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Cancer Chemother Pharmacol. 2008 Feb;61(2):291-9. Epub 2007 Apr 12.

Pharmacodynamic characterization of gemcitabine cytotoxicity in an in vitro cell culture bioreactor system.

Author information

1
Department of Experimental and Clinical Pharmacology, College of Pharmacy and Comprehensive Cancer Center, University of Minnesota, 308 Harvard St SE, Minneapolis, MN 55455, USA. kirst002@umn.edu

Abstract

PURPOSE:

Gemcitabine, a pyrimidine nucleoside, is approved for the treatment of non-small cell lung cancer, pancreatic carcinoma, and breast cancer. Chemotherapy regimens are determined experimentally with static tissue culture systems, animal models, and in Phase I clinical trials. The aim of this study was to assess for gemcitabine-induced cell death following infusion of drug under clinically-relevant conditions of infusion rate and drug exposure in an in vitro bioreactor system.

METHODS:

To estimate an appropriate harvest time for cells from the bioreactor after drug treatment, we estimated the temporal relationship between gemcitabine treatment for 1 h and cell death at a later time point with monolayer growth assays (i.e., static culture). Afterward, 5.3 mg gemcitabine was infused over 0.5 h in the bioreactor, followed by mono-exponential decay, simulating patient concentration-time profiles (n = 4). Controls were run with drug-free media (n = 4). Cells were harvested from the bioreactor at a later time point and assessed for cell death by flow cytometry.

RESULTS:

According to monolayer growth assay results, cytotoxicity became more apparent with increasing time. The E Max for cells 48 h after treatment was 50% and after 144 h, 93% (P = 0.022; t test), while flow cytometry showed complete DNA degradation by 120 h. Gemcitabine was infused in the bioreactor. The gemcitabine area under the concentration-time curve (AUC) was 56.4 microM h and the maximum concentration was 87.5 +/- 2.65 microM. Flow cytometry results were as follows: the G1 fraction decreased from 65.1 +/- 4.91 to 28.6 +/- 12% (P = 0.005) and subG1 increased from 14.1 +/- 5.28 to 42.6 +/- 9.78% (P = 0.004) relative to control. An increase in apoptotic cells was observed by TUNEL assay.

CONCLUSIONS:

The in vitro bioreactor system will be expanded to test additional cell lines, and will serve as a useful model system for assessing the role of drug pharmacokinetics in delivery of optimized anticancer treatment.

PMID:
17429628
DOI:
10.1007/s00280-007-0474-z
[Indexed for MEDLINE]

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