Peptidomimetic of stabilized alpha-helix of EZH2 which disrupt the EZH2-EED interaction leading to reduced H3K27me3 and EZH2 protein levels. SAH-EZH2 is capable of inducing growth arrest in leukemia cells and shows antiproliferative effects in B-cell lymphoma cell lines. This evidence concerns the gene EZH2 and B-cell non-Hodgkin lymphoma.