In Part C, patients receive IL-12 at one dose level above the MTD obtained in Part A using the optimal schedule for the test dose determined in Part B. Dose escalation continues in cohorts of 3-6 patients until the MTD is determined. The MTD is defined as the dose below that at which 2 of 6 patients experience DLT. Patients may continue to receive IL-12 until they have no measurable disease or until disease progression.