The study will be conducted in two phases. Prior to initiating treatment as part of this study, patients will be administered a single imaging dose of 131I-TM601, IV, to demonstrate tumor uptake. Only patients demonstrating tumor uptake will remain on the study. During the first, Dose Escalation Phase of the study, eligible patients will be assigned in groups of 3-6 (depending upon the treatment response seen at each dose) to dose cohorts of between 2-5 weekly IV doses of 131I-TM601, with escalation to the next highest dose dependent upon demonstrated tolerance in the previous dosing group. Patients enrolled in the second phase will be assigned to a dose determined by the experience in the first phase.