Since AZD6738, an Ataxia Telangiectasia and Rad3 related (ATR) serine/threonine protein kinase inhibitor, has been shown to induce synthetic lethality on TP53‐ or ATM‐defective CLL cells,38 we determined the response of our CRISPR/Cas9‐edited cell lines to this inhibitor. This evidence concerns the gene TP53 and B-cell chronic lymphocytic leukemia.