Study of Adherence to and Patient Satisfaction with Exemestane and Everolimus in Postmenopausal Women with HR-Positive, HER2-Negative Advanced Breast Cancer

Everolimus (Afinitor) in combination with exemestane (Aromasin) has been approved for the treatment of postmenopausal women with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative, endocrine-resistant advanced breast cancer. This study investigated treatment adherence, tolerability, satisfaction, and efficacy.

Veerle Foulon, PhD, Researcher, Clinical Pharmacology and Pharmacotherapy, Katholieke Universiteit Leuven, Belgium, and colleagues designed a prospective, noninterventional, noncontrolled, multicentric observational study to evaluate adherence defined as the proportion of days on which the medicine was taken as prescribed during the total treatment period.

To capture patients’ experience and satisfaction with the treatment and perceived care, 3 validated questionnaires were administered throughout the study. Progression-free survival was the primary measure of medication efficacy.

For nearly 2 years between 2015 and 2017, a total of 58 women (median age, 65 years) from 7 oncology centers were included in the study, after an average of 34 months of being diagnosed with stage IV disease; 62.1% of women had disease involvement in ≥3 organs, and 84.5% had ≥2 previous treatment lines for metastatic disease.

For the adjusted adherence rate of the combination therapy, 13.8% of patients showed optimal adherence (100%).

Treatment interruption occurred in 10.3% and 62.1% of patients with exemestane and everolimus, respectively. The mean time of treatment pause with exemestane and everolimus was 34.3 ± 19.1 days and 24.3 ± 16.5 days, respectively. Treatment was interrupted multiple times in some patients. The most common side effect was mucositis (N = 26 at 1 month, of whom 8 patients had grade 3 and 15 patients had grade 2). Treatment with the combination of everolimus and exemestane was stopped in 10.4% of patients due to side effects. The median progression-free survival was 170 days. With regard to quality of life, patients scored lowest on emotional and functional well-being.

Adherence to everolimus and exemestane combination therapy was low although patients were closely monitored, and measures were taken to overcome side effects. Many patients needed to interrupt the treatment due to side effects; treatment is perceived as intensive. Nevertheless, median progression-free survival is 170 days, even when used late in the therapeutic journey of patients with breast cancer.