This study investigates genetic dependencies and resistance mechanisms to Werner helicase inhibitors (WRNi) in microsatellite-unstable (MSI) cancer models. To define determinants of WRN dependency and acquired resistance, we performed genome-wide CRISPR-Cas9 knockout screens, CRISPR base-editing mutagenesis screens targeting WRN, targeted sequencing of resistance-associated variants, bulk RNA sequencing, and whole-genome sequencing. The datasets deposited in EGA comprise raw sequencing files from CRISPR-Cas9 knockout screens, CRISPR base-editing screens, targeted DNA sequencing, RNA-seq experiments, and whole-genome sequencing of parental and drug-treated cell populations, including models with spontaneously acquired resistance. These data enable investigation of WRN synthetic lethality, genetic modifiers of WRNi response, and genomic alterations emerging under selective pressure.