The Drug-Drug Interaction Potential of Antiviral Agents for the Treatment of Chronic Hepatitis C Infection

Analyzing risk factors and developing a stratification system for hepatocellular carcinoma recurrence after interferon-free direct-acting antiviral therapy in chronic hepatitis C patients

BACKGROUND

The introduction of direct-acting antiviral agents (DAAs) has revolutionized the therapeutic landscape of chronic hepatitis C (CHC), however real-world data on the risk factors of hepatocellular carcinoma (HCC) recurrence following DAA treatment in CHC-HCC patients are limited in Taiwan. We aimed to evaluate the therapeutic efficacy of DAAs in Taiwanese patients with prior hepatitis C virus (HCV)-induced HCC and identify the posttreatment risk factors for HCC recurrence.

METHODS

Between January 2017 and August 2021, 208 CHC-HCC patients underwent DAA treatment at Taipei Veterans General Hospital. Among them, 94 patients met the inclusion criteria (Barcelona clinic liver cancer [BCLC] stage 0/A after treatment with complete radiological response) for analysis. Comprehensive demographic, clinical, and laboratory data were collected before and after DAA treatment. The primary outcome was HCC recurrence post-DAA treatment, and independent variables were assessed using multivariate Cox proportional hazards models.

RESULTS

The mean age of the enrolled patients was 75.9 ± 8.9 years; 44.7% were male, and 94.7% were Child-Pugh class A. Before DAA treatment, 31.9% experienced HCC recurrence. The median follow-up after DAA treatment was 22.1 months (interquartile range, 8.6-35.9 months). After treatment, 95.7% of the patients achieved a sustained virological response (SVR 12 ), but HCC recurrence occurred in 54.3%. Cumulative HCC recurrence rates after treatment were 31.1% at 1 year, 57.3% at 3 years, and 68.5% at up to 5.69 years. Multivariate analysis revealed that prior HCC recurrence before DAA treatment (hazard ratio [HR] = 3.15, p = 0.001), no SVR 12 after treatment (HR = 6.829, p = 0.016), 12-week posttreatment alpha-fetoprotein (AFP) level >10 ng/mL (HR = 2.34, p = 0.036), and BCLC A3 lesions (two or three nodules without any tumor exceeding 3 cm) (HR = 2.31, p = 0.039) were independent risk factors for HCC recurrence. We further developed a risk stratification system based on these significant independent factors.

CONCLUSION

This investigation underscores the critical influence of factors such as prior HCC recurrence, successful attainment of SVR 12 , posttreatment AFP level, and specific tumor characteristics in determining the risk of HCC recurrence after treatment with DAAs. Our proposed innovative risk stratification system may not only contribute to enhanced personalized care but also holds the potential to optimize treatment outcomes.

SASLT guidelines: Update in treatment of hepatitis C virus infection, 2024

ABSTRACT

Hepatitis C virus (HCV) infection has been a major global health concern, with a significant impact on public health. In recent years, there have been remarkable advancements in our understanding of HCV and the development of novel therapeutic agents. The Saudi Society for the Study of Liver Disease and Transplantation formed a working group to develop HCV practice guidelines in Saudi Arabia. The methodology used to create these guidelines involved a comprehensive review of available evidence, local data, and major international practice guidelines regarding HCV management. This updated guideline encompasses critical aspects of HCV care, including screening and diagnosis, assessing the severity of liver disease, and treatment strategies. The aim of this updated guideline is to assist healthcare providers in the management of HCV in Saudi Arabia. It summarizes the latest local studies on HCV epidemiology, significant changes in virus prevalence, and the importance of universal screening, particularly among high-risk populations. Moreover, it discusses the promising potential for HCV elimination as a public health threat by 2030, driven by effective treatment and comprehensive prevention strategies. This guideline also highlights evolving recommendations for advancing disease management, including the treatment of HCV patients with decompensated cirrhosis, treatment of those who have previously failed treatment with the newer medications, management in the context of liver transplantation and hepatocellular carcinoma, and treatment for special populations.

Mechanisms and Clinical Significance of Pharmacokinetic Drug Interactions Mediated by FDA and EMA-approved Hepatitis C Direct-Acting Antiviral Agents

The treatment of patients infected with the hepatitis C virus (HCV) has been revolutionised by the development of direct-acting antiviral agents (DAAs) that target specific HCV proteins involved in viral replication. The first DAAs were associated with clinical problems such as adverse drug reactions and pharmacokinetic drug-drug interactions (DDIs). Current FDA/EMA-approved treatments are combinations of DAAs that simultaneously target the HCV N5A-protein, the HCV N5B-polymerase and the HCV NS3/4A-protease. Adverse events and DDIs are less likely with these DAA combinations but several DDIs of potential clinical significance remain. Much of the available information on the interaction of DAAs with CYP drug-metabolising enzymes and influx and efflux transporters is contained in regulatory summaries and is focused on DDIs of likely clinical importance. Important DDIs perpetrated by current DAAs include increases in the pharmacokinetic exposure to statins and dabigatran. Some mechanistic information can be deduced. Although the free concentrations of DAAs in serum are very low, a number of these DDIs are likely mediated by the inhibition of systemic influx transporters, especially OATP1B1/1B3. Other DDIs may arise by DAA-mediated inhibition of intestinal efflux transporters, which increases the systemic concentrations of some coadministered drugs. Conversely, DAAs are victims of DDIs mediated by cyclosporin, ketoconazole, omeprazole and HIV antiretroviral drug combinations, especially when boosted by ritonavir and, to a lesser extent, cobicistat. In addition, concurrent administration of inducers, such as rifampicin, carbamazepine and efavirenz, decreases exposure to some DAAs. Drug-drug interactions that increase the accumulation of HCV N3/4A-protease inhibitors like grazoprevir may exacerbate hepatic injury in HCV patients.

Residual risk of hepatocellular carcinoma development for chronic hepatitis C patients treated by all oral direct-acting antivirals with sustained virological response

BACKGROUND

The treatment of chronic hepatitis C (CHC) infection underwent a significant transformation with the introduction of all-oral direct-acting anti-virals (DAAs). These medications offered a high success rate in treatment, shorter duration, good tolerability, and expanded treatment options. However, a residual risk of hepatocellular carcinoma (HCC) development remained for a few patients even after achieving sustained virological response (SVR). To date, there is a lack of real-world data on evaluating risk factors associated with de novo HCC in CHC patients post-SVR, particularly in Taiwan.

METHODS

Between January 2017 and December 2019, a total of 671 consecutive CHC patients who achieved SVR after receiving DAAs were included for analysis. Patients with a history of HCC or liver transplantation prior to DAAs, a short follow-up period (<1 year), or treatment failure with DAAs were excluded. The primary outcome was the development of HCC following the initiation of DAAs. Variables associated with the primary outcome were assessed using multivariate Cox proportional hazards models.

RESULTS

The mean age of the enrolled patients was 65.1 ± 12.8 years, with 39.6% of them being male. Among the patients, 30.6% had advanced (F3-4) fibrosis, and the median follow-up period was 2.90 years. The cumulative incidence of HCC in CHC patients post-SVR12 was 1.6% at 1 year, 4.4% at 2 years, 4.8% at 3 years, 5.3% at 4 years, and 6.1% at 4.8 years, respectively. Variables independently associated with de novo HCC were advanced liver fibrosis (hazard ratio [HR] = 6.745; 95% CI = 1.960-23.218; p = 0.002), end-of-treatment 12 weeks (EOT 12 ) alpha-fetoprotein (AFP) >7 ng/mL (HR = 3.059; 95% CI = 1.215-7.669; p = 0.018), EOT 12 albumin-bilirubin (ALBI) grade ≥ 2 (HR = 2.664; 95% CI = 1.158-6.128; p = 0.021), and body mass index (BMI) ≥ 25 kg/m 2 (HR = 2.214; 95% CI = 1.011-4.852; p = 0.047).

CONCLUSION

Despite achieving viral clearance with DAAs, CHC patients still face a residual risk of de novo HCC. Establishing a risk stratification model based on independent variables could facilitate the prediction of future HCC development and enhance screening strategies.

