e13017 Background: Activation of the mammalian target of rapamycin intracellular signaling pathway is one of the mechanisms of endocrine resistance in breast cancer. The addition of everolimus to exemestane improves progression-free survival (PFS) in patients with hormone receptor positive (HR+) advanced breast cancer (ABC) previously treated with nonsteroidal aromatase inhibitors (NSAIs). The aim of this study was to assess the effectiveness and safety of everolimus plus exemestane in patients with HR+ ABC. Methods: We retrospectively evaluated patients with HR+, HER2 negative ABC treated with everolimus/exemestane that recurred or progressed during/after treatment with NSAIs in a portuguese comprehensive cancer center. Study endpoints were PFS, overall survival (OS), overall response rate and adverse events. Results: Between April 2014 and September 2020, 63 female patients were treated with everolimus/exemestane. Median age was 59 years (36-79), and all had performance status ECOG ≤2. Seventeen (27.0%) patients had bone metastasis alone, 39 (61.9%) had bone and visceral metastasis, 25 (39.7%) had metastasis in 3 or more sites and 87.3% had previous hormone-sensitive disease. Before everolimus/exemestane, 61 (96.8%) patients were being treated with palliative endocrine therapy (alone or in combination with CDK4/6 inhibitors) or chemotherapy (ChT) and 2 (3.2%) patients were under adjuvant endocrine therapy. Median follow-up time was 12.8 months (1.4-74.6), with 39 patients alive. Overall response rate was 14.3% (1 complete response and 8 partial responses) and 45 patients had stable disease. Median PFS was 5.6 months (CI95% 2.4-8.8) and median OS was 25.4 months (CI95% 10.3-40.5). Subgroup analysis regarding PFS was statistically significant for previous treatment with CDK4/6 inhibitors (p = 0.026) and for site of metastasis (p = 0.025). In the subgroup of patients that previously underwent palliative ChT, median PFS was 4.0 months (CI95% 0.2-9.6) and median OS was 18.6 months (CI95% 8.2-29.0). For patients that did not receive previous palliative ChT, median PFS was 5.8 months (CI95% 3.8-7.8) and median OS was 43.5 months (CI95% 2.0-85.0). Grade 3 and 4 adverse events occurred in 21 (33.3%) patients, and were: nausea, anorexia, rash, headache, haematologic toxicity, hepatic cytolysis, hyperglycaemia, pneumonitis, oral mucositis and acute kidney failure with need for haemodialysis. Fifty-five (87.3%) patients suspended everolimus, 34 (54.0%) due to disease progression and 21 (33.3%) due to toxicity. Conclusions: Our results confirm the effectiveness and safety of everolimus/exemestane in real-world setting and support its use mainly before palliative ChT. Everolimus/exemestane in HR+ ABC is feasible in the clinic, with toxicity manageable under close surveillance.
276O Pooled analysis of patient (pt)-reported quality of life (QOL) in the MONALEESA (ML)-2, -3, and -7 trials of ribociclib (RIB) plus endocrine therapy (ET) to treat hormone receptor–positive, HER2-negative (HR+/HER2−) advanced breast cancer (ABC)
