Gene amplification as means for determining therapeutic strategies in human cancers

Pharmacogenomic analysis aspires to identify individuals with specific genetic characteristics in order to predict a positive response or reduce a negative response to a therapeutic modality. While the search continues for the many single nucleotide polymorphisms which will be used in such genetic analyses, other genetic alterations in specific cell types have proven useful in determining the potential for response to therapy. One such genetic alteration is amplification of entire gene sequences which results in overexpression of a gene product or protein. Amplification of the HER2 (neu, erbB-2) oncogene is found in up to 35% of human breast cancers and is associated with a poor prognosis. In addition, this genetic alteration may predict response to various therapeutic modalities. Assays are available to detect the HER2 protein receptor or copies of the HER2 gene sequence to determine eligibility for Herceptin treatment or adriamycin treatment in node positive patients, respectively. This model represents a somatic event used in the functional determination of a therapeutic strategy.