Imatinib Mesylate in Treating Patients With Progressive, Refractory, or Recurrent Stage II or Stage III Testicular or Ovarian Cancer

Inclusion Criteria: * Histologically confirmed pure testicular seminoma or ovarian germ cell dysgerminoma * Histologic documentation of metastatic/recurrent disease not required * Alpha-fetoprotein level must be normal, unless abnormal level is explained by other conditions and approved by the study chair * Clinical stage II or III * Progressive, refractory, or recurrent disease, meeting at least 1 of the following criteria: * Measurable progressive disease * Biopsy-proven residual disease * Persistently elevated or rising B-human chorionic gonadotropin (HCG) titers, defined as at least 2 values above the upper limit of normal (ULN) * Cisplatin-refractory disease without option of potentially curative therapy, meeting 1 of the following criteria: * Failed high-dose chemotherapy with peripheral blood stem cell transplantation (PBSCT) or autologous bone marrow transplantation (AuBMT) * Ineligible for or refused PBSCT or AuBMT * Unlikely to achieve long-term benefit from PBSCT or AuBMT * Current evidence of metastatic disease * Unidimensionally measurable target lesions * At least 20 mm by conventional techniques (e.g., physical examination for clinically palpable lymph nodes and superficial skin lesions or chest x-ray for clearly defined lung lesions surrounded by aerated lung) * At least 10 mm by spiral CT scan or MRI * If measurable disease is confined to a solitary lesion, then its neoplastic nature must be confirmed by histology * Ultrasound may not be used to measure tumor lesions that are not easily accessible clinically * Non-measurable/non-target lesions, with HCG at least ULN, including the following: * Bone lesions * Pleural or pericardial effusions * Ascites * CNS lesions * Leptomeningeal disease * Irradiated lesions, unless progression documented after radiotherapy * Performance status - ECOG 0-2 * Granulocyte count at least 1,500/mm\^3 * Platelet count at least 100,000/mm\^3 * Hemoglobin at least 9 g/dL (transfusion allowed) * Bilirubin no greater than 1.5 times upper limit of normal (ULN) * SGOT/SGPT no greater than 2.5 times ULN * Creatinine no greater than 1.5 times ULN * No other severe and/or uncontrolled concurrent medical illness * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective barrier contraception during and for 3 months after study participation * See Disease Characteristics * See Disease Characteristics * At least 4 weeks since prior chemotherapy * No concurrent chemotherapy * No concurrent hormonal therapy except steroids for adrenal failure, hormones for non-disease-related conditions (e.g., insulin for diabetes), or intermittent dexamethasone as an antiemetic * See Disease Characteristics * At least 4 weeks since prior radiotherapy * Prior radiotherapy to a symptomatic lesion or one that may produce disability (e.g., unstable femur) allowed * No concurrent palliative radiotherapy * No concurrent grapefruit juice * No concurrent warfarin for therapeutic anticoagulation (concurrent mini-dose warfarin \[1 mg orally per day\] as prophylaxis allowed)