Lapatinib and Ixabepilone for the Treatment of Metastatic Breast Cancer.

Breast cancer is the second leading cause of cancer death in women. Treatment options for advanced-stage disease, although numerous, remain suboptimal. Lapatinib and ixabepilone are two new agents approved by the United States Food and Drug Administration (FDA) in 2007 for the treatment of locally advanced breast cancer (LABC) or metastatic breast cancer (MBC). When added to the existing endocrine therapies--single-agent cytotoxic therapies and combination chemotherapy regimens--lapatinib and ixabepilone offer potential treatment strategies for disease that has become resistant to trastuzumab and the taxanes, respectively. Lapatinib is an oral dual tyrosine kinase inhibitor against members of the human epidermal growth factor receptor (HER) family (HER1 or epidermal growth factor receptor [EGFR], and HER2). It is indicated for combination therapy with capecitabine for the treatment of patients with HER2-overexpressing LABC or MBC whose disease has progressed after receiving previous treatment with an anthracycline, a taxane, and trastuzumab. Of note, lapatinib is the first FDA-approved tyrosine kinase inhibitor indicated for use in MBC. Ixabepilone, the first FDA-approved analog of the antimicrotubule agent epothilone B, is indicated as monotherapy for the treatment of LABC or MBC in patients whose tumors are refractory or resistant to anthracyclines, taxanes, and capecitabine. It is also indicated in combination with capecitabine for treatment of LABC or MBC that is resistant to anthracycline and taxane. Both lapatinib and ixabepilone are fairly well tolerated. The most common toxicities with lapatinib are diarrhea (65%) and hand-and-foot syndrome (53%), whereas peripheral neuropathy (62%), fatigue (56%), and neutropenia (54%) are most common with ixabepilone. Though the conventional standard end point of overall survival has not yet been assessed in clinical trials, these agents have been shown to improve surrogate markers of clinical benefit: progression-free survival and the related time to progression. Future clinical trials should focus on elucidation of optimal combination or sequential therapies, as well as patient-specific therapies based on tumor characteristics, such as biomarkers and tumor subtypes. [ABSTRACT FROM AUTHOR]