Paclitaxel and Trastuzumab With or Without Lapatinib in Treating Patients With Stage II or Stage III Breast Cancer That Can Be Removed by Surgery

PRIMARY OBJECTIVE: I. To determine if the pathologic complete response (pCR) in the breast to neoadjuvant weekly paclitaxel with trastuzumab plus lapatinib (THL) is 20% greater than the pCR to weekly paclitaxel with trastuzumab alone (TH). SECONDARY OBJECTIVES: I. To determine the pathologic complete response in the breast and axilla, using American Joint Committee on Cancer (AJCC) Tumor, Lymph Nodes and Metastasis (TMN) criteria (version 6), to neoadjuvant weekly paclitaxel plus human epidermal growth factor 2 (HER2)- targeted therapy in patients with HER2-positive operable breast cancer. II. To evaluate residual cancer burden (RCB) as a predictor of long term relapse free survival (RFS) and overall survival (OS). III. To document the toxicity of all chemotherapeutic regimens (THL, TH). IV. To determine the correlation between clinical, radiographic and pathologic response. V. To compare overall survival (OS), relapse free survival (RFS) and time to first failure (TFF) among the treatment groups. VI. To obtain blood, fresh frozen and fixed tumor tissue to test specific hypotheses for which biomarker data exist and to evaluate biomarkers in blood, serum and tissue that are likely to influence response to and toxicity of trastuzumab alone or trastuzumab plus lapatinib, when given with paclitaxel. VII. To determine the surgical practice patterns for breast conservation and sentinel lymphadenectomy in patients undergoing neoadjuvant chemotherapy. VIII. To determine the radiotherapy practice patterns for post-mastectomy and regional nodal irradiation in patients undergoing neoadjuvant chemotherapy. IX. To evaluate pharmacogenomic determinants of toxicity. OUTLINE: Patients are randomized to 1 of 3 treatment arms. ARM I: Patients receive trastuzumab IV over 30-90 minutes and paclitaxel IV over 1 hour once weekly and lapatinib ditosylate orally (PO) once daily for 16 weeks in the absence of disease progression or unacceptable toxicity. ARM II: Patients receive trastuzumab and paclitaxel as in arm I. ARM III: Patients receive paclitaxel and lapatinib ditosylate as in arm I. (Discontinued as of 6-15-11) Within 42 days after completion of neoadjuvant therapy, patients in both arms undergo definitive surgery (breast conservation or total mastectomy). After completion of study treatment, patients are followed every 6 months for 2 years and then annually for up to 10 years.