A clinician's guide to drug-drug interactions with direct-acting antiviral agents for the treatment of hepatitis C viral infection

Molecular Factors and Pathways of Hepatotoxicity Associated with HIV/SARS-CoV-2 Protease Inhibitors

Antiviral protease inhibitors are peptidomimetic molecules that block the active catalytic center of viral proteases and, thereby, prevent the cleavage of viral polyprotein precursors into maturation. They continue to be a key class of antiviral drugs that can be used either as boosters for other classes of antivirals or as major components of current regimens in therapies for the treatment of infections with human immunodeficiency virus (HIV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, sustained/lifelong treatment with the drugs or drugs combined with other substance(s) often leads to severe hepatic side effects such as lipid abnormalities, insulin resistance, and hepatotoxicity. The underlying pathogenic mechanisms are not fully known and are under continuous investigation. This review focuses on the general as well as specific molecular mechanisms of the protease inhibitor-induced hepatotoxicity involving transporter proteins, apolipoprotein B, cytochrome P450 isozymes, insulin-receptor substrate 1, Akt/PKB signaling, lipogenic factors, UDP-glucuronosyltransferase, pregnane X receptor, hepatocyte nuclear factor 4α, reactive oxygen species, inflammatory cytokines, off-target proteases, and small GTPase Rab proteins related to ER-Golgi trafficking, organelle stress, and liver injury. Potential pharmaceutical/therapeutic solutions to antiviral drug-induced hepatic side effects are also discussed.

Effects of aged garlic and ginkgo biloba extracts on the pharmacokinetics of sofosbuvir in rats

Sofosbuvir is a direct acting antiviral (DAA) approved for the treatment of hepatitis C virus (HCV). Sofosbuvir is a substrate of P-glycoprotein (P-gp). For this reason, inhibitors, or inducers of intestinal P-gp may alter plasma concentration of sofosbuvir and increase or decrease its efficacy causing a significant change in its pharmacokinetic parameters. The purpose of study was to evaluate the pharmacokinetic interaction between either aged garlic or ginkgo biloba extracts with sofosbuvir through targeting P-gp as well as the possible toxicities in rats. Rats were divided into four groups and treated for 14 days with saline, verapamil (15 mg/kg, PO), aged garlic extract (120 mg/kg, PO) or ginkgo biloba extract (25 mg/kg, PO) followed by a single oral dose of sofosbuvir (40 mg/kg). Validated LC-MS/MS was used to determine sofosbuvir and its metabolite GS-331007 in rat plasma. Aged garlic extract caused a significant decrease of sofosbuvir AUC_(0-t) by 36% while ginkgo biloba extract caused a significant increase of sofosbuvir AUC_(0-t) by 11%. Ginkgo biloba extract exhibited significant increase of sofosbuvir t_1/2 by 60%, while aged garlic extract significantly increased sofosbuvir clearance by 63%. The pharmacokinetic parameters of GS-331007 were not affected. The inhibitory action of ginkgo biloba on P-gp and the subsequent increase in sofosbuvir plasma concentration did not show a significant risk of renal or hepatic toxicity. Conversely, although aged garlic extracts increased intestinal P-gp expression, they did not alter C_max and T_max of sofosbuvir and did not induce significant hepatic or renal toxicities. This article is protected by copyright. All rights reserved.

Special Considerations in the Management of HIV and Viral Hepatitis Coinfections in Liver Transplantation

Modern therapies for hepatitis B virus, hepatitis C virus, and human immunodeficiency virus have become so effective that patients treated for these conditions can have normal life-expectancies. Suitable livers for transplantation remain a scarce and valuable resource. As such, significant efforts have been made to expand donation criteria at many centers. This constant pressure, coupled with the increasing effectiveness of antiviral therapies, has meant that more and more patients infected with hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV) may be considered appropriate donors in the right circumstances. Patients with these infections are also more likely to be considered appropriate transplantation recipients than in the past. The treatment of HBV, HCV, and HIV after liver transplantation (LT) can be challenging and complicated by viral coinfections. The various pharmaceutical agents used to treat these infections, as well as the immunosuppressants used post-LT must be carefully balanced for maximum efficacy, and to avoid resistance and drug–drug interactions.

