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Purpose The mammalian target of rapamycin inhibitor everolimus targets aberrant signaling through the PI3K/AKT/mammalian target of rapamycin pathway, a mechanism of resistance to anti-estrogen therapy in estrogen receptor (ER)-positive breast cancer. We hypothesized that everolimus plus the selective ER downregulator fulvestrant would be more efficacious than fulvestrant alone in ER-positive metastatic breast cancer resistant to aromatase inhibitor (AI) therapy. Patients and Methods This randomized, double-blind, placebo-controlled, phase II study included 131 postmenopausal women with ER-positive, human epidermal growth factor receptor 2-negative, AI-resistant metastatic breast cancer randomly assigned to fulvestrant (500 mg days 1 and 15 of cycle 1, then day 1 of cycles 2 and beyond) plus everolimus or placebo. The study was designed to have 90% power to detect a 70% improvement in median progression-free survival from 5.4 months to 9.2 months. Secondary end points included objective response and clinical benefit rate (response or stable disease for at least 24 weeks). Prophylactic corticosteroid mouth rinses were not used. Results The addition of everolimus to fulvestrant improved the median progression-free survival from 5.1 to 10.3 months (hazard ratio, 0.61 [95% CI, 0.40 to 0.92]; stratified log-rank P = .02), indicating that the primary trial end point was met. Objective response rates were similar (18.2% v 12.3%; P = .47), but the clinical benefit rate was significantly higher in the everolimus arm (63.6% v 41.5%; P = .01). Adverse events of all grades occurred more often in the everolimus arm, including oral mucositis (53% v 12%), fatigue (42% v 22%), rash (38% v 5%), anemia (31% v. 6%), diarrhea (23% v 8%), hyperglycemia (19% v 5%), hypertriglyceridemia (17% v 3%), and pneumonitis (17% v 0%), although grade 3 to 4 events were uncommon. Conclusion Everolimus enhances the efficacy of fulvestrant in AI-resistant, ER-positive metastatic breast cancer.

Although not yet practice changing in early-stage triple-negative breast cancer, growing evidence suggests that neoadjuvant platinum-based therapy is active and that some patients may benefit from such an approach. Recent randomized phase III data suggests that carboplatin has comparable efficacy to docetaxel as first-line therapy in unselected advanced triple-negative breast cancer. In both settings, the efficacy of such treatment appears to be influenced by BRCA1/2 mutation status, with carriers of these mutations experiencing higher response rates. To optimize patient selection, biomarkers of response need to be incorporated into randomized clinical trials and validated. In addition to BRCA1/2, it is likely that measures of genomic instability and other germline biomarkers beyond BRCA1/2 may be associated with therapeutic sensitivity., (Copyright © 2015 by the National Comprehensive Cancer Network.)