Evaluation of Plasma miR-17-5p, miR-24-3p and miRNA-223-3p Profile of Hepatitis C Virus-Infected Patients after Treatment with Direct-Acting Antivirals

The expression of miR-223-3p, miR-17-5p, and miR-24-3p was evaluated in hepatitis C virus (HCV) patient serum samples, collected before DAA treatment and after a sustained virological response (SVR). Fifty HCV patients were stratified based on their liver damage stages into three different subgroups (21 with chronic hepatitis-CH, 15 with cirrhosis, and 14 with hepatocellular carcinoma-HCC). Considering the entire HCV population, the miRNA expression levels were significantly downregulated after the SVR compared to pre-treatment ones (p < 0.05). Stratifying the patients based on liver damage, the post-SVR values of the three miRNAs were significantly downregulated compared to the pre-treatment levels for both cirrhosis and HCC patients. No significant differences emerged from the analysis of the CH group. To our knowledge, this is the first study to detail the behavior of miR-223-3p, miR-17-5p, and miR-24-3p levels in patients with HCV-related CH, cirrhosis, and HCC after DAA therapy. Our findings show that HCV-infected patients have different miRNA profiles before and after treatment with DAAs, strongly suggesting that miRNAs may be involved in the pathogenesis of HCV-related damage. In this respect, the correlation observed among the three studied miRNAs could imply that they share common pathways by which they contribute the progression of HCV-induced chronic liver damage.

Cardiac toxicity associated with pharmacokinetic drug-drug interaction between crizotinib and sofosbuvir/velpatasvir: A case report

This case report describes a pharmacokinetic drug-drug interaction between crizotinib, a tyrosine kinase inhibitor, and sofosbuvir/velpatasvir, a direct-acting antiviral drug, leading to cardiac toxicity. A 75-year-old man, with no cardiovascular history but a diagnosis of metastatic nonsmall cell lung cancer with mesenchymal-epithelial transition exon-14 deletion and hepatitis C virus infection genotype 1A, received both crizotinib and sofosbuvir/velpatasvir. Crizotinib was well tolerated, but 1 week after sofosbuvir/velpatasvir initiation, the patient experienced bilateral lower-limb oedema and class III New York Heart Association dyspnoea. We assumed that increased exposure to crizotinib could account for this cardiac toxicity. Drug causality was probable according to the Naranjo scale. We hypothesized a reciprocal interaction between crizotinib and velpatasvir, mediated by both cytochrome 3A4 (CYP3A4) and P-glycoprotein (P-gp). Clinicians should be aware of the risk of drug-drug interactions between direct-acting antiviral agents that inhibit CYP3A4 (glecaprevir) and/or P-gp (voxilaprevir, velpatasvir) and anticancer tyrosine kinase inhibitors that are mostly CYP3A4 and/or P-gp substrates (gefitinib, afatinib, erlotinib, crizotinib, ceritinib, lorlatinib, brigatinib, capmatinib etc.).

General Framework to Quantitatively Predict Pharmacokinetic Induction Drug-Drug Interactions Using In Vitro Data

INTRODUCTION

Metabolic inducers can expose people with polypharmacy to adverse health outcomes. A limited fraction of potential drug-drug interactions (DDIs) have been or can ethically be studied in clinical trials, leaving the vast majority unexplored. In the present study, an algorithm has been developed to predict the induction DDI magnitude, integrating data related to drug-metabolising enzymes.

METHODS

The area under the curve ratio (AUC_ratio) resulting from the DDI with a victim drug in the presence and absence of an inducer (rifampicin, rifabutin, efavirenz, or carbamazepine) was predicted from various in vitro parameters and then correlated with the clinical AUC_ratio (N = 319). In vitro data including fraction unbound in plasma, substrate specificity and induction potential for cytochrome P450s, phase II enzymes and uptake, and efflux transporters were integrated. To represent the interaction potential, the in vitro metabolic metric (IVMM) was generated by combining the fraction of substrate metabolised by each hepatic enzyme of interest with the corresponding in vitro fold increase in enzyme activity (E) value for the inducer.

RESULTS

Two independent variables were deemed significant and included in the algorithm: IVMM and fraction unbound in plasma. The observed and predicted magnitudes of the DDIs were categorised accordingly: no induction, mild, moderate, and strong induction. DDIs were assumed to be well classified if the predictions were in the same category as the observations, or if the ratio between these two was < 1.5-fold. This algorithm correctly classified 70.5% of the DDIs.

CONCLUSION

This research presents a rapid screening tool to identify the magnitude of potential DDIs utilising in vitro data which can be highly advantageous in early drug development.

Evaluation of Drug Interactions in Patients Treated with DAAs for Hepatitis C Therapy with Comorbidities and Cardiovascular Issues-A Delphi Consensus Project

Orally administered direct-acting antivirals (DAAs) have dramatically changed the possibility of curing HCV (hepatitis C virus) infection, with the two principal HCV regimens based on the combination of glecaprevir + pibrentasvir (GLE-PIB) and sofosbuvir + velpatasvir (SOF-VEL). A combination of drugs containing NS3/4A protease inhibitors, as well as the fact that almost all HCV patients can be treated at present, may expose patients to a higher rate of drug-drug interactions (DDIs). The hepatitis C treatment recommendations from the EASL (European Association for the Study of the Liver) state that, prior to starting treatment with a DAA, a detailed drug history should be taken; yet, the decision on managing the potential DDIs is not always clear. For this reason, a group of Italian cardiologists and hepatologists promoted a survey among colleagues to assess the controversial issues when treating patients with chronic hepatitis C taking concomitant cardiovascular drugs, aiming to reach a consensus on the best practice to apply when treating a patient with chronic hepatitis C who is taking concomitant drugs for cardiovascular diseases. Two consecutive questionnaires were proposed between June and July 2022 to a qualitative Expert Panel (EP) of 14 gastroenterologists, infectologists, hepatologists, and internists, with statistical analyses performed on 100% of the responses for both questionnaires. Agreement among experts was assessed following the Delphi method as developed by the RAND Corporation. The interviewed experts consider DDIs a critical clinical problem to be evaluated in HCV patients. Therefore, dose changes, drug substitution, and discontinuation of concomitant cardiovascular drugs should be discouraged, even if planned for a relatively short period. Since oral DAAs have different DDIs profiles, hepatologists should prefer the antiviral DAA combination presenting the lowest instance of potential interactions.

Direct antiviral agents (DAAs) and their use in pregnant women with hepatitis C (HCV)

INTRODUCTION

Direct-Acting Antiviral Agents (DAAs) provide safer, efficacious, tolerable, and curative therapy for women with hepatitis C. Their preferred safety and efficacy profile make them potential therapies for the elimination of perinatal transmission of hepatitis C virus (HCV). However, DAAs are not currently recommended for use during pregnancy due to limited pharmacokinetic and safety data.

AREAS COVERED

This review covers the different DAA drug combinations, the available data on their pharmacodynamic and pharmacokinetic properties, how the physiology in pregnancy can potentially affect DAA drug disposition, known drug-drug interactions with DAAs, and available and planned epidemiological and pharmacokinetic studies on DAA use during pregnancy. Although no large randomized clinical trials or prospective cohort studies involving DAAs have been completed in pregnancy, the currently available studies demonstrate no significant changes in pharmacokinetics, and no major safety concerns in women with hepatitis C.

EXPERT OPINION

Initial pharmacokinetic and safety data suggest that DAAs have high efficacy and a low risk of adverse events during pregnancy. As more pharmacokinetic and epidemiologic data become available, DAAs could become a preferred option for treating HCV during pregnancy and elimination of perinatal transmission of hepatitis C virus.

Integrating Management of Hepatitis C Infection into Primary Care: the Key to Hepatitis C Elimination Efforts

Elimination of hepatitis C virus (HCV), a leading cause of liver disease in the USA and globally, has been made possible with the advent of highly efficacious direct acting antivirals (DAAs). DAA regimens offer cure of HCV with 8-12 weeks of a well-tolerated once daily therapy. With increasingly straightforward diagnostic and treatment algorithms, HCV infection can be managed not only by specialists, but also by primary care providers. Engaging primary care providers greatly increases capacity to diagnose and treat chronic HCV and ultimately make HCV elimination a reality. However, barriers remain at each step in the HCV cascade of care from screening to evaluation and treatment. Since primary care is at the forefront of patient contact, it represents the ideal place to concentrate efforts to identify barriers and implement solutions to achieve universal HCV screening and increase curative treatment.

Safety and effectiveness of direct-acting antivirals in patients with chronic hepatitis C and chronic kidney disease

BACKGROUND/AIMS

To evaluate the effectiveness and safety of direct acting antivirals (DAAs) available in chronic kidney disease (CKD) patients with hepatitis C virus (HCV) infection in Korea.

