Breast Cancer

, Volume 25, Issue 4, pp 479–488 | Cite as

Cyclin-dependent kinase 4/6 inhibitors as first-line treatment for post-menopausal metastatic hormone receptor-positive breast cancer patients: a systematic review and meta-analysis of phase III randomized clinical trials

  • Allan Ramos-EsquivelEmail author
  • Hellen Hernández-Steller
  • Marie-France Savard
  • Denis Ulises Landaverde
Original Article



To compare the efficacy and toxicity of the combination of cyclin-dependent kinase 4/6 (CDK 4/6) inhibitors and nonsteroidal aromatase inhibitors (AI) versus AI alone as first-line therapy for patients with advanced hormone receptor-positive breast cancer.

Materials and methods

Phase III randomized clinical trials (RCT) were identified after a systematic review of electronic databases. A random-effect model was used to determine the pooled hazard ratio (HR) for progression-free survival (PFS) using the inverse-variance method. The Mantel–Haenszel method was used to calculate the pooled odds ratio (OR) for overall response, clinical benefit rate and treatment-related side effects. Heterogeneity was measured using the tau-squared and I2 statistics.


After a systematic search, three phase III RCT (n = 1827) were included. The use of CDK 4/6 inhibitors (abemaciclib, palbociclib, and ribociclib) in combination with an AI was significantly associated with longer PFS compared to the use of letrozole or anastrozole alone (HR: 0.57; 95% CI 0.50–0.65; p < 0.00001), with no significant heterogeneity among trials. Similarly, overall response rate and clinical benefit rate were higher for patients who received the combination therapy than for patients allocated to AI alone. Grade 3 or higher treatment-related side effects were more frequently reported for patients who received CDK 4/6 inhibitors (OR: 7.51; 95% CI 6.01–9.38; p < 0.00001), these included mainly neutropenia, leukopenia and anemia.


The addition of CDK 4/6 inhibitors (either abemaciclib, palbociclib, or ribociclib) to an AI (anastrozole or letrozole) significantly improved PFS, overall response rate, and clinical benefit rate in comparison with a nonsteroidal AI alone.


Abemaciclib Breast cancer Cyclin-dependent kinase Palbociclib Ribociclib 




Compliance with ethical standards

Conflict of interest

There are no conflicts of interest to disclose.

Supplementary material

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Copyright information

© The Japanese Breast Cancer Society 2018

Authors and Affiliations

  • Allan Ramos-Esquivel
    • 1
    • 2
    Email author
  • Hellen Hernández-Steller
    • 1
  • Marie-France Savard
    • 3
  • Denis Ulises Landaverde
    • 2
    • 4
  1. 1.Departamento de Oncología MédicaHospital San Juan de DiosSan JoseCosta Rica
  2. 2.Escuela de MedicinaUniversidad de Costa RicaSan JoseCosta Rica
  3. 3.Department of OncologyMcGill UniversityMontrealCanada
  4. 4.Departamento de Oncología MédicaHospital MéxicoSan JoseCosta Rica

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