title: A humanized immunoenzyme with enhanced activity for glucuronide prodrug activation in the tumor microenvironment.
abstract: Antibody-directed enzyme prodrug therapy (ADEPT) utilizing β-glucuronidase is a promising method to enhance the therapeutic index of cancer chemotherapy. In this approach, an immunoenzyme (antibody-β-glucuronidase fusion protein) is employed to selectively activate anticancer glucuronide prodrugs in the tumor microenvironment. A major roadblock to the clinical translation of this therapeutic strategy, however, is the low enzymatic activity and strong immunogenicity of the current generation of immunoenzymes. To overcome this problem, we fused a humanized single-chain antibody (scFv) of mAb CC49 to S2, a human β-glucuronidase (hβG) variant that displays enhanced catalytic activity for prodrug hydrolysis. Here, we show that hcc49-S2 displayed 100-fold greater binding avidity than hcc49 scFv, possessed greater enzymatic activity than wild-type hβG, and more effectively killed antigen-positive cancer cells exposed to an anticancer glucuronide prodrug as compared to an analogous hβG immunoenzyme. Treatment of tumor-bearing mice with hcc49-S2 followed by prodrug significantly delayed tumor growth as compared to hcc49-hβG. Our study shows that hcc49-S2 is a promising targeted enzyme for cancer treatment and demonstrates that enhancement of human enzyme catalytic activity is a powerful approach to improve immunoenzyme efficacy.
authors: Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan.
authors: Kai-Chuan
authors: KC
authors: Chen
authors: Shih-Yen
authors: SY
authors: Wu
authors: Yu-Lin
authors: YL
authors: Leu
authors: Zeljko M
authors: ZM
authors: Prijovich
authors: Bing-Mae
authors: BM
authors: Chen
authors: Hsin-Ell
authors: HE
authors: Wang
authors: Tian-Lu
authors: TL
authors: Cheng
authors: Steve R
authors: SR
authors: Roffler
mesh_terms: D000818:Animals; D000912:Antibodies, Neoplasm / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D000970:Antineoplastic Agents / Q000378:metabolism / Q000494:pharmacology; D055162:Biocatalysis; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005966:Glucuronidase / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D020719:Glucuronides / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D016513:Mice, SCID; D057054:Molecular Imaging; D041681:NIH 3T3 Cells; D011355:Prodrugs / Q000378:metabolism* / Q000494:pharmacology; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D013329:Structure-Activity Relationship; D059016:Tumor Microenvironment; D023041:Xenograft Model Antitumor Assays
chemical_list: D000912:Antibodies, Neoplasm; D000970:Antineoplastic Agents; C091202:B72.3 antibody; D020719:Glucuronides; D011355:Prodrugs; D011993:Recombinant Fusion Proteins; D005966:Glucuronidase