METHODS

In a retrospective, multicenter cohort study, 362 patients were enrolled from 2015 to 2019. The effectiveness and safety of DAAs including glecaprevir/pibrentasvir, sofosubvir/ribavirin, ledipasvir/sofosbuvir, and daclatasvir/asunaprevir were analyzed for patients according to CKD stage. We evaluated sustained virologic response at week 12 after treatment (SVR12) as primary endpoint. The effectiveness and safety were also evaluated according to CKD stage.

RESULTS

Among 362 patients, 307 patients completed DAAs treatment and follow-up period after end of treatment. The subjects comprised 87 patients (62 with CKD stage 3 and 25 with CKD stage (4-5), of whom 22 were undergoing hemodialysis). HCV patients with CKD stage 1 and 2 (estimated glomerular filtration rate [eGFR] ≥ 60 mL/min/1.73 m2) showed SVR12 of 97.2% and 95.4% respectively. SVR12 of CKD stage 3 and 4-5 (eGFR &lt; 60 mL/min/1.73 m2) patients was 91.9% and 91.6% respectively. Patients undergoing hemodialysis achieved SVR12 (90.9%). Treatment failure of DAAs in stage 1, 2, 3, and 4-5 was 2.8%, 2.7%, 1.6%, and 4%. DAAs showed good safety profile and did not affect deterioration of renal function.

CONCLUSION

DAAs shows comparable SVR12 and safety in CKD patients (stage 3, 4, and 5) with HCV compared with patients with stage 1 and 2. The effectiveness and safety of DAAs may be related to the treatment duration. Therefore, it is important to select adequate regimens of DAAs and to increase treatment adherence.

hsa-miR-17-5p: A Possible Predictor of Ombitasvir/Paritaprevir/Ritonavir + Dasabuvir ± Ribavirin Therapy Efficacy in Hepatitis C Infection

Although persistent sustained viral response rates are increased in hepatitis C infection following administration of direct-acting antiviral (DAA) agents, the pre-use predictive parameters of these antivirals and the clinical progression in patients post-treatment remain unknown. To obtain data pertaining to the predictive parameters prior to the use of ombitavir/paritaprevir/ritonavir + dasabuvir and the clinical progression in patients following antiviral treatment. The expression profiles of miR-223-3p, miR-17-5p, miR-24-3p, and TLR2 - 196 to - 174 del/ins polymorphisms from the blood/serum of 34 hepatitis C virus (HCV)-infected patients pre- and post-ombitavir/paritaprevir/ritonavir + dasabuvir treatment were determined by RT-qPCR. The expression levels of miR-17-5p (P < 0.001) and miR-24-3p (P = 0.011) were significantly downregulated post-treatment as compared with those pre-treatment; however, there was no significant difference between these two groups in terms of miR-223-3p expression. In addition, there was no significant difference in TLR2 genotype or allele distribution between pre-and post-treatment (P > 0.05); nevertheless, the TLR2 del allele was decreased post-treatment (16.2%) as compared with that pre-treatment (19.1%), although the difference was not statistically significant. Moreover, a significant difference was found between the mRNA levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and HCV RNA pre-and post-treatment (P < 0.05). Further, miR-17-5p expression correlated with both ALT and AST mRNA levels post-treatment (P.

Safety of direct acting antiviral treatment for hepatitis C in oncologic setting: A clinical experience and a literature review

With a globally estimated 58 million people affected by, chronic hepatitis C virus (HCV) infection still represents a hard challenge for scientific community. A chronic course can occur among patients with a weak innate ad adaptive response with cirrhosis and malignancies as main consequences. Oncologic patients undergoing chemotherapy represent a special immunocompromised population predisposed to HCV reactivation (HCVr) with undesirable changes in cancer treatment and outcome. Aim of the study highlight the possibility of HCVr in oncologic population eligible to chemotherapy and its threatening consequences on cancer treatment; underline the importance of HCV screening before oncologic therapy and the utility of direct aging antivirals (DAAs). A comprehensive overview of scientific literature has been made. Terms searched in PubMed were: “HCV reactivation in oncologic setting” “HCV screening”, “second generation DAAs”. Pharmacokinetic and Pharmacodynamics characteristics of DAAs are reported, along with drug - drug interactions among chemotherapeutic drug classes regimens and DAAs. Clinical trials conducted among oncologic adults with HCV infection eligible to both chemotherapy and DAAs were analyzed. Viral eradication with DAAs in oncologic patients affected by HCV infection is safe and helps liver recovery, allowing the initiation of cancer treatment no compromising its course and success.

From Pharmacogenetics to Pharmaco-Omics:Milestones and Future Directions

The origins of pharmacogenetics date back to the 1950s, when it was established that inter-individual differences in drug response are partially determined by genetic factors. Since then, pharmacogenetics has grown into its own field, motivated by the translation of identified gene-drug interactions into therapeutic applications. Despite numerous challenges ahead, our understanding of the human pharmacogenetic landscape has greatly improved thanks to the integration of tools originating from disciplines as diverse as biochemistry, molecular biology, statistics, and computer sciences. In this review, we discuss past, present, and future developments of pharmacogenetics methodology, focusing on three milestones: how early research established the genetic basis of drug responses, how technological progress made it possible to assess the full extent of pharmacological variants, and how multi-dimensional omics datasets can improve the identification, functional validation, and mechanistic understanding of the interplay between genes and drugs. We outline novel strategies to repurpose and integrate molecular and clinical data originating from biobanks to gain insights analogous to those obtained from randomized controlled trials. Emphasizing the importance of increased diversity, we envision future directions for the field that should pave the way to the clinical implementation of pharmacogenetics.

Evaluation of the Potency of Anti-HIV and Anti-HCV Drugs to Inhibit P-Glycoprotein Mediated Efflux of Digoxin in Caco-2 Cell Line and Human Precision-Cut Intestinal Slices

The inhibition of P-glycoprotein (ABCB1) could lead to increased drug plasma concentrations and hence increase drug toxicity. The evaluation of a drug’s ability to inhibit ABCB1 is complicated by the presence of several transport-competent sites within the ABCB1 binding pocket, making it difficult to select appropriate substrates. Here, we investigate the capacity of antiretrovirals and direct-acting antivirals to inhibit the ABCB1-mediated intestinal efflux of [³H]-digoxin and compare it with our previous rhodamine123 study. At concentrations of up to 100 µM, asunaprevir, atazanavir, daclatasvir, darunavir, elbasvir, etravirine, grazoprevir, ledipasvir, lopinavir, rilpivirine, ritonavir, saquinavir, and velpatasvir inhibited [³H]-digoxin transport in Caco-2 cells and/or in precision-cut intestinal slices prepared from the human jejunum (hPCIS). However, abacavir, dolutegravir, maraviroc, sofosbuvir, tenofovir disoproxil fumarate, and zidovudine had no inhibitory effect. We thus found that most of the tested antivirals have a high potential to cause drug–drug interactions on intestinal ABCB1. Comparing the Caco-2 and hPCIS experimental models, we conclude that the Caco-2 transport assay is more sensitive, but the results obtained using hPCIS agree better with reported in vivo observations. More inhibitors were identified when using digoxin as the ABCB1 probe substrate than when using rhodamine123. However, both approaches had limitations, indicating that inhibitory potency should be tested with at least these two ABCB1 probes.

Sofosbuvir-based antiviral therapy provided highly treatment efficacy, safety, and good tolerability for Taiwanese chronic hepatitis C patients with decompensated cirrhosis

BACKGROUND

For patients with hepatitis C virus (HCV)-related decompensated cirrhosis, poor prognosis was documented due to the development of portal hypertension-related complications and hepatocellular carcinoma. Sofosbuvir-based direct-acting antiviral agents (DAAs) has revolutionized the treatment landscape of HCV, particularly in this subpopulation. To date, real-world efficacy, tolerability, and safety profiles for Taiwanese HCV-related decompensated cirrhosis treated by DAAs have not been reported.

METHODS

Between December 2015 and June 2020, 50 consecutive HCV-related Child-Turcotte-Pugh (CTP) classes B or C cirrhotics treated by sofosbuvir-based DAAs (with daclatasvir: 7, with ledipasvir: 32, with velpatasvir: 10, with ledipasvir then shifted to velpatasvir: 1) were enrolled. Forty-seven (94%) patients used DAAs in combination with low-dose ribavirin. SVR12 was defined by undetectable HCV RNA (<15 IU/mL) at treatment end and 12 weeks after the completion of therapy.

