EZH1 and cancer: Likewise, the pathognomonic SS18-SSX fusion protein in synovial sarcomas induces a state of SMARCB1-deficiency, conferring cancer cells with this chromosomal translocation sensitive to tazemetostat.700 Some H3K27me3-high malignancies are relatively tolerant to EZH2 inhibitors due to EZH1 compensation for EZH2 loss.701 This necessitates the development of EZH1/2 dual inhibitors, including valemetostat.