Serum and cellular ribavirin pharmacokinetic and concentration-effect analysis in HCV patients receiving sofosbuvir plus ribavirin

Ribavirin and cellular ribavirin-triphosphate concentrations in blood and bronchoalveolar lavage fluid in two lung transplant patients with respiratory syncytial virus

Respiratory syncytial virus (RSV) is responsible for significant morbidity and mortality in the lung transplant population. Oral and aerosolized ribavirin may improve outcomes in lung transplant patients with RSV; however, data relating ribavirin concentrations in plasma and intracellular ribavirin triphosphate (iRTP) concentrations in blood and bronchoalveolar lavage (BAL) fluid cells with efficacy and safety are lacking. We describe ribavirin and iRTP concentrations within various compartments in two adult lung transplant recipients with RSV who were sampled throughout successful treatment courses with oral and inhaled ribavirin. In patient 1, iRTP BAL concentrations decreased by 45% over 3 days after changing inhaled ribavirin to oral (6.32 to 3.43 pmol/10⁶ cells). In patient 2, iRTP BAL concentrations were 103 pmol/10⁶ cells after 5 days of oral followed by 5 days of inhaled ribavirin. Further study is needed to describe ribavirin pharmacokinetics in the respiratory compartment to inform clinical use of ribavirin for respiratory viruses.

Effects of sofosbuvir-based hepatitis C treatment on the pharmacokinetics of tenofovir in HIV/HCV-coinfected individuals receiving tenofovir disoproxil fumarate

Background

The nucleotide analogues tenofovir and sofosbuvir are considered to have low potential for drug interactions.

Objectives

To determine the effect of sofosbuvir-based HCV treatment on plasma concentrations of tenofovir and cellular concentrations of tenofovir diphosphate.

Methods

HIV-infected participants with acute HCV were treated for 12 weeks with sofosbuvir + ribavirin in Cohort 1 or 8 weeks with ledipasvir/sofosbuvir in Cohort 2 of AIDS Clinical Trials Group study 5327. Only participants taking tenofovir disoproxil fumarate were included in this analysis. Tenofovir in plasma, tenofovir diphosphate in dried blood spots and tenofovir diphosphate in PBMCs were measured pre-HCV therapy and longitudinally during the study using validated LC/MS-MS.

Results

Fifteen and 22 men completed Cohorts 1 and 2, respectively. In Cohort 1, tenofovir diphosphate was 4.3-fold higher (95% CI geometric mean ratio 2.46-7.67; P = 0.0001) in dried blood spots and 2.3-fold higher (95% CI 1.09-4.92; P = 0.03) in PBMCs following 12 weeks of sofosbuvir + ribavirin versus study entry. Tenofovir in the plasma was unchanged. In Cohort 2, tenofovir diphosphate was 17.8-fold higher (95% CI 12.77-24.86; P < 0.0001) in dried blood spots after 8 weeks of ledipasvir/sofosbuvir versus study entry. Tenofovir plasma concentrations were 2.1-fold higher (95% CI 1.44-2.91; P = 0.0005). Despite the increase in cellular tenofovir diphosphate concentrations, only a small decline in CLCR (6%-7%) was observed in both cohorts between study entry and end of treatment.

Conclusions

These data indicate an unexpected drug interaction with tenofovir disoproxil fumarate and sofosbuvir at the cellular level. Additional studies are needed to determine the mechanism and clinical significance.

Comparison of the effect of direct-acting antiviral with and without ribavirin on cyclosporine and tacrolimus clearance values: results from the ANRS CO23 CUPILT cohort

PURPOSE

Direct-acting antiviral agents have demonstrated their efficacy in treating HCV recurrence after liver transplantation and particularly the sofosbuvir/daclatasvir combination. Pharmacokinetic data on both calcineurin inhibitors and direct-acting antiviral exposure in liver transplant recipients remain sparse.

METHODS

Patients were enrolled from the ANRS CO23 CUPILT cohort. All patients treated with sofosbuvir/daclatasvir with or without ribavirin were included in this study when blood samples were available to estimate the clearance of immunosuppressive therapy before direct-acting antiviral initiation and during follow-up. Apparent tacrolimus and cyclosporine clearances were estimated from trough concentrations measured using validated quality control assays.

