A Real-world Study of Everolimus Plus Aromatase Inhibitor in Hormone Receptor-positive, HER2-negative Advanced Breast Cancer

Background/Aim: Everolimus in combination with exemestane was shown to offer benefit versus exemestane monotherapy in hormone receptor (HR)-positive, HER2negative advanced breast cancer patients who progressed after aromatase inhibitor (AI) therapy. Patients and Methods: The medical records of metastatic breast cancer patients, treated with everolimus, were retrospectively reviewed to generate real life safety and efficacy data. Results: Sixty-eight percent of the patients had received chemotherapy (for early or metastatic disease) and 26% had received chemotherapy for metastatic disease. Among the 25 included patients, the most common adverse events were fatigue, neutropenia, epistaxis, stomatitis, and pneumonitis. Toxicity led to treatment discontinuation in 3 patients (12%). The median progression-free survival (PFS) was 7 months (95%CI=3.510.5). With a median follow-up of 73.3 months, the median overall survival was not reached. Twenty-five percent of the patients had received prior therapy with CDK4/6 inhibitors. Median PFS was significantly shorter in this subgroup (p=0.025). There was also a trend towards a longer PFS in patients with grade 3 breast cancer (p=0.085) and in patients receiving everolimus as first-line treatment (p=0.081). Some long responses were noted, with four patients exhibiting a PFS >5 years. Conclusion: These real-life data show that everolimus in combination with AI in patients with HER2negative, HR-positive advanced breast cancer is an effective treatment with an acceptable toxicity profile.