The nucleotide prodrug CERC‐913 improves mtDNA content in primary hepatocytes from DGUOK‐deficient rats

Abstract

Loss-of-function mutations in the deoxyguanosine kinase (DGUOK) gene result in a mitochondrial DNA (mtDNA) depletion syndrome. DGUOK plays an important role in converting deoxyribonucleosides to deoxyribonucleoside monophosphates via the salvage pathway for mtDNA synthesis. DGUOK deficiency manifests predominantly in the liver; the most common cause of death is liver failure within the first year of life and no therapeutic options are currently available. in vitro supplementation with deoxyguanosine or deoxyguanosine monophosphate (dGMP) were reported to rescue mtDNA depletion in DGUOK-deficient, patient-derived fibroblasts and myoblasts. CERC-913, a novel ProTide prodrug of dGMP, was designed to bypass defective DGUOK while improving permeability and stability relative to nucleoside monophosphates. To evaluate CERC-913 for its ability to rescue mtDNA depletion, we developed a primary hepatocyte culture model using liver tissue from DGUOK-deficient rats. DGUOK knockout rat hepatocyte cultures exhibit severely reduced mtDNA copy number (10%) relative to wild type by qPCR and mtDNA content remains stable for up to 8 days in culture. CERC-913 increased mtDNA content in DGUOK-deficient hepatocytes up to 2.4-fold after 4 days of treatment in a dose-dependent fashion, which was significantly more effective than dGMP at similar concentrations. These early results suggest primary hepatocyte culture is a useful model for the study of mtDNA depletion syndromes and that CERC-913 treatment can improve mtDNA content in this model. K E Y W O R D S deoxyguanosine kinase, deoxyguanosine kinase deficiency, mtDNA depletion syndrome, primary hepatocyte cell culture, ProTide † Please note that we are requesting co-first authorship for authors Mark Vanden Avond and Hui Meng as they both did extensive proportions of the work at all levels.

Editorial: Mitochondrial medicine special issue

“…Two novel treatments at a preclinical stage of evaluation are presented: a reactive oxygen species scavenger JP4-039 for sulfite oxidase deficiency 12 and a nucleotide prodrug CERC-913 proposed for deoxyguanosine kinase deficiency. 13 Finally, a phase II open label prospective trial of (+)-epicatechin in Friedreich ataxia 14 reflects the increasing number of clinical trials being conducted in mitochondrial diseases.…”

“…This special issue of the journal focused on mitochondrial medicine also includes a position paper on the diagnosis and management of mitochondrial neurogastrointestinal encephalomyopathy, 8 the first description of pathogenic variants in OGDH , 9 and expansion of the phenotypic description of ECHS1 and HIBCH 10 and TANGO2 11 deficiencies. Two novel treatments at a preclinical stage of evaluation are presented: a reactive oxygen species scavenger JP4‐039 for sulfite oxidase deficiency 12 and a nucleotide prodrug CERC‐913 proposed for deoxyguanosine kinase deficiency 13 . Finally, a phase II open label prospective trial of (+)‐epicatechin in Friedreich ataxia 14 reflects the increasing number of clinical trials being conducted in mitochondrial diseases.…”