In Part A, patients receive intravenous interleukin-12 (IL-12) twice a week for 6 weeks. Courses are repeated until patients achieve a complete response or there is disease progression. Dose escalation of IL-12 continues in cohorts of 3-6 patients until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose below that at which 2 of 6 patients experience dose limiting toxicity (DLT).