MSH6 and neoplasm: In 107 patients’ initial tumor tissues, we only detected MMR mutations (MSH6, MLH1, MSH2, or PMS2) in two IDH-mutant initial tumors (2 of 107, 1.8%) (Figure 1B), while MMR mutations were present in 7/43 (16.3%) patients’ temporally paired cf-tDNA samples; none of their tissues had MMR mutations identified (Figure 1D).