The present invention is directed to methods for the treatment of gefitinib and/or erlotinib resistant cancer. An individual with cancer is monitored for cancer progression following treatment with gefitinib and/or erlotinib. Progression of the cancer is indicative that the cancer is resistant to gefitinib and/or erlotinib. Once progression of cancer is noted, the subject is administered a pharmaceutical composition comprising an irreversible epidermal growth factor receptor (EGFR) inhibitor. In preferred embodiments, the irreversible EGFR inhibitor is EKB-569, HKI-272 and HKI-357.
