Nelfinavir Mesylate in Treating Patients With Recurrent, Metastatic, or Unresectable Liposarcoma

Inclusion * Patients must have histologically confirmed liposarcoma, which is recurrent, metastatic or unresectable * There is no limit to prior chemotherapy regimens; in addition, patients may have prior radiation * All patients must have measurable disease, defined as lesions that can be accurately measured in at least one dimension (\>= 20 mm with conventional techniques or \>= 10mm with spiral CT scan); pleural effusions and ascites will not be considered measurable, but may be present in addition to the measurable lesion(s) * ECOG (Eastern Cooperative Oncology Group) performance status of 0, 1, or 2; patients should have an expected survival of at least 3 months * Absolute neutrophil count \>= 1,000/ul * Platelets \>= 75000/ul * Total bilirubin =\< 2.0 g/dl * AST(SGOT)/ALT(SGPT) =\< 2.0X institutional upper limit of normal * Brain metastasis is not an exclusion; however, patients are only eligible if they have had successful control of the brain tumor(s) by surgery or radiation therapy * All prior therapy must have been completed at least 3 weeks prior to the patient's entry on this trial * No concurrent chemotherapy, radiotherapy, immunotherapy or other investigational agents * Women of child-bearing potential and men must agree to use adequate contraception (barrier method of birth control) prior to study entry and for the duration of study participation; should a women become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately * Ability to understand and willingness to sign a written informed consent document Exclusion * Patient has had prior treatment with or is currently taking a protease inhibitor * Patients enrolled cannot be on the following medications: cisapride, triazolam, midazolam, ergot derivatives, amiodarone, quinidine, dihydropyridine calcium antagonists (amlodipine, felodipine, isradipine, nicardipine, nifedipine, nimodipine, and nisoldipine), sildenafil, dilantin, rifampin or oral contraceptives * Uncontrolled intercurrent illness * Patients must have recovered from any expected toxicities of previous chemotherapy or radiation therapy