NS5A Inhibitor Research Articles

Prevalence of resistance-associated substitutions and retreatment of patients failing a glecaprevir/pibrentasvir regimen.

To investigate resistance-associated substitutions (RASs) as well as retreatment efficacies in a large cohort of European patients with failure of glecaprevir/pibrentasvir. Patients were identified from three European Resistance Reference centres in Spain, Italy and Germany. Sequencing of NS3, NS5A and NS5B was conducted and substitutions associated with resistance to direct antiviral agents were analysed. Clinical and virological parameters were documented retrospectively and retreatment efficacies were evaluated. We evaluated 90 glecaprevir/pibrentasvir failures [3a (n = 36), 1a (n = 23), 2a/2c (n = 20), 1b (n = 10) and 4d (n = 1)]. Ten patients were cirrhotic, two had previous exposure to PEG-interferon and seven were coinfected with HIV; 80 had been treated for 8 weeks. Overall, 31 patients (34.4%) failed glecaprevir/pibrentasvir without any NS3 or NS5A RASs, 62.4% (53/85) showed RASs in NS5A, 15.6% (13/83) in NS3 and 10% (9/90) in both NS5A and NS3. Infection with HCV genotypes 1a and 3a was associated with a higher prevalence of NS5A RASs. Patients harbouring two (n = 34) or more (n = 8) RASs in NS5A were frequent. Retreatment was initiated in 56 patients, almost all (n = 52) with sofosbuvir/velpatasvir/voxilaprevir. The overall sustained virological response rate was 97.8% in patients with end-of-follow-up data available. One-third of patients failed glecaprevir/pibrentasvir without resistance. RASs in NS5A were more prevalent than in NS3 and were frequently observed as dual and triple combination patterns, with a high impact on NS5A inhibitor activity, particularly in genotypes 1a and 3a. Retreatment of glecaprevir/pibrentasvir failures with sofosbuvir/velpatasvir/voxilaprevir achieved viral suppression across all genotypes.

THU411 - Resistance-associated variants conferring quite a high level of resistance to all approved NS5A inhibitors in genotype 2 hepatitis C virus

THU411 - Resistance-associated variants conferring quite a high level of resistance to all approved NS5A inhibitors in genotype 2 hepatitis C virus

SAR study of bisamides as cyclophilin a inhibitors for the development of host-targeting therapy for hepatitis C virus infection

The therapy of chronic hepatitis C virus infections has significantly improved with the development of direct-acting antivirals (DAAs), which contain NS3/4A protease, NS5A, and NS5B polymerase inhibitors. However, mutations in specific residues in these viral target genes are associated with resistance to the DAAs. Especially inhibitors of NS3/4A protease and NS5A, such as grazoprevir and velpatasvir, have a low barrier to resistant mutations. As a result, the mutations influence the virological outcomes after DAA treatment. CypA inhibitors, as host-targeted agents, act on host factors to inhibit HCV replication, exhibiting a high resistance barrier and pan-genotype activities against HCV. Therefore, they can be developed into alternative, more effective anti-HCV agents. However, CypA inhibitors are natural products and analogs. Based on previous studies, bisamide derivatives were designed and synthesized to develop a novel class of CypA inhibitors. Bisamide derivative 7c is a promising compound with potent anti-HCV activity at subtoxic concentrations. Surface plasmon resonance experiments revealed that 7c directly binds to CypA. All these studies indicated that the derivative 7c is a potent CypA inhibitor, which can be used as a host-targeted agent in combination with other antiviral agents for anti-HCV treatment.

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.

