title: Antitumor activities and pharmacokinetics of silatecans DB-67 and DB-91.
abstract: DB-67 and its lactone homolog DB-91 are derivatives of topoisomerase I inhibitor camptothecin (CPT) with silyl moiety, which may exhibit a slower inactivation process by changed kinetics of protein binding and/or hydrolysis of its lactone ring and result in increased antitumor activity and decreased toxicity. Pharmacokinetic properties and antitumor activities of the two silatecans were studied and compared. The lactone ring of DB-91 is more stable than those of all the other CPT derivatives in mouse plasma. Both silatecans were metabolized faster than CPT in mouse and human liver microsomes. Pharmacokinetic study revealed a plasma elimination half-life (t(1/2)) of 33 and 94min for DB-67 and DB-91, respectively; similar systemic exposure in plasma between DB-67 and DB-91; and similar volume of distribution at the steady state between DB-67 and DB-91, approximately 15-fold smaller than that of CPT. While DB-91 showed limited activities, DB-67 exhibited activities against the growth of in vivo-like histocultured human tumors and s.c. xenografted human tumors in nude mice. In conclusion, DB-67 is more effective, compared to DB-91, against human tumor growth in in vitro, in vivo-like and in vivo systems. Further pre-clinical and clinical investigations of DB-67 are warranted.
authors: Division of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Miaoli, Taiwan.
authors: Teng-Kuang
authors: TK
authors: Yeh
authors: Chien-Ming
authors: CM
authors: Li
authors: Ching-Ping
authors: CP
authors: Chen
authors: Jiuun-Jye
authors: JJ
authors: Chuu
authors: Chen-Lung
authors: CL
authors: Huang
authors: Hsin-Sheng
authors: HS
authors: Wang
authors: Chien-Chang
authors: CC
authors: Shen
authors: Tien-Yi
authors: TY
authors: Lee
authors: Chi-Yen
authors: CY
authors: Chang
authors: Chung-Ming
authors: CM
authors: Chang
authors: Yu-Sheng
authors: YS
authors: Chao
authors: Chin-Tarng
authors: CT
authors: Lin
authors: Jang-Yang
authors: JY
authors: Chang
authors: Chiung-Tong
authors: CT
authors: Chen
mesh_terms: D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology*; D002166:Camptothecin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid; D019008:Drug Resistance, Neoplasm; D004355:Drug Stability; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology*; D005260:Female; D006207:Half-Life; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D008862:Microsomes, Liver / Q000378:metabolism; D009369:Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D017646:Organosilicon Compounds / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology*; D013997:Time Factors; D059004:Topoisomerase I Inhibitors; D047368:Tumor Burden / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
chemical_list: C548684:7-tert-butyldimethylsilyl-10-hydroxyhomocamptothecin; D000972:Antineoplastic Agents, Phytogenic; D004791:Enzyme Inhibitors; D017646:Organosilicon Compounds; D059004:Topoisomerase I Inhibitors; C415575:7-tert-butyldimethylsilyl-10-hydroxycamptothecin; D002166:Camptothecin