Conclusions: In this study, we found that patient treated with ICIs have similar outcomes in the presence of germline vs. somatic MMR mutations in MSI-H CRC. The presence of an associated BRAF V600E mutation, which occurs in non-LS MSI-H CRC conferred worse outcomes.
https://ascopubs.org/doi/10.1200/JCO.2024.42.3_suppl.175
Immunotherapy increases the body’s ability to identify and attack these cells, and cancers that have high microsatellite instability actually help this effort. As the cells continue to mutate and replicate DNA several times, they create more and more proteins that the body doesn’t recognise as normal.
Before immunotherapy, MSI used to be very bad news for patients with advanced cancers. Because they can mutate rapidly, cancer cells can begin to differentiate from each other and change significantly. Cancer can, for example, gain the ability to metastasize to a different organ or better evade the immune system. With advances in immunotherapy, that prognosis is changing, but that is a very recent shift in just the last few years. Now we know that if you have cancer with MSI, even if it’s late stage, it has a good chance of responding to immunotherapy.
Lynch Syndrome Ireland 