RESULTS

Sixty-seven mainly male patients (79%) were included, with a mean age of 57 years and mean MELD score of 8.2; 50 were on tacrolimus, 17 on cyclosporine. Ribavirin was combined with sofosbuvir/daclatasvir in 52% of patients. Cyclosporine clearance remained unchanged as well as tacrolimus clearance under the ribavirin-free regimen. Tacrolimus clearance increased 4 weeks after direct-acting antivirals and ribavirin initiation versus baseline (geometric mean ratio 1.81; 90% CI 1.30-2.52). Patients under ribavirin had a significantly higher fibrosis stage (> 2) (p = 0.02) and lower haemoglobin during direct-acting antiviral treatment (p = 0.02) which impacted tacrolimus measurements. Direct-acting antiviral exposure was within the expected range.

CONCLUSION

Our study demonstrated that liver transplant patients with a recurrence of hepatitis C who are initiating ribavirin combined with a sofosbuvir-daclatasvir direct-acting antiviral regimen may be at risk of lower tacrolimus concentrations because of probable ribavirin-induced anaemia and higher fibrosis score, although there are no effects on cyclosporine levels.

TRIAL REGISTRATION

NCT01944527.

Tolerability of Erythrocyte Ribavirin Triphosphate Concentrations Depends on the ITPA Genotype

BACKGROUND

Ribavirin (RBV) is an antiviral drug that is part of the current standard therapy for chronic hepatitis C (CHC). It is enzymatically converted to ribavirin triphosphate (RTP) that inhibits the activity of viral RNA polymerase, thereby preventing viral replication. However, one of its adverse effects includes hemolytic anemia that limits its application. The variant of ITPA (inosine triphosphatase), which dephosphorylates inosine triphosphate to inosine monophosphate, is a protective factor for RBV-induced anemia. RTP is an important metabolite required for ribavirin action. This study evaluated the time-dependent association of RTP concentrations in erythrocytes, RBV-induced toxicity, and virological response to RBV treatment for hepatitis C.

METHODS

A total of 28 Japanese patients with CHC were treated with RBV/peg-interferon/simeprevir or RBV/sofosbuvir and were genotyped for ITPA variants (rs1127354 and rs7270101). We measured RTP concentrations in erythrocytes in a total of 76 samples collected at 4, 8, and 12 weeks from the initiation of treatment.

RESULTS

The ITPA rs1127354 variant was found in 7 patients. This was associated with significantly higher RTP concentrations in erythrocytes than in the wild-type patients (P < 0.001). Moreover, a significant correlation was observed between RTP concentrations and decline in hemoglobin (Hb) levels from baseline values in ITPA wild type and rs1127354 variant 12 weeks after treatment initiation (P < 0.01; r = -0.618 and -0.967, respectively). Multiple regression analysis revealed that ITPA genotype and erythrocyte RTP concentrations were major factors associated with reduced Hb levels in RBV therapy for CHC. However, we did not find any association between erythrocyte concentrations and virological response.

CONCLUSIONS

The increased tolerability to RTP concentrations in erythrocytes in the ITPA variant rs1127354 plays a role in preventing RBV-induced severe anemia in this ITPA variant.

Safety and efficacy of sofosbuvir and ribavirin for genotype 2 hepatitis C Japanese patients with renal dysfunction

AIM

The safety and efficacy of sofosbuvir (SOF) and ribavirin (RBV) have not been well clarified in patients with renal dysfunction because clinical trials have not included such patients. We evaluated the safety and efficacy of SOF and RBV for genotype 2 hepatitis C virus (HCV)-infected patients with renal dysfunction.

METHODS

The study included genotype 2 HCV-infected patients who received SOF and RBV between July 2014 and May 2017. The sustained virologic response (SVR) after the treatment and safety during the therapy were evaluated according to renal function.

RESULTS

A total of 231 patients were included in this study. The median age was 62 years old, and 45.9% (106/231) were men. Of the 231 patients, 191 (82.8%) and 40 (17.2%) were classified as having chronic kidney disease (CKD) stages G1/2 and G3, respectively. The overall SVR rate was 97% (224/231). The SVR rates in patients with CKD stages G1, 2, G3a, and G3b were 98.1%, 98.6%, 87.9%, and 100%, respectively, and this therapy was tolerated. Multivariate analysis indicated that renal dysfunction was significantly associated with a non-SVR (odds ratio, 6.963; 95% confidence interval, 1.494-32.41; P = 0.013). The patients with renal dysfunction were older, had advanced liver fibrosis, lower baseline platelet and hemoglobin levels, and a higher rate of RBV dose reduction.

