Alvocidib and Oxaliplatin With or Without Fluorouracil and Leucovorin Calcium in Treating Patients With Relapsed or Refractory Germ Cell Tumors

Inclusion Criteria: * Histologically confirmed germ cell tumor (GCT) * Seminoma or non-seminoma * Progressive disease after prior cisplatin-based therapy AND meets 1 of the following criteria: * Not considered to be a candidate for potentially curative therapy * Previously treated with high-dose chemotherapy regimens * Does not wish to undergo potentially curative high-dose therapy * Measurable or evaluable disease, as defined by 1 of the following criteria: * Unidimensionally measurable metastatic disease, defined as ≥ 1 malignant tumor mass that can be accurately measured in ≥ 1 dimension as ≥ 20 mm by conventional CT scan or MRI or as ≥ 10 mm by spiral CT scan * Bone lesions, ascites, peritoneal carcinomatosis, miliary lesions, pleural or pericardial effusions, lymphangitis of the skin or lung, cystic lesions, or irradiated lesions are not considered measurable disease * Patients with measurable disease only (i.e., normal tumor markers) must have ≥ 1 site of disease that has not been previously irradiated * Elevation of alpha-fetoprotein \> 15 ng/mL and/or elevation of beta-human chorionic gonadotropin \> 2.2 mIU/L * If tumor markers are not elevated, ≥ 1 site of measurable disease must be present * No known untreated CNS metastasis or primary CNS tumor * Patients who have undergone local treatment for brain metastases and whose brain metastases are demonstrated to be stable by repeat imaging studies performed ≥ 4 weeks after treatment are eligible * Karnofsky performance status 70-100% * ANC ≥ 1,000/mm\^3 * Platelet count ≥ 100,000/mm\^3 * Hemoglobin ≥ 8.0 g/dL * Serum creatinine ≤ 2.0 times upper limit of normal (ULN) * Total serum bilirubin ≤ 1.5 times ULN * AST and ALT ≤ 2.5 times ULN (unless elevation is due to underlying malignancy) * Not pregnant or nursing * Negative pregnancy test by ultrasound * Fertile patients must use effective contraception * Willing and able to comply with scheduled study visits, treatment plans, laboratory tests, follow-up tests for safety or effectiveness, and other study procedures * Mediport or Broviac access required for patients enrolled in part B of the study * No serious active infections * No significant (≥ grade 2) or persistent ongoing toxicity, including peripheral neuropathy, from prior therapy * None of the following within the past 6 months: * Myocardial infarction * Severe/unstable angina * Coronary/peripheral artery bypass graft * Symptomatic congestive heart failure * Cerebrovascular accident or transient ischemic attack * Pulmonary embolism * No contraindication to any of the study drugs * No other severe acute or chronic medical or psychiatric condition or laboratory abnormality that may increase the risk associated with study participation or study drug administration, interfere with the interpretation of study results, and, in the judgement of the investigator, may make the patient inappropriate for study entry * No concurrent anti-retroviral therapy for HIV-positive patients * Recovered from prior radiotherapy or surgery * Residual grade 1 toxicities allowed * No prior alvocidib * At least 2 weeks since prior chemotherapy (6 weeks for nitrosoureas or mitomycin C), immunotherapy, or radiotherapy * More than 4 weeks since prior major surgery * No other concurrent approved or investigational anticancer treatment, including surgery, radiotherapy, chemotherapy, biologic-response modifiers, hormone therapy, or immunotherapy * No concurrent participation in another investigational treatment clinical trial * Concurrent participation in supportive care trials or non-treatment trials (e.g., quality of life or laboratory analysis studies) allowed * No concurrent vitamins, antioxidants, herbal preparations, or supplements, except for a single-tablet multivitamin