17. Absence of an activating mutation (Exon 19 deletion or Exon 21 L858R mutation) in the epidermal growth factor receptor (EGFR) in the pre-treatment biopsy of the tumor. Patients with activating EGFR mutations are eligible if they have progressed following treatment with erlotinib. A pretreatment tumor biopsy must be available for analysis. If a biopsy has not been performed prior to entry, then a biopsy will be required.