- Arm II: Patients receive gemcitabine hydrochloride and erlotinib hydrochloride as in arm I and panitumumab IV over 1 hour on days 1 and 15. Treatment repeats every 28 days for 2 courses. Patients achieving a CR after 2 courses receive 2 additional courses of treatment; patients achieving a PR receive retreatment as above in the absence of disease progression or unacceptable toxicity. Patients achieving a CR after 4 courses of treatment receive maintenance therapy comprising erlotinib hydrochloride daily and panitumumab every 2 weeks until the first disease progression. After the first progression, patients are retreated with gemcitabine hydrochloride, erlotinib hydrochloride, and panitumumab until second progression (using the first progression tumor measurements as the new baseline reference).