Molecular characterization of hepatitis C virus for subtype determination and resistance-associated substitutions detection among Chinese voluntary blood donors

BackgroundThe high prevalence of hepatitis C virus (HCV) infection and the resulting burden of the disease are significant issues to public health worldwide. Although direct-acting antiviral drugs (DAAs) with good tolerance and bioavailability are available, resistance-associated substitutions (RASs) often jeopardize the successful sustainment of virological responses in HCV treatment. High-frequency baseline RASs in treatment-naïve patients can lead to failures in DAA treatment. Clinical data on HCV RASs in patients from China are limited and require investigations. Methods262 HCV RNA positive plasma from Chinese blood donors were genotyped and amplified with subtype-specific primers for NS3 and NS5A regions. RASs were analyzed using Geno2pheno. The codon usage of each resistance-associated substitution was calculated for genetic barrier analysis. ResultsThe two main subtypes in mainland China were 1b and 2a, followed by subtype 6a, 3b, 3a, and 1a. In NS3 region of 1b subtype, substitutions (T54S, V55A, Y56F, Q80 K/L, S122 G/T, R117 H/C, V170I and S174A) were present in 89.7% (96/107) of the samples. Other RASs (M28L, R30Q, P58 L/S and Y93H) were observed in 22.1% (25/113) of the samples in NS5A region. A crucial RAS, Q80K, and two other mutations (S122G + V170I) was identified in the same sequence, which reduced its susceptibility to protease inhibitor ASV and resulted in resistance to SMV. In NS5A, Y93H was detected in 9.7% (11/113) of the 1b samples, leading to medium-to-high level resistance to all six commercialized NS5A inhibitors. S122G-NS3 and Y93H-NS5A occurred simultaneously in 38.1% (7/22) of the samples with mutations in both two regions. Moreover, codon usage of S122G-NS3 and Y93H-NS5A revealed that both variants had the lowest genetic barrier and required only one transition to confer resistance. ConclusionsLow genetic barriers facilitated the generation of resistance mutants and threated the efficacy of DAA regimens. The baseline RASs posed a great challenge to real-world DAA application.

Real-word efficacy of sofosbuvir, velpatasvir plus ribavirin therapy for chronic hepatitis patients who failed to prior DAA therapy with NS5A-P32 deletion mutated HCV infection.

The hepatitis C virus (HCV) NS5A-P32 deletion (P32del) confers potent resistance to NS5A inhibitors. Chronic hepatitis C patients in whom NS5A-P32del variants had emerged during prior direct-acting antiviral (DAA) therapy with an NS5A inhibitor show poor response to DAA retreatment. Here, we report three patients with HCV NS5A-P32del infection who were treated with sofosbuvir, velpatasvir plus ribavirin (SOF/VEL + RBV) in a real-world setting. The patients developed HCV NS5A-P32del, L31F + P32del, or L31V + P32del variants following failure of daclatasvir plus asunaprevir (DCV/ASV) therapy. One of the patients failed to respond to subsequent DCV/ASV and beclabuvir therapy, and the remaining two patients failed to respond to subsequent glecaprevir and pibrentasvir therapy. All three patients completed 24-week SOF/VEL + RBV therapy. Serum HCV RNA became negative at the end of the therapy in all three patients. Two patients with NS5A-P32del and NS5A-L31F + P32del achieved sustained virological response 12weeks after completion of treatment (SVR12), but HCV relapsed in the remaining NS5A-L13V + P32del patient. Direct sequence analysis detected no additional variants within either the NS5A or NS5B regions at the time of relapse. In conclusion, three patients with prior NS5A-P32del-associated DAA treatment failure received 24weeks of SOF/VEL + RBV therapy, and two of the patients achieved SVR12.

Symmetric benzidine derivatives as anti-HCV agents: Insight into the nature, stereochemistry of the capping amino acid and the size of the terminal capping carbamates

Novel symmetric molecules, bearing a benzidine prolinamide core, two terminal carbamate caps of variable sizes and nature, including natural and unnatural amino acids were developed. Several terminal N-carbamate substituents of the core structure, ranging from linear methyl, ethyl and butyl groups to branching isobutyl group; and an aromatic substituent were also synthesized.Series 1 has hydrophobic AA residues, namely S and R phenylglycine and a terminal carbamate capping group, whereas Series 2 bears sulphur containing amino acids, specifically S and R methionine and the natural R methylcysteine. The novel compounds were tested for their inhibitory activity (EC50) and their cytotoxicity (CC50), using an HCV 1b (Con1) reporter replicon cell line. Compound 4 with the unnatural capping residue, bearing d-Phenylglycine amino acid residue and N-isobutyloxycarbonyl capping group, was the most active within the two series, with EC50 = 0.0067 nM. Moreover, it showed high SI50 > 14788524 and was not cytotoxic at the highest tested concentration (100 μΜ), indicating its safety profile. Compound 4 also inhibited HCV genotypes 2a, 3a and 4a. Compared to the clinically approved NS5A inhibitor Daclatasvir, compound 4 shows higher activity against genotypes 1b and 3a, as well as improved safety profile.

