Single Agent Alimta in Poor Performance Status in Non-small Cell Lung Cancer

Pemetrexed is designed to block enzymes in the body that are important for tumor growth. Pemetrexed is commercially approved for the treatment of NSCLC but not for poor performance status patients. If participants are found to be eligible to take part in this study, they will receive pemetrexed once every 3 weeks through a needle in their vein over about 10 minutes. Every 3 weeks is considered 1 treatment cycle. Once the treatment has started, they will return to the clinic before every treatment cycle. At these visits, they will have a physical exam, a performance status evaluation, and routine blood (about 3-4 teaspoons) and urine tests. They will have a chest x-ray and will be asked to complete a questionnaire about how you are feeling. they will also have a CT or MRI scan after Cycle 1 and every odd cycle from then on. They are required to take folic acid by mouth every day for 5 days before the first dose of pemetrexed and continuing until 3 weeks after your last dose of pemetrexed. They will also receive an injection of vitamin B12 into your muscle before first dose of pemetrexed. The vitamin B12 injection will be repeated every 9 weeks until 3 weeks after their last dose of pemetrexed. They will also to take a few low-dose steroid (dexamethasone) tablets twice a day before treatment, the day of treatment, and the day after each treatment. These will be taken to decrease the risk of rash and nausea caused by pemetrexed. They may continue treatment with pemetrexed until your tumor grows or an unacceptable side effect occurs. They will be evaluated for symptoms 1-2 times per week while you are receiving treatment and then 2 weeks after stopping study treatment until 6 months after stopping treatment. When they stop treatment on this study, they will have a physical exam, routine blood (3-4 teaspoons) and urine tests, and a chest x-ray. The study doctor may ask them to visit University of Texas MD Anderson Cancer Center or be contacted by phone for follow-up on how they are doing. This is an investigational study. The FDA has approved pemetrexed for the treatment of advanced NSCLC after earlier treatment with chemotherapy, and for the treatment for malignant mesothelioma in combination with cisplatin. About 70 patients will take part in this study. All will be enrolled at MD Anderson.