The primary objective is to evaluate the safety and tolerability of IMMU-132 as a single agent administered in 3-week treatment cycles for up to 8 cycles, in previously treated patients with advanced epithelial cancer. IMMU-132 targets the TROP-2 antigen which is expressed on a variety of cancers. The antibody, RS7, is attached to SN38, which is the active metabolite of irinotecan.This is planned as a multi-center study. Depending on toxicity, 3-6 patients per dose cohort may be enrolled in up to 4 planned dose levels during Phase I dose escalation, for a maximum total enrollment of 24 patients. In Phase II, up to 50 evaluable patients per select cancer types will be studied at up to 2 dose levels at or below the maximum acceptable dose determined in Phase I.