Due to the high prevalence of CCNE1 gain/amplification and RB1 loss, mutation or deletion, palbociclib is expected to be ineffective in the majority of primary HGSOC but may be selectively applied in cyclin E1-low, RB1-proficient cancers [9], or as follow-up treatment in CDK2 inhibitor-resistant cancers. Here, RB1 is linked to cancer.