RESULTS

The mean age of the enrolled patients was 68.1 ± 11.2 years, 18% of the patients were CTP class C, and the baseline HCV RNA level was 5.42 ± 1.2 log10 IU/mL. The genotype distribution was as follows: 1a: 3; 1b: 34; 2: 9; 6: 3; and one patient with an unclassified HCV genotype. After DAAs treatment, the rates of undetectable HCV RNA at week 4 and at the end of the treatment were 88.9% and 98.0%, respectively. Subjective adverse events were reported by 42.0% of the patients, but they were generally mild and could be relieved by medications. One patient did not finish therapy due to sepsis with multiple organ dysfunction. The overall SVR12 rate was 96.0% (CTP class B: 97.6%, CTP class C: 88.9%). A significant improvement in hepatic functional reserve was noted after successful antiviral therapy.

CONCLUSION

For patients with HCV-related decompensated cirrhosis, which has been considered a contraindication for interferon-based therapy, sofosbuvir-based all-oral DAAs provided high treatment efficacy, acceptable safety, and good tolerability.

Safety and efficacy of glecaprevir and pibrentasvir in north Tohoku Japanese patients with genotype 1/2 hepatitis C virus infection

Background and aims

To assess the efficacy and safety of treatment with glecaprevir/pibrentasvir in Japanese patients with genotype (GT) 1/2 hepatitis C virus (HCV) infection in a real‐world clinical setting.

Methods

A total of 230 patients from 12 centers in northern Tohoku Japan with chronic hepatitis (CH) or compensated liver cirrhosis (LC) and GT1/2 HCV infection were treated with glecaprevir/pibrentasvir and followed up for 12 weeks after treatment completion. Those patients were evaluated by dividing them into the following three groups: CH GT1/2 HCV‐infected, direct‐acting antiviral agents (DAA)‐naive patients received 8 weeks of treatment (8‐week initial treatment group), compensated LC GT1/2 HCV‐infected, DAA‐naive patients received 12 weeks of treatment (12‐week initial treatment group), and GT1/2 HCV‐infected patients with previous failed DAA treatment were assigned to 12‐week treatment (12‐week re‐treatment group).

Results

The overall sustained virologic response (SVR) rate in the modified intention‐to‐treat population was 99% (222/225). The SVR rate in 8‐week initial treatment group, 12‐week initial treatment group, and 12‐week re‐treatment group were 99% (118/119), 98% (104/106), and 97% (56/58), respectively. SVR rates based on chronic kidney disease (CKD) stage were 99% in stage 1/2, 96% in stage 3, and 100% in stage 4/5 patients. SVR rate among the three treatment groups was not influenced by CKD stage. Furthermore, all 18 patients (six in the 8‐week initial treatment group, 12 in 12‐week initial treatment group) who underwent hemodialysis attained SVR. Serious treatment‐associated adverse events (grade ≥ 3) occurred in 12 patients (5.2%). Five patients (2.2%) discontinued treatment because of adverse events; however, three of these patients achieved SVR.

Conclusion

Primary treatment and re‐treatment with glecaprevir/pibrentasvir are effective and safe for patients without decompensated LC and GT1/2 HCV infection in a real‐world clinical setting. Furthermore, the SVR rate was not influenced by CKD stage.

Outcomes of short-duration antiviral prophylaxis for hepatitis C positive donor kidney transplants

Trials describing 4- to 12-week courses of direct-acting antiviral drugs (DAAs) to treat hepatitis C virus (HCV) transmission from infected donors to uninfected kidney transplant recipients (D+/R- transplants) may be limited in "real-world" application by costs and delayed access to DAAs. We previously reported HCV transmission of 13% among D+/R- transplants with 2- to 4-day pangenotypic sofosbuvir/velpatasvir (SOF/VEL) perioperative prophylaxis, where one patient with HCV transmission was a nonresponder to first-line full-course DAA. Here, we report new data with a 7-day prophylaxis protocol (N = 50), as well as cumulative treatment and outcome data on all HCV D+/R- transplants (N = 102). Overall, nine patients (9/102; 9%; 95% CI: 5%-16%) developed HCV transmission, with a significant decline noted in the 7-day group (2/50; 4%; 95% CI: 0%-13%) compared with 2- to 4-day prophylaxis (7/52; 13%; 95% CI: 5%-25%). All patients with HCV transmission achieved sustained virologic response post full-course therapy (including one nonresponder from initial trial). A 1:1 matched analysis (N = 102) with contemporary HCV D-/R- transplants (controls) showed that although the pretransplant wait time was significantly shorter for D+/R- compared with D-/R- (mean: 1.8 vs. 4.4 years; p < .001), there were no differences in infections, rejection, development of de novo donor-specific antibody, or transplant outcomes up to 6 months of transplant.

Drug-Drug Interactions in Italian Patients with Chronic Hepatitis C Treated with Pangenotypic Direct Acting Agents: Insights from a Real-World Study

This Italian observational real-world study aims to assess in chronic hepatitis C virus (HCV) patients treated with pangenotypic direct acting agents (pDAAs) glecaprevir/pibrentasvir (GLE/PIB) or sofosbuvir/velpatasvir (SOF/VEL) the potential drug-drug interactions (DDIs) with concomitant medications prescribed, with a focus on cardiovascular and system nervous (CNS) co-medications. Data were collected from administrative databases covering 6.9 million health-assisted individuals. All patients prescribed SOF/VEL or GLE/PIB between 11/2017 and 12/2018 were included. Patients were analyzed while on DAA. DDIs were identified according to the Liverpool University tool. Overall, 3181 HCV patients were included: 1619 in the GLE/PIB cohort and 1562 in the SOF/VEL cohort. SOF/VEL patients were generally older than GLE/PIB ones (mean age 58.4 vs. 53.1, p < 0.001) and had more cardiovascular and CNS comorbidities (58% vs. 42%, p < 0.001 and 33% vs. 28%, p = 0.002, respectively). Contraindications due to DDIs in the GLE/PIB cohort affected 9.3% and 3.2% of patients before and on DAA, respectively, while the percentages in the SOF/VEL cohort were 3.2% before and 0.4% after pDAAs initiation. Among GLE/PIB patients, 2.7% had cardiovascular drugs (all statins) contraindicated while on DAA. The potential DDIs between cardiovascular drugs and SOF/VEL were mainly with statins (5%). SOF/VEL was prescribed in patients with older age and with more cardiovascular and CNS comorbidities. Despite this, a proportion of contraindicated drugs lower than that of GLE/PIB was registered.

Current treatment for hepatitis C virus/human immunodeficiency virus coinfection in adults

Hepatitis C virus (HCV)/human immunodeficiency virus (HIV) coinfection is a major problem among HIV-infected patients, resulting in increased morbidity and mortality rates due to the acceleration of liver fibrosis progression by HIV, leading to liver cirrhosis and hepatocellular carcinoma. Although the efficacy of direct-acting antiviral therapy in patients with HIV/HCV coinfection and HCV monoinfection are similar in terms of sustained virologic response rate, there are some additional complications that arise in the treatment of patients with HIV/HCV coinfection, including drug-drug interactions and HCV reinfection due to the high risk behavior of these patients. This review will summarize the current management of HIV/HCV coinfection.

Management and Treatment of Hepatitis C: Are There Still Unsolved Problems and Unique Populations?

Direct-acting antivirals (DAA) have revolutionized the treatment of patients with chronic hepatitis C virus (HCV) infection, possibly leading to HCV elimination by 2030 as endorsed by the World Health Organization (WHO). However, some patients belonging to the so-called unique or special populations are referred to as difficult-to-treat due to unreached sustained virological response, potential drug side effects or interactions or co-morbidities. Several years after the DAA introduction and on the basis of excellent findings in terms of efficacy and safety, some doubts arise around the exact meaning of the special population designation and whether this group of patients actually exists. The aim of this review is to discuss and analyze current evidence on the management and treatment of the so-called "unique populations". We placed particular emphasis on patients with decompensated cirrhosis, chronic kidney disease (CKD), coinfections, rare genotypes, and previous treatment failure, in order to provide physicians with an updated overview of the actual problems and needs in the current scenario.