Evaluation of a specialty hepatitis C virus telephone pharmacy service

PURPOSE

Direct-acting antivirals (DAAs) used to treat hepatitis C virus (HCV) infection are associated with significant drug-drug interactions (DDIs). Pharmacists are well positioned to identify and mitigate these DDIs. Data to guide assessment of the impact of HCV specialty pharmacy services on identifying and addressing DDIs with DAAs are lacking. The overall purpose of the study described here was to determine the incidence and severity of DDIs identified by specialty pharmacists among patients treated with DAAs prior to and 1 month into therapy.

METHODS

An observational, retrospective study was conducted to evaluate the impact of specialty pharmacy services in mitigating DDIs associated with use of DAAs. Adult patients with HCV infection (n = 200) who received DAAs and were enrolled with a specialty pharmacy service over a 1-year period were included. Endpoints included number, severity, and type of DDIs and DDIs per patient at baseline and 1 month into therapy, pharmacists' interventions, and safety and clinical outcomes.

RESULTS

Fifty-nine percent of patients had at least 1 DDI. A total of 170 DDIs were identified (137 at baseline and 33 at 1-month follow-up), and the mean number of DDIs per patient significantly decreased from baseline to 1-month follow-up (from 1.38 to 0.16, P < 0.0001). The rate of "potentially clinically significant" or "critical" interactions was significantly lower at 1-month follow-up vs baseline assessment (69.6% vs 81.7%, P < 0.0001). The most commonly identified DDIs involved acid suppressive medications (49.6% and 66.6% of DDIs at baseline and follow-up assessment, respectively) and cardiovascular medications (26.2% and 21.2%, respectively). Total number of DDI interventions was 131, with an acceptance rate of 85%. Most common intervention was patient education and monitoring.

CONCLUSION

Approximately 60% of patients had DDIs with DAAs. Implementing HCV specialty pharmacy services significantly decreased DDIs while maintaining SVR12.

The use of organs from hepatitis C virus-viremic donors into uninfected recipients

PURPOSE OF REVIEW

There has been an ongoing disparity between the number of organs available for solid organ transplantation (SOT) relative to the need. This has resulted in significant waitlist mortality, may affect transplant outcomes due to transplants being performed on sicker patients and may even increase healthcare costs due to extended hospital stays. Transplanting organs from hepatitis C virus (HCV)-infected donors into uninfected recipients (D+/R-) is now a reality, due to the advent of highly affective direct-acting antivirals (DAAs) which not only have very high efficacy, but also a favorable side effect and drug-drug interaction profile.

RECENT FINDINGS

Data from multiple centers reporting outcomes of kidney, liver, heart, lung and liver-kidney transplant during the past few years reveal that SOT from HCV-infected donors into noninfected recipients is safe, efficacious and can result in excellent recipient outcomes, with an opportunity to decrease the time on the waitlist, waitlist mortality and to improve outcomes after transplant due to less morbidity at the time of surgery. When livers are the transplanted organ, 8-12 weeks of DAA treatment will be required. For other organs, 2-4 weeks is likely sufficient. The available DAAs have profiles such that patients with all genotypes, with or without renal insufficiency an on renal replacement therapy and those who fail treatment may be successfully treated, with a sustained virologic response rate of more than 95%. Based upon the available data, starting DAAs shortly after transplant will likely limit posttransplant complications. that This will require cooperation between the transplant team, transplant hospital and insurer providing medication coverage.

SUMMARY

SOT from HCV infected recipients is safe, is associated with excellent outcomes and should be considered for recipients who would benefit from receiving an organ earlier than they would if they waited for an organ from an uninfected donor.

Potential interactions between pangenotypic direct-acting antivirals and concomitant cardiovascular therapies in patients with chronic hepatitis C virus infection

OBJECTIVE

To identify potential drug interactions (DIs) between pangenotypic direct-acting antivirals (pDAAs) and concomitant cardiovascular (CV) therapies in patients with chronic hepatitis C (CHC).

METHODS

A retrospective observational study was carried out. Patients ≥18 years of age diagnosed with CHC and treated with pDAAs during 2017 were included. Information was collected on concomitant CV therapies and potential DIs [www.hep-druginteractions.org]. The pDAAs analyzed were sofosbuvir/velpatasvir (SOF/VEL), glecaprevir/pibrentasvir (GLE/PIB) and sofosbuvir/velpatasvir/voxilaprevir (SOF/VEL/VOX). An analysis including lipid-lowering drugs was also performed.

