Effect of visceral metastases on the efficacy and safety of everolimus in postmenopausal women with advanced breast cancer: Subgroup analysis from the BOLERO-2 study

Abstract

BackgroundEverolimus (EVE; an inhibitor of mammalian target of rapamycin [mTOR]) enhances treatment options for postmenopausal women with hormone-receptor-positive (HR+), human epidermal growth factor receptor-2-negative (HER2–) advanced breast cancer (ABC) who progress on a non-steroidal aromatase inhibitor (NSAI). This is especially true for patients with visceral disease, which is associated with poor prognosis. The BOLERO-2 (Breast cancer trial of OraLEveROlimus-2) trial showed that combination treatment with EVE and exemestane (EXE) versus placebo (PBO)+EXE prolonged progression-free survival (PFS) by both investigator (7.8 versus 3.2months, respectively) and independent (11.0 versus 4.1months, respectively) central assessment in postmenopausal women with HR+, HER2– ABC recurring/progressing during/after NSAI therapy. The BOLERO-2 trial included a substantial proportion of patients with visceral metastases (56%). MethodsPrespecified exploratory subgroup analysis conducted to evaluate the efficacy and safety of EVE+EXE versus PBO+EXE in a prospectively defined subgroup of patients with visceral metastases. FindingsAt a median follow-up of 18months, EVE+EXE significantly prolonged median PFS compared with PBO+EXE both in patients with visceral metastases (N=406; 6.8 versus 2.8months) and in those without visceral metastases (N=318; 9.9 versus 4.2months). Improvements in PFS with EVE+EXE versus PBO+EXE were also observed in patients with visceral metastases regardless of Eastern Cooperative Oncology Group performance status (ECOG PS). Patients with visceral metastases and ECOG PS 0 had a median PFS of 6.8months with EVE+EXE versus 2.8months with PBO+EXE. Among patients with visceral metastases and ECOG PS ⩾1, EVE+EXE treatment more than tripled median PFS compared with PBO+EXE (6.8 versus 1.5months). InterpretationAdding EVE to EXE markedly extended PFS by ⩾4months among patients with HR+ HER2– ABC regardless of the presence of visceral metastases. FundingNovartis.