Figure 53. EGFR mutation status must be determined in order to ensure that erlotinib is only used in those cases where it will provide benefit.

The EGFR activating and TKI resistance mutations are clustered in the tyrosine kinase domain (see Figure 52) between amino acids 688 and 875 of the EGFR protein, so that mutation analysis can be focussed on the coding sequences for this region. Abbreviation: NSCLC, non-small cell lung cancer.