0794GCC: Pentamidine in Treating Patients With Relapsed or Refractory Melanoma

DISEASE CHARACTERISTICS: * Histologically confirmed melanoma * Relapsed or refractory disease * Tumor expresses wild-type p53 * Measurable S100B by immunohistochemistry * Measurable disease, defined as at least one lesion that can be accurately measured in at least one dimension (longest diameter to be recorded) as ≥ 20 mm by conventional techniques or as ≥ 10 mm by spiral CT scan * Tumor amenable to biopsy * Must have been evaluated for potentially curative resection * No unstable or symptomatic brain metastases (e.g., seizures, headache related to tumor, or presence of neurologic deficits attributable to tumor) * Patients with stable brain metastases (by CT scan or MRI) are eligible provided they were treated with local therapy \> 4 weeks ago AND do not require maintenance steroid treatment PATIENT CHARACTERISTICS: * Eastern Cooperative Oncology Group (ECOG) performance status 0-2 * Life expectancy \> 12 weeks * White Blood Cell count (WBC) ≥ 3,000/mcL * Absolute Neutrophil Count (ANC) ≥ 1,500/mcL * Platelet count ≥ 80,000/mcL * Hemoglobin ≥ 8 g/dL * Total bilirubin ≤ 1.5 times normal * aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤ 2.5 times upper limit of normal * Creatinine ≤ 1.5 times normal or creatinine clearance ≥ 60 mL/min * Not pregnant or nursing * Fertile patients must use effective contraception during and for ≥ 3 months after completion of study treatment * Able to take oral medications on a regular basis * No history of allergic reactions attributed to pentamidine * Mean Corrected QT Interval (QTc) ≤ 470 msec (with Bazett's correction) on screening ECG * No history of familial long QT syndrome * Proteinuria ≤ 1 on two consecutive dipsticks taken ≥ 1 week apart * No concurrent uncontrolled illness including, but not limited to, any of the following: * Hypertension * Ongoing or active infection * Symptomatic congestive heart failure * Unstable angina pectoris * Renal failure * Cardiac arrhythmia * Psychiatric illness/social situations that would limit compliance with study requirements PRIOR CONCURRENT THERAPY: * Recovered from all prior therapy * Any number of prior chemotherapy regimens allowed * More than 4 weeks since prior chemotherapy (6 weeks for nitrosoureas or mitomycin C) * More than 4 weeks since prior radiotherapy or major surgery * More than 30 days since prior participation in an investigational trial * No concurrent medication that may markedly affect renal function (e.g., vancomycin, amphotericin, zoledronic acid) * No concurrent combination antiretroviral therapy for HIV-positive patients * No other concurrent investigational agents