CONCLUSIONS

Sofosbuvir and RBV therapy is highly effective and safe for genotype 2 HCV-infected Japanese patients. However, attention should be paid to baseline renal function when SOF- and RBV-containing regimens are used for patients with renal dysfunction.

Sofosbuvir and Ribavirin Liver Pharmacokinetics in Patients Infected with Hepatitis C Virus

Sofosbuvir and ribavirin exert their anti-hepatitis C virus (anti-HCV) activity following metabolic activation in the liver. However, intrahepatic concentrations of the pharmacologically active nucleotide metabolites in humans are poorly characterized due to the inaccessibility of tissue and technical challenges with measuring nucleotide levels. A clinical study assessing the efficacy of sofosbuvir and ribavirin administered prior to liver transplantation to prevent HCV recurrence provided a unique opportunity to quantify nucleotide concentrations in human liver. We analyzed nucleotides using high-performance liquid chromatography coupled to tandem mass spectrometry in liver tissue from 30 HCV-infected patients with hepatocellular carcinoma who were administered sofosbuvir (400 mg/day) and ribavirin (1,000 to 1,200 mg/day) for 3 to 52 weeks prior to liver transplantation. Median total hepatic metabolite concentrations (the sum of nucleoside and mono-, di-, and triphosphates) were 77.1 μM for sofosbuvir and 361 μM for ribavirin in patients on therapy at the time of transplantation. Ribavirin and sofosbuvir efficiently loaded the liver, with total hepatic metabolite concentrations exceeding maximal levels in plasma by approximately 30-fold. Ribavirin metabolite levels suggest that its monophosphate is in great excess of its inhibition constant for IMP dehydrogenase and that its triphosphate is approaching the binding constant for incorporation by the HCV NS5B RNA-dependent RNA polymerase. In accordance with the potent antiviral activity of sofosbuvir, these results demonstrate that the liver triphosphate levels achieved following sofosbuvir administration greatly exceed the inhibition constant for HCV NS5B. In conclusion, this study expands the quantitative understanding of the pharmacology of sofosbuvir and ribavirin by establishing efficient hepatic delivery in the clinic. (This study has been registered at ClinicalTrials.gov under identifier NCT01559844.).

Liver decompensation predicts ribavirin overexposure in hepatitis C virus patients treated with direct-acting antivirals

AIM

To determine whether ribavirin (RBV) concentrations differ according to cirrhosis stage among cirrhotic patients treated with interferon-free regimens.

METHODS

We included patients with hepatitis C virus and cirrhosis [Child-Pugh (CP) A or B], Glomerular Filtration Rate ≥ 60 mL/min, who started therapy with DAAs and weight-based RBV between October 2014 and February 2016. RBV plasma levels were assessed during the treatment. We focused our analysis on the first 8 wk of therapy.

RESULTS

We studied 68 patients: 54 with compensated (CP-B) and 14 with decompensated (CP-A) cirrhosis. Patients with decompensated cirrhosis displayed significantly higher RBV concentrations than those with compensated cirrhosis at week 1, 2, 4 and 8 (P < 0.035). RBV levels were positively correlated with Hb loss over the treatment (P < 0.04). Majority (71%) of CP-B patients required a RBV dosage reduction during the treatment. After adjustment for confounders, Child-Pugh class remained significantly associated (95%CI: 35, 348, P = 0.017) to RBV levels, independently from baseline per-Kg RBV dosage.

CONCLUSION

Liver decompensation might affect RBV clearance leading to an overexposure and increased related toxicities in decompensated cirrhosis. Our findings underscore the importance of an early ribavirin therapeutic drug monitoring and suggest that an initial lower RBV dose, rather than weight-based, might be considered in those with advanced liver disease (CP-B) treated with direct-acting antivirals.

Efficiency and Safety of an Early Dose Adjustment of Ribavirin in Patients Infected With Hepatitis C Underexposed to the Drug and Treated With Peginterferon Ribavirin

BACKGROUND

Ribavirin exposure after the first dose (D0AUC0-4h) >1755 mcg·h·L is predictive of sustained virological response (SVR) in patients with hepatitis C treated with peginterferon and ribavirin. The aim of this study was to test the benefit of ribavirin early dose adjustment based on this target in naïve patients infected with genotype 1.

