Utility of the 70-Gene MammaPrint Assay for Prediction of Benefit From Extended Letrozole Therapy in the NRG Oncology/NSABP B-42 Trial.

PURPOSE: MammaPrint (MP) determines distant metastatic risk and may improve patient selection for extended endocrine therapy (EET). This study examined MP in predicting extended letrozole therapy (ELT) benefit in patients with early-stage breast cancer (BC) from the NSABP B-42 trial. PATIENTS AND METHODS: MP was tested in 1,866 patients randomly assigned to receive ELT or placebo. The primary end point was distant recurrence (DR). Secondary end points were disease-free survival (DFS) and BC-free interval (BCFI). Tumors were classified as MP high risk (MP-HR) or low risk (MP-LR). MP-LR tumors were further classified as ultralow risk (MP-UL) or low non-ultralow risk (MP-LNUL). RESULTS: There was no statistically significant difference in ELT benefit on DR between MP-HR and MP-LR (interaction P = .38). MP-LR tumors (n = 1,160) exhibited a statistically significant 10-year benefit of 3.7% for DR (hazard ratio [HR], 0.43 [95% CI, 0.25 to 0.74]; P = .002), whereas MP-HR tumors (n = 706) exhibited a nonsignificant 2.4% benefit (HR, 0.65 [95% CI, 0.34 to 1.24]; P = .19). The 10-year ELT benefit was significant for DFS (7.8%) and BCFI (7.0%) for MP-LR tumors, whereas MP-HR tumors did not significantly benefit (interaction DFS: P = .015, BCFI: P = .006). In exploratory analysis, the 10-year ELT benefit was significant and more pronounced in MP-LNUL (n = 908) tumors: 4.0% for DR, 9.5% for DFS, and 7.9% for BCFI; the benefit in MP-UL (n = 252) tumors was not significant: 3% for DR, 1.8% for DFS, and 4.1% for BCFI. CONCLUSION: The primary hypothesis of predictive ability of MP on DR was not confirmed. However, the secondary outcomes demonstrated MP was predictive of ELT response and identified a subset of patients with early-stage hormone receptor-positive BC (MP-LR) with improved outcomes from ELT. These data could have important clinical implications in patient selection beyond clinical risk assessment for EET.

Lapatinib as a component of neoadjuvant therapy for HER2-positive operable breast cancer (NSABP protocol B-41): an open-label, randomised phase 3 trial.

BACKGROUND: We studied the effect on tumour response to neoadjuvant therapy of the substitution of lapatinib for trastuzumab in combination with weekly paclitaxel after doxorubicin plus cyclophosphamide treatment, and of the addition of lapatinib and trastuzumab combined after doxorubicin plus cyclophosphamide treatment in patients with HER2-positive operable breast cancer to determine whether there would be a benefit of dual HER2 blockade in these patients. METHODS: For this open-label, randomised phase 3 trial we recruited women aged 18 years or older with an ECOG performance status of 0 or 1 with operable HER2-positive breast cancer. Each received four cycles of standard doxorubicin 60 mg/m(2) and cyclophosphamide 600 mg/m(2) intravenously on day 1 every 3 weeks followed by four cycles of weekly paclitaxel (80 mg/m(2)) intravenously on days 1, 8, and 15, every 4 weeks. Concurrently with weekly paclitaxel, patients received either trastuzumab (4 mg/kg load, then 2 mg/kg intravenously) weekly until surgery, lapatinib (1250 mg orally) daily until surgery, or weekly trastuzumab plus lapatinib (750 mg orally) daily until surgery. After surgery, all patients received trastuzumab to complete 52 weeks of HER2-targeted therapy. Randomisation (ratio 1:1:1) was done centrally with stratification by clinical tumour size, clinical nodal status, hormone-receptor status, and age. The primary endpoint was the pathological complete response in the breast, and analysis was performed on an intention-to-treat population. FINDINGS: Patient accrual started on July 16, 2007, and was completed on June 30, 2011; 529 women were enrolled in the trial. 519 patients had their pathological response determined. Breast pathological complete response was noted in 93 (52·5%, 95% CI 44·9-59·5) of 177 patients in the trastuzumab group, 91 (53·2%, 45·4-60·3) of 171 patients in the lapatinib group (p=0·9852); and 106 (62·0%, 54·3-68·8) of 171 patients in the combination group (p=0·095). The most common grade 3 and 4 toxic effects were neutropenia (29 [16%] patients in the trastuzumab group [grade 4 in five patients (3%), 28 [16%] in the lapatinib group [grade 4 in eight patients (5%)], and 29 [17%] in the combination group [grade 4 in nine patients (5%)]) and grade 3 diarrhoea (four [2%] patients in the trastuzumab group, 35 [20%] in the lapatinib group, and 46 [27%] in the combination group; p<0·0001). Symptomatic congestive heart failure defined as New York Heart Association Class III or IV events occurred in seven (4%) patients in the trastuzumab group, seven (4%) in the lapatinib group, and one (<1%) in the combination group; p=0·185). INTERPRETATION: Substitution of lapatinib for trastuzumab in combination with chemotherapy resulted in similar high percentages of pathological complete response. Combined HER2-targeted therapy produced a numerically but insignificantly higher pathological complete response percentage than single-agent HER2-directed therapy; these findings are consistent with results from other studies. Trials are being undertaken to further assess these findings in the adjuvant setting.