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Studies of the efficacy and pharmacology of irinotecan against human colon tumor xenograft models
Irinotecan, administered i.v. on days 1-5 and 8-12 [(dx5)2 i.v.] has demonstrated significant activity against advanced human tumor xenografts. To explore the feasibility of prolonged oral administration of irinotecan, we compared the efficacy of oral and i.v. irinotecan on the (dx5)2 schedule. We a...
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Published in: | Clinical cancer research 1998-03, Vol.4 (3), p.743-753 |
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Main Authors: | , , , , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Online Access: | Get full text |
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Summary: | Irinotecan, administered i.v. on days 1-5 and 8-12 [(dx5)2 i.v.] has demonstrated significant activity against advanced human
tumor xenografts. To explore the feasibility of prolonged oral administration of irinotecan, we compared the efficacy of oral
and i.v. irinotecan on the (dx5)2 schedule. We also evaluated oral therapy for 12 consecutive weeks [(dx5)12] at 25 and 50
mg/kg and two consecutive 5-day courses repeated every 21 days for up to four cycles ([(dx5)2]4) at 50 and 75 mg/kg/dose in
a series of human colon carcinoma xenograft lines. In addition, we evaluated the effect of a sensitive (HC1) and resistant
(ELC2) human colon adenocarcinoma xenograft on irinotecan and SN-38 lactone disposition after administration of irinotecan
10 mg/kg i.v. and 10 and 25 mg/kg p.o. Irinotecan i.v. at 40 mg/kg and oral at 50 and 75 mg/kg on the (dx5)2 schedule had
similar activity against the panel of adult colon adenocarcinoma xenografts. Irinotecan given p.o. also demonstrated significant
activity against a topotecan-resistant derivative, VRC5/TOPO. Oral administration of 75 mg/kg [(dx5)2]4 and 50 mg/kg (dx5)12
achieved complete response in five of seven xenograft lines evaluated. After i.v. administration, mice bearing HC1 xenografts
had 43% greater SN-38 lactone systemic exposure compared to those with ELC2 xenografts and non-tumor-bearing mice. After oral
(10 mg/kg) administration, there was a 5-fold higher molar formation of SN-38 lactone compared to i.v. (10 mg/kg) administration
in tumor and non-tumor-bearing mice. SN-38 systemic exposure associated with the lowest oral dose (25 mg/kg) achieving complete
response for HC1 was 942.6 ng/ml x h. These results emphasize the importance of pharmacokinetic studies as part of tumor response
studies in xenograft models. |
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ISSN: | 1078-0432 1557-3265 |