OUTLINE: This is a dose escalation, multicenter study. Patients undergo a stereotactic biopsy under MR/CT guidance. Catheters are then placed into the tumor under stereotactic guidance. The catheter is filled with IL-4(38-37)-PE38KDEL immunotoxin (IL-4 toxin), with infusion beginning 24 hours after catheter insertion. The IL-4 toxin is infused over 4 days. The catheter is removed 45 minutes after the infusion is completed and a MR scan is performed. Cohorts of 3 patients each receive escalating doses of IL-4 toxin until the maximum tolerated dose (MTD) is reached. The MTD is defined as the dose preceding the dose at which 2 of 3 patients experience dose limiting toxicity. Patients are followed every 4 weeks for 16 weeks, then every 8 weeks for up to 3 years.