ERþ Breast cancers resistant to prolonged neoadjuvant letrozole exhibit an e2f4 transcriptional program sensitive to cdk4/6 inhibitors

Angel L. Guerrero-Zotano, Thomas P. Stricker, Luigi Formisano, Katherine E. Hutchinson, Daniel G. Stover, Kyung Min Lee, Luis J. Schwarz, Jennifer M. Giltnane, Monica V. Estrada, Valerie M. Jansen, Alberto Servetto, Joaquín Gavila, J. Perez Fidalgo Alejandro, Ana Lluch, Antonio Llombart-Cussac, Mohamed Amine Bayar, Stefan Michiels, Fabrice Andre, Monica Arnedos, Vicente GuillemAmparo Ruiz-Simon, Carlos L. Arteaga

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


Purpose: This study aimed to identify biomarkers of resistance to endocrine therapy in estrogen receptor–positive (ERþ) breast cancers treated with prolonged neoadjuvant letrozole. Experimental Design: We performed targeted DNA and RNA sequencing in 68 ERþ breast cancers from patients treated with preoperative letrozole (median, 7 months). Results: Twenty-four tumors (35%) exhibited a PEPI score 4 and/or recurred after a median of 58 months and were considered endocrine resistant. Integration of the 47 most upregulated genes (log FC > 1, FDR < 0.03) in letrozole-resistant tumors with transcription-binding data showed significant overlap with 20 E2F4-regulated genes (P ¼ 2.56E15). In patients treated with the CDK4/6 inhibitor palbociclib before surgery, treatment significantly decreased expression of 24 of the 47 most upregulated genes in letrozole-resistant tumors, including 18 of the 20 E2F4 target genes. In long-term estrogen-deprived ERþ breast cancer cells, palbociclib also downregulated all 20 E2F4 target genes and P-RB levels, whereas the ER downregulator fulvestrant or paclitaxel only partially suppressed expression of this set of genes and had no effect on P-RB. Finally, an E2F4 activation signature was strongly associated with resistance to aromatase inhibitors in the ACOSOG Z1031B neoadjuvant trial and with an increased risk of relapse in adjuvant-treated ERþ tumors in METABRIC. Conclusions: In tumors resistant to prolonged neoadjuvant letrozole, we identified a gene expression signature of E2F4 target activation. CDK4/6 inhibition suppressed E2F4 target gene expression in estrogen-deprived ERþ breast cancer cells and in patients' ERþ tumors, suggesting a potential benefit of adjuvant CDK4/6 inhibitors in patients with ERþ breast cancer who fail to respond to preoperative estrogen deprivation.

Original languageEnglish (US)
Pages (from-to)2517-2529
Number of pages13
JournalClinical Cancer Research
Issue number11
StatePublished - Jun 1 2018

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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