METHODS

A multicenter randomized controlled trial with two parallel groups; fixed-dose (FD) group: standard of care in 2010-2011, ie, peginterferon-α2a 180 mcg·wk and weight-based ribavirin 1000-1200 mg/d during 48 weeks; adapted-dose (AD) group: increase of ribavirin dose if D0AUC0-4h <1755 mcg·h·L.

RESULTS

A total of 221 patients were included, 110 in the AD group and 111 in the FD group with similar baseline characteristics. In the perprotocol analysis, SVR was higher in the AD group (55.1% versus 40.4%; P = 0.042), especially in patients with D0AUC0-4h <1755 mcg·h·L (54.3% versus 31.9%; P = 0.029). In the intention-to-treat analysis, the difference was not significant (50% versus 41%; P = 0.197). Ribavirin trough concentrations (C0s) at week 4 of treatment (intention-to-treat analysis) were higher in patients achieving SVR (2.06 versus 1.72 mg/L, P = 0.003). In the subgroup of patients with AUC0-4h <1755 mcg·h·L, 46% of patients with AD achieved a C0 >2.0 mg/L versus 22% of patients with FD (P = 0.013). Grade 1 anemia (but not other grades) was more frequent in the AD group (70% versus 48%, P = 0.001). The number of dose reductions or discontinuation of ribavirin was similar in both groups.

CONCLUSIONS

Early ribavirin dose adjustment increases SVR in patients underexposed to ribavirin without increasing grade II-IV anemia. Such a strategy could be useful in patients with no access to new antiviral drugs.

The role of ITPA and ribavirin transporter genes polymorphisms in prediction of ribavirin-induced anaemia in chronic hepatitis C Egyptian patients

Few data are available concerning the roles of polymorphisms of inosine triphosphatase (ITPA) gene and ribavirin (RBV) transporter genes in the prediction of RBV-induced anaemia among Egyptians with chronic hepatitis C (CHC). Genotyping of three ITPA gene variants and two variants of RBV transporter genes has been performed in 123 patients under pegylated interferon-α/ribavirin treatment. The baseline haemoglobin and ITPA rs1127354 CA/AA have been found as predictors of anaemia at 4, 8 and 12 weeks of RBV therapy. In addition, ITPA rs7270101 AC/CC and age predicted anaemia after 12 weeks of therapy. In conclusion, the ITPA variant rs1127354C>A significantly predict RBV-induced anaemia during the first 3 months of treatment and it is recommended to be assessed before RBV administration.

ITPA polymorphism effects on decrease of hemoglobin during sofosbuvir and ribavirin combination treatment for chronic hepatitis C

BACKGROUND

Polymorphisms in the inosine triphosphatase (ITPA) gene is associated with anemia induced by peg-interferon (PEG-IFN) plus ribavirin (RBV) treatment for patients with chronic hepatitis C virus (HCV) infection. However, the effect of ITPA polymorphism on sofosbuvir plus RBV treatment is unknown.

METHODS

Two hundred and forty-four patients with chronic HCV genotype 2 infection without decompensated liver cirrhosis were treated with sofosbuvir plus RBV for 12 weeks. The effects of ITPA polymorphism on hemoglobin levels and RBV dose reduction and treatment response were analyzed. ITPA (rs1127354) was genotyped using the Invader assay. Multivariate regression analysis was performed to identify factors associated with sustained virological response (SVR).

RESULTS

Overall, SVR12 was achieved in 231 (94.7%) patients, based on intention to treat analysis. During the therapy, reduction of hemoglobin levels was significantly greater in ITPA genotype CC patients than CA/AA patients. Therefore, the cumulative proportion of patients with RBV dose reduction was significantly higher and total dose of RBV was significantly lower in patients with CC genotype compared to CA/AA genotypes. SVR12 rates were similar between ITPA genotypes CC and CA/AA (94.7 and 94.4%, respectively, P = 0.933). Multivariate logistic regression analysis identified FIB4 index <3.25 (odds ratio [OR], 9.388 for ≥3.25; P = 0.005) and low body weight (OR, 1.059, for high body weight; P = 0.017) as independent predictors for SVR12.

CONCLUSIONS

ITPA polymorphism influences hemoglobin levels and incidence of RBV dose reduction during sofosbuvir plus RBV therapy. However, ITPA genotype CC patients can expect a curative effect equivalent to CA/AA patients for chronic HCV genotype 2 infection.

