Single nucleotide polymorphisms associated with elevated alanine aminotransferase in patients receiving asunaprevir plus daclatasvir combination therapy for chronic hepatitis C.

AIMS: Drug-induced liver damage characterized by serum alanine aminotransferase (ALT) elevation often occurs in direct-acting antiviral (DAA) combination therapy for chronic hepatitis C virus (HCV) infection. This study explored single nucleotide polymorphisms (SNPs) at drug metabolism- or transport-related genes that were associated with ALT elevation in asunaprevir plus daclatasvir therapy. METHODS: Subjects were 185 Japanese patients with chronic HCV genotype 1b infection who received asunaprevir plus daclatasvir therapy. Tag SNPs at possible metabolizing enzyme and transporter genes, which were involved in the pharmacokinetics of asunaprevir and daclatasvir, were selected. RESULTS: Among the tag SNPs analyzed, CYP3A4 rs4646437 was significantly associated with ALT elevation (p = 0.013): maximum ALT values in patients with genotype CC were higher than those in patients with genotype non-CC (allele T). The proportion of grades 2-4 in genotype CC patients were significantly greater than those in genotype non-CC patients (p = 0.028). No patients with genotype non-CC showed grade ≥2 ALT elevation. In multivariate analysis, rs4646437 genotype CC and cirrhosis were significant, independent factors associated with grade ≥1 ALT elevation (odds ratio, 2.83 and 1.88; p = 0.040 and 0.045, respectively). In exploratory analyses, although serum concentrations of asunaprevir and daclatasvir were not correlated with maximum ALT values or rs4646437 genotypes, asunaprevir concentrations in patients with grade ≥1 ALT elevation were significantly higher than those in patients with grade <1 ALT elevation (P = 0.023). CONCLUSIONS: CYP3A4 rs4646437 was found to be significantly and independently associated with ALT elevation in Japanese patients receiving ASV plus DCV therapy. Notably, none of the patients with rs4646437 genotype non-CC (allele T) had grade ≥2 ALT elevation. SNP genotyping prior to treatment might be useful for carefully monitoring patients to complete treatment safely.

Several factors including ITPA polymorphism influence ribavirin-induced anemia in chronic hepatitis C.

AIM: To construct formulae for predicting the likelihood of ribavirin-induced anemia in pegylated interferon α plus ribavirin for chronic hepatitis C. METHODS: Five hundred and sixty-one Japanese patients with hepatitis C virus genotype 1b who had received combination treatment were enrolled and assigned randomly to the derivation and confirmatory groups. Single nucleotide polymorphisms at or nearby ITPA were genotyped by real-time detection polymerase chain reaction. Factors influencing significant anemia (hemoglobin concentration < 10.0 g/dL at week 4 of treatment) and significant hemoglobin decline (declining concentrations > 3.0 g/dL at week 4) were analyzed using multiple regression analyses. Prediction formulae were constructed by significantly independent factors. RESULTS: Multivariate analysis for the derivation group identified four independent factors associated with significant hemoglobin decline: hemoglobin decline at week 2 [P = 3.29 × 10(-17), odds ratio (OR) = 7.54 (g/dL)], estimated glomerular filtration rate [P = 2.16 × 10(-4), OR = 0.962 (mL/min/1.73 m(2))], rs1127354 (P = 5.75 × 10(-4), OR = 10.94) and baseline hemoglobin [P = 7.86 × 10(-4), OR = 1.50 (g/dL)]. Using the model constructed by these factors, positive and negative predictive values and predictive accuracy were 79.8%, 88.8% and 86.2%, respectively. For the confirmatory group, they were 83.3%, 91.0% and 88.3%. These factors were closely correlated with significant anemia. However, the model could not be constructed, because no patients with rs1127354 minor genotype CA/AA had significant anemia. CONCLUSION: Reliable formulae for predicting the likelihood of ribavirin-induced anemia were constructed. Such modeling may be useful in developing individual tailoring and optimization of ribavirin dosage.

Contribution of ribavirin transporter gene polymorphism to treatment response in peginterferon plus ribavirin therapy for HCV genotype 1b patients.

BACKGROUND: Standard-dose ribavirin is crucial for the standard-of-care treatment of chronic hepatitis C virus (HCV) infection. Equilibrative nucleoside transporter 1 (ENT1), encoded by SLC29A1 gene, is the main transporter that imports ribavirin into human hepatocytes. AIMS: To determine whether single nucleotide polymorphisms (SNPs) at the SLC29A1 gene could influence the probability of treatment response compared with other baseline and host genetic factors. METHODS: A total of 526 East Asian patients monoinfected with HCV genotype 1b who had received pegylated interferon alpha plus ribavirin therapy were enrolled in this study. They were assigned randomly to the derivation and confirmatory groups. SNPs related to the IL28B, ITPA and SLC29A1 genes were genotyped using real-time detection polymerase chain reaction. Factors associated with sustained virological response (SVR) were analysed using multiple logistic regression analysis. RESULTS: Multivariate analysis for the derivation group identified six baseline variables significantly and independently associated with SVR: age [P = 0.023, odds ratio (OR) = 0.97], gender (P = 0.0047, OR = 2.25), platelet count (P = 0.00017, OR = 1.11), viral load (P = 0.00026, OR = 0.54), IL28B SNP rs12979860 (P = 1.09 × 10(-7) , OR = 8.68) and SLC29A1 SNP rs6932345 (P = 0.030, OR = 1.85). Using the model constructed by these independent variables, positive and negative predictive values and predictive accuracy were 73.3, 70.1 and 71.9% respectively. For the confirmatory group, they were 71.4, 84.6 and 75.3% respectively. The SLC29A1 and IL28B SNPs were also significantly associated with rapid virological response. CONCLUSIONS: The SNP at the major ribavirin transporter ENT1 gene SLC29A1 was one of significantly independent factors influencing treatment response, although the impact on the prediction was small.