Preoperative Chemotherapy With Paclitaxel, Gemcitabine, and Lapatinib (Tykerb®) (PGT)

Unlike adjuvant chemotherapy, primary (preoperative) chemotherapy will shrink tumor and allow some patients to become candidates for conservative surgery and avoid mastectomy. It also is an in vivo chemosensitivity test and the result is a predictive marker for clinical outcomes. Paclitaxel is a highly active antitumor agent that promotes microtubule assembly by binding to tubulin and inhibiting depolymerization. Paclitaxel has been shown to be an effective agent in the treatment of breast cancer. Gemcitabine is a cytosine arabinoside prodrug analog and shows response rates of 15% to 46% as a single agent with very low toxicity. The combination of gemcitabine and paclitaxel is valuable because of the different mechanisms of action of each drug and their non-overlapping toxicities. Phase II studies of paclitaxel plus gemcitabine in anthracycline-pretreated metastatic breast cancer showed good tolerance and encouraging response rates (40%-55%). Paclitaxel plus gemcitabine combination showed overall survival benefit compared to paclitaxel alone in patients with metastatic breast cancer in an interim overall survival report. A phase II study with preoperative paclitaxel and gemcitabine in stage II/III showed 18 % pCR rate at NCC (ASCO 2007 abstract #11080) In HER2 positive breast cancer, HER2 targeted therapies with trastuzumab and lapatinib have shown much improved clinical response in palliative setting. It also showed that adding trastuzumab to sequential paclitaxel and FEC chemotherapy significantly increased pCR (25% vs 66.7%) in preoperative setting for HER2 positive disease. Recently, paclitaxel, gemcitabine, and trastuzumab combination (PGH) for 6 cycles in patients with HER2 positive and node positive operable breast cancer observed a strikingly high pCR rate in both tumor and LN in an interim analysis of multicenter phase II preoperative study in Korea (28 of 47 (61%)). Lapatinib (Tykerb®), a dual tyrosine kinase inhibitor of ErbB1 and HER2 signaling pathways and it has shown to inhibit the growth of HER2 overexpressing breast cancer cells that do not respond to trastuzumab after long-term conditioning. We will examine the hypothesis that paclitaxel, gemcitabine, and lapatinib (Tykerb®) (PGT) combination could improve the pathological complete response rate of HER2 positive breast cancer when applied as a preoperative chemotherapy.