Sofosbuvir Plus Ribavirin Without Interferon for Treatment of Acute Hepatitis C Virus Infection in HIV-1-Infected Individuals: SWIFT-C

Background

Historically, acute hepatitis C virus (HCV) infection was treated with shorter durations of interferon-containing therapies. In the era of direct-acting antivirals (DAAs), it is unclear whether the efficacy of treatment achieved in chronic infection can be maintained with abbreviated courses of therapy during the acute phase.

Methods

The sofosbuvir-containing regimens without interferon for treatment of acute HCV in HIV-1 infected individuals (SWIFT-C) is an open-label, 2-cohort clinical trial in which the first cohort assessed for the safety and efficacy of 12 weeks of sofosbuvir plus ribavirin for the treatment of acute HCV infection in participants with chronic human immunodeficiency virus type 1 (HIV-1) infection. This is a preplanned analysis of the first cohort, which had a planned accrual of 17 participants.

Results

Seventeen men (11 Hispanic, 6 white, median age 45 years) were enrolled. Most (88%) had HCV genotype-1 infection and few (24%) had the favorable IL28B CC genotype. Median baseline HCV RNA was 2 280 000 IU/mL (interquartile range, 272 000-4 230 000). Ten participants (59%) achieved the primary outcome of SVR12 (90% confidence interval, 36%-78%), failing to establish noninferiority. All treatment failures were due to viral relapse (41%). There were no premature treatment discontinuations. The only factor that differed between participants who achieved SVR vs those who relapsed was ribavirin concentration at the end of treatment.

Conclusion

Sofosbuvir-ribavirin for 12 weeks for the treatment of acute HCV genotype-1 infection in HIV-1-infected persons results in a high relapse rate. Preliminary studies of DAA combination therapies suggest improved response rates, although the adequate duration of therapy remains unclear.

Clinical Trials Registration

NCT02128217.

Hematological adverse effects and pharmacokinetics of ribavirin in pigs following intramuscular administration

Ribavirin (RBV) is a synthetic guanosine analog that is used as a drug against various viral diseases in humans. The in vitro antiviral effects of ribavirin against porcine viruses were demonstrated in several studies. The purposes of this study were to evaluate the adverse effects and pharmacokinetics of ribavirin following its intramuscular (IM) injection in pigs. Ribavirin was formulated as a double-oil emulsion (RBV-DOE) and gel (RBV-Gel), which were injected into the pigs as single-dose IM injections. After injection of RBV, all of the pigs were monitored. The collected serum and whole blood samples were analyzed by liquid chromatography-tandem mass spectrometry and complete blood count analysis, respectively. All of the ribavirin-treated pigs showed significant decreases in body weight compared to the control groups. Severe clinical signs including dyspnea, anorexia, weakness, and depression were present in ribavirin-treated pigs until 5 days postinjection (dpi). The ribavirin-treated groups showed significant decrease in the number of red blood cells and hemoglobin concentration until 8 dpi. The mean half-life of the RBV-DOE and RBV-Gel was 27.949 ± 2.783 h and 37.374 ± 3.502 h, respectively. The mean peak serum concentration (C_max ) and area under the serum concentration-time curve from time zero to infinity (AUC_inf ) of RBV-DOE were 8340.000 ± 2562.577 ng/mL and 16 0095.430 ± 61 253.400 h·ng/mL, respectively. The C_max and AUC_inf of RBV-Gel were 15 300.000 ± 3764.306 ng/mL and 207526.260 ± 63656.390 h·ng/mL, respectively. The results of this study provided the index of side effect and pharmacokinetics of ribavirin in pigs, which should be considered before clinical application.

Variant Inosine Triphosphatase Phenotypes Are Associated With Increased Ribavirin Triphosphate Levels

