The study was to comprise two stages. In Stage I, the recommended dose (RD) for Proxinium was to be determined based on the rate of dose-limiting toxicities (DLTs) within each dose cohort. A DLT was defined as the occurrence of excessive toxicity during the first four weeks of each patient's treatment with Proxinium during Stage I of the study, before the RD had been determined. The RD was to be established as the highest dose at which one or fewer patients out of six within a dose cohort experienced a DLT. The initial dose level was to be 500 µg, and three patients were to be initially enrolled into this dose cohort.