Resistance-associated substitutions in patients with chronic hepatitis C virus genotype 4 infection.

Data on the prevalence of resistance-associated substitutions (RASs) and their implications for treatment with direct-acting antivirals (DAAs) are sparse in European patients with HCV genotype 4. This study investigated RASs before and after DAA failure in different genotype 4 subtypes and evaluated retreatment efficacies. Samples of 195 genotype 4-infected patients were collected in the European Resistance Database and investigated for NS3, NS5A and NS5B RASs. Retreatment efficacies in DAA failure patients were analysed retrospectively. After NS5A inhibitor (NS5Ai) failure, subtype 4r was frequent (30%) compared to DAA-naïve patients (5%) and the number of NS5A RASs was significantly higher in subtype 4r compared to 4a or 4d (median three RASs vs no or one RAS, respectively, P<.0001). RASsL28V, L30R and M31L pre-existed in subtype 4r and were maintained after NS5Ai failure. Typical subtype 4r RASs were located in subdomain 1a of NS5A, close to membrane interaction and protein-protein interaction sites that are responsible for multimerization and hence viral replication. Retreatment of 37 DAA failure patients was highly effective with 100% SVR in prior SOF/RBV, PI/SOF and PI/NS5Ai failures. Secondary virologic failures were rare (n=2; subtype 4d and 4r) and only observed in prior NS5Ai/SOF failures (SVR 90%). In conclusion, subtype 4r harboured considerably more RASs compared to other subtypes. A resistance-tailored retreatment using first- and second-generation DAAs was highly effective with SVR rates ≥90% across all subtypes and first-line treatment regimens.

Pre-existing minor variants with NS5A L31M/V-Y93H double substitution are closely linked to virologic failure with asunaprevir plus daclatasvir treatment for genotype 1b hepatitis C virus infection.

BackgroundL31 and Y93 in the NS5A region of the hepatitis C virus (HCV) are the most important substitution positions associated with resistance to direct-acting antiviral (DAA) treatment.MethodsWe analyzed the frequency of NS5A L31M/V and Y93/H in NS5A inhibitor-naive HCV genotype 1 patients who received asunaprevir plus daclatasvir combination treatment using a conventional sequencing method and a deep sequencing method that can distinguish a single substitution at either position and a double substitution at both positions with a 0.1% detection threshold.ResultsThe frequency of substitutions at both sites using the conventional method was very low, with 1 in 14 non-responders and 0 in 42 randomly selected responder patients. On the other hand, for the deep sequencing method, cases with double substitutions in the tandem sequence were detected in 8/14 non-responders and 1/42 responders (p<0.0001). For the conventional method, substitutions were detected at any position in 6/14 non-responders and 2/42 responders (p = 0.0019), with a clear difference between the two groups. The difference was also clear with the deep sequencing method, with 11/14 non-responders and 8/42 responders. Interestingly, for the deep sequencing method, the single substitution of L31 was found in 6/14 non-responders and 7/42 responders, whereas single substitutions of Y93 or double substitutions were found in 7/14 vs. 1/42 and 8/14 vs. 1/42 patients, respectively.ConclusionsNS5A L31 and Y93 substitutions were detected in tandem by the deep sequencing methods in several genotype 1 patients, who may be more resistant to DAA treatment containing an NS5A inhibitor.