Edoxaban and the Issue of Drug-Drug Interactions: From Pharmacology to Clinical Practice

Edoxaban, a direct factor Xa inhibitor, is the latest of the non-vitamin K antagonist oral anticoagulants (NOACs). Despite being marketed later than other NOACs, its use is now spreading in current clinical practice, being indicated for both thromboprophylaxis in patients with non-valvular atrial fibrillation (NVAF) and for the treatment and prevention of venous thromboembolism (VTE). In patients with multiple conditions, the contemporary administration of several drugs can cause relevant drug-drug interactions (DDIs), which can affect drugs' pharmacokinetics and pharmacodynamics. Usually, all the NOACs are considered to have significantly fewer DDIs than vitamin K antagonists; notwithstanding, this is actually not true, all of them are affected by DDIs with drugs that can influence the activity (induction or inhibition) of P-glycoprotein (P-gp) and cytochrome P450 3A4, both responsible for the disposition and metabolism of NOACs to a different extent. In this review/expert opinion, we focused on an extensive report of edoxaban DDIs. All the relevant drugs categories have been examined to report on significant DDIs, discussing the impact on edoxaban pharmacokinetics and pharmacodynamics, and the evidence for dose adjustment. Our analysis found that, despite a restrained number of interactions, some strong inhibitors/inducers of P-gp and drug-metabolising enzymes can affect edoxaban concentration, just as it happens with other NOACs, implying the need for a dose adjustment. However, our analysis of edoxaban DDIs suggests that given the small propensity for interactions of this agent, its use represents an acceptable clinical decision. Still, DDIs can be significant in certain clinical situations and a careful evaluation is always needed when prescribing NOACs.

Well tolerability and highly effective treatment response for hepatitis C virus-human immunodeficiency virus-coinfected patients treated by all-oral direct-acting antivirals

BACKGROUND

Hepatitis C virus (HCV) and human immunodeficiency virus (HIV) coinfection is common because the two pathogens share their transmission route. Studies have suggested that coinfection is associated with accelerated hepatic fibrosis, increased hepatic decompensation, and hepatocellular carcinoma development. Historically, the sustained virological response (SVR) rates for patients undergoing pegylated interferon (PEG-IFN)-based therapy are poor owing to advanced liver disease, immune dysfunction, and poor medical adherence. This study aimed to investigate the efficacy and safety of oral direct-acting antivirals (DAAs) in HCV-HIV-coinfected patients.

METHODS

Between January 2017 and February 2020, 52 consecutive HCV-HIV-coinfected patients treated with oral DAAs (paritaprevir/ritonavir, ombitasvir, and dasabuvir: 7; daclatasvir and asunaprevir: 1; glecaprevir and pibrentasvir: 15; and sofosbuvir-based drugs: 29) were enrolled. The DAA regimen was selected based on the genotype/subtypes, patient characteristics, potential drug-drug interaction profiles, and health insurance reimbursement criteria. SVR12 was defined as undetectable HCV RNA (<15 IU/mL) at the end of therapy and 12 weeks after therapy completion.

RESULTS

The mean age of the enrolled patients was 42 ± 10.2 years; 92.3% of the patients were male and 32.7% had advanced fibrosis or cirrhosis. Nine (17.3%) patients had failed previous IFN therapy. The genotype distribution was as follows: 1a: 8; 1b: 23; 2: 14; 3: 1; and 6: 6. The baseline HCV RNA level before DAA administration was 6.56 ± 0.9 log10 IU/mL, and 67.3% of patients had baseline HCV RNA >2 000 000 IU/mL. After posttreatment follow-up, all 52 patients (100%) achieved SVR12. Subjective and laboratory adverse events during therapy were generally mild, and none of the patients terminated therapy early.

CONCLUSION

A highly effective treatment response and good tolerability were achieved using the oral DAAs for the HCV-HIV-coinfected patient population, which has been considered difficult to treat using IFN-based therapy in the past with urgent unmet medical needs.

Direct-acting antiviral treatments display excellent outcomes even in older HCV-infected patients at increased risk of fibrosis

Background

This study compared the efficacy and tolerability of available direct-acting antiviral (DAA) regimens between individuals aged 60 years and older and younger patients in a real-life setting. Specifically, we aimed to provide evidence of the efficacy and safety of DAAs in the treatment of older adults in Tianjin, China.

Methods

In this retrospective observational cohort study, patients with chronic hepatitis C virus (HCV) were enrolled between April 2018 and December 2019 at 2 tertiary hospitals in Tianjin, China. We assessed the sustained virologic response (SVR) 12 weeks (SVR12) after DAA treatment, and adverse events in two groups using age stratification by comparing older adults (≥60 years) and younger adults (<60 years). Logistic regression analyses were performed to explore the risk factors associated with the SVR12.

Results

Of 1,106 patients, 440 (39.8%) were ≥60 years of age. The overall SVR12 rate was 97.8% in the entire cohort. In the older adult group, the SVR12 rate was 98.0% (431/440) compared to 97.7% (651/666) in the younger adult group. A multivariate analysis showed that (I) age was not predictive of SVR; and (II) the variables of treatment-experience [adjusted odds ratio (aOR) =27.53; 95% confidence interval (CI) =3.35–226.08; P=0.002] and aspartate aminotransferase (AST) (aOR =1.02; 95% CI =1.01–1.04; P=0.027) were independently associated with the SVR12 in the older adult group. All of the available DAA regimens were well-tolerated in older adult group.

Conclusions

Chinese older adults with chronic HCV infection showed a significantly higher percentage of fibrosis; however, the available different DAA regimens were safe, well-tolerated, and achieved high rates of SVR in all age subgroups. Our observations suggest that DAA treatment should not be withheld even from older patients suffering from chronic HCV.

Metabolism of Direct-acting Antiviral Agents (DAAs) in Hepatitis C Therapy: A Review of the Literature

BACKGROUND

Hepatitis C virus (HCV) infection is still one of the leading causes of chronic liver disease, with chronically infected making up approximately 1% of the global population. Of those infected, 70% (55-85%) will develop chronic HCV infection. Chronic HCV infection causes substantial morbidity and mortality, with complications including cirrhosis, end-stage liver disease, hepatocellular carcinoma, and eventually death.

OBJECTIVE

Therapeutic options for chronic HCV infection have evolved dramatically since 2014, with a translation from pegylated interferon and ribavirin (associated with suboptimal cure and high treatment-related toxicity) to oral direct-acting antiviral treatment. There are four classes of direct-acting antivirals which differ by their mechanism of action and therapeutic target. They are all pointed to proteins that form the cytoplasmic viral replication complex. Multiple studies have demonstrated that direct-acting antiviral therapy is extremely well tolerated, highly efficacious, with few side effects.

METHODS

We performed an indexed MEDLINE search with keywords regarding specific direct-acting antiviral regimes and their pharmacokinetics, drug-drug interactions, and metabolism in specific settings of pregnancy, lactation, liver cirrhosis, liver transplantation and HCC risk, kidney failure and kidney transplantation.

RESULTS

We present a comprehensive overview of specific direct-acting antiviral metabolism and drug-drug interaction issues in different settings.

CONCLUSION

Despite its complex pharmacokinetics and the possibility of drug-drug interactions, direct-acting antivirals are highly efficacious in providing viral clearance, which is an obvious advantage compared to possible interactions or side effects. They should be administered cautiously in patients with other comorbidities, and with tight control of immunosuppressive therapy.

Drug-Drug Interactions of Newly Approved Direct-Acting Antiviral Agents in Patients with Hepatitis C

Hepatitis C is a major health problem worldwide, frequently resulting in cirrhosis and increasing the risk of hepatocellular carcinoma significantly. In recent years, the advent of direct-acting antivirals (DAAs) has dramatically improved the therapeutic outcomes in hepatitis C patients. In the last two years, several new DAA combinations have been approved for the treatment of the hepatitis C virus (HCV) infection, including elbasvir/grazoprevir, sofosbuvir/velpatasvir, sofosbuvir/velpatasvir/voxilaprevir, and glecaprevir/pibrentasvir. The newly approved DAA regimens may be prescribed with other drugs simultaneously, increasing the potential of pharmacokinetic interactions. Therefore, the knowledge and management of drug-drug interactions (DDIs) with DAAs should be considered a key issue in HCV therapy. This review summarizes researches of DDIs focusing on newly approved DAAs (elbasvir, grazoprevir, velpatasvir, voxilaprevir, glecaprevir, pibrentasvir) for patients undergoing HCV treatment to provide clinical consideration for comedication. With respect to DDIs, newly approved DAA regimens, including elbasvir/grazoprevir, sofosbuvir/velpatasvir, sofosbuvir/velpatasvir/voxilaprevir, and glecaprevir/pibrentasvir, are safely applicable.

Safety and efficacy of sofosbuvir/velpatasvir/voxilaprevir in post-liver transplant patients with previous direct-acting antiviral failure: Six case reports

BACKGROUND

Direct-acting antiviral (DAA) therapy regimens are highly effective at eliminating hepatitis C virus (HCV) infection but rates of sustained virologic response (SVR) are lower in patients with decompensated cirrhosis or hepatocellular carcinoma. Since many of these patients will be referred for liver transplant, they will require retreatment after transplantation. Sofosbuvir/velpatasvir/voxilaprevir (SOF/VEL/VOX) is recommended by guidelines as the preferred regimen to treat HCV in DAA-experienced patients following liver transplant however there is limited data.

