EGFR Mutation Screening
Tyrosine kinases (TK) regulate many cell signaling pathways, and when over-expressed may contribute to the development of cancer.
TK over-expression may occur by a somatic mutation or chromosomal alteration.
Epidermal growth factor receptor (EGFR) is a member of the ErbB-3 family of cell surface membrane receptors. Activation of EGFR leads to TK activation which in turn leads to a cascade of signaling events, including cell proliferation, adhesion, inhibition of apoptosis, increased angiogenesis and resistance to chemotherapy.
Increased activity at the EGFR has been shown to occur with a variety of solid tumours. The EGFR is highly expressed in almost 90 per cent of non-small cell lung cancers.
Many tumours depend on the mutated kinase for their continued survival, and therefore cancer therapy is aimed at inhibiting this dependency.
The EGFR is the target for a number of novel TK inhibitors used today. Gefitinib (Iressa) is one such inhibitor. It acts to reversibly compete with ATP at a critical binding site within the EGFR molecule, thereby inhibiting its activity.
Recent studies have identified that virtually all patients who respond to Gefitinib were found to have a somatic mutation within the kinase domain of the EGFR gene (exons 18-21). Tumours with such mutations are more sensitive to inhibition by Gefitinib.
A similar association has been reported for responsiveness to Tarceva (Erlotinib), another small molecule drug directed at the kinase domain of the EGFR protein.
Specimen Required:
Formalin-fixed paraffin embedded tissue containing at least 20% tumour is required. Either of the following is acceptable.
1 The entire tissue block can be sent which will be sectioned, macro-dissected and processed, then returned following analysis.
2 Eight, seven micron unstained sections on labelled glass slides, together with one H&E stained section.
| Assay Performed: | Twice per week |
| Medicare Rebate: | No |