- Arm I: Patients receive gemcitabine hydrochloride IV over 30 minutes on days 1, 8, and 15 and oral erlotinib hydrochloride once daily on days 1-28. Treatment repeats every 28 days for 2 courses. Patients achieving a complete response (CR) after 2 courses receive 2 additional courses of treatment; patients achieving a partial response (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 until the first disease progression. After the first progression, patients are retreated with gemcitabine hydrochloride and erlotinib hydrochloride until second progression (using the first progression tumor measurements as the new baseline reference).