CASE SUMMARY

We present the cases of six liver transplant recipients who had previous treatment failure with sofosbuvir-based DAA therapy prior to transplantation and who then received SOF/VEL/VOX after transplant.

CONCLUSION

This case series demonstrate the real-world efficacy and safety of SOF/VEL/VOX in the post liver transplant setting. Treatment was successful with all patients achieving SVR, it was well tolerated, and there were minimal drug-drug interactions with their immunosuppressants.

Clinical Experience of Patients With Hepatitis C Treated With Direct-Acting Antivirals After Heart Transplantation

BACKGROUND

Hepatitis C increases the mortality and morbidity of patients after heart transplant. Direct-acting antivirals (DAAs) are the primary drugs for hepatitis C treatment. However, such drugs are expensive and frequently unaffordable for patients. In DAA treatment, the assessment of drug interaction is crucial.

METHODS

We investigated a retrospective case series study from January 2017 to December 2019. Sustained virologic response 12 (SVR12) was used to assess the effectiveness of DAA treatment. Data on patients' demographic information, timing of hepatitis C virus (HCV) infection (before or after heart transplant), HCV genotypes and viral loads, DAAs used (branded drugs or generic drugs), and drug interaction assessments were collected.

RESULTS

Fifteen heart transplant patients received hepatitis C treatments during the study period, 11 of whom were infected because their donors had hepatitis C. After DAA treatment, HCV was undetectable in all patients, and 93.3% of them achieved SVR12. Nine patients used the generic sofosbuvir/velpatasvir, and 88.9% of them achieved SVR12. A total of 256 drugs were used with DAAs; 51 records of drug interactions were noted, 3 of which were contraindications, and the remaining records were potential interactions. Patients who used sofosbuvir or elbasvir/grazoprevir experienced fewer drug interactions.

CONCLUSIONS

DAA treatment is effective for hepatitis C treatment in patients after heart transplant. Patients who cannot afford branded drugs because of their prices can use generic drugs as an alternative. Drug interactions must be surveyed during DAA treatment.

Clinically Relevant Interactions between Atypical Antipsychotics and Anti-Infective Agents

This is a comprehensive review of the literature on drug interactions (DIs) between atypical antipsychotics and anti-infective agents that focuses on those DIs with the potential to be clinically relevant and classifies them as pharmacokinetic (PK) or pharmacodynamic (PD) DIs. PubMed searches were conducted for each of the atypical antipsychotics and most commonly used anti-infective agents (13 atypical antipsychotics by 61 anti-infective agents/classes leading to 793 individual searches). Additional relevant articles were obtained from citations and from prior review articles written by the authors. Based on prior DI articles and our current understanding of PK and PD mechanism, we developed tables with practical recommendations for clinicians for: antibiotic DIs, antitubercular DIs, antifungal DIs, antiviral DIs, and other anti-infective DIs. Another table reflects that in clinical practice, DIs between atypical antipsychotics and anti-infective agents occur in patients also suffering an infection that may also influence the PK and PD mechanisms of both drugs (the atypical antipsychotic and the anti-infective agent(s)). These tables reflect the currently available literature and our current knowledge of the field and will need to be updated as new DI information becomes available.

Fluoxazolevir inhibits hepatitis C virus infection in humanized chimeric mice by blocking viral membrane fusion

Fluoxazolevir is an aryloxazole-based entry inhibitor of hepatitis C virus (HCV). We show that fluoxazolevir inhibits fusion of HCV with hepatic cells by binding HCV envelope protein 1 to prevent fusion. Nine of ten fluoxazolevir resistance-associated substitutions are in envelope protein 1, and four are in a putative fusion peptide. Pharmacokinetic studies in mice, rats and dogs revealed that fluoxazolevir localizes to the liver. A 4-week intraperitoneal regimen of fluoxazolevir in humanized chimeric mice infected with HCV genotypes 1b, 2a or 3 resulted in a 2-log reduction in viraemia, without evidence of drug resistance. In comparison, daclatasvir, an approved HCV drug, suppressed more than 3 log of viraemia but is associated with the emergence of resistance-associated substitutions in mice. Combination therapy using fluoxazolevir and daclatasvir cleared HCV genotypes 1b and 3 in mice. Fluoxazolevir combined with glecaprevir and pibrentasvir was also effective in clearing multidrug-resistant HCV replication in mice. Fluoxazolevir may be promising as the next generation of combination drug cocktails for HCV treatment.

Real-world clinical outcomes among individuals with chronic HCV infection in China: CCgenos study

BACKGROUND

This 5-year follow-up of the CCgenos cross-sectional study aimed to observe real-life outcomes in a cohort of 997 Han Chinese patients with chronic HCV infection and to explore the impacts of HCV genotype, patient characteristics and treatment status.

METHODS

Clinical information and centralized HCV RNA measures were collected every 6/3 months for untreated/treated patients. Overall disease progression was defined as ≥1 of: de novo development of cirrhosis, Child-Turcotte-Pugh score increased by ≥2 points (if cirrhosis at baseline), progression to decompensated cirrhosis, hepatocellular carcinoma (HCC), liver transplant or death. Cox regression assessed risk factors for the time from estimated infection to cirrhosis or HCC. Logistic regression assessed risk factors for incidence rates of cirrhosis and overall disease progression.

RESULTS

281 of 514 patients enrolled across China completed 5 years of follow-up. Overall disease progression occurred in 36/364 (9.9%) treated patients and 35/148 (23.6%) untreated patients (odds ratio = 0.35; 95% CI 0.21, 0.59; P<0.0001). Overall disease progression occurred in 6/231 (2.6%) patients achieving sustained virological response at 24 weeks (SVR24) versus 11/82 (13.4%) who did not (P=0.0002). Cirrhosis development was significantly associated with abnormal aspartate aminotransferase (AST), age ≥40 years, body mass index ≥28 kg/m², HCV GT1, platelet count <100×10⁹/l, and AST to platelet ratio index (APRI) ≥2 (multivariate Cox regression, P<0.05). HCC was significantly associated with HCV GT1 and platelet count <100×10⁹/l (multivariate Cox regression, P<0.05).

CONCLUSIONS

Achieving SVR24 significantly reduced the probability of overall disease progression but no significant difference was seen for both cirrhosis and HCC during 5 years of follow-up.

In silico identification of drug candidates against COVID-19

The COVID-19 pandemic has caused unprecedented health and economic crisis throughout the world. However, there is no effective medication or therapeutic strategy for treatment of this disease currently. Here, to elucidate the inhibitory effects, we first tested binding affinities of 11 HIV-1 protease inhibitors or their pharmacoenhancers docked onto SARS-CoV-2 main protease (M pro ), and 12 nucleotide-analog inhibitors docked onto RNA dependent RNA polymerase (RdRp). To further obtain the effective drug candidates, we screened 728 approved drugs via virtual screening on SARS-CoV-2 M pro . Our results demonstrate that remdesivir shows the best binding energy on RdRp and saquinvir is the best inhibitor of M pro . Based on the binding energies, we also list 10 top-ranked approved drugs which can be potential inhibitors for M pro . Overall, our results do not only propose drug candidates for further experiments and clinical trials but also pave the way for future lead optimization and drug design.

COVID-19 and Gastrointestinal Disease: Implications for the Gastroenterologist

BACKGROUND

COVID-19 was initially considered a respiratory disease but the SARS-CoV-2 virus can lead to serious systemic consequences affecting major organs including the digestive system.

SUMMARY

This review brings new clinically important information for the gastroenterologist. This includes: the mechanisms of tissue damage seen with the SARS-CoV-2 virus; the consequences of immunosuppression in patients with inflammatory bowel disease (IBD) and chronic liver disease with the additional risks of decompensation in patients with cirrhosis; the impact of COVID-19 on gastrointestinal emergencies, on gastrointestinal endoscopy, diagnosis and treatments. These highlight the need to understand the clinical pharmacology, toxicology and therapeutic implications of drugs commonly used by gastroenterologists and their links with COVID-19. Key Messages: Any part of the digestive system may be affected by the SARS-CoV-2 virus, and those with pre-existing disease are at greatest risk of adverse outcomes. The risk for drug-drug interactions is considerable in patients seriously ill with COVID-19 who often require mechanical ventilation and life support. Some repurposed drugs used against SARS-CoV-2 can cause or aggravate some of the COVID-19-related gastrointestinal symptoms and can also induce liver injury. Ongoing clinical studies will hopefully identify effective drugs with a more favourable risk-benefit ratio than many initially tried treatments.

