Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
2505661 | International Journal of Pharmaceutics | 2008 | 9 Pages |
Abstract
Metronomic chemotherapy is a novel approach to the control of advanced cancer, as it appears to preferentially inhibit endothelial cell activity in the growing vasculature of tumors. Doxorubicin-containing sterically stabilized liposomes (DXR-SL) accumulate in large amounts in tumor tissue, resulting in enhanced antitumor effects of the encapsulated DXR. In the present study, it was hypothesized that metronomic chemotherapy may further augment the accumulation of DXR-SL, improving its therapeutic efficacy. This study tests the antitumor efficacy for the combination of a metronomic cyclophosphamide (CPA)-dosing schedule with sequential intravenous injections of DXR-SL in the treatment of lung metastatic B16BL6 melanoma-bearing mice. Three dosing schedules for the combination of metronomic CPA injections (s.c. 170Â mg/kg every 6 days) plus either a low or a high dose of DXR-SL (i.v. 1 or 5Â mg/kg every 6 days) were set: Schedule I, DXR-SL was given 3 days before the first CPA treatment; Schedule II, DXR-SL and CPA were given simultaneously; and, Schedule III, DXR-SL was given 3 days after the first CPA treatment. Lung weight and median survival time (MST) were evaluated. As expected, both the dosing schedule as well as the dose of DXR-SL improved therapeutic efficacy. Schedule I with the low DXR dose and Schedule II with the low or high DXR dose significantly increased MST, compared with regular metronomic CPA therapy. Under the dosing schedules (Schedule I with the low DXR dose and Schedule II with the high DXR), there was a strong relationship between increased MST and decreased lung weight. However, Schedule I with high DXR dose resulted in significantly lower lung weights, but did not increase MST, suggesting that chemotherapy may result in increased toxicity in some conditions. Although treatment regimens require optimization, the results of the present study may prove useful in further explorations of combining metronomic chemotherapy with liposomal anticancer drugs in the treatment of solid tumors.
Keywords
CHOLmPEG2000-DSPETSP-1MTDhEPCDXRWBCCPAMSTThrombospondin-1EPRMaximum tolerated doseCombination therapyDoxorubicinmedian survival timemononuclear phagocyte systemCyclophosphamideMetronomic chemotherapyPegylated liposomeEnhanced permeability and retentionMPshydrogenated egg phosphatidylcholinepolyethylene glycolPEGcholesterolwhite blood cells
Related Topics
Health Sciences
Pharmacology, Toxicology and Pharmaceutical Science
Pharmaceutical Science
Authors
Emi Shiraga, Jose Mario Barichello, Tatsuhiro Ishida, Hiroshi Kiwada,