Long-term breast cancer response to CDK4/6 inhibition defined by TP53-mediated geroconversion
Rei Kudo, Anton Safonov, Catherine Jones, Enrico Moiso, Jonathan R. Dry, Hong Shao, Sharanya Nag, Edaise M. da Silva, Selma Yeni Yildirim, Qing Li, Elizabeth O’Connell, Payal T. Patel, Marie Will, Atsushi Fushimi, Marimar Benitez, Martina Bradić, Fan Li, Harikrishna Nakshatri, Dhivya R. Sudhan, Christopher R. Denz, Iker Huerga Sanchez, Jorge S. Reis-Filho, Shom Goel, Andrew Koff, Britta Weigelt, Qamar J. Khan, Pedram Razavi, Sarat Chandarlapaty
Abstract
Inhibition of CDK4/6 kinases has led to improved outcomes in breast cancer. Nevertheless, only a minority of patients experience long-term disease control. Using a large, clinically annotated cohort of patients with metastatic hormone receptor-positive (HR+) breast cancer, we identify TP53 loss (27.6%) and MDM2 amplification (6.4%) to be associated with lack of long-term disease control. Human breast cancer models reveal that p53 loss does not alter CDK4/6 activity or G1 blockade but instead promotes drug-insensitive p130 phosphorylation by CDK2. The persistence of phospho-p130 prevents DREAM complex assembly, enabling cell-cycle re-entry and tumor progression. Inhibitors of CDK2 can overcome p53 loss, leading to geroconversion and manifestation of senescence phenotypes. Complete inhibition of both CDK4/6 and CDK2 kinases appears to be necessary to facilitate long-term response across genomically diverse HR+ breast cancers. • TP53 mutation is associated with lack of long-term disease control on CDK4/6i • p53 deficiency suppresses DREAM complex in BC cells, enabling cell-cycle re-entry • Disruption of DREAM complex is sufficient to promote long-term CDK4/6i resistance • Inhibition of CDK2 overcomes p53 loss, promoting geroconversion and disease control Kudo et al. demonstrate that TP53 loss in HR+ breast cancer is clinically associated with long-term failure of CDK4/6i due to cellular escape from quiescence via impaired DREAM complex assembly. Selective CDK2 inhibition is found to reinforce p130 dephosphorylation in p53 mutant models and facilitate durable tumor growth suppression.