ABSTRACT
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.
Subject(s)
Acyclovir/pharmacology , Antiviral Agents/pharmacology , Cytomegalovirus Infections/prevention & control , Ganciclovir/analogs & derivatives , Pyrophosphatases/genetics , Acyclovir/therapeutic use , Adolescent , Adult , Aged , Animals , Antibiotic Prophylaxis , Antiviral Agents/therapeutic use , Biological Variation, Population/genetics , Cell Line , Child , Child, Preschool , Crystallography, X-Ray , Cytomegalovirus/drug effects , Cytomegalovirus/genetics , Cytomegalovirus/isolation & purification , Cytomegalovirus Infections/diagnosis , Cytomegalovirus Infections/etiology , Cytomegalovirus Infections/virology , DNA, Viral/blood , DNA, Viral/isolation & purification , Disease Models, Animal , Drug Resistance, Viral , Female , Ganciclovir/pharmacology , Ganciclovir/therapeutic use , Hematopoietic Stem Cell Transplantation/adverse effects , Host Microbial Interactions/genetics , Humans , Infant , Infant, Newborn , Male , Middle Aged , Muromegalovirus/isolation & purification , Muromegalovirus/pathogenicity , Pharmacogenomic Variants , Polymorphism, Single Nucleotide , Pyrophosphatases/metabolism , Pyrophosphatases/ultrastructure , Treatment Outcome , Young AdultABSTRACT
Thiopurines (eg, 6-mercaptopurine [MP]) are highly efficacious antileukemic agents, but they are also associated with dose-limiting toxicities. Recent studies by us and others have identified inherited NUDT15 deficiency as a novel genetic cause of thiopurine toxicity, and there is a strong rationale for NUDT15-guided dose individualization to preemptively mitigate adverse effects of these drugs. Using CRISPR-Cas9 genome editing, we established a Nudt15-/- mouse model to evaluate the effectiveness of this strategy in vivo. Across MP dosages, Nudt15-/- mice experienced severe leukopenia, rapid weight loss, earlier death resulting from toxicity, and more bone marrow hypocellularity compared with wild-type mice. Nudt15-/- mice also showed excessive accumulation of a thiopurine active metabolite (ie, DNA-incorporated thioguanine nucleotides [DNA-TG]) in an MP dose-dependent fashion, as a plausible cause of increased toxicity. MP dose reduction effectively normalized systemic exposure to DNA-TG in Nudt15-/- mice and largely eliminated Nudt15 deficiency-mediated toxicity. In 95 children with acute lymphoblastic leukemia, MP dose adjustment also directly led to alteration in DNA-TG levels, the effects of which were proportional to the degree of NUDT15 deficiency. Using leukemia-bearing mice with concordant Nudt15 genotype in leukemia and host, we also confirmed that therapeutic efficacy was preserved in Nudt15-/- mice receiving a reduced MP dose compared with Nudt15+/+ counterparts exposed to a standard dose. In conclusion, we demonstrated that NUDT15 genotype-guided MP dose individualization can preemptively mitigate toxicity without compromising therapeutic efficacy.
Subject(s)
Antimetabolites, Antineoplastic/therapeutic use , Leukemia/drug therapy , Mercaptopurine/therapeutic use , Phosphoric Diester Hydrolases/genetics , Animals , Antimetabolites, Antineoplastic/administration & dosage , Antimetabolites, Antineoplastic/toxicity , CRISPR-Cas Systems , Child , Drug Dosage Calculations , Drug Evaluation, Preclinical , Gene Deletion , Gene Editing , Genotype , Humans , Leukemia/genetics , Leukemia/pathology , Mercaptopurine/administration & dosage , Mercaptopurine/toxicity , Mice , Mice, Knockout , Pyrophosphatases/geneticsABSTRACT
The purpose of this study was to provide a pharmacokinetics/pharmacodynamics and toxicokinetics/toxicodynamics bridging of kinase inhibitors by identifying the relationship between their clinical and preclinical (rat, dog, and monkey) data on exposure and efficacy/toxicity. For the eight kinase inhibitors approved in Japan (imatinib, gefitinib, erlotinib, sorafenib, sunitinib, nilotinib, dasatinib, and lapatinib), the human unbound area under the concentration-time curve at steady state (AUC(ss,u)) at the clinical dose correlated well with animal AUC(ss,u) at the no-observed-adverse-effect level (NOAEL) or maximum tolerated dose (MTD). The best correlation was observed for rat AUC(ss,u) at the MTD (p < 0.001). E(max) model analysis was performed using the efficacy of each drug in xenograft mice, and the efficacy at the human AUC of the clinical dose was evaluated. The predicted efficacy at the human AUC of the clinical dose varied from far below E(max) to around E(max) even in the tumor for which use of the drugs had been accepted. These results suggest that rat AUC(ss,u) at the MTD, but not the efficacy in xenograft mice, may be a useful parameter to estimate the human clinical dose of kinase inhibitors, which seems to be currently determined by toxicity rather than efficacy.