Preclinical profile of antitumor activity of a novel hydrophilic camptothecin, ST1968.
ST1968 is a novel hydrophilic camptothecin (CPT) derivative of the 7-oxyiminomethyl series. Because ST1968 retained ability to form remarkably stable cleavable complexes, this study was done to investigate its preclinical profile of antitumor activity in a large panel of human tumor models, including irinotecan-resistant tumors. Although less potent than SN38 in vitro, i.v. administered ST1968 caused a marked tumor inhibition, superior to that of irinotecan, in most tested models. ST1968 exhibited an impressive activity against several tumors including models of ovarian and colon carcinoma in which a high rate of cures was observed. In the most responsive tumors, complete and persistent tumor regressions were achieved even with low suboptimal doses. Even tumors derived from intrinsically resistant cells exhibited a significant responsiveness. Histologic analysis of treated tumors supports a contribution of both proapoptotic and antiangiogenic effects to ST1968 antitumor efficacy. A study done in yeast cells transformed with CPT-resistant mutant forms of topoisomerase I documented that, in contrast to other tested CPT, ST1968 was active against yeasts expressing the mutant K720E enzyme. Based on its outstanding efficacy superior to that of irinotecan and of its good therapeutic index, ST1968 has been selected for clinical development.
Pisano
Claudio
C
Sigma-Tau, Pomezia, Italy.
De Cesare
Michelandrea
M
Beretta
Giovanni Luca
GL
Zuco
Valentina
V
Pratesi
Graziella
G
Penco
Sergio
S
Vesci
Loredana
L
Foderà
Rosanna
R
Ferrara
Fabiana Fosca
FF
Guglielmi
Mario Berardino
MB
Carminati
Paolo
P
Dallavalle
Sabrina
S
Morini
Gabriella
G
Merlini
Lucio
L
Orlandi
Augusto
A
Zunino
Franco
F
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002166:Camptothecin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology*; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004264:DNA Topoisomerases, Type I / Q000378:metabolism; D005260:Female; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D050296:Microbial Viability / Q000187:drug effects; D050505:Mutant Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000187:drug effects; D019772:Topotecan / Q000494:pharmacology; D023041:Xenograft Model Antitumor Assays
D000970:Antineoplastic Agents; D050505:Mutant Proteins; D019772:Topotecan; D004264:DNA Topoisomerases, Type I; C531200:namitecan; D002166:Camptothecin