The DNA-PKcs inhibitor AZD7648 enhances CRISPR-Cas9-directed homology-directed repair efficiencies, with potential for clinical utility, but its possible on-target consequences are unknown. We found that genome editing with AZD7648 causes frequent kilobase-scale and megabase-scale deletions, chromosome arm loss and translocations. These large-scale chromosomal alterations evade detection through typical genome editing assays, prompting caution in deploying AZD7648 and reinforcing the need to investigate multiple types of potential editing outcomes.
© 2024. The Author(s).