RESULTS

In total, 1286 patients (mean age 64.9 years, 56.6% men) were recruited. The percentages of potential DIs with CV drugs were 1.9% contraindications, 38.1% clinically significant and 2.4% weak. When lipid-lowering drugs were included, the percentages of potential DIs with CV drugs were 10.3% contraindications, 46.3% clinically significant and 3.2% weak. Potential DIs associated with each pDAA were as follows (contraindications; clinically significant; weak): SOF/VEL (1.4%; 23.0%; 0.9%), GLE/PIB (12.8%; 60.8%; 4.7%) and SOF/VEL/VOX (16.6%; 55.1%; 4.9%).

CONCLUSIONS

Approximately on third of patients with CHC are concomitantly treated with CV drugs. SOF/VEL may have fewer DIs with CV drugs than other pDAAs.

Influence of drug-drug interactions on effectiveness and safety of direct-acting antivirals against hepatitis C virus

OBJECTIVES

Direct-acting antivirals are the recommended treatment for hepatitis C-infected patients. Drug-drug interactions with concomitant treatments can cause lack of effectiveness and/or safety. The objective of this study is to characterise drug-drug interactions of direct-acting antivirals and to analyse their influence both on the effectiveness of antiviral treatment and on the overall safety of pharmacological treatment in hepatitis C-infected patients.

METHODS

Observational and prospective cohort study for 3 years in the pharmaceutical care outpatient consultation of a general hospital, undertaking detection, evaluation and management of drug-drug interactions by clinical pharmacists and physicians. The main outcome measures were sustained virologic response at week 12 for effectiveness and serious drug-related adverse events for safety. Multivariate statistical analysis applied to: (a) patient basal characteristics related to presence of drug-drug interactions; (b) previous antiviral treatments, viral genotype, cirrhosis, decompensations and presence of drug-drug interactions related to the effectiveness of direct-acting antivirals.

RESULTS

Of a total of 1092 patients, the majority of them were men, around 60 years old and HCV-genotype 1 mono-infected, with a high basal viral load, naive to antiviral treatment, treated with ledipasvir/sofosbuvir and without cirrhosis. 24.5% had drug-drug interactions. Proton pump inhibitors were the concomitant drugs that caused the most drug-drug interactions. Age ≥65 years and direct-acting antivirals based on protease inhibitors were independently related to the presence of drug-drug interactions (p≤0.012). All (100%) of the therapeutic recommendations based on detected drug-drug interactions were implemented; 97.7% of patients with interactions versus 99.0% without them reached sustained virologic failure (p=0.109). The serious adverse events rates were 1.5% and 1.3% in patients with and without drug-drug interactions, respectively (p=0.841).

CONCLUSIONS

Drug-drug interactions are frequent among hepatitis C-infected patients receiving treatment with direct-acting antivirals. However, the collaboration between physicians and clinical pharmacists makes it possible to detect, evaluate, avoid or clinically manage these drug-drug interactions, in order to maintain whole treatment therapeutic safety and the effectiveness of direct-acting antivirals.

Drug-Drug Interactions in Children and Adolescents Receiving Ledipasvir/Sofosbuvir for the Treatment of Hepatitis C Virus Infection

BACKGROUND AND OBJECTIVE

Drug-drug interactions need to be considered to optimize the pharmacotherapeutic outcome of direct-acting antivirals. The aim of this study was to report on possible drug-drug interactions between ledipasvir/sofosbuvir and other medications received by children and adolescents with hepatitis C virus, in addition to suggested management for these drug-drug interactions.

METHODS

Hepatitis C virus-infected children and adolescents, 12-17 years of age and/or weighing ≥ 35 kg, who presented to the Pediatric Hepatology Unit at Cairo University Pediatric Hospitals for ledipasvir/sofosbuvir treatment were included. Medication history was taken including long-term medications for chronic conditions and on-demand medications for inter-current illnesses. Medications were reviewed by the Kasr Alainy Drug Information Center to identify possible drug-drug interactions with prescribed ledipasvir/sofosbuvir and their management. HEP Drug Interactions provided by the University of Liverpool, Lexicomp^®, and Medscape were the utilized references. Each drug-drug interaction was assigned a risk rating of A, B, C, D, or X.