Individuals with lower inosine triphosphatase (ITPA) enzyme activity have a reduced likelihood of experiencing hemolytic anemia during hepatitis C virus (HCV) treatment containing ribavirin (RBV). Because ITPA degrades purines and RBV is a purine analogue, it is conceivable that ITPA activity may affect intracellular RBV concentrations. Here we assessed the association between ITPA activity phenotype and concentrations of RBV triphosphate (RBV-TP) in red blood cells (RBCs) during HCV treatment. RBV-TP was quantified in the RBCs of 177 HCV-infected individuals at a median (range) of 84 (19 to 336) days into HCV treatment that included RBV. Mean (SD) RBV-TP concentrations were 92.8 (51.6), 101.3 (53.5), 184.8 (84.5), and 197.7 (64.6) pmol/106 cells for 100%, 60%, 30%, and ≤10% ITPA activity groups, respectively. Overall, RBV-TP was approximately 2-fold higher in patients with ≤30% ITPA activity compared to 100% activity (P < .0001). Despite higher RBV-TP levels, individuals with variant ITPA phenotypes had less anemia. The 100% activity group had, on average, a -2.20 g/dL drop in hemoglobin vs -1.43 g/dL (P = .04) for 60% activity, -1.14 g/dL (P = .008) for 30% activity, and -0.70 g/dL (P = .06) for ≤10% activity. This finding of higher RBV-TP concentrations in RBCs in ITPA variants was unexpected given that ITPA activity-deficient individuals have a reduced likelihood of RBV-induced anemia. It also refutes the hypothesis that the mechanism by which ITPA variants are protected against anemia is due to lower RBV-TP levels in RBCs.

High Efficacy of ABT-493 and ABT-530 Treatment in Patients With HCV Genotype 1 or 3 Infection and Compensated Cirrhosis

BACKGROUND & AIMS

The combination of ABT-493 (NS3/4A protease inhibitor) plus ABT-530 (NS5A inhibitor) has shown high rates of sustained virologic response at post-treatment week 12 (SVR12) in noncirrhotic patients infected with hepatitis C virus (HCV) genotypes (GTs) 1-6. We describe 2 open-label phase 2 studies investigating the efficacy and safety of ABT-493 plus ABT-530 with or without ribavirin (RBV) in GT1- or GT3-infected patients with compensated cirrhosis.

METHODS

Patients with GT1 infection received 200 mg ABT-493 plus 120 mg ABT-530 for 12 weeks. Patients with GT3 infection were randomized 1:1 to receive 300 mg ABT-493 plus 120 mg ABT-530 with or without once-daily 800 mg RBV for 12 weeks; treatment-experienced patients who were not treated with RBV received 16 weeks of therapy. Efficacy was measured by SVR12, defined as an HCV-RNA level less than 25 IU/mL. Adverse events and laboratory parameters were evaluated throughout the study.

RESULTS

Twenty-seven patients with GT1 infection and 55 patients with GT3 infection were enrolled. The majority were treatment-naive (84%) and male (65%). In patients with GT1 infection, SVR12 was achieved by 96% (26 of 27; 95% confidence interval [CI], 82-99) of patients, with 1 relapse. Among GT3-infected patients, SVR12 was achieved in 96% (27 of 28; 95% CI, 82-99) of patients in the RBV-free arm (1 relapse), and in 100% (27 of 27; 95% CI, 88-100) in the RBV-containing arm. The most common adverse events were headache, fatigue, and nausea. Laboratory abnormalities were rare; no patient discontinued treatment.

CONCLUSIONS

In cirrhotic HCV GT1- or GT3-infected patients, ABT-493 plus ABT-530 with or without RBV achieved SVR12 rates of 96%-100% and was well tolerated. ClinicalTrials.gov identifiers NCT02243280 and NCT02243293.

Dual sofosbuvir and ribavirin therapy for chronic hepatitis C infection

Sofosbuvir is the first pan-genotypic direct acting antiviral agent to be approved. This article provides an overview of the pharmacology of sofosbuvir and ribavirin and a comprehensive summary of the phase 2 and 3 studies supporting dual sofosbuvir and ribavirin therapy for chronic hepatitis C infection. With the production of generic formulations of sofosbuvir, we anticipate this regimen leading the first wave for widespread, IFN-free treatment and becoming first line for all genotypes (including genotype 1) for much of the world-in particular in developing and middle income countries. We discuss the continued challenges with this regimen including among patients with decompensated liver disease and post-liver transplant, and renal failure. We address concerns of emerging resistance. We also discuss the future prospects including the global uptake of sofosbuvir and ribavirin for the treatment of all genotypes.

Influence of Ribavirin Serum Levels on Outcome of Antiviral Treatment and Anemia in Hepatitis C Virus Infection

BACKGROUND

Ribavirin blood levels vary considerably between patients with standard weight-based dosing. Their impact on sustained virological response (SVR) with pegylated interferon and ribavirin is controversial, but has mostly been studied before the IL28b gene polymorphism as a possible confounder was discovered.

