The purpose of this study is to investigate how ketoconazole (Nizoral) affects the pharmacokinetics (how the study drug is affected by the body and broken down) and pharmacodynamics (how the study drug acts on the body) of the active ingredient in the study drug Velcade (bortezomib).

Inclusion Criteria:

• Male and female patients 18 years of age or older, with a diagnosis of advanced solid tumor for which no curative or other treatment of higher priority is available
• Karnofsky Performance Status (KPS) equal to or greater than 70%
• Normal liver function tests (aspartate transaminase [AST] or alanine transaminase [ALT] equal to or less than 2 x upper limit of normal [ULN])
• Total bilirubin equal to or less than 1.5 x ULN
• Calculated creatinine clearance equal to or greater than 50 mL/min
• Normal serum calcium

Exclusion Criteria:

• Patients with significant cardiac disease
• Equal to or greater than Grade 2 neuropathy
• Active hepatitis
• HIV infection
• Secondary malignancy
• Transfusion-dependent or received extensive radiation therapy, systemic chemotherapy, or other antineoplastic therapy within 4 weeks of enrollment
• Patients taking concomitant medications having inhibitory or inducing activity for CYP 3A4