Dual Block with Lapatinib and Trastuzumab Versus Single-Agent Trastuzumab Combined with Chemotherapy as Neoadjuvant Treatment of HER2-Positive Breast Cancer: A Meta-analysis of Randomized Trials.

PURPOSE: (Neo)adjuvant treatment with chemotherapy plus trastuzumab reduces recurrence and death risk in HER2-positive (HER2(+)) breast cancer. Randomized trials assessed HER2 dual block by adding lapatinib to trastuzumab and chemotherapy in the neoadjuvant setting using pathologic complete response (pCR) as the outcome measure. We conducted a meta-analysis of randomized trials testing neoadjuvant dual block with lapatinib and trastuzumab versus trastuzumab alone in HER2(+) breast cancer. EXPERIMENTAL
DESIGN: Trials were identified by Medline (PubMed), ISI Web of Science (Science Citation Index Expanded), Embase, Cochrane library, and reference lists of published studies, review articles, editorials, and by hand-searched reports from major cancer meeting reports.
RESULTS: Six randomized trials including 1,155 patients were identified, of whom 483 (41.8%) were hormone receptor-negative, 672 (58.2%) hormone receptor-positive, 534 (46.2%) received taxanes alone, and 621 (53.8%) anthracyclines plus taxanes or the docetaxel-carboplatin regimen. Overall, the dual block was associated with a significant 13% absolute improvement in pCR rate compared with single-agent trastuzumab (summary risk difference, SRD 0.13; 95% CI, 0.08-0.19). The activity was greater in hormone receptor-negative patients who received chemotherapy with taxanes alone (SRD 0.25; 95% CI, 0.13-0.37), compared to hormone receptor-positive or hormone receptor-negative disease treated with anthracyclines plus taxanes or the docetaxel-carboplatin regimen (SRD 0.09; 95% CI, 0.02-0.15; Pinteraction = 0.05).
CONCLUSIONS: On the basis of ΔpCR data, the dual block with trastuzumab and lapatinib plus chemotherapy is a very active treatment only in HER2(+) and hormone receptor-negative breast cancer treated with taxane monochemotherapy. Clin Cancer Res; 22(18); 4594-603. ©2016 AACR. ©2016 American Association for Cancer Research.