Loss of IDH1 and IDH2 mutations during the evolution of metastatic chondrosarcoma.

Driver mutations in IDH1 and IDH2 are initiating events in the evolution of chondrosarcoma and several other cancer types. Here, we present evidence that mutant IDH1 is recurrently lost in metastatic central chondrosarcoma. This may reflect either relaxed positive selection for the mutant IDH1 locus, or negative selection for the hypermethylation phenotype later in tumor evolution. This finding highlights the challenge for therapeutic intervention by mutant IDH1 inhibitors in chondrosarcoma.