ERBB2 and breast cancer: In support of this, the TERT E4 removal strategy, when performed in bulk (i.e., without selection or enrichment of edited cells), did indeed enhance the efficacy of Herceptin, an Food and Drug Administration (FDA) approved monoclonal antibody drug for treating HER2 positive breast cancer [41], in inhibiting the growth of breast cancer SKBR3 cells (Supplementary Figure S3).