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Purpose: To investigate whether anti-vascular endothelial growth factor therapy with bevacizumab prolongs progression-free survival (PFS) when added to first-line letrozole as treatment of hormone receptor-positive metastatic breast cancer (MBC)., Patients and Methods: Women with hormone receptor-positive MBC were randomly assigned 1:1 in a multicenter, open-label, phase III trial of letrozole (2.5 mg orally per day) with or without bevacizumab (15 mg/kg intravenously once every 3 weeks) within strata defined by measurable disease and disease-free interval. This trial had 90% power to detect a 50% improvement in median PFS from 6 to 9 months. Using a one-sided α = .025, a target sample size of 352 patients was planned., Results: From May 2008 to November 2011, 350 women were recruited; 343 received treatment and were observed for efficacy and safety. Median age was 58 years (range, 25 to 87 years). Sixty-two percent had measurable disease, and 45% had de novo MBC. At a median follow-up of 39 months, the addition of bevacizumab resulted in a significant reduction in the hazard of progression (hazard ratio, 0.75; 95% CI, 0.59 to 0.96; P = .016) and a prolongation in median PFS from 15.6 months with letrozole to 20.2 months with letrozole plus bevacizumab. There was no significant difference in overall survival (hazard ratio, 0.87; 95% CI, 0.65 to 1.18; P = .188), with median overall survival of 43.9 months with letrozole versus 47.2 months with letrozole plus bevacizumab. The largest increases in incidence of grade 3 to 4 treatment-related toxicities with the addition of bevacizumab were hypertension (24% v 2%) and proteinuria (11% v 0%)., Conclusion: The addition of bevacizumab to letrozole improved PFS in hormone receptor-positive MBC, but this benefit was associated with a markedly increased risk of grade 3 to 4 toxicities. Research on predictive markers will be required to clarify the role of bevacizumab in this setting., Competing Interests: Authors’ disclosures of potential conflicts of interest are found in the article online at www.jco.org. contributions are found at the end of this article., (© 2016 by American Society of Clinical Oncology.)

Purpose: CALGB 40302 sought to determine whether lapatinib would improve progression-free survival (PFS) among women with hormone receptor-positive metastatic breast cancer treated with fulvestrant., Patients and Methods: Eligible women had estrogen receptor-positive and/or progesterone receptor-positive tumors, regardless of human epidermal growth factor receptor 2 (HER2) status, and prior aromatase inhibitor treatment. Patients received fulvestrant 500 mg intramuscularly on day 1, followed by 250 mg on days 15 and 28 and every 4 weeks thereafter, and either lapatinib 1,500 mg or placebo daily. The study planned to accrue 324 patients and was powered for a 50% improvement in PFS with lapatinib from 5 to 7.5 months., Results: At the third planned interim analysis, the futility boundary was crossed, and the data and safety monitoring board recommend study closure, having accrued 295 patients. At the final analysis, there was no difference in PFS (hazard ratio [HR] of placebo to lapatinib, 1.04; 95% CI, 0.82 to 1.33; P = .37); median PFS was 4.7 months for fulvestrant plus lapatinib versus 3.8 months for fulvestrant plus placebo. There was no difference in overall survival (OS) (HR, 0.91; 95% CI, 0.68 to 1.21; P = .25). For HER2-normal tumors, median PFS did not differ by treatment arm (4.1 v 3.8 months). For HER2-positive tumors, lapatinib was associated with longer median PFS (5.9 v 3.3 months), but the differential treatment effect by HER2 status was not significant (P = .53). The most frequent toxicities were diarrhea, fatigue, and rash associated with lapatinib., Conclusion: Adding lapatinib to fulvestrant does not improve PFS or OS in advanced ER-positive breast cancer and is more toxic., (© 2014 by American Society of Clinical Oncology.)