RESULTS

Sixty hepatitis C virus-infected children and adolescents assigned to receive ledipasvir/sofosbuvir were enrolled. Thirty percent of patients had associated chronic co-morbid conditions. The overall number of medications received was 48; 39 were prescribed as long-term medications with a median of 3 (interquartile range 4.24) medications per patient. Proton pump inhibitors, antacids, histamine H₂ receptor antagonists, sodium bicarbonate, and colchicine were reported to be associated with a drug-drug interaction risk D necessitating therapy modification, which occurred prior to administration.

CONCLUSIONS

Early identification and prompt response to drug-drug interactions with the aid of pharmacists optimize the pharmacotherapeutic outcome and eliminate possible morbidities when using direct-acting antivirals in children and adolescents with hepatitis C virus.

International Liver Transplantation Society Asian Consensus on the Management of Hepatitis C Virus Infection in Resource Limited Setting-From Noncirrhotic to Decompensated Disease and After Liver Transplantation

BACKGROUND

The population of Asia exceeds 4.4 billion people. Chronic hepatitis C virus (HCV) infection in Asia is characterized by specific distribution of genotypes, lack of access to specific therapeutic agents, relatively high cost of treatment, and lack of experienced healthcare providers. Clear consensus on the diagnosis, management, and monitoring of HCV infection specific to the Asian region is a major unmet need. The consensus guidelines documents that have been published to date by major medical societies presume access to an array of direct acting antiviral agents and diagnostic tests that are not broadly applicable to resource limited settings, including Asia.

METHODS

To address the lack of an Asia-specific set of HCV treatment guidelines, we assembled a panel of 15 HCV experts in the field of hepatology from India, Indonesia, Myanmar, Vietnam, Pakistan, Philippines, and Mongolia convened in April 2017 to review the updated literature and provide recommendations on the diagnosis and management of chronic HCV infection that reflects local conditions.

RESULTS

An evidence-based comprehensive compilation of the literature supported by the graded recommendations from the expert panel for the optimization of the diagnosis, pretreatment, on treatment, and posttreatment assessments, and management of chronic HCV infection has been presented in this article.

CONCLUSIONS

With the evolving treatment landscape and addition of several new direct-acting antiviral agents and combination regimens into the therapeutic armamentarium, the current article may serve as a guide to the clinicians in optimizing the diagnosis and treatment selection for the management of chronic HCV infection in resource-limited settings.

Comorbidities, concomitant medications and potential drug-drug interactions with interferon-free direct-acting antiviral agents in hepatitis C patients in Taiwan

BACKGROUND

While direct-acting antivirals have been approved for treating hepatitis C, the guidelines highlight the importance of considering potential drug-drug interactions between DAAs and concomitant medications.

AIM

To assess comorbidity prevalence, concomitant medication use and potential drug-drug interactions between DAAs and concomitant medications for hepatitis C patients in Taiwan.

METHODS

This cross-sectional study enrolled 822 patients from May to August 2016 in Taiwan. Patient demographics, comorbidities and concomitant medications were evaluated by physician surveys.

RESULTS

A total of 709 (86.3%) patients had ≥1 comorbidity; the most prevalent comorbidity categories were diseases of the digestive system (40.1%), circulatory system (38.7%) and endocrine/nutritional/metabolic diseases (35.2%). Elderly patients had more comorbidities. A total of 622 (75.7%) patients received ≥1 concomitant medication; the average number of concomitant medications was 3.2. The most common concomitant medication classes were cardiovascular (34.4%), gastrointestinal (25.7%) and central nervous system drugs (22.7%). Among patients without cirrhosis or with compensated cirrhosis, contraindications were most prevalent with paritaprevir/ritonavir/ombitasvir plus dasabuvir, daclatasvir/asunaprevir and glecaprevir/pibrentasvir (13.3%, 6.0% and 5.4% respectively), and least prevalent with sofosbuvir, sofosbuvir/daclatasvir, sofosbuvir/ledipasvir and sofosbuvir/velpatasvir (0.8%, 1.3%, 1.4% and 2.1% respectively). Sofosbuvir-based regimens had no contraindications in patients with decompensated cirrhosis.

CONCLUSION

Our population represented an elderly demographic, with a high prevalence of comorbidities and widespread use of concomitant medications. The potential drug-drug interactions between these concomitant medications and DAA regimens differed, with the fewest potential interactions with sofosbuvir-based regimens.

