The impact of FGFR3 mutation on the tumor immune infiltrate has recently been studied with single-cell RNA sequencing in a UTUC tissue specimen: FGFR3-mutated patients had T-cell phenotypes with more active/exhausted Th17-like CD4 cells, lower regulatory T cells, and more CD8/cytotoxic cells in the naïve state, a phenotype that could favor ICI response [45]. The gene discussed is FGFR3; the disease is neoplasm.