Efficacy of NS5A inhibitors against unusual and potentially difficult-to-treat HCV subtypes commonly found in sub-Saharan Africa and South East Asia

The efficacy of NS5A inhibitors against several less common subtypes of hepatitis C virus (HCV) is poorly characterised. Some subtypes including 3b, 3g, 6u and 6v commonly harbour amino acid residues in NS5A that may confer resistance to direct-acting antivirals (DAAs) in other common subtypes. Data from patients also suggest that 1l and 4r with amino acid substitutions at positions 28-31 and 93 in NS5A are relatively resistant to DAA therapy. In this study, we tested the efficacy of daclatasvir, elbasvir, ledipasvir, pibrentasvir and velpatasvir against these subtypes using the SGR-JFH1 replicon backbone. NS5A inhibitors showed different levels of efficacy with only pibrentasvir effective against all tested subtypes. Daclatasvir and ledipasvir were ineffective against 6u and 6v (half maximal effective concentration [EC50] values of 239-321 nM) while 3b and 3g were only susceptible to pibrentasvir. Analysis of effects of individual mutations indicated that Q30R in 1l increased the EC50 of ledipasvir by 18-fold, conferring intermediate resistance, while those of L31M and Y93H in 4r induced increases in EC50 values of 2,100- and 3,575-fold (high-level resistance). The high ledipasvir EC50 values of 1l with the Q30R substitution, 4r L31M and 4r Y93H may explain the treatment failure in patients who were infected with these viruses and treated with ledipasvir+ sofosbuvir. This study also shows the ineffectiveness of the first generation NS5A inhibitors against 6u and 6v, and confirms the inherent resistance of 3b and 3g to most NS5A inhibitors. Clinical studies to confirm invivo sensitivity to NS5A inhibitors are urgently needed so that rational, effective treatment strategies may be developed for unusual subtypes. Little is known about the efficacy of NS5A inhibitors against some "unusual" hepatitis C virus (HCV) subtypes including 1l, 3b, 3g, 4r, 6u and 6v. In this study, we manufactured HCV replicons which express the NS5A protein from the unusual HCV subtypes 1l, 3b, 3g, 4r, 6u, 6v. We then tested the effect of the NS5A inhibitors daclatasvir, elbasvir, ledipasvir, pibrentasvir and velpatasvir on blocking replication, using these replicons. We show that these replicons are resistant at some level to all NS5A inhibitors other than pibrentasvir.

Impact of an Open Access Nationwide Treatment Model on Hepatitis C Virus Antiviral Drug Resistance.

Direct acting antivirals (DAAs) have revolutionized hepatitis C virus (HCV) treatment, but drug resistance could undermine proposed global elimination targets. Real‐world studies are needed to inform the impact of widespread DAA treatment on antiviral resistance in the community. The prevalence and range of posttreatment resistance‐associated substitutions (RASs) was determined in Australian patients with open access to DAAs through a wide range of prescribers. NS3, NS5A, and NS5B regions were amplified by polymerase chain reaction and analyzed by population sequencing. Clinically relevant RASs were identified using online databases (ReCALL and Geno2Pheno[hcv]). Of 572 samples, 60% were from genotype 3 and 27% from genotype 1a. Ninety‐two percent of people failed a DAA regimen containing an NS5A inhibitor, including 10% with a pangenotype regimen. NS5A RASs were detected in 72% of people with genotype 1 and 80% with genotype 3. For genotype 1, there was a range of RASs across the NS5A region, while for genotype 3, the Y93H RAS predominated (72%). The prevalence of NS3 RASs was higher in people exposed to an NS3 inhibitor (35% vs. 3.9%; P < 0.0001). NS5B resistance was rare, with a single case of sofosbuvir resistance. Multiclass drug resistance was found in 33% of people exposed to both NS3 and NS5A inhibitors. Conclusion: The high prevalence of NS5A RASs among people failing DAA therapy reinforces the importance of specific retreatment regimens, ideally guided by resistance testing. The impact of multiclass drug resistance on retreatment in people exposed to both NS3 and NS5A inhibitors needs to be assessed in real‐world studies. Surveillance for increasing antiviral resistance during treatment scale‐up is essential to maintain the efficacy of current DAA regimens.