Comorbidities and co-medications in populations with and without chronic hepatitis C virus infection in Japan between 2015 and 2016

BACKGROUND

Direct-acting anti-viral agents have improved the treatment of chronic hepatitis C virus (HCV) infection, but this treatment is challenging for patients using co-medications because of potential drug-drug interactions. This study aimed to examine the comorbidities and co-medications of Japanese chronic HCV patients by age group, compared with a non-HCV patient population.

METHODS

This was a retrospective observational study using a hospital-based medical claims database. We extracted data of patients with chronic HCV aged ≥18 years, and age-, sex-, and hospital-matched patients without HCV, for the period from January 2015 to November 2016, and then examined chronic comorbidities, long-term co-medications, and medications prescribed at least once during the study period.

RESULTS

We analysed data from 128,967 chronic HCV patients and 515,868 non-HCV patients. The median age was 70 years, and 51.0% of patients were male. More chronic HCV patients than non-HCV patients (70.5% vs. 47.1%) had at least one comorbidity, and older patients had more comorbidities than younger patients. The most common comorbidities in chronic HCV patients were diseases of oesophagus, stomach and duodenum (41.7%), followed by hypertensive diseases (31.4%). Chronic HCV patients used co-medications more commonly than non-HCV patients, and older patients used more co-medications. The most common long-term co-medications in chronic HCV patients were proton pump inhibitors (14.0%), which were prescribed to 31.9% of chronic HCV patients at least once during the study period.

CONCLUSIONS

Patients with chronic HCV in Japan had more comorbidities than patients without chronic HCV regardless of age. Particularly older patients, who constitute the majority of the HCV patient population in Japan, commonly had multiple comorbidities and used co-medications. To optimise HCV treatment, physicians need to know the exact medication profiles of patients and take appropriate action to manage drug-drug interactions.

Impact of comorbidities on patient outcomes after interferon-free therapy-induced viral eradication in hepatitis C

BACKGROUND & AIMS

Patients with advanced liver fibrosis remain at risk of cirrhosis-related outcomes and those with severe comorbidities may not benefit from hepatitis C (HCV) eradication. We aimed to collect data on all-cause mortality and relevant clinical events within the first two years of direct-acting antiviral therapy, whilst determining the prognostic capability of a comorbidity-based model.

METHODS

This was a prospective non-interventional study, from the beginning of direct-acting antiviral therapy to the event of interest (mortality) or up to two years of follow-up, including 14 Spanish University Hospitals. Patients with HCV infection, irrespective of liver fibrosis stage, who received direct-acting antiviral therapy were used to build an estimation and a validation cohort. Comorbidity was assessed according to Charlson comorbidity and CirCom indexes.

RESULTS

A total of 3.4% (65/1,891) of individuals died within the first year, while 5.4% (102/1,891) died during the study. After adjusting for cirrhosis, platelet count, alanine aminotransferase and sex, the following factors were independently associated with one-year mortality: Charlson index (hazard ratio [HR] 1.55; 95% CI 1.29-1.86; p = 0.0001), bilirubin (HR 1.39; 95% CI 1.11-1.75; p = 0.004), age (HR 1.06 95% CI 1.02-1.11; p = 0.005), international normalized ratio (HR 3.49; 95% CI 1.36-8.97; p = 0.010), and albumin (HR 0.18; 95% CI 0.09-0.37; p = 0.0001). HepCom score showed a good calibration and discrimination (C-statistics 0.90), and was superior to the other prognostic scores (model for end-stage liver disease 0.81, Child-Pugh 0.72, CirCom 0.68) regarding one- and two-year mortality. HepCom score identified low- (≤5.7 points: 2%-3%) and high-risk (≥25 points: 56%-59%) mortality groups, both in the estimation and validation cohorts. The distribution of clinical events was similar between groups.

CONCLUSIONS

The HepCom score, a combination of Charlson comorbidity index, age, and liver function (international normalized ratio, albumin, and bilirubin) enables detection of a group at high risk of one- and two-year mortality, and relevant clinical events, after starting direct-acting antiviral therapy.

LAY SUMMARY

The prognosis of patients with severe comorbidities may not benefit from HCV viral clearance. An algorithm to decide who will benefit from the treatment is needed to manage the chronic HCV infection better.

Direct-acting antiviral treatment for patients with hepatocellular carcinoma

PURPOSE OF REVIEW

Hepatocellular carcinoma (HCC) affects a significant portion of patients with hepatitis C. The use of direct-acting antiviral (DAA) agents has transformed the disease outcomes in this patient group.