METHODS

The impact of serum ribavirin trough levels at week 4, at the end of treatment and of mean levels across the entire antiviral treatment with pegylated interferon and ribavirin on relapse, SVR rates and anemia was retrospectively studied by univariate and multivariable logistic regression analyses in 214 patients with HCV genotype 1-4 infection, including 88 patients with available IL28b genotyping.

RESULTS

Mean ribavirin levels varied between 0.68-5.65 mg/l and significantly differed between patients with or without SVR. By multivariable regression including age, sex, HCV viral load, HCV genotype, liver fibrosis stage, prior treatments, immunosuppression and IL28b genotype, ribavirin levels consistently displayed significant influence on SVR and relapse without indication for a specific importance of higher concentrations early or late in the treatment course. Although hemoglobin decline was on average more pronounced in patients with higher ribavirin levels, hemoglobin remained relatively stable in a significant proportion of these, indicating that ribavirin levels alone are insufficient to predict anemia.

CONCLUSION

While data are scarce to draw conclusions applicable for modern DAA therapies, these results support ribavirin treatment based on serum levels instead of purely weight-based dosing in combination with pegylated interferon.

Pharmacogenetics of ribavirin-induced anemia in HCV patients

Dual therapy (pegylated interferon plus ribavirin) was considered the standard of care for hepatitis C virus (HCV) treatment until 2011, when the first-wave direct-acting antivirals were added to this regimen for HCV genotype-1 patients to increase the sustained virological response rate. The second-wave direct-acting antivirals entered the clinical use also in some ribavirin (RBV)- and/or interferon-free combinations. Nevertheless, since some of the new therapeutic regimens also include RBV and its use results still associated with hemolytic anemia, this requires countermeasures to be prevented. These include the identification of several host predictive factors involved in RBV absorption, distribution, metabolism, elimination and many others that might influence this toxic effect. For this reason, we provided an overview of the potential role of pharmacogenomics in predisposing RBV-treated HCV patients to anemia.

Plasma and intracellular ribavirin concentrations are not significantly altered by abacavir in hepatitis C virus-infected patients

OBJECTIVES

The objective of this study was to evaluate the effects of abacavir on intracellular ribavirin triphosphate and plasma ribavirin trough concentrations.

METHODS

Hepatitis C virus-infected subjects who had been cured or failed prior treatment were randomized to 8 weeks of ribavirin alone (N = 14; weight-based dosing) or weight-based ribavirin + abacavir (N = 14; 300 mg orally every 12 h). Ribavirin trough concentrations were measured on days 14, 28, 42 and 56; PBMCs for ribavirin triphosphate determination were sampled on days 28 and 56, pre-dose and at 6 and 12 h post-dose. ClinicalTrials.gov: NCT01052701.

RESULTS

Twenty-six subjects completed the study (24 males, 17 Caucasians, median age 52 years); 2 were excluded for missed pharmacokinetic visits. Fourteen subjects received ribavirin + abacavir and 12 received ribavirin alone. Mean ± SD plasma ribavirin trough concentrations (μg/mL) on days 14, 28, 42 and 56, respectively, were not significantly different with coadministration of abacavir (1.54 ± 0.60, 1.93 ± 0.54, 2.14 ± 0.73 and 2.54 ± 1.05) compared with ribavirin alone (1.48 ± 0.32, 2.08 ± 0.41, 2.32 ± 0.47 and 2.60 ± 0.62) (P > 0.40). Mean ribavirin triphosphate intracellular concentrations (pmol/10(6) cells) on days 28 and 56, respectively, did not differ statistically between abacavir users (11.98 ± 9.86 and 15.87 ± 12.52) and non-users (15.91 ± 15.58 and 15.93 ± 12.69) (P > 0.4). Adverse events were mild or moderate, except for three grade 3 occurrences of transaminitis, cholecystitis and low absolute neutrophil count that resolved and were judged not attributable to study medications.

CONCLUSIONS

Abacavir did not significantly alter ribavirin or ribavirin triphosphate concentrations.

