Targeting Cyclin K-CDK12 Synergizes with ATR Inhibition by Limiting RPA Chromatin Loading in Triple-Negative Breast Cancer [ChIP-seq]

However, clinical and genomic studies have not clearly linked CDK12 inactivation to HRD. Here, we demonstrate that cyclin K-CDK12 depletion drives a replication stress (RS)-associated vulnerability through RPA regulation.

A DNA damage response-focused CRISPR screen identified DNA replication factors and ATR activators as top sensitizers to cyclin K degradation. Consistently, cyclin K-CDK12 depletion synergized with ATR inhibition in triple-negative breast cancer (TNBC) models. Cyclin K degradation reduces RPA chromatin loading and impairs ATR activation, compromising cellular tolerance to RS and increasing susceptibility to ATR inhibition.