- Phase I: Patients undergo intensity modulated radiotherapy (IMRT) once daily, 5 days a week, for 6 weeks. Patients receive pemetrexed disodium IV over 10 minutes on day 1 of radiotherapy. Treatment with pemetrexed disodium repeats every 21 days for 2 courses in the absence of disease progression or unacceptable toxicity. Patients also receive oral erlotinib hydrochloride once daily beginning on day 1 of radiotherapy and continuing for up to 2 years in the absence of disease progression or unacceptable toxicity.