Samuraciclib, an oral CDK7 inhibitor, showed improved clinical benefit when combined with fulvestrant in women with advanced HR-positive, HER2-negative breast cancer previously treated with CDK4/6 inhibitors, according to a randomized trial published in Nature Communications. The result positions CDK7 as a potential next-line cell-cycle and transcription-control target in a setting defined by resistance to CDK4/6 blockade. For clinicians, the pairing with fulvestrant is particularly relevant for endocrine resistance management where options after CDK4/6 failure are still limited. The trial adds randomized evidence to a therapeutic area that has increasingly focused on transcriptional dependencies and broader kinase network suppression.