The elastic net models were applied to breast cancer samples from CALGB 40601 (NCT00770809); this neoadjuvant trial of HER2 + breast cancer encompassed three arms treated with a combination of paclitaxel + trastuzumab, paclitaxel + lapatinib, and paclitaxel + lapatinib + trastuzumab. The gene discussed is ERBB2; the disease is breast cancer.