Outcome of Treatment of Chronic Hepatitis C Patients by New Antiviral Drugs

HCV constitutes a significant health burden worldwide. Hepatitis C is a disease with significant globalimpact. Egypt has a high prevalence of HCV worldwide (&gt;10%) . In Africa and the western Pacific theprevalence (? 3%) is significantly higher than in North America and Europe (&lt;2%). In general, everyonewith chronic HCV should receive antiviral therapy. This is because patients who are cured of their HCVinfection benefit from reduction in the risk of hepatocellular carcinoma, liver related mortality and even allcausemortality.In general, everyone with chronic HCV should receive antiviral therapy, treatment should begiven first to patients with advanced fibrosis and high risk for liver-related complications. Also, patients withsevere extrahepatic HCV manifestations should be given high priority. The timing of treatment in patientswith mild liver disease can be individualized. This review provides insight into clinical studies of NS3/4Aprotease inhibitors, NS5B viral polymerase inhibitor (nucleotide and non-nucleotide), and NS5A inhibitors,alone and in combination.

Study the Response of Qurevo (Ombitasvir, Paritaprevir and Ritonavir) in End Stage Renal Disease Patients with Hepatitis C Virus

Abstract Background According to the WHO there are 185 million people infected with HCV in the world.Egypt has the highest prevalence of hepatitis C virus (HCV) in the world reaching 13% equating to an estimated 12 million Egyptians . HCV is one of the main causes of liver cirrhosis and hepatocellular carcinoma.HCV can develop kidney disease because of extrahepatic manifestations of HCV or as a disease process independent of the HCV infection.In addition, hemodialysis has been a risk factor for acquiring HCV infection. The prevalence of HCV infection is high in patients with ESRD, on hemodialysis ranges from 6% to 60% in different parts of the world. Several studies show that patients on hemodialysis have an increased overall mortality risk if they have chronic HCV when compared with those on dialysis who do not have HCV. Antiviral treatment in CKD patients can be complicated because many of the agents used for anti-HCV therapy can accumulate to toxic levels in the setting of renal impairment. Treatment of HCV compensated cirrhosis with the new DAA therapy Qurevo “ombitasvir/paritaprevir/ritonavir” with ribavirin in ESRD was approved in many countries. Aim of the study To evaluate the efficacy and safety of Qurevo/Ribavirin regimen in ESRD Egyptian patients who are infected with hepatitis C virus (HCV) . Patients and Methods A prospective cohort study evaluated the outcome of 12-week ombitasvir (NS5A inhibitor)/paritaprevir (NS3/4A protease inhibitor)/ritonavir with ribavirin combination therapy for 50 ESRD patients with HCV at the hepatic virology clinic at Ain Shams University hospital over a period of 15 months (from December 2016 to February 2018). The primary endpoint was sustained virologic response 12 weeks after therapy (SVR12). Results 50 ESRD patients with a mean age of 51.4 years, range from 23-77 years were enrolled.The SVR12 rate was 96% (48/50); 2 patients had virologic failure. As regards adverse events, the most frequent was fatigue/asthenia in 44 patients (88%) and worsening anemia (Hb dropped to &amp;lt; 10 g/dl) in 42 patients (84%). GIT upset occurred in 10 patients (20%), sleep disorders in 8 patients (16%), decreased appetite in 8 patients (16%),respiratory distress in 6 patients (12%), headache, dizziness in 6 patients(12%). Muscle spasms in 4 patients (8%). Itching(pruritis) occurred in 3 patients(6%).2 patients (4%) were non-responders to treatment and another 2 (4%) were relapsers.Death occurred in 4 patients (8%) due to myocardial infarction, pulmonary edema, severe hypotension on hemodialysis sessions, shock due to blood loss in retroperitoneal hematoma following peritoneal dialysis. Hepatic decompensation, hypersenisitivity (angioedema), teratogenicity and drug interactions did not occur in any patient (0%).Other events occurred in 11 patients (22%). They were parenchymal liver changes in ultrasound at the end of therapy after being normal before therapy (in 3 patients), thrombocytopenia, increased alkaline phosphatase, hiccough, deterioration of hypertension, urinary tract infection, lower limb cellulitis, vaginal bleeding, chest infection(in 1 patient each). SVR12 was achieved in 100% of patients who had to stop or modify ribavirin dose;this means that Ribavirin absence didn’t affect the sustained viral response in these patients. Conclusion Our results confirm the efficacy of Qurevo “ombitasvir/paritaprevir/ritonavir” with Ribavirin combination therapy in ESRD patients with HCV infection, with anemia as the most frequent adverse event.

