The novel lipophilic camptothecin analogue gimatecan is very active in vitro in human neuroblastoma: A comparative study with SN38 and topotecan

• Published in: Biochemical pharmacology Vol. 70; no. 8; pp. 1125 - 1136
• Main Authors: Di Francesco, Angela Maria, Riccardi, Anna Shirley, Barone, Giuseppe, Rutella, Sergio, Meco, Daniela, Frapolli, Roberta, Zucchetti, Massimo, D’Incalci, Maurizio, Pisano, Claudio, Carminati, Paolo, Riccardi, Riccardo
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 15-10-2005; Elsevier Science
• Subjects: Alkaline comet assay; Antineoplastic agents; Antineoplastic Agents - pharmacology; Biological and medical sciences; Camptothecin - analogs & derivatives; Camptothecin - pharmacology; Camptothecins; Caspase 3; Caspases - metabolism; Cell Cycle; Cell Line, Tumor; Chemotherapy; Comet Assay; DNA strand breaks; Gimatecan; Humans; In Situ Nick-End Labeling; In Vitro Techniques; Medical sciences; Neuroblastoma; Neuroblastoma - pathology; Neurology; Pharmacology. Drug treatments; Topoisomerase I inhibitors; Topotecan - pharmacology; Tumors of the nervous system. Phacomatoses; Camptothecins; Neuroblastoma; Gimatecan; Topoisomerase I inhibitors; Alkaline comet assay; DNA strand breaks; Antineoplastic agent; Human; Nervous system diseases; Enzyme; DNA topoisomerase; Enzyme inhibitor; Topotecan; Malignant tumor; In vitro; Comet assay; Alkaloid; Isomerases; Single strand break; Antiviral; Autonomic neuropathy; Comparative study
• ISSN: 0006-2952; 1873-2968
• DOI: 10.1016/j.bcp.2005.07.009

Neuroblastoma is one of the most common extracranial solid tumours in childhood with a poor prognosis in its advanced stage. Treatment failure is often associated to the occurrence of drug resistance. To date, treatment of paediatric neuroblastoma is still dismal, and therefore novel effective drugs are awaited. In recent years, an increasing interest has concentrated on camptothecin analogues. Topotecan and irinotecan, the only two clinically relevant camptothecin derivatives to date, have entered clinical trials in neuroblastoma but so far the results have been disappointing. Gimatecan (ST1481, LBQ707; 7-
t-butoxyiminomethylcamptothecin), is a novel lipophilic camptothecin derivative that was selected from a series of lipophilic analogues rationally designed and synthesized in order to overcome some of the main drawbacks of conventional camptothecins, limiting their clinical efficacy. Gimatecan is endowed with potent antitumour activity, strong topoisomerase I inhibition, stable drug–target interactions and a better pharmacological profile. The present study deals with the comparative evaluation of cellular pharmacology features of gimatecan, topotecan and SN38 in neuroblastoma cell lines. We show that, despite the lowest intracellular accumulation, gimatecan was the most active among the camptothecin analogues studied. Our findings suggest that the high activity of gimatecan in neuroblastoma is related to the ability of this novel analogue to cause a very high number of DNA breaks as assessed by the Comet assay in both cellular or sub-cellular systems. We propose that DNA strand breaks efficiency as measured by the Comet assay might provide important information about the stability of the ternary complexes induced by camptothecin compounds.