CDK4,6 Inhibition in Breast Cancer

CE / CME

Experts Discuss the Role of CDK4/6 Inhibitors in HR+/HER2- Breast Cancer
Credits Available

Physicians: Maximum of 0.50 AMA PRA Category 1 Credit

ABIM MOC: maximum of 0.50 Medical Knowledge MOC point

Released: July 09, 2024

Expiration: July 08, 2025

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Case Description



  • 57-yr-old postmenopausal woman had history of high-risk node-positive ER+/HER2- early breast cancer in 2021; she underwent surgery, received adjuvant chemotherapy and adjuvant radiotherapy, and was started on letrozole

  • She also started adjuvant abemaciclib but did not want additional medication and stopped it in early 2022 after 6 mo

  • She presents in spring 2024 with gradual fatigue and weight loss; imaging is notable for findings consistent with MBC, with lesions in bone, mediastinal lymph nodes, and 2 liver lesions

  • Liver biopsy confirms MBC: ER 50%, PgR 30%, HER2 1+

  • ctDNA evaluation shows an ESR1 mutation and a PIK3CA mutation

  • Laboratory testing is normal; despite her symptoms, she continues to work full time and walks her dog daily

Which first-line systemic therapy would you recommend?