Antitumor activity of the combination of vinorelbine and gemcitabine in patients with HR + /HER2- advanced breast cancer after CDK4/6 inhibitor.

OBJECTIVES: To evaluate the clinical benefit of the vinorelbine-gemcitabine every two weeks (VNR-GEMQ2W) regimen in patients with hormone receptor-positive (HR +)/HER2- advanced breast cancer (ABC) treated at a tertiary care hospital and with previous progression on cyclin-dependent kinase 4 and 6 inhibitors (CDK4/6i).

STUDY DESIGN: A retrospective analysis was conducted on women treated for HR + /HER2-ABC, with VNR 25 mg/m2 and GEM 1000 mg/m2 administered every two weeks between 2019 and 2024 at a single hospital.

MAIN OUTCOME MEASURES: Progression-free survival (PFS), overall response rate (ORR), overall survival, and treatment-related adverse events (AEs) evaluated according to CTCAE version 5.0 were retrospectively analyzed. A subanalysis of the data was performed based on major prognostic factors.

RESULTS: A total of 53 patients were included, with a median age of 56.70 years. The majority had visceral metastases (81.13%). Patients had received a median of three prior lines of therapy - two lines of endocrine therapy and one line of chemotherapy. The median follow-up time was 28 months [interquartile range 15-34]. The median PFS was 4.27 months (95% confidence interval 3.25-6.34), and ORR was 18.87%. Grade ≥ 3 neutropenia was the most frequent severe AE (10.77%), with no treatment discontinuations due to toxicity. Only one case of grade 2 alopecia was reported (1.88%).

CONCLUSIONS: Administering after CDK4/6i and capecitabine, VNR-GEMQ2W regimen shows activity in HR + /HER2- ABC and a manageable safety profile. This regimen should be considered as a potential control arm in the design of future clinical trials targeting HR + /HER2- ABC.