RECENT FINDINGS

Hepatitis C virus (HCV) response to DAAs can be affected by the presence of HCC, whereas DAA therapy may affect the risk of HCC recurrence in patients with a history of HCC.

SUMMARY

Emerging data are demonstrating lower sustained virologic response (SVR) rates in patients with HCC compared with patients without HCC. Conflicting studies have also suggested that rates of HCC recurrence in patients with a history of HCC can potentially be increased or decreased on DAA therapy. This review will provide a brief overview of these data and inform practitioners on important considerations to make when prescribing DAA therapy for patients with HCV and HCC.

Incidence of Drug Interactions Identified by Clinical Pharmacists in Veterans Initiating Treatment for Chronic Hepatitis C Infection

BACKGROUND

Many direct-acting antivirals (DAAs) have drug-drug interactions (DDIs) with the potential to affect efficacy and safety.

OBJECTIVE

To describe the incidence and severity of DDIs with DAAs identified by the hepatitis C virus (HCV) clinical pharmacist within a Veterans Affairs health care system.

METHODS

This single-center, retrospective cohort study evaluated patients with HCV treated with DAA therapy. Primary end points included the total number of identified DDIs, percentage of patients with at least 1 DDI, mean number of DDIs per patient, and the number of DDIs by severity category. Additional end points included characterization of interacting drugs, clinical consequence of interaction, intervention recommended, acceptance rate of actionable recommendations, and achievement of sustained virological response 12 weeks after treatment (SVR12).

RESULTS

A total of 300 patients were included. There were 554 identified DDIs, and 80.3% of patients had at least 1 DDI, with an average of 1.85 DDIs per patient; 76% of the DDIs identified were categorized as either a potentially clinically significant or critical interaction. The most common DDIs involved acid suppression agents (20%). Patient monitoring was the most commonly recommended intervention (59%), followed by dose modification of the interacting medication (30%). There was no difference in SVR12 between patients with at least 1 DDI compared with those with no DDIs (94.8% vs 95.8%; P = 0.73). There were a total of 227 actionable recommendations, with an acceptance rate of 84.1%.

CONCLUSIONS

This study suggests that DDIs are prevalent among patients treated with DAAs for HCV. A HCV clinical pharmacist can help optimize patient care by identifying DDIs and recommending interventions to providers.

Potential nephrotoxicity of sofosbuvir-based treatment in patients infected with hepatitis C virus: a review on incidence, type and risk factors

INTRODUCTION

There was no report of nephrotoxicity during clinical trials assessed sofosbuvir for treatment of hepatitis C (HCV) infection. This may be due to excluding patients with severe kidney dysfunction, as a main population at risk for drug-induced nephrotoxicity from these studies. There are some reports of acute kidney injury (AKI) possibly related to sofosbuvir-containing treatments from real-life experiences. Areas covered: Available data on epidemiology, type, and possible risk factors for nephrotoxicity of sofosbuvir-containing treatment are reviewed. Related articles were collected by searching Scopus, Pubmed, and Science direct. Search terms were 'sofosbuvir', 'nephrotoxicity', 'acute kidney injury', 'renal impairment', and "direct acting antiviral agents. Expert commentary: AKI may happen in 1-15% of patients who are treated with sofosbuvir-containing regimens. Compared with patients with normal kidney function, higher incidences of AKI have been reported in patients with baseline moderate to severe kidney dysfunction. Median time to AKI is 9 weeks after starting sofosbuvir. Baseline renal impairment, presence of ascites, diabetes or concomitant use of nephrotoxic drugs are possible risk factors for sofosbuvir-induced AKI. AKI following sofosbuvir-containing treatment is characterized by histological feature of acute interstitial nephritis and may be reversible following drug discontinuation. Monitoring of kidney function is recommended in sofosbuvir-treated patients.

