A statistical approach for analyzing data from the in vivo Pig-a gene mutation assay

Publication date: July 2018Source: Mutation Research/Genetic Toxicology and Environmental Mutagenesis, Volume 831Author(s): Bernd-Wolfgang Igl, Stephen D. Dertinger, Vasily N. Dobrovolsky, Marian Raschke, Andreas Sutter, Richardus VonkAbstractThe in vivo Pig-a gene mutation assay serves to evaluate the genotoxic potential of chemicals. In the rat blood-based assay, the lack of CD59 on the surface of erythrocytes is quantified via fluorophore-labeled antibodies in conjunction with flow cytometric analysis to determine the frequency of Pig-a mutant phenotype cells. The assay has achieved regulatory relevance as it is suggested as an in vivo follow-up test for Ames mutagens in the recent ICH M7 [25] step 4 document. However, very little work exists regarding suitable statistical approaches for analyzing Pig-a data. In the current report, we present a statistical strategy based on a two factor model involving ‘treatment’ and ‘time’ incl. their interaction and a baseline covariate for log proportions to compare treatment and vehicle data per time point as well as in time. In doing so, multiple contrast tests allow us to discover time-related changes within and between treatment groups in addition to multiple treatment comparisons to a control group per single time point. We compare our proposed strategy with the results of classical Dunnett and Wilcoxon-Mann-Whitney tests using two data sets describing the mode of action of Chlorambucil and Glycidyl methacrylate both analy...
Source: Mutation Research Genetic Toxicology and Environmental Mutagenesis - Category: Genetics & Stem Cells Source Type: research