PDEPT: Polymer-Directed Enzyme Prodrug Therapy. 2. HPMA Copolymer--lactamase and HPMA Copolymer-C-Dox as a Model Comb
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- 作者：Ronit Satchi-Fainaro ; Hanna Hailu ; John W. Davies ; Clive Summerford ; and Ruth Duncan
- 刊名：Bioconjugate Chemistry
- 出版年：2003
- 出版时间：July 2003
- 年：2003
- 卷：14
- 期：4
- 页码：797 - 804
- 全文大小：168K
- 年卷期：v.14,no.4(July 2003)
- ISSN：1520-4812
文摘
Polymer-directed enzyme prodrug therapy (PDEPT) is a novel two-step antitumor approach that usesa combination of a polymeric prodrug and polymer-enzyme conjugate to generate a cytotoxic drugrapidly and selectively at the tumor site. Previously we have shown that N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer-bound cathepsin B can release doxorubicin intratumorally froman HPMA copolymer conjugate PK1. Here we describe for the first time the synthesis and biologicalcharacterization of a PDEPT model combination that uses an HPMA-copolymer-methacryloyl-glycine-glycine-cephalosporin-doxorubicin (HPMA-co-MA-GG-C-Dox) as the macromolecular prodrug andan HPMA copolymer conjugate containing the nonmammalian enzyme 
-lactamase (HPMA-co-MA-GG--L) as the activating component. HPMA-co-MA-GG-C-Dox had a molecular weight of ~31 600Da and a C-Dox content of 5.85 wt %. Whereas free -L has a molecular weight of 45 kDa, the HPMA-co-MA-GG--L conjugate had a molecular weight in the range of 75-150 kDa, and followingpurification no free enzyme was detectable. Against the cephalosporin C or HPMA-co-MA-GG-C-Dox substrates, the HPMA-co-MA-GG--L conjugate retained 70% and 80% of its activity, respectively.In vivo 125I-labeled HPMA-co-MA-GG--L showed prolonged plasma concentration and greater tumortargeting than 125I-labeled -L due to the enhanced permeability and retention (EPR) effect. Moreover,administration of HPMA-co-MA-GG-C-Dox iv to mice bearing sc B16F10 melanoma followed after 5h by HPMA-co-MA-GG--L led to release of free Dox. The PDEPT combination caused a significantdecrease in tumor growth (T/C = 132%) whereas neither free Dox nor HPMA-co-MA-GG-C-Dox alonedisplayed activity. The PDEPT combination displayed no toxicity at the doses used, so furtherevaluation of this approach to establish the maximum tolerated dose (MTD) is recommended.
-lactamase (HPMA-co-MA-GG--L) as the activating component. HPMA-co-MA-GG-C-Dox had a molecular weight of ~31 600Da and a C-Dox content of 5.85 wt %. Whereas free -L has a molecular weight of 45 kDa, the HPMA-co-MA-GG--L conjugate had a molecular weight in the range of 75-150 kDa, and followingpurification no free enzyme was detectable. Against the cephalosporin C or HPMA-co-MA-GG-C-Dox substrates, the HPMA-co-MA-GG--L conjugate retained 70% and 80% of its activity, respectively.In vivo 125I-labeled HPMA-co-MA-GG--L showed prolonged plasma concentration and greater tumortargeting than 125I-labeled -L due to the enhanced permeability and retention (EPR) effect. Moreover,administration of HPMA-co-MA-GG-C-Dox iv to mice bearing sc B16F10 melanoma followed after 5h by HPMA-co-MA-GG--L led to release of free Dox. The PDEPT combination caused a significantdecrease in tumor growth (T/C = 132%) whereas neither free Dox nor HPMA-co-MA-GG-C-Dox alonedisplayed activity. The PDEPT combination displayed no toxicity at the doses used, so furtherevaluation of this approach to establish the maximum tolerated dose (MTD) is recommended.