Dose escalation from the 5 mg/kg cohort to the 7.5 mg/kg cohort will depend on the safety profile following a single dose of 5 mg/kg. Once all subjects are enrolled in the 5 mg/kg cohort and 4 weeks have elapsed since the sixth subject in the cohort has received the first infusion, dose escalation to the 7.5 mg/kg cohort may occur if ≤1 DLT has occurred in the 5 mg/kg cohort. Dose escalation to the 10 mg/kg cohort may occur 4 weeks after the sixth subject in the 7.5 mg/kg/dose cohort has received the first infusion (with ≤1 DLT). Dose escalation to the 15 and 20 mg/kg cohorts may occur 4 weeks after the sixth subject in the previous cohort has received the first infusion (with ≤1 DLT). Up to six additional subjects may be enrolled in the MTD dose cohort or in the 20 mg/kg dose cohort if MTD is not attained.