Improved Characteristics of a Human -Glucuronidase-Antibody Conjugate after Deglycosylation for Use in Antibody-Direc
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- 作者：Pieter H. J. Houba ; Epie Boven ; and Hidde J. Haisma
- 刊名：Bioconjugate Chemistry
- 出版年：1996
- 出版时间：September 1996
- 年：1996
- 卷：7
- 期：5
- 页码：606 - 611
- 全文大小：164K
- 年卷期：v.7,no.5(September 1996)
- ISSN：1520-4812
文摘
Antibody-directed enzyme prodrug therapy (ADEPT) aims at the specificactivation of relativelynontoxic prodrugs into active drugs at the tumor site. One of theenzymes described to be useful inADEPT is human 
-glucuronidase (GUS), which is expected to have lowimmunogenicity in patients.A major obstacle for the use of GUS, however, is its rapidglycan-specific hepatic clearance. Thecarbohydrates of GUS have been modified by subsequent treatment withNaIO4 and NaBH4 to improveits retention in the circulation. The modification of GUS did notdecrease the enzyme activity. Invitro it was demonstrated that a conjugate prepared with a pancarcinomaspecific monoclonal antibody(mAb) 323/A3 and the modified enzyme (mGUS), when bound to tumor cells,was capable of completeprodrug activation. In vivo, the 323/A3-mGUS conjugate wascleared faster from the circulation ofBALB/c mice (t1/2 = 9 h) than mAb 323/A3(t1/2 = 32 h), but it was retained in thecirculation muchlonger than an immunoconjugate prepared with native GUS(t1/2 = 24 min). In nude micebearingsubcutaneous OVCAR-3 tumors the distribution of 323/A3-mGUS wasqualitatively comparable tothat of mAb 323/A3. The 323/A3-mGUS conjugate showed specificlocalization in the tumor but toa lesser extent than mAb 323/A3 (2.7% vs 6.4% injected dose per gramat 1 day after iv injection). Afavorable tumor-to-blood ratio of >2 was observed for the conjugate at7 days after administration,which is necessary for tumor-specific prodrug activation.
-glucuronidase (GUS), which is expected to have lowimmunogenicity in patients.A major obstacle for the use of GUS, however, is its rapidglycan-specific hepatic clearance. Thecarbohydrates of GUS have been modified by subsequent treatment withNaIO4 and NaBH4 to improveits retention in the circulation. The modification of GUS did notdecrease the enzyme activity. Invitro it was demonstrated that a conjugate prepared with a pancarcinomaspecific monoclonal antibody(mAb) 323/A3 and the modified enzyme (mGUS), when bound to tumor cells,was capable of completeprodrug activation. In vivo, the 323/A3-mGUS conjugate wascleared faster from the circulation ofBALB/c mice (t1/2 = 9 h) than mAb 323/A3(t1/2 = 32 h), but it was retained in thecirculation muchlonger than an immunoconjugate prepared with native GUS(t1/2 = 24 min). In nude micebearingsubcutaneous OVCAR-3 tumors the distribution of 323/A3-mGUS wasqualitatively comparable tothat of mAb 323/A3. The 323/A3-mGUS conjugate showed specificlocalization in the tumor but toa lesser extent than mAb 323/A3 (2.7% vs 6.4% injected dose per gramat 1 day after iv injection). Afavorable tumor-to-blood ratio of >2 was observed for the conjugate at7 days after administration,which is necessary for tumor-specific prodrug activation.