Clinical Pharmacokinetics of the Novel HIV-1 Non-Nucleoside Reverse Transcriptase Inhibitor Doravirine: An Assessment of the Effect of Patient Characteristics and Drug-Drug Interactions

Doravirine (MK-1439) is a novel non-nucleoside reverse transcriptase inhibitor indicated for the combination treatment of human immunodeficiency virus type-1 (HIV-1) infection. The recommended dose is 100 mg once daily. This review summarizes the pharmacokinetics of doravirine, the influence of intrinsic factors, and its drug-drug interaction (DDI) profile. Following oral administration, doravirine is rapidly absorbed (median time to maximum plasma concentration, 1-4 h) and undergoes cytochrome P450 (CYP)3A-mediated oxidative metabolism. Steady-state geometric means for AUC0-24, C24, and Cmax in individuals with HIV-1 following administration of doravirine 100 mg once daily are 37.8 μM·h, 930 nM, and 2260 nM, respectively. Age, gender, severe renal impairment, and moderate hepatic impairment have no clinically meaningful effect on doravirine pharmacokinetics, and there is limited potential for DDIs. No dose adjustment is necessary when doravirine is co-administered with strong CYP3A inhibitors. However, doravirine is contraindicated with strong CYP3A inducers (e.g., rifampin), and dose adjustment of doravirine is recommended for co-administration with the moderate CYP3A inducer, rifabutin. Included in this review are clinical trial data from phase I pharmacokinetic trials, including DDI trials and trials in participants with renal and hepatic disease but without HIV-1 infection (N = 326), as well as phase I, II, and III safety and efficacy trials in participants living with HIV-1 (N = 991). Based on these data, the pharmacokinetic profile of doravirine supports its use in diverse populations living with HIV-1 and allows co-administration with various antiretroviral agents and treatments for commonly occurring co-morbidities.

Review of Clinically Relevant Drug Interactions with Next Generation Hepatitis C Direct-acting Antiviral Agents

In this review, we examine the pharmacokinetics and clinically relevant drug interactions of the newer generation direct-acting antivirals (DAAs) for the treatment of chronic hepatitis C, specifically sofosbuvir/velpatasvir (Epclusa®), sofosbuvir/velpatasvir/voxilaprevir (Vosevi®), glecaprevir/pibrentasvir (Maviret®), and elbasvir/grazoprevir (Zepatier®). We searched MEDLINE (1948-January 2020), Embase (1964-January 2020), Google, and GoogleScholar using the terms pharmacokinetics, drug interaction, drug metabolism, sofosbuvir, velpatasvir, Epclusa, voxilaprevir, Vosevi, glecaprevir, pibrentasvir, Maviret, elbasvir, grazoprevir, and Zepatier, from inception to January 13, 2020. The search was limited to randomized controlled trials, in vitro studies, prospective and retrospective human studies, drug monographs, abstracts, and conference proceedings. All relevant published literature on pharmacokinetic and pharmacodynamic interactions involving DAAs were reviewed and the data extracted. Numerous clinically relevant drug-drug interactions (DDIs) were identified with the newer generation DAAs and commonly prescribed drugs. NS3/4A protease inhibitors are more likely to be involved in DDIs, followed by NS5A inhibitors and NS5B polymerase inhibitor. The majority of clinically relevant DDIs are predictable, according to known pharmacokinetic, pharmacodynamics, and physicochemical properties of DAAs; however, in select cases, unpredictable DDIs do occur. As expected, many drug interactions exist between newer generation DAAs and commonly prescribed medications. While the majority of clinically relevant interactions are predictable, many require therapeutic dose adjustment or careful selection of non-interacting drugs. In select cases, severe and unpredictable drug interactions can occur. Clinicians should consult hepatitis C virus pharmacotherapy experts and tertiary drug interaction resources when initiating DAA therapy in patients taking other medications.

Facial and bilateral lower extremity edema due to drug-drug interactions in a patient with hepatitis C virus infection and benign prostate hypertrophy: A case report

BACKGROUND

New direct-acting antivirals (DAAs)-based anti-hepatitis C virus (HCV) therapies are highly effective in patients with HCV infection. However, safety data are lacking regarding HCV treatment with DAAs and drugs for comorbidities.

CASE SUMMARY

Herein, we reported a case of HCV-infection in a 46-year-old man with benign prostatic hypertrophy. The patient received sofosbuvir/velpatasvir as well as methadone maintenance therapy for drug abuse. The viral load became negative at week 1 post treatment. He developed facial and bilateral lower extremity edema 48 h after starting receiving tamsulosin. Edema disappeared 10 d after treatment with oral furosemide and spironolactone.

CONCLUSION

In conclusion, this is the first case of an acute edema in the course of treatment with new DAAs, methadone and tamsulosin. These agents are useful in clinical management of patients with HCV infection, particularly in men with benign prostatic hypertrophy. Clinicians should be aware of potential drug-drug interactions in this subset of patients.

Drug Interactions with Gender-Affirming Hormone Therapy: Focus on Antiretrovirals and Direct Acting Antivirals

INTRODUCTION

Gender-affirming care may include hormonal therapy to attain desired health outcomes in transgender (trans) individuals. To provide safe, affirming medical care for trans patients, health care providers must identify and manage drug-drug interactions (DDIs) between gender affirming hormonal therapy (GAHT) and other medication therapies.

AREAS COVERED

This review summarizes available data on DDIs between GAHT and antiretrovirals (ARVs) or hepatitis C direct acting antivirals (DAAs). Potential pharmacokinetic and pharmacodynamic DDIs are predicted based on GAHT, ARV, and DAA pharmacology and adverse event profiles. Clinical management strategies are discussed.

EXPERT OPINION

GAHT may be involved in pharmacokinetic and/or pharmacodynamic DDIs. Certain ARV classes (non-nucleoside reverse transcriptase inhibitors, protease inhibitors) may alter GAHT disposition, whereas selected ARVs (unboosted integrase inhibitors, doravirine, or rilpivirine) may have less impact on GAHT. DAAs may interact with GAHT, but the clinical relevance is unclear. ARV- and/or DAA-associated side effects (including depression, cardiovascular disease, hyperlipidemia) are important to consider in the clinical management of trans patients. Clinicians must evaluate potential DDIs and overlapping side effects between ARVs, DAAs and GAHT when providing care for trans patients.

MK-571, a Cysteinyl Leukotriene Receptor 1 Antagonist, Inhibits Hepatitis C Virus Replication

The quinoline MK-571 is the most commonly used inhibitor of multidrug resistance protein-1 (MRP-1) but was originally developed as a cysteinyl leukotriene receptor 1 (CysLTR1) antagonist. While studying the modulatory effect of MRP-1 on anti-hepatitis C virus (HCV) direct-acting antiviral (DAA) efficiency, we observed an unexpected anti-HCV effect of compound MK-571 alone. This anti-HCV activity was characterized in Huh7.5 cells stably harboring a subgenomic genotype 1b replicon. A dose-dependent decrease of HCV RNA levels was observed upon MK-571 administration, with a 50% effective concentration (EC₅₀ ± standard deviation) of 9 ± 0.

The quinoline MK-571 is the most commonly used inhibitor of multidrug resistance protein-1 (MRP-1) but was originally developed as a cysteinyl leukotriene receptor 1 (CysLTR1) antagonist. While studying the modulatory effect of MRP-1 on anti-hepatitis C virus (HCV) direct-acting antiviral (DAA) efficiency, we observed an unexpected anti-HCV effect of compound MK-571 alone. This anti-HCV activity was characterized in Huh7.5 cells stably harboring a subgenomic genotype 1b replicon. A dose-dependent decrease of HCV RNA levels was observed upon MK-571 administration, with a 50% effective concentration (EC₅₀ ± standard deviation) of 9 ± 0.3 μM and a maximum HCV RNA level reduction of approximatively 1 log₁₀. MK-571 also reduced the replication of the HCV full-length J6/JFH1 model in a dose-dependent manner. However, probenecid and apigenin homodimer (APN), two specific inhibitors of MRP-1, had no effect on HCV replication. In contrast, the CysLTR1 antagonist SR2640 increased HCV-subgenomic replicon (SGR) RNA levels in a dose-dependent manner, with a maximum increase of 10-fold. In addition, a combination of natural CysLTR1 agonist (LTD4) or antagonists (zafirlukast, cinalukast, and SR2640) with MK-571 completely reversed its antiviral effect, suggesting its anti-HCV activity is related to CysLTR1 rather to MRP-1 inhibition. In conclusion, we showed that MK-571 inhibits HCV replication in hepatoma cell cultures by acting as a CysLTR1 receptor antagonist, thus unraveling a new host-virus interaction in the HCV life cycle.

