Germline mutations in BRCA1/2 predispose individuals to breast cancer (termed germline-mutated BRCA1/2 breast cancer, gBRCA-BC) by impairing homologous recombination (HR) and causing genomic instability. HR also repairs DNA lesions caused by platinum agents and PARP inhibitors. Triple-negative breast cancers (TNBCs) harbor subpopulations with BRCA1/2 mutations, hypothesized to be especially platinum-sensitive. Cancers in putative ‘BRCAness’ subgroups—tumors with BRCA1 methylation; low levels of BRCA1 mRNA (BRCA1 mRNA-low); or mutational signatures for HR deficiency and those with basal phenotypes—may also be sensitive to platinum. We assessed the efficacy of carboplatin and another mechanistically distinct therapy, docetaxel, in a phase 3 trial in subjects with unselected advanced TNBC. A prespecified protocol enabled biomarker–treatment interaction analyses in gBRCA-BC and BRCAness subgroups. The primary endpoint was objective response rate (ORR). In the unselected population (376 subjects; 188 carboplatin, 188 docetaxel), carboplatin was not more active than docetaxel (ORR, 31.4% versus 34.0%, respectively; P = 0.66). In contrast, in subjects with gBRCA-BC, carboplatin had double the ORR of docetaxel (68% versus 33%, respectively; biomarker, treatment interaction P = 0.01). Such benefit was not observed for subjects with BRCA1 methylation, BRCA1 mRNA-low tumors or a high score in a Myriad HRD assay. Significant interaction between treatment and the basal-like subtype was driven by high docetaxel response in the nonbasal subgroup. We conclude that patients with advanced TNBC benefit from characterization of BRCA1/2 mutations, but not BRCA1 methylation or Myriad HRD analyses, to inform choices on platinum-based chemotherapy. Additionally, gene expression analysis of basal-like cancers may also influence treatment selection.

Purpose: The efficacy and safety of combining bevacizumab (7.5 and 15 mg/kg) with docetaxel as first-line therapy for human epidermal growth factor receptor 2 (HER2) –negative, locally recurrent or metastatic breast cancer (MBC) was investigated in a three-arm, placebo-controlled, phase III trial. Patients and Methods: Patients (N = 736) were randomly assigned to docetaxel 100 mg/m² plus either placebo or bevacizumab 7.5 or 15 mg/kg every 3 weeks. The primary end point was progression-free survival (PFS); secondary end points included best overall response, duration of response, time to treatment failure, overall survival, and safety. Results: Combination of bevacizumab 15 mg/kg, but not 7.5 mg/kg, with docetaxel showed superior median PFS (mPFS) to placebo plus docetaxel in unstratified analysis (placebo mPFS, 8.2 months; 7.5 mg/kg mPFS, 9.0 months [hazard ratio (HR), 0.86; P = .12]; 15 mg/kg mPFS, 10.1 months [HR, 0.77; P = .006]) and stratified analysis (placebo mPFS, 8.1 months; 7.5 mg/kg mPFS, 9.0 months [HR, 0.80; P = .045]; 15 mg/kg mPFS, 10.0 months [HR, 0.67; P < .001]). Response rates in patients with measurable disease at baseline also increased with bevacizumab 15 mg/kg (46% [placebo] v 55% [7.5 mg/kg; P = .07] and 64% [15 mg/kg; P < .001]). Combination with bevacizumab had limited impact on the known toxicity profile of docetaxel. Conclusion: Combination of bevacizumab with docetaxel did not significantly impact on the safety profile of docetaxel. Bevacizumab 15 mg/kg every 3 weeks significantly increased PFS when combined with docetaxel as first-line therapy for MBC compared with docetaxel plus placebo.

Purpose Previous analyses of the Breast International Group (BIG) 1-98 four-arm study compared initial therapy with letrozole or tamoxifen including patients randomly assigned to sequential treatment whose information was censored at the time of therapy change. Because this presentation may unduly reflect early events, the present analysis is limited to patients randomly assigned to the continuous therapy arms and includes protocol-defined updated results. Patients and Methods Four thousand nine hundred twenty-two of the 8,028 postmenopausal women with receptor-positive early breast cancer randomly assigned (double-blind) to the BIG 1-98 trial were assigned to 5 years of continuous adjuvant therapy with either letrozole or tamoxifen; the remainder of women were assigned to receive the agents in sequence. Disease-free survival (DFS) was the primary end point. Results At a median follow-up time of 51 months, we observed 352 DFS events among 2,463 women receiving letrozole and 418 events among 2,459 women receiving tamoxifen. This reflected an 18% reduction in the risk of an event (hazard ratio, 0.82; 95% CI, 0.71 to 0.95; P = .007). No predefined subsets showed differential benefit. Adverse events were similar to previous reports. Patients on tamoxifen experienced more thromboembolic events, endometrial pathology, hot flashes, night sweats, and vaginal bleeding. Patients on letrozole experienced more bone fractures, arthralgia, low-grade hypercholesterolemia, and cardiovascular events other than ischemia and cardiac failure. Conclusion The present updated analysis, which was limited to patients on monotherapy arms in BIG 1-98, yields results similar to those from the previous primary analysis but more directly comparable with results from other trials of continuous therapy using a single endocrine agent.

Purpose TAnDEM is the first randomized phase III study to combine a hormonal agent and trastuzumab without chemotherapy as treatment for human epidermal growth factor receptor 2 (HER2)/hormone receptor–copositive metastatic breast cancer (MBC). Patients and Methods Postmenopausal women with HER2/hormone receptor–copositive MBC were randomly assigned to anastrozole (1 mg/d orally) with or without trastuzumab (4 mg/kg intravenous infusion on day 1, then 2 mg/kg every week) until progression. The primary end point was progression-free survival (PFS) in the intent-to-treat population. Results Overall, 103 patients received trastuzumab plus anastrozole; 104 received anastrozole alone. Patients in the trastuzumab plus anastrozole arm experienced significant improvements in PFS compared with patients receiving anastrozole alone (hazard ratio = 0.63; 95% CI, 0.47 to 0.84; median PFS, 4.8 v 2.4 months; log-rank P = .0016). In patients with centrally confirmed hormone receptor positivity (n = 150), median PFS was 5.6 and 3.8 months in the trastuzumab plus anastrozole and anastrozole alone arms, respectively (log-rank P = .006). Overall survival in the overall and centrally confirmed hormone receptor–positive populations showed no statistically significant treatment difference; however, 70% of patients in the anastrozole alone arm crossed over to receive trastuzumab after progression on anastrozole alone. Incidence of grade 3 and 4 adverse events was 23% and 5%, respectively, in the trastuzumab plus anastrozole arm, and 15% and 1%, respectively, in the anastrozole alone arm; one patient in the combination arm experienced New York Heart Association class II congestive heart failure. Conclusion Trastuzumab plus anastrozole improves outcomes for patients with HER2/hormone receptor–copositive MBC compared with anastrozole alone, although adverse events and serious adverse events were more frequent with the combination.