AG2037 in Treating Patients With Advanced, Metastatic, or Recurrent Solid Tumors

DISEASE CHARACTERISTICS: * Histologically or cytologically confirmed solid tumor * Advanced, metastatic, or recurrent disease * No curative therapy exists * Measurable or evaluable disease PATIENT CHARACTERISTICS: Age: * 18 and over Performance status: * WHO 0-2 Life expectancy: * At least 3 months Hematopoietic: * Absolute granulocyte count at least 1,500/mm\^3 * Platelet count at least 100,000/mm\^3 * Hemoglobin at least 9 g/dL Hepatic: * Bilirubin no greater than 1.5 mg/dL (unless due to Gilbert's syndrome) * SGOT OR SGPT no greater than 2 times upper limit of normal (ULN) (5 times ULN if liver metastases present) Renal: * Creatinine no greater than 1.5 mg/dL * Creatinine clearance at least 60 mL/min Other: * No unstable or severe concurrent medical condition that would preclude study participation * No sociological or familial condition that would preclude study compliance * No psychological or addictive disorder that would preclude study compliance * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception PRIOR CONCURRENT THERAPY: Biologic therapy: * Not specified Chemotherapy: * At least 4 weeks since prior chemotherapy (6 weeks for nitrosourea or mitomycin) and recovered Endocrine therapy: * Not specified Radiotherapy: * At least 4 weeks since prior radiotherapy and recovered * No prior radiotherapy to more than 40% of bone marrow Surgery: * Not specified Other: * At least 2 weeks since prior blood transfusions * At least 4 weeks since prior investigational agent and recovered * No prior glycinamide ribonucleotide formyltransferase (GARFT) inhibitor * No concurrent extradietary folate supplements * No concurrent allopurinol * No other concurrent anticancer or investigational agents