Ribavirin: Past, present and future

Before the advent of direct acting antiviral agents (DAAs) ribavirin, associated to pegylated-interferon played a crucial role in the treatment of chronic hepatitis C, preventing relapses and breakthroughs. In the present era of new potent DAAs, a place is still devoted to the drug. Ribavirin associated with sofosbuvir alone is efficient in the treatment of most cases of G2 infected patients. All options currently available for the last difficult-to-treat cirrhotic G3 patients contain ribavirin. Reducing treatment duration to 12 wk in G1 or G4 cirrhotic compensated patients is feasible thanks to ribavirin. Retreating patients with acquired anti NS5A resistance-associated variants using ribavirin-based strategies could be useful. The addition of ribavirin with DAAs combinations however, leads to more frequent but mild adverse events especially in cirrhotic patients. Preliminary data with interferon-free second generation DAAs combinations without ribavirin suggest that future of the drug is jeopardized even in difficult-to-treat patients: The optimization of ribavirin dosage according to an early monitoring of blood levels has been suggested to be relevant in double therapy with peginterferon or sofosbuvir but not with very potent combinations of more than two DAAs.

Ribavirin concentration determines treatment success of first-generation DAA-based chronic HCV therapy

BACKGROUND

Monitoring ribavirin concentrations during hepatitis C treatment with dual therapy can help optimize treatment response and minimize anaemia. A defined therapeutic range for ribavirin during direct-acting antiviral-based therapies is lacking. This analysis explores whether a therapeutic range for ribavirin concentrations can be defined in patients treated with boceprevir- or telaprevir-based triple therapies.

METHODS

Treatment-naive patients from ADVANCE, ILLUMINATE, OPTIMIZE and SPRINT-2, and treatment-experienced patients from RESPOND-2 were included. Multivariable logistic regression analyses were performed to evaluate whether ribavirin concentrations were an independent predictor of sustained virological response or anaemia. Optimal cutoff values and the percentage of patients within the proposed therapeutic range were determined, along with the associated chance of response.

RESULTS

Overall, 1,502 patients were included. In both regimens, ribavirin concentrations were significantly associated with anaemia (haemoglobin level <10 g/dl) at all time points (1.75 < odds ratio [OR] <2.45) and sustained virological response was associated with ribavirin concentrations at week 8 (OR=1.43 for telaprevir and 1.78 for boceprevir). A therapeutic range for ribavirin at week 8 of 2.2-3.5 mg/l was defined for telaprevir treatment. Of the 48% of patients with a concentration within this range, 81% achieved sustained virological response and only 5.1% reported anaemia. For boceprevir treatment, the week 8 optimal range was defined as 2.2-3.6 mg/l and 50% of patients had a concentration within this range, of whom 69% achieved sustained virological response and 46% developed anaemia.

CONCLUSIONS

We established the therapeutic range for ribavirin in boceprevir- and telaprevir-based therapy that balances safety and efficacy.

The impact of ribavirin plasma concentration on the efficacy of the interferon-sparing regimen, sofosbuvir and ribavirin

BACKGROUND

Ribavirin augments sustained virological response when administered with pegylated interferon for the treatment of chronic HCV infection. The impact of ribavirin plasma concentration on outcome in individuals receiving interferon-free regimens has not been evaluated.

METHODS

Stored plasma samples were retrieved for 47 treatment-naive subjects who received sofosbuvir and weight-based ribavirin for 12-24 weeks in the Phase IIb QUANTUM study. Week 1, 4 and 8 ribavirin plasma concentrations (mg/l) were quantified using high-performance liquid chromatography with UV detection.

RESULTS

Sustained virological response at 12 weeks post treatment was observed in 55% with all treatment failures due to relapse. The median ribavirin plasma concentration increased from week 1 (1.58 mg/l, IQR 1.44-2.24) to week 4 (2.23 mg/l, IQR 1.69-2.87) and week 8 (2.67 mg/l, IQR 2.10-3.26) with wide variability at steady state. Median week 4 ribavirin plasma concentration was 2.25 mg/l (IQR 1.63-3.05) in those with a sustained virological response as compared to 2.07 mg/l (IQR 1.79-2.86) in those with treatment failure (OR 1.35; 95% CI 0.76, 2.39; P=0.3). No significant association between ribavirin plasma concentration and treatment response was noted at weeks 1 or 8.

CONCLUSIONS

We found no evidence of an association between ribavirin plasma concentrations and relapse suggesting that, as opposed to interferon-based therapy, suboptimal ribavirin plasma concentrations did not explain the high rate of virological failure with this regimen. Our findings suggest that in interferon-free ribavirin-containing regimens, concerns over ribavirin dosing to achieve previously determined target plasma concentrations are unnecessary.