Usage of HCV viremic organs in liver transplantation to anti-HCV negative recipients: The current status and review of literature

Liver transplantation is the main curative therapy for end-stage liver disease. The number of transplanted organs is increasing globally. However, the number of available organs in the pool is insufficient, considering the excessive number of patients on the waiting list, which is a major concern for transplant programs. Hepatitis C infection (HCV) is a common indication for liver transplantation, and in recent years, a major progress has been made in its treatment with direct-acting antiviral (DAA) agents. HCV-positive livers have been transplanted to HCV-positive recipients for a long time. The high rate of sustained virologic response through DAA has brought new treatment options for the patients during the pre- and post-transplantation periods. Recently, there have been few reports of transplanting the available HCV-positive organs to HCV noninfected recipients. However, there is not yet an agreement on the optimal selection of patients who would benefit from such transplantation, and this has become a current topic of interest. Thus, we aim to review the current literature on this evolving topic.

Use of HCV-infected organs in solid organ transplantation: An ethical challenge but plausible option

Due to the unfortunate epidemic of opioid overdose deaths among people who inject drugs (PWID) in North America, there has been an increase in the availability of hepatitis C (HCV)-positive organs for transplantation and consequently the potential to decrease waiting times for solid organ transplantation if an HCV-uninfected recipient is willing to accept an HCV-positive donor. The confidence in this potential new strategy comes as a result of the advent of safe and highly effective pan-genotypic direct-acting antivirals (DAAs). This promising strategy has been the most widely studied in kidney transplantation. Liver transplantation has positive results preliminarily, but has even less available data because viable HCV-infected donor livers are typically transplanted into HCV-infected individuals. Further, while HCV-infected heart and lung transplantation, which face additional post-transplant issues, have shown encouraging results, these studies are small scale and are limited by short-term follow-up. Thus, it would be premature to implement this strategy as standard of care without large scale clinical and real-world trials and longer-term follow-up studies. Further, the ethics of this practice need to be considered. While some transplant professionals argue that more harm will be done by not utilizing HCV-infected organs, others contend that cautiously conducted multi-centre studies involving extensive post-transplant follow-up are paramount prior to endorsing widespread implementation of this strategy. The ethical permissibility of this practice hinges on whether access to DAA therapy can be secured in advance, and prospective recipients understand and accept all the risks associated with acquiring HCV.

Anti-HIV and Anti-Hepatitis C Virus Drugs Inhibit P-Glycoprotein Efflux Activity in Caco-2 Cells and Precision-Cut Rat and Human Intestinal Slices

P-glycoprotein (ABCB1), an ATP-binding-cassette efflux transporter, limits intestinal absorption of its substrates and is a common site of drug-drug interactions (DDIs). ABCB1 has been suggested to interact with many antivirals used to treat HIV and/or chronic hepatitis C virus (HCV) infections. Using bidirectional transport experiments in Caco-2 cells and a recently established ex vivo model of accumulation in precision-cut intestinal slices (PCIS) prepared from rat ileum or human jejunum, we evaluated the potential of anti-HIV and anti-HCV antivirals to inhibit intestinal ABCB1. Lopinavir, ritonavir, saquinavir, atazanavir, maraviroc, ledipasvir, and daclatasvir inhibited the efflux of a model ABCB1 substrate, rhodamine 123 (RHD123), in Caco-2 cells and rat-derived PCIS. Lopinavir, ritonavir, saquinavir, and atazanavir also significantly inhibited RHD123 efflux in human-derived PCIS, while possible interindividual variability was observed in the inhibition of intestinal ABCB1 by maraviroc, ledipasvir, and daclatasvir. Abacavir, zidovudine, tenofovir disoproxil fumarate, etravirine, and rilpivirine did not inhibit intestinal ABCB1. In conclusion, using recently established ex vivo methods for measuring drug accumulation in rat- and human-derived PCIS, we have demonstrated that some antivirals have a high potential for DDIs on intestinal ABCB1. Our data help clarify the molecular mechanisms responsible for reported increases in the bioavailability of ABCB1 substrates, including antivirals and drugs prescribed to treat comorbidity. These results could help guide the selection of combination pharmacotherapies and/or suitable dosing schemes for patients infected with HIV and/or HCV.

Management of Virologic Failure and HIV Drug Resistance

Approximately 20% of people with HIV in the United States prescribed antiretroviral therapy are not virally suppressed. Thus, optimal management of virologic failure has a critical role in the ability to improve viral suppression rates to improve long-term health outcomes for those infected and to achieve epidemic control. This article discusses the causes of virologic failure, the use of resistance testing to guide management after failure, interpretation and relevance of HIV drug resistance patterns, considerations for selection of second-line and salvage therapies, and management of virologic failure in special populations.

Effectiveness and safety of sofosbuvir-based therapy against chronic hepatitis C infection after successful kidney transplantation

BACKGROUND

Direct-acting antivirals (DAAs), including sofosbuvir (SOF), are recommended for treatment of chronic hepatitis C virus (HCV) infection. However, few studies have investigated the effectiveness and safety of new DAAs in kidney transplant recipients (KTRs).

OBJECTIVES

To assess the effectiveness and safety of SOF-based therapy in stable KTRs.

PATIENTS AND METHODS

Forty KTRs were treated with SOF-based regimens. Rapid, end-therapeutic, and sustained virologic responses were assessed, as was liver stiffness by elastometry. Safety was monitored by measuring the estimated glomerular filtration rate (eGFR), blood hemoglobin (Hb) concentration, proteinuria, and blood trough levels of calcineurin inhibitors (CNIs). Other side effects were also recorded.

RESULTS

The effectiveness of DAAs was 100% at all time points. The therapy did not significantly influence eGFR or proteinuria, but significantly decreased mean blood Hb levels (13.5 ± 2.0 vs 11.6 ± 1.9, respectively, P < 0.001), which required a dose reduction or cessation of ribavirin (RBV) in 50% of patients. A profound, significant decrease in initial CNI concentrations was also observed during treatment in the majority of patients within the first month of therapy.

CONCLUSIONS

In this cohort of KTRs, the new SOF-based therapies were characterized by 100% effectiveness and good safety profiles. However, in patients co-treated with RBV, close blood Hb monitoring and early RBV dose reduction are necessary. In the majority of KTRs, antiviral therapy leads to a substantial and early decrease in CNIs levels, thus frequent measurement of CNI levels is necessary during SOF-based therapy.

Drug-Drug Interactions Potential of Direct-Acting Antivirals for the treatment of Chronic Hepatitis C Virus infection

The advent of direct-acting antiviral agents (DAAs) has transformed the hepatitis C virus (HCV) therapeutic landscape in terms of efficacy and safety, with a cure rate of more than 90%. However, an important potential for drug-drug interactions (DDIs) is expected with these combinations, particularly in patients with other comorbidities (e.g. HIV co-infection, cardiovascular diseases). Each DAA can be a substrate, an inhibitor and/or an inducer of metabolic enzymes and drug efflux transporters. DAAs can act as both victims and perpetrators of DDIs and can sometimes increase the risk and/or intensity of side effects or limit the efficacy of treatment. Therefore, knowledge and management of DDIs with DAAs should be considered a key issue of HCV therapy. This review describes the pharmacokinetic profile of currently used and recommended DAA regimens and summarizes available data regarding DDIs to optimize HCV treatment in clinical practice.

A changing paradigm: management and treatment of the HCV/HIV-co-infected patient

Hepatitis C virus (HCV) treatment in HIV/HCV co-infected individuals has renewed relevance given the ongoing opioid crisis and rise of new HIV and HCV infections associated with injection drug use. Patients co-infected with HIV and HCV demonstrate increased rates of hepatic fibrosis, progression to liver failure, and liver-related mortality. HIV co-infection does not impact outcomes of current HCV treatments, and patients should be treated the same as HCV mono-infected persons, though attention to drug:drug interactions is required. In this review, we discuss the mechanisms mediating injury to the liver in HIV mono-infection and HIV/HCV co-infection, and present the landmark trials of HCV treatment in HIV-infected individuals.