an excellent tool for identifying the small but significant number of prostate cancer patients that may be treated effectively with checkpoint inhibitors.
A Little Bit of Good News
The old saying that “no news is good news” is never true when it comes to cancer research. Even a little bit of good news is better than no news at all, and this new development in being able to pinpoint, using genetic testing, if a prostate cancer patient has a tumor that is susceptible to being treated by a checkpoint inhibitor can be a major game changer for those patients.
Yes, it’s still a relatively rare occurrence to be diagnosed with an MMR-deficient prostate cancer. Yet now, knowing that such a cancer may respond well to specifically targeted immunotherapy from checkpoint inhibitors doesn’t just provide relief to patients that happened to be diagnosed with this rare form of prostate cancer; it provides hope that further research will be able to identify other types of cancers that may respond favorably to similar treatments in the future.
Every new piece of knowledge we gain in treating cancer is a boon, as they typically act as stepping stones to better and more effective treatments for all types of cancer and not just prostate cancers. Given enough time and effort, medical science may be able to reduce cancer to something people die from to something people can treat like any other illness.
