Folate-mediated targeting of polymeric conjugates of gemcitabine.

The synthesis of two new macromolecular prodrugs for active tumor targeting was set up. Gemcitabine (2'-deoxy-2',2'-difluorocytidine) was conjugated to alpha,beta-poly(N-2-hydroxyethyl)-DL-aspartamide (PHEA) through succinyl or diglycolyl hydrolysable spacers. The targeting agent folic acid was attached to the macromolecular backbone through the aminocaproic spacer. The two conjugates [PHEA-(5'-succinylgemcitabine)-1'-carboxypentyl-folamide and PHEA-(5'-diglycolyl-gemcitabine)-1'-carboxypentyl-folamide], were purified and extensively characterised by spectroscopic (UV, IR and NMR) and chromatographic analyses to determine the correct chemical structure, the purity degree and the reaction yi…