Efficacy and Safety of Direct-acting Antivirals in Hepatitis C Virus-infected Patients Taking Proton Pump Inhibitors

Background and Aims: Direct-acting antiviral (DAA) therapy is the cornerstone of the treatment of chronic hepatitis C virus (HCV) infection. Eradication of HCV, predicted by the attainment of a sustained virologic response (SVR) 12 weeks following DAA therapy, is the goal of this treatment. Interestingly, recent studies have reported the possible association between HCV-infected patients with DAA therapy concomitant use of proton pump inhibitors (PPIs) and lower odds of achieving SVR. This meta-analysis was conducted to summarize all available data and to estimate this potential association. Methods: Comprehensive literature review was conducted by first searching the Medline and Embase databases through March 2017 to identify all studies that investigated the safety and efficacy of DAAs in patients with HCV infection taking PPIs versus those without PPIs. Adjusted point estimates from each study were combined by the generic inverse variance method of DerSimonian and Laird. Results: Nine cohort studies with 32,684 participants met the eligibility criteria and were included in the meta-analysis. The use of PPIs concomitant with DAAs among HCV-infected patients was associated with lower odds of achieving SVR compared with non-PPI users (pooled odds ratio (OR): 0.74, 95% confidence interval (CI): 0.63-0.88, I2 = 24%). Subgroup analysis addressed the association between PPIs use and SVR12 demonstrated the association of PPI users showing lower odds of achieving SVR12 compared with those with no use of PPIs (pooled OR: 0.68, 95% CI: 0.51-0.9, I2 = 33%). Conclusions: This study demonstrated a significantly increased risk of failure to achieve SVR in HCV-infected patients taking DAA with PPIs compared to non-PPI users. Providers should consider whether PPI therapy is indicated for patients and withdraw of PPI therapy in the absence of indications, especially while on DAA therapy.

Nephrotoxicity Associated with Concomitant Use of Ledipasvir-Sofosbuvir and Tenofovir in a Patient with Hepatitis C Virus and Human Immunodeficiency Virus Coinfection

Direct-acting antivirals (DAAs) have revolutionized the treatment of hepatitis C virus (HCV) infection, with superior efficacy and safety compared to interferon-based therapies. Despite these improvements, drug interactions with DAAs exist and may be clinically relevant in human immunodeficiency virus (HIV)-coinfected patients. We present a case of nephrotoxicity associated with concomitant use of tenofovir disoproxil fumarate (TDF) and ledipasvir-sofosbuvir (LDV-SOF). A 56-year-old woman with HIV infection who had been taking efavirenz/tenofovir/emtricitabine (EFV/TDF/FTC) for 6 years developed acute kidney injury 8 weeks after initiating LDV-SOF for the treatment of HCV infection. Her serum creatinine concentration peaked at 10 mg/dL, compared with her baseline concentration of 0.9-1 mg/dL. Kidney biopsy revealed acute tubular necrosis and acute interstitial nephritis. Both LDV-SOF and TDF were discontinued, and the patient's serum creatinine concentration decreased to 1.3 mg/dL over the following 6 weeks. We postulate that this adverse drug reaction may have been secondary to the known interaction between ledipasvir and TDF, which results in increased TDF exposure. Despite knowledge of this interaction, LDV-SOF is commonly prescribed in patients with HIV-HCV coinfection, as patients who received LDV-SOF- and TDF-containing regimens in trials have not demonstrated adverse clinical consequences related to this interaction. This case highlights the rare but potentially serious nephrotoxicity that can result from TDF toxicity and serves as a reminder to clinicians to implement close renal function monitoring in patients receiving both LDV-SOF and TDF. Clinicians prescribing LDV-SOF to HCV-HIV-coinfected patients receiving TDF should be cautious about use with concomitant nephrotoxic medications and monitor markers of tubular dysfunction, including urinary phosphorus excretion, and renal injury at baseline and week 4 of therapy. Tenofovir alafenamide and alternative DAAs may also have a role in the management of patients at high risk for renal adverse effects from TDF.

The New Era of Hepatitis C: Therapy in Liver Transplant Recipients

Hepatitis C virus (HCV) is the leading cause of end-stage liver disease in both Europe and the United States and is the most common reason for liver transplant. In the absence of antiviral therapy, recurrent infection is the norm with subsequent graft hepatitis and impaired survival. Whether it may be better to postpone therapy in patients in whom higher risk of failure and toxicity is coupled with lower chance of liver function improvement likely depends on several factors, including waiting time, center allocation policy, presence of hepatocellular carcinoma and local prevalence of anti-HCV-positive donors.

