MRC1 and cancer: Another confounder was that 3 of our 9 SWI/SNF-altered tumors were dMMR; however, our analysis shows that 5 of the 6 MMR-proficient, SWI/SNF-altered cancers achieved a PR, while no objective responses were seen in the 4 patients without SWI/SNF alterations who were treated with immunotherapy (and were MMR proficient).