Pemetrexed as Second-Line Therapy in Treating Patients With Hormone Refractory Prostate Cancer

OUTLINE: This is a multi-center study. * Pemetrexed 500mg/m2 will be administered intravenously over approximately 10-minutes on Day 1 of a 21-day cycle. * Folic Acid (350-1000 mcg. PO daily) will be taken by patients to reduce toxicity. At least 5 daily doses of folic acid must be taken during the 7-day period preceding the first dose of pemetrexed, and dosing should continue during the full course of therapy and for 21 days after the last dose of pemetrexed. * Vitamin B12 (1000 µg) will be administered as an intramuscular injection during the week preceding the first dose of pemetrexed and every 3 cycles thereafter. Subsequent vitamin B12 injections may be given the same day as pemetrexed. Performance Status: Karnofsky Performance Status 70-100 Life expectancy \> 12 weeks Hematopoietic: * Absolute Neutrophil Count (ANC) \> 1500/mm3 * Platelet count \> 100,000/mm3 * Hemoglobin \> 9 g/dL Hepatic: * Bilirubin \< 1.5 X upper limit of normal (unless due to Gilbert's disease) * Alkaline phosphatase and Alanine Transanimase (ALT) (SGPT) \< 3 X upper limit of normal (ULN); may be \< 5 X ULN for patients with liver metastases. Alkaline phosphatase may be any value for patients with bone metastases. Renal: * Calculated creatinine clearance \>45 mL/min based on the standard Cockroft and Gault formula Cardiovascular: * No congestive heart failure requiring therapy or New York Heart Association (NYHA) class II or greater or active angina or known myocardial infarction within 12 months prior to study * No unstable angina, uncontrolled congestive heart failure, or unstable symptomatic arrhythmia requiring medication within 6 months prior to being registered for protocol therapy * Subjects with chronic atrial arrhythmia, i.e., atrial fibrillation, paroxysmal supraventricular tachycardia, or controlled hypertension are eligible Pulmonary: * Not specified