Managing drug-drug interactions with new direct-acting antiviral agents in chronic hepatitis C

Several direct-acting antiviral agents (DAAs) have marketing authorization in Europe and in the USA and have changed the landscape of hepatitis C treatment: each DAA has its own metabolism and drug-drug interactions (DDIs), and managing them is a challenge. To compile the pharmacokinetics and DDI data of the new DAA and to provide a guide for management of DDI. An indexed MEDLINE search was conducted using the keywords: DAA, hepatitis C, simeprevir, daclatasvir, ledipasvir, sofosbuvir, 3D regimen (paritaprevir/ritonavir, ombitasvir, dasabuvir), DDI and pharmacokinetics. Data were also collected from hepatology, and infectious disease and clinical pharmacology conferences abstracts. Food can play a role in the absorption of DAAs. Most of the interactions are linked to metabolism (cytochrome P450-3 A4 [CYP3A4]) or hepatic and/or intestinal transporters (organic anion-transporting polypeptide and P-glycoprotein [P-gp]). To a lesser extent other pathways can be involved such as breast cancer resistance protein transporter or UDP-glucuronosyltransferase metabolism. DDI are more likely to occur with 3D regimen, daclatasvir, simeprevir and ledipasvir, as they are all both substrates and inhibitors of P-gp and/or CYP3A4, than with sofosbuvir. They can increase concentrations of coadministered drugs and their concentrations may be influenced by P-gp or CYP3A4 inducers or inhibitors. Overdosage or low dosage can be encountered with potent inducers or inhibitors of CYP3A4 or drugs with a narrow therapeutic range. The key to interpret DDI data is a good understanding of the pharmacokinetic profiles of the drugs involved. Their ability to inhibit CYP450-3A4 and transporters (hepatic and/or intestinal) can have significant clinical consequences.

Concomitant use of direct-acting antivirals and chemotherapy in hepatitis C virus-infected patients with cancer

BACKGROUND

Antiviral therapy improves hepatic outcomes in hepatitis C virus (HCV)-infected cancer patients. However, such patients are not treated simultaneously with antivirals and chemotherapy, owing to overlapping toxicities with previous standard of care treatment of pegylated interferon and ribavirin.

AIM

To examine the safety and clinically-significant drug-drug interactions observed in patients who received simultaneous treatment with direct-acting antivirals (DAAs) and chemotherapy.

METHODS

Safety was determined by the presence of adverse events which were graded according to the division of AIDS Table (version 2.0). Adverse events were monitored throughout antiviral treatment and up to 3 months after its completion. Drug-drug interactions were assessed using current online databases. Sustained virological response (SVR) was defined as absence of serum HCV RNA 12 weeks after end of DAA treatment. Cirrhosis was diagnosed via imaging, biopsy or with the use of non-invasive fibrosis markers.

RESULTS

Twenty-one patients received concomitant treatment with DAAs and chemotherapy between January 2013 and September 2016. Concomitant treatment was started either for virological (14; 67%) or oncologic (7; 33%) reasons. DAAs used were sofosbuvir, ledipasvir, simeprevir, daclatasvir ± ribavirin. The adverse events observed were mainly constitutional (12; 57%), hematological and gastrointestinal (7; 33% each). Physicians changed the DAA regimens in two patients (10%) in anticipation of drug-drug interactions with daclatasvir and dexamethasone. The overall SVR rate was 95% (20/21).

CONCLUSIONS

Hepatitis C virus-targeted antiviral therapy can be used concomitantly with selected anti-neoplastic agents under close monitoring for drug-drug interactions. This therapeutic intervention may prevent delay in the administration of chemotherapy in HCV-infected cancer patients.

How I treat hepatitis C virus infection in patients with hematologic malignancies

Hepatitis C virus (HCV) infection is not uncommon in cancer patients. Over the past 5 years, treatment of chronic HCV infection in patients with hematologic malignancies has evolved rapidly as safe and effective direct-acting antivirals (DAAs) have become the standard-of-care treatment. Today, chronic HCV infection should not prevent a patient from receiving cancer therapy or participating in clinical trials of chemotherapy because most infected patients can achieve virologic cure. Elimination of HCV from infected cancer patients confers virologic, hepatic, and oncologic advantages. Similar to the optimal therapy for HCV-infected patients without cancer, the optimal therapy for HCV-infected patients with cancer is evolving rapidly. The choice of regimens with DAAs should be individualized after thorough assessment for potential hematologic toxic effects and drug-drug interactions. This study presents clinical scenarios of HCV-infected patients with hematologic malignancies, focusing on diagnosis, clinical and laboratory presentations, complications, and DAA therapy. An up-to-date treatment algorithm is presented.