The effectiveness and safety of glecaprevir/pibrentasvir in chronic hepatitis C patients with refractory factors in the real world: a comprehensive analysis of a prospective multicenter study

Direct-acting anti-virals (DAAs) have markedly improved the effectiveness of anti-viral therapy for chronic hepatitis C (CHC) patients. In a phase III trial in Japan, treatment with the NS3/4A protease inhibitor glecaprevir and the NS5A inhibitor pibrentasvir (G/P) resulted in a small number of patients with refractory factors. We aimed to evaluate the effectiveness and safety of G/P, especially among patients with these refractory factors, and the influence of these factors on treatment. In a prospective, multicenter study involving 33 medical institutions, 1439 patients were treated with G/P, and their efficacy, safety, and most frequent adverse effects (AEs) were analyzed. Overall SVR12 rates were 99.1% (1397/1410) in the per-protocol-analysis, and genotype sustained virologic response SVR12 rates were: genotype 1, 99.4% (707/711); genotype 2, 99.4% (670/674); genotype 3, 80.0% (16/20). DAA-naïve patients (p = 0.008) with HCV genotype except 3 (genotype 1 vs. 3, p = 2.68 × 10-5; genotype 2 vs. 3, p = 3.28 × 10-5) had significantly higher SVR12 rates. No significant difference was observed between CKD stage 1-3 (99.1% [1209/1220]) and chronic kidney disease (CKD) stage 4-5 (98.9% [188/190]) patients, or between cirrhotic (99.0% [398/402]) and non-cirrhotic (99.1% [999/1008]) patients. Multiple logistic regression analysis revealed that genotype 3 [OR 33.404, 95% CI (7.512-148.550), p value (p = 4.06 × 10-5)] and past experience of IFN-free DAAs [OR 3.977, 95% CI (1.153-13.725), p value (p = 0.029)] were both significantly independent predictors of non-SVR12. AEs were reported in 28.2% of patients, and 1.6% discontinued treatment owing to drug-related AEs. AEs were significantly higher in CKD stage 4-5 (41.6% [79/190]) than CKD stage 1-3 (26.1% [319/1220]) patients (p = 2.00 × 10-5). AEs were also significantly higher in cirrhotic (38.6% [155/402]) than in non-cirrhotic (24.1% [243/1008]) (p = 2.91 × 10-18) patients. G/P regimen is highly effective and safe to treat CHC patients even with refractory factors such as CKD and advanced liver fibrosis. However, patients with past experience of IFN-free DAA treatment and genotype 3, CKD stage 4 or 5, and advanced liver fibrosis should be more closely observed.

Prevalence of HCV resistance-associated substitutions among treatment-failure patients receiving direct-acting antiviral agents.

Direct-acting antiviral (DAA) failure, which is mainly associated with the selection of resistance-associated substitutions (RASs), is not rare in HCV treatment. RAS data collected from published literature and RAS prevalence were integrated using meta-analysis. DAA-failure-associated RASs were identified by comparing their prevalence between DAA-failure and DAA-naïve patients. Prevalences of emerging RASs that occurred during treatment were also estimated. A total of 2932 DAA-naïve patients and 1466 DAA-failure patients were included. Significant differences in the prevalence of RASs were found in 76 scenarios that involved 34 RASs (11 in NS3, 18 in NS5A and 5 in NS5B), 4 genotypes (GTs) (GT1a, GT1b and GT3-4) and 14 DAAs (6 NS3 protease inhibitors [PIs], 6 NS5A inhibitors and 2 NS5B inhibitors). For NS3, the DAA-failure-associated RASs included V36L, Y56H, Q80K/R, R155K, A156T and D168A/E/L/T/V/Y. Substitutions at R155 and D168 were dominant for most NS3 PIs. For NS5A, DAA-failure-associated RASs included K24R, Q30R, L31M, and P32L in GT1a; R30Q/H, L31F/I/M/V, P58S, and Y93H in GT1b; A30K, L31M and Y93H in GT3; and M31V and Y93H in GT4. Y93H was the most prevalent RAS for NS5A inhibitors. DAA-failure-associated RASs were found at only five positions in NS5B. The majority of DAA-failure patients relapsed. A significant difference was detected for only four RAS sites between relapse patients and nonresponse/breakthrough patients. The RAS prevalence in DAA-failure patients varied among the HCV GTs and DAA regimens. The identified treatment-selected resistance patterns for broadly used DAA regimens will enable the selection of optimized retreatment options.

