Clinical and translational results of CALGB 40601: A neoadjuvant phase III trial of weekly paclitaxel and trastuzumab with or without lapatinib for HER2-positive breast cancer.

Breast Cancer - HER2/ER
Session Type and Session Title: 
Oral Abstract Session, Breast Cancer - HER2/ER
Abstract Number: 
J Clin Oncol 31, 2013 (suppl; abstr 500)
Lisa A. Carey, Donald A. Berry, David Ollila, Lyndsay Harris, Ian E. Krop, Douglas Weckstein, Norah Lynn Henry, Carey K. Anders, Constance Cirrincione, Eric P. Winer, Charles M. Perou, Clifford Hudis, Alliance; The University of North Carolina at Chapel Hill, Chapel Hill, NC; The University of Texas MD Anderson Cancer Center, Houston, TX; Case Western/Seidman Cancer Center, Cleveland, OH; Dana-Farber Cancer Institute, Boston, MA; New Hampshire Oncology-Hematology, PA, Hooksett, NH; University of Michigan Medical Center, Ann Arbor, MI; The University of North Carolina at Chapel Hill, Lineberger Comprehensive Cancer Center, Chapel Hill, NC; Alliance Statistical Center, Duke University, Durham, NC; Memorial Sloan-Kettering Cancer Center, New York, NY

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Abstract Disclosures


Background: Recent trials in HER2-positive (HER2+) breast cancer (BrCa) demonstrate increased pathological complete response (pCR) using dual HER2-targeting in the neoadjuvant setting and increased progression-free survival in metastatic disease. CALGB 40601 aimed to further quantify the pCR rates of weekly paclitaxel (T) and trastuzumab (H) alone or combined HER2-blockade of H with the small molecule lapatinib (L), and to identify biomarkers of sensitivity to these HER2-targeted agents. Methods: Eligible patients had newly diagnosed, noninflammatory stage II-III HER2+ BrCa and were randomized to receive T (80mg/m2/week IV) + H (4mg/kg then 2mg/kg/week IV) alone (TH) or with the addition of L (750 mg/d PO) (THL) for 16 weeks preoperatively. A third arm, T + L (1500 mg/d) (TL), was closed early when negative efficacy and toxicity data emerged from preliminary analysis of ALTTO. After surgery, 4 cycles of adjuvant dose-dense AC and 1 year H was recommended. Tumors were biopsied for research before therapy; post-Rx samples of residual disease were requested. The primary endpoint was in-breast pCR rate; the study had 85% power to detect an increase from 30% (TH) to 50% (THL). Results: 305 patients were randomized (118 THL, 120 TH, 67 TL); 68% were clinical stage II and 59% hormone receptor-positive. Grade 3+ toxicity was higher among L-containing arms, including neutropenia (12% TL, 7% THL, 2% TH), rash (15% TL, 14% THL, 2% TH), and diarrhea (20% TL, 20% THL, 2% TH). Breast pCR rates with 95% confidence limits were: 51% (42-60%) THL, 40% (32-49%) TH, 32% (22-44%) TL. pCR rate in the TH arm was higher than previous studies, and was not significantly different from THL (p=0.11). We will present molecular subtype, sequence and gene copy number abnormalities in primary tumors and residual disease. Conclusions: pCR rate was higher with combined THL compared with standard TH but did not reach statistical significance. These results are qualitatively similar to other neoadjuvant studies in HER2+ BrCa, and contribute to estimates of pCR rates after these agents. Tissue-based studies may illuminate which patients benefit from HER2-targeting using these agents. Clinical trial information: NCT00770809.