HER2 (ERBB2) - Treatment predictive marker for cancer

The HER2 gene encodes for a member of the epidermal growth factor (EGF) receptor family, namely the v-erb-b2 avian erythroblastic leukemia viral oncogene homolog 2 (ERBB2). This gene is frequently over-expressed in various cancers, particularly breast cancer, and leads to increased proliferation and association with poor outcome. Evaluation of HER2 protein levels can thus be of prognostic value but more importantly, HER2 status is also treatment predictive since several drugs that specifically target and inhibit HER2 activity are available. These drugs are only efficient in HER2 over-expressing tumors.