Irinotecan (CPT-11) is a key drug for the treatment of various cancers. CPT-11 can be considered to be a prodrug, since it needs to be activated into the toxic drug SN-38 by the enzyme carboxylesterase. However, CPT-11 may induce severe diarrhea and bone marrow suppression as adverse effects, thus leading to treatment interruption. The tumor-specific activation of CPT-11 is a possible strategy to avoid the severe toxicities by reducing the serum concentration of CPT-11. In this study, we constructed human liver carboxylesterase-2 fused with anticarcinoembryonic antigen (CEA) scFv as a targeting molecule. The recombinant enzyme anchors onto the tumor cell surface CEA, and thus metabolize CPT-11 extracellularly. In addition a secreted tumor-targeted form of carboxylesterase should help prevent the leakage of the enzyme from the site of the tumor into the circulation. This fusion protein showed CPT-11 activation to SN-38 and specific binding to CEA-expressing cells. In combination with CPT-11, the recombinant carboxylesterase protein exerted antiproliferative effects on human cancer cells. This recombinant enzyme is, therefore, a promising new tool in enzyme prodrug therapy for the treatment of carcinoma with CPT-11.
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Uchino J, Takayama K, Harada A, Sone T, Harada T, Curiel DT, Kuroki M, Nakanishi Y (2008) Tumor targeting carboxylesterase fused with anti-CEA scFv improve the anticancer effect with a less toxic dose of irinotecan Cancer Gene Therapy15: 94-100
Uchino J, Takayama K, Harada A, Sone T, Harada T, Curiel DT, Kuroki M, Nakanishi Y (2008) Cancer Gene Therapy15: 94-100
