acyclovir and ganciclovir-triphosphate

Nucleobase and nucleoside analogs (NNA) are widely used as anti-viral and anti-cancer agents, and NNA phosphorylation is essential for the activity of this class of drugs. Recently, diphosphatase NUDT15 was linked to thiopurine metabolism with NUDT15 polymorphism associated with drug toxicity in patients. Profiling NNA drugs, we identify acyclovir (ACV) and ganciclovir (GCV) as two new NNAs metabolized by NUDT15. NUDT15 hydrolyzes ACV and GCV triphosphate metabolites, reducing their effects against cytomegalovirus (CMV) in vitro. Loss of NUDT15 potentiates cytotoxicity of ACV and GCV in host cells. In hematopoietic stem cell transplant patients, the risk of CMV viremia following ACV prophylaxis is associated with NUDT15 genotype (P = 0.015). Donor NUDT15 deficiency is linked to graft failure in patients receiving CMV-seropositive stem cells (P = 0.047). In conclusion, NUDT15 is an important metabolizing enzyme for ACV and GCV, and NUDT15 variation contributes to inter-patient variability in their therapeutic effects.

Topics: Acyclovir; Adolescent; Adult; Aged; Animals; Antibiotic Prophylaxis; Antiviral Agents; Biological Variation, Population; Cell Line; Child; Child, Preschool; Crystallography, X-Ray; Cytomegalovirus; Cytomegalovirus Infections; Disease Models, Animal; DNA, Viral; Drug Resistance, Viral; Female; Ganciclovir; Hematopoietic Stem Cell Transplantation; Host Microbial Interactions; Humans; Infant; Infant, Newborn; Male; Middle Aged; Muromegalovirus; Pharmacogenomic Variants; Polymorphism, Single Nucleotide; Pyrophosphatases; Treatment Outcome; Young Adult

Acyclovir triphosphate, ganciclovir triphosphate and penciclovir triphosphate inhibited DNA polymerases alpha, delta, and epsilon. Each triphosphate preferentially inhibited pol delta, although ganciclovir triphosphate was the most impressive of the three; the Ki for inhibition of pol delta was 2 microM (competitive with dGTP), while the Kis for inhibition of pol alpha and epsilon were 80 and 140 microM, respectively. Each of the compounds was polymerized by pol alpha, delta, and epsilon. Incorporation of acyclovir triphosphate resulted in immediate chain termination, whereas incorporation of ganciclovir triphosphate often allowed polymerization of additional dNTPs. Interestingly, chain termination most often occurred after polymerization of just one additional dNTP onto the ganciclovir monophosphate. All three compounds were very weak inhibitors of DNA primase. Acyclovir triphosphate, however, was a unique inhibitor of the pol alpha-catalyzed elongation of primase-synthesized primers. Immediately after DNA primase synthesized a primer, pol alpha frequently incorporated acyclovir triphosphate with consequent chain termination. If, however, pol alpha did not immediately polymerize acyclovir triphosphate onto the primase-synthesized primer, further dNTPs were readily added and acyclovir triphosphate was incorporated much less frequently.

Topics: Acyclovir; Animals; Base Sequence; Cattle; DNA; DNA Polymerase II; DNA Polymerase III; DNA Primase; Ganciclovir; Guanosine; Humans; In Vitro Techniques; Kinetics; Molecular Sequence Data; Nucleic Acid Synthesis Inhibitors; Oligodeoxyribonucleotides; RNA Nucleotidyltransferases; Substrate Specificity