Current Cancer Drug Targets

Ruiwen Zhang 
Texas Tech University Health Sciences Center
1300 Coulter Drive
Amarillo, TX 79106
USA

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Beyond Trastuzumab: Overcoming Resistance to Targeted HER-2 Therapy in Breast Cancer

Author(s): Philippe L. Bedard, Evandro de Azambuja, Fatima Cardoso.

Abstract:

Overexpression of the human epidermal growth factor receptor 2 (HER-2) represents a biological subclass of breast cancer with distinct molecular alterations, clinical behavior, and response to systemic therapy. Trastuzumab is a monoclonal antibody directed against HER-2 which has revolutionized the management of both early and advanced breast cancer. It may exert its anti-cancer effects through inhibition of intracellular signaling, upregulation of p27, impaired angiogenesis, induction of immune-mediated destruction, and blockade of cleavage of the extracellular domain of HER-2. In spite of its robust clinical activity, most women with metastatic HER-2 overexpressing breast cancer eventually progress on trastuzumab therapy. Possible mechanisms of resistance include: altered receptor antibody interaction, PTEN loss and enhanced Akt signaling, p27 loss, signaling through other receptors. Preclinical experiments, clinical experience with the use of trastuzumab beyond progression, and a recent phase III clinical trial with Lapatinib, a dual EGFR/HER-2 tyrosine kinase inhibitor, demonstrate that the HER-2 signaling axis remains an important therapeutic target even after progression on trastuzumab. A variety of novel strategies are currently in development to exploit this pathway following the onset of resistance, such as receptor antibodies, sheddase inhibitors, signal transduction inhibitors, heat shock protein inhibitors, proteasome inhibitors, anti-angiogenic agents, and immune-stimulatory therapies, either as single agents or in combination with trastuzumab. Rational clinical trial design, with attention to appropriate patient selection and prospective collection of biological material, is needed to ensure that the new generation of anti-HER-2 targeted therapies realizes its promise in the treatment of trastuzumab-resistant disease.

Keywords: Breast neoplasms, erbB-2 receptor, monoclonal antibodies, protein-tyrosine kinases

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Article Details

VOLUME: 9
ISSUE: 2
Year: 2009
Page: [148 - 162]
Pages: 15
DOI: 10.2174/156800909787581024
Price: $58