Phase II Trial of PS-341 (Bortezomib, NSC-681239) Followed by the Addition of Gemcitabine at Progression in Recurrent or Metastatic Nasopharyngeal Carcinoma

Histologically-proven nasopharyngeal carcinoma. Non-keratinizing (WHO Type II) or undifferentiated (WHO Type III). Stage IVC at diagnosis or disease has persisted, metastasized or recurred after definitive surgery, and/or radiation, and/or chemotherapy. Must have measurable disease. Measurable disease assessed within 28 days prior and non-measurable disease assessed within 42 days prior. No CNS mets. Must seek consent to submit specimens. No prior therapy with PS-341 or other proteasome inhibitors. No more than one prior chemo for metastatic/recurrent NPC, with treatment completed at least 28 days prior. Chemo given as adjuvant or radiosensitizer for initial locally advanced dz allowed provided treatment completed at least 24 weeks prior. Prior RT and/or surgery allowed if completed at least 28 days prior. Within 28 days prior: serum creatinine </= 1.5 x IULN OR measured or calculated creatinine clearance >/= 60 mL/min; ANC >/= 1,500/mcl; platelets >/=100,000/mcl; bilirubin </= IULN; liver enzymes </= 2.5 x IULN. Zubrod 0-2. 18 years of age or older. No peripheral neuropathy > Grade 1. No MI within 6 months prior. No Class III or IV cardiac problems, uncontrolled angina, severe uncontrolled ventricular arrhythmias, or ECG evidence of acute ischemia or active conduction system abnormalities. No HAART-receiving HIV-positive patients. No known hypersensitivity to PS-341, boron or mannitol. No pregnant or nursing women.