OUTLINE: This is a dose escalation study. Patients receive LMB-7 intrathecally on days 1, 3, and 5. Treatment may be repeated every 4 weeks if the patient does not demonstrate HAMA neutralizing antibodies to PE-38 in CSF, has stable or responding disease, and has not experienced greater than grade II toxicity. Three to six patients are entered at each dose level. Dose escalation continues until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose preceding that at which 2 of 6 patients experience grade 3 or worse toxicity or a neuroradiology toxicity score of 10 or greater.