Patent ID: 8067175

Claim:
A method for predicting development of acquired resistance to the therapeutic effects of gefitinib or erlotinib in a patient that is suffering from a cancer, wherein the method comprises the steps of: (a) obtaining a sample from the patient, wherein the cancer harbors a somatic gain-of-function mutation in the tyrosine kinase domain of EGFR that enhances the sensitivity of the cancer to gefitinib or erlotinib selected from the group consisting of (1) a multi-nucleotide in frame deletion in exon 19 involving elimination of four amino acids, Leu-Arg-Glu-Ala and (2) a single nucleotide substitution of a G or a T at nucleotide 2573 in exon 21, and (b) testing the sample to determine whether the gene encoding EGFR is present in a mutant form that encodes a T790M mutant of EGFR in addition to the somatic gain of function mutation, wherein a finding that the mutant form is present indicates that the cancer has become or will become resistant to gefitinib or erlotinib.