COMBINED NS5A & NS5B NUCLEOTIDE INHIBITOR THERAPY FOR PATIENTS WITH CHRONIC HEPATITIS C WITH STAGE 5 CHRONIC KIDNEY DISEASE ON HEMODIALYSIS.

Hepatitis C virus (HCV) infection is the most common hepatotropic viral infection affecting the patients on maintenance hemodialysis. Treatment of chronic HCV infection in stage 4 and 5 CKD includes a combination of elbasvir/grazoprevir and glecaprevir/pibrentasvir, which are not available in many countries. Hence, we have conducted this study to look for the safety and efficacy of sofosbuvir combination therapy in this difficult to treat population. We conducted a single-center, prospective, open-label study in which Stage 5 CKD patients on maintenance hemodialysis with HCV infection. Total of 18 patients was included. sofosbuvir with daclatasvir or ledipasvir was used according to genotype for 12 weeks. HCV RNA, genotype, transient elastography (TE) was considered for every patient. HCV RNA was quantified at 4th week, 12th week and 12 weeks post-treatment to look for sustained virologic response (SVR 12). Infection due to genotype 1 was seen in 12 (66.7%) patients followed by genotype 3 in 4 (22.3%) with each patient of genotype 2 and 5. The median value of HCV RNA was 2,35,000 IU/mL. On TE, all had liver stiffness of <9.4 KPa. All patients had HCV RNA of <15 IU/mL at 4th and 12th week of treatment and 12 weeks post-treatment. No significant change in hemoglobin, eGFR and liver stiffness was observed. Full dose sofosbuvir i.e. 400 mg, in combination with NS5A inhibitors daclatasvir or ledipasvir is found to be safe and effective in patients with end stage renal disease, who are on maintenance hemodialysis.

Retreatment of patients with chronic hepatitis C, subtype 1b and cirrhosis, who failed previous direct-acting antiviral therapy including first- and second-generation NS5A inhibitors with ombitasvir/paritaprevir/ritonavir, dasabuvir+sofosbuvir+ribavirin.

The use of direct-acting antiviral agents (DAAs) in patients with chronic HCV genotype 1 infection results in sustained virologic response (SVR) rates of 95%-97%, but 3%-5% of patients experience virologic failure. We observed 17 patients infected with HCV subtype 1b who failed previous treatment with DAA, including 13 subjects (76.5%) with liver cirrhosis. Twelve subjects (70.6%) previously received NS5A inhibitors of the first generation (ledipasvir or daclatasvir) and five subjects (29.4%) - the second generation (velpatasvir). All patients were retreated with a combination of ombitasvir/paritaprevir/ritonavir and dasabuvir (3D) with sofosbuvir (SOF) and ribavirin (RBV). We compared SVR12 rates depending on fibrosis stage, presence of just single or double NS5A mutations (L31M/V/I and/or Y93H), and on the generation of previously used NS5A inhibitor. Observed SVR12 rates were as follows: 94.1% (16/17 patients) overall; 100% in patients without cirrhosis (n=4) vs 92.3% in those with cirrhosis (n=13); 100% with single L31M/V/I or Y93H mutation (n=7) vs 88.9% with double mutations (n=9); 100% in patients who previously failed first generation (n=12) vs 80.0% in those failed second-generation NS5A inhibitors (n=5). Retreatment with 3D+0SOF+RBV was highly effective and safe in patients with chronic HCV GT1b infection who failed previous use of NS5A inhibitors. Fibrosis stage, baseline presence of NS5A RAS mutations and the generation of previously used NS5A inhibitors may impact the probability of achieving SVR12 , but statistical significance was not demonstrated in our small retrospective cohort. Further studies in a larger population are needed to confirm or not the predictive value of these baseline factors.

