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Poster Display session 2

2151 - Clinical outcome and toxicity data in patients with advanced breast cancer treated with cyclin-dependent kinase 4/6 (CDK4/6) inhibitors combined with endocrine therapy in a real-world clinical setting.


29 Sep 2019


Poster Display session 2


Tumour Site

Breast Cancer


Elena Fountzilas


Annals of Oncology (2019) 30 (suppl_5): v104-v142. 10.1093/annonc/mdz242


E. Fountzilas, G. Koliou, V. Rapti, A. Nikolakopoulos, A. Christopoulou, E. Moirogiorgou, I. Binas, G. Aravantinos, L. Kostadima, A. Nikolaidi, S. Karteri, F. Zagouri, Z. Saridaki, A. Molfeta, P. Oikonomopoulou, E. Res, D. Tryfonopoulos, G. Koumakis, G. Fountzilas, E. Razis

Author affiliations

  • Data Office, Hellenic Cooperative Oncology Group (HeCOG), 11524 - Athens/GR


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Abstract 2151


Clinical trials evaluating treatment with cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) in combination with aromatase inhibitors (AI) or fulvestrant have shown promising clinical benefit in patients with advanced breast cancer. We evaluated real-world clinical outcomes and toxicity rates in patients with advanced breast cancer who received treatment with CDK4/6i in routine clinical practice.


We retrospectively reviewed medical records of patients with advanced hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative breast cancer treated at Departments of Oncology-affiliated with the Hellenic Cooperative Oncology Group (HeCOG). All patients received hormonal therapy in combination with CDK4/6i as first-, second- or third-line of treatment and beyond. The primary end point was progression-free survival (PFS).


From 07/2015 to 03/2019, 191 women were treated with CDK4/6i combined with endocrine therapy (median age: 52.2 years, postmenopausal 87, 45.5%); 86 (45%) patients received CDK4/6i in combination with AI and 105 (55%) with fulvestrant. CDK4/6i were administered as first-line treatment in 65 (34%) patients, second-line treatment in 39 (20.4%) and third-line and beyond in 83 (43.5%) patients. The median follow-up was 54.3 months (95%CI 43.0-61.2). The median PFS for patients who received first-line treatment was 18.7 months, second-line treatment 11.5 months and ≥3 lines of treatment 7.5 months. The median overall survival since the initiation of CDK4-6i treatment was 23.2 months (95% CI 20.4-30.3). The most common adverse events were neutropenia (100 patients, 52.4%) and fatigue (24, 12.6%). Grade 3-4 adverse events occurred in 55 (28.8%) patients, while 2 (1.0%) patients permanently discontinued treatment due to toxicity.


Among patients with HR-positive advanced breast cancer treated with CDK4/6i combined with endocrine, the estimated PFS was comparable to previously reported data. Treatment was well tolerated, with a low drug discontinuation rate.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

Hellenic Cooperative Oncology Group.


Hellenic Cooperative Oncology Group (HeCOG).


E. Fountzilas: Travel / Accommodation / Expenses: K.A.M ONCOLOGY / HEMATOLOGY; Travel / Accommodation / Expenses: Merck; Shareholder / Stockholder / Stock options: Deciphera. G. Aravantinos: Advisory / Consultancy: Novartis; Advisory / Consultancy: Bristol-Myers Squibb; Advisory / Consultancy: Roche Hellas; Advisory / Consultancy: AstraZeneca; Advisory / Consultancy: Sanofi; Advisory / Consultancy: Amgen; Advisory / Consultancy: Genesis Pharma; Advisory / Consultancy: Merck; Advisory / Consultancy: Pfizer. G. Fountzilas: Advisory / Consultancy: Pfizer; Advisory / Consultancy: Sanofi; Advisory / Consultancy: Roche; Honoraria (self): AstraZeneca. E. Razis: Honoraria (self), Advisory / Consultancy: Novartis; Travel / Accommodation / Expenses: Genesis Pharmaceuticals; Travel / Accommodation / Expenses: Pfizer; Travel / Accommodation / Expenses: Roche; Travel / Accommodation / Expenses: , Bristol-Myers Squibb; Travel / Accommodation / Expenses: Genekor. All other authors have declared no conflicts of interest.

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