“…It has been reported that the substitution on 20-OH group of 10-HCPT can substantially reduce the tendency for lactone ring opening and increase the solubility, and a variety of conjugates that link 10-HCPT via 20-OH group have been performed, including PEG-camptothecin conjugate, polyglutamate-camptothecin conjugate, PEG-SN38 conjugate and PAMAM-camptothecin conjugate, some of them have entered into the phase of clinical research (Bhatt et al, 2003;Cheng et al, 2004;Fleming et al, 2004;Samor et al, 2008;Joralemon et al, 2010;Tong & Cheng, 2010). Except improving the solubility and stability of 10-HCPT, polymer conjugate can also prolong circulation time through avoiding rapid clearance by the renal and reticuloendothelial systems (RES), decrease side effects, passive target tumor tissues via the enhanced permeability and retention (EPR) effect and improve bioavailability (Li & Wallace, 2008;Maeda et al, 2009;Torchilin, 2011).…”