Safety and efficacy of daclatasvir at doses other than 60 mg daily in HIV/HCV co-infected subjects: Data from the ICONA/HepaICONA foundation cohorts

BackgroundDaclatasvir (DCV) is a HCV NS5A inhibitor whose plasma exposure may be influenced by co-administration with inducers or inhibitors of CYP3A4 such as many antiretrovirals. AimsDescribe the use of different DCV dosages; assess if dose prescription complies with Summaries of Product Characteristics (SmPC); evaluate safety and efficacy of 60 versus 30/90 mg and adequate (i.e. concordant with SmPC) versus incorrect prescriptions. MethodsRetrospective analysis of patients included in ICONA/HepaICONA starting a DCV-including treatment. Incidence rates of liver adverse events (LAE) were calculated; Poisson regression model was used to identify factors associated with LAE. Results311 patients were included: 250 (80.4%) received DCV at a dosage of 60 mg, 52 (16.7%) 30 mg and 9 (2.9%) 90 mg. An inadequate dosage was used in 18 individuals (5.8%). No difference in SVR was observed (93.8% with 60 mg and 94.2% with 30/90 mg, p = 0.910; 93.5% with adequate and 100% with incorrect dosage, p = 0.277). There were 36 LAE with no differences in the two-paired groups. Decompensated liver disease was a risk factor for LAE (aRR = 2.37; p = 0.034), while HIV RNA < 50 copies/ml resulted protective (aRR = 0.22; p = 0.003). ConclusionsDCV use resulted in high SVR rate regardless of dosage and correctness of prescription.

Stability indicating validated RP-HPLC method for Simultaneous estimation of Elbasvir and Grazopravir in Bulk and Pharmaceutical Dosage form

Elbasvir a NS5A inhibitor is used in combination of Grazoprevir (NS3/4A protease inhibitor) for the treatment of chronic Hepatitis C, an infectious liver disease caused by infection with Hepatitis C Virus (HCV) under the trade name Zepatiar®. A stability indicating reverse phase HPLC method was developed and validated for the determination of Elbasvir and Grazoprevir in tablet dosage form. A waters Alliance HPLC with Zorbax eclipse XDB C18 (250 x 4.6 mm) 3.5μ columnwas used for chromatographic separation. A mobile phase consisting of potassium dihydrogen phosphate buffer pH adjusted to 4.0: acetonitrile (40: 60v/v) with a flow rate of 1.0 mL/min was used, the UV detection was carried out at 260 nm. The established method was linear, accurate and precise over the range of 12.5 to 75 μg/mL with a regression equation of Y=20782X+2849.4 and correlation coefficient of 0.9995for elbasvir and linear over the range of 25–150 μg/mL with a regression equation of Y=14897X+20611 and correlation coefficient of 0.9992for Grazoprevir. The validated method demonstrated high sensitivity, accuracy, precision, selectivity and robustness. The method demonstrated high selectivity in presence of degradants produced during the stress conditions when Elbasvir and Grazoprevir were subjected to acid, alkali, oxidation, thermal and photolytic degradation.

Discovery of a novel unsymmetrical structural class of HCV NS5A inhibitors with low picomolar antiviral activity

A novel unsymmetrical structural class of HCV NS5A inhibitors showing picomolar range antiviral activity has been identified. An unsymmetrical lead compound 2, generated from a substructure of a known symmetrical inhibitor 1, was optimized by extension of its substituents to interact with the hitherto unexplored site of the target protein. This approach afforded novel highly potent unsymmetrical inhibitor 20, which not only equally inhibited HCV genotypes1a, 1b, and 2a with EC50 values in the picomolar range, but also inhibited the 1a Q30K mutant induced by a launched symmetrical inhibitor daclatasvir with an EC50 in the low nanomolar range.