A Pilot Study of Rapid Haplotyping Procedure for Personalized Dosing of Dichloroacetate (DCA) in Healthy Volunteers

Pyruvate dehydrogenase complex (PDC) deficiency (PDCD) is a rare disease of mitochondrial energy failure with the life of expectancy of affected children severely truncated. Treatment of PDCD remains a serious, unmet challenge. Dichloroacetate (DCA) represents the first targeted therapy for PDCD by stimulating residual PDC activity. Cumulative experience with DCA has revealed dose accumulation in a subset of the population. This can be abated through personalized dosing of DCA, assigned by haplotype variation in the gene encoding glutathione transferase zeta 1 (GSTZ1), which biotransforms DCA to glyoxylate. Haplotype variations in GSTZ1 influence the kinetics and dynamics of chronically administered DCA. A single dose of DCA has a bioavailability approaching unity and is widely distributed throughout the body. The plasma half-life (t ½) is \~1 hr in drug-naïve subjects. Gender does not influence DCA kinetics or metabolism. The major route of biotransformation is via dehalogenation to glyoxylate by glutathione transferase zeta 1 (GSTZ1). DCA is a mechanism-based inhibitor of GSTZ1, so repeated administration results in increased plasma t ½ and decreased clearance.