Real world SOF/VEL/VOX retreatment outcomes and viral resistance analysis for HCV patients with prior failure to DAA therapy

Retreatment of Hepatitis C Virus Among People Who Inject Drugs

BACKGROUND

Hepatitis C virus (HCV) is a leading cause of infectious disease death in the United States. Although highly effective direct-acting antiviral (DAA) regimens are well established, retreatment among people who inject drugs (PWID) has not been sufficiently studied. This study assessed DAA retreatment outcomes and associated factors.

METHODS

We performed analyses of longitudinal data from the HERO Study, a US-based multi-site pragmatic randomized trial conducted in 8 states to evaluate effectiveness of 2 HCV care models among DAA treatment-naïve PWID in opioid treatment programs and community clinics. After initial HERO Study sofosbuvir/velpatasvir (SOF/VEL) treatment, participants eligible for retreatment were identified, from 15 September 2016 to 13 September 2021. This analysis characterizes participants who either did not achieve sustained virologic response (SVR) or were reinfected with HCV post-SVR. We compared categorical variables using Fisher exact test and continuous variables using the Welch 2 sample t test for means and an asymptotic 2-sample Mood median test.

RESULTS

One hundred four participants were identified as eligible for retreatment. Less than half, 43 (41.3%), initiated retreatment. Among the 25 who initiated retreatment and for whom SVR results were available, 24 achieved SVR (96%). Participants who did not achieve SVR initiated retreatment more promptly than participants reinfected post-SVR (respectively, 471 vs 784 days on average, P < .001).

CONCLUSIONS

After reinfection or not achieving SVR with the first DAA regimen, retreated PWID achieved higher SVR rates than with initial DAA treatment. To attain HCV elimination and benefit individual and public health, assisting PWID with accessing prompt retreatment is crucial.

Retreatment of patients with chronic hepatitis C, subtype 3a, and cirrhosis, who previously failed a regimen containing second-generation NS5A inhibitors with sofosbuvir + glecaprevir/pibrentasvir and ribavirin for 16-24 weeks

The outcomes of retreatment patients infected with hepatitis C virus genotype 3, cirrhosis, with velpatasvir may be affected by treatment failure with velpatasvir. The efficacy of SOF+GLE/PIB+RIB 16-24 weeks of treatment has been shown. The presence of NS5A resistance-associated substitution mutations, including Y93H, and the number and regimens of the past failed therapy do not influence the likelihood of achieving sustained virological response. When velpatasvir treatment fails, pibrentasvir should be used as the first choice for retreatment.

A systematic review of sofosbuvir/velpatasvir/voxilaprevir in HCV patients previously treated with direct-acting antivirals

The importance of sofosbuvir/velpatasvir/voxilaprevir (SOF/VEL/VOX) remains crucial in managing chronic HCV infection among patients who have experienced treatment failure and relapse after prior use of direct-acting antivirals (DAAs), as evidenced by high SVR12. However, limited real-world data exists on safety and efficacy. Therefore, the study’s goal was to conduct a qualitative systematic review to assess SOF/VEL/VOX’s effectiveness and safety. Thorough searches spanned PubMed, Embase, and Scopus, from 2015 to August 1st, 2023. The outcomes assessed were SVR12 and treatment-related adverse events (AEs). We identified and analyzed 12 studies in which SVR12 of the per-protocol (PP) population was 96.7% and of the intention-to-treat (ITT) population was 92.6% showing excellent efficacy of SOF/VEL/VOX. SVR12 rates notably differed among patients: those without GT3 infection (94.20%) and without cirrhosis (97.60%) experienced higher rates compared to patients having GT3 infection (87.40%) and cirrhotic patients (94.20%). Treatment-related AEs were also recorded. To summarize, our study presents evidence that SOF/VEL/VOX serves as an extremely safe and efficacious therapy for HCV-infected patients, previously treated with DAAs.

Real-life effectiveness of sofosbuvir/velpatasvir/voxilaprevir in hepatitis C patients previously treated with sofosbuvir/velpatasvir or glecaprevir/pibrentasvir

BACKGROUND

Sofosbuvir, velpatasvir and voxilaprevir (SOF/VEL/VOX) is the recommended rescue therapy for patients with chronic hepatitis C infection who fail direct-acting antivirals (DAAs). Data are limited on the effectiveness of this treatment after the current first-line therapies. Our aim was to analyse the effectiveness and safety of SOF/VEL/VOX among patients failing sofosbuvir/velpatasvir (SOF/VEL) or glecaprevir/pibrentasvir (GLE/PIB).

METHODS

Retrospective multicentre study (26 Spanish hospitals), including chronic hepatitis C patients unsuccessfully treated with SOF/VEL or GLE/PIB, and retreated with SOF/VEL/VOX ± ribavirin for 12 weeks between December 2017 and December 2022.

RESULTS

In total, 142 patients included: 100 (70.4%) had failed SOF/VEL and 42 (29.6%) GLE/PIB. Patients were mainly men (84.5%), White (93.9%), with hepatitis C virus genotype (GT) 3 (49.6%) and 47.2% had liver cirrhosis. Sustained virological response (SVR) was evaluated in 132 patients who completed SOF/VEL/VOX and were followed 12 weeks after end of treatment; 117 (88.6%) achieved SVR. There were no significant differences in SVR rates according to initial DAA treatment (SOF/VEL 87.9% vs. GLE/PIB 90.2%, p = 0.8), cirrhosis (no cirrhosis 90% vs. cirrhosis 87.1%, p = 0.6) or GT3 infection (non-GT3 91.9% vs. GT3 85.5%, p = 0.3). However, when considering the concurrent presence of SOF/VEL treatment, cirrhosis and GT3 infection, SVR rates dropped to 82.8%. Ribavirin was added in 8 (6%) patients, all achieved SVR.

CONCLUSION

SOF/VEL/VOX is an effective rescue therapy for failures to SOF/VEL or GLE/PIB, with an SVR of 88.6%. Factors previously linked to lower SVR rates, such as GT3 infection, cirrhosis and first-line therapy with SOF/VEL were not associated with lower SVRs.

Effects of comorbid conditions and prescribed chronic medications on the treatment plan for chronic hepatitis C infection: A cross-sectional retrospective study

Background

Chronic hepatitis C (CHC) infection is a potentially life-threatening condition characterized by various complications, including end-stage liver disease and cirrhosis. The mortality rate associated with CHC has been increasing due to the presence of comorbidities and the use of chronic medications. Therefore, the objective of this study was to investigate the impact of these comorbidities and chronic medications on the treatment plan for CHC.

Methods

To achieve this objective, a cross-sectional retrospective study was conducted at a tertiary hospital in Jeddah, Saudi Arabia. The study population included patients aged 12 years and above who were diagnosed with CHC between 2016 and 2021. Patients below the age of 12 were excluded from the study. A total of 170 patients with CHC were included in the analysis. The study aimed to evaluate the relationship between CHC complications and the treatment approach.

Results

The mean age of the study participants was 66.78 years, with a higher proportion of female patients. The findings revealed a significant association between hypertension (p = 0.042) and cirrhosis (p = 0.007) with changes in the treatment plan for CHC. Moreover, the presence of diabetes mellitus (p = 0.045), renal diseases (p < 0.001), and hypothyroidism (p = 0.004) were significantly associated with HCV clearance after the initiation of therapy. Additionally, the use of proton pump inhibitors (p = 0.033) and levothyroxine (p = 0.025) was found to be associated with a higher rate of CHC clearance.

Conclusion

In conclusion, this study highlights the prevalence of comorbid conditions and the use of chronic medications among patients with CHC. The findings emphasize the importance of considering the effects of comorbidities and chronic medications when developing treatment plans for CHC infections. By taking these factors into account, healthcare professionals can optimize the management of CHC and improve patient outcomes.

Hepatitis C Virus Antiviral Drug Resistance and Salvage Therapy Outcomes Across Australia

Background

Hepatitis C virus (HCV) infection can now be cured with well-tolerated direct-acting antiviral (DAA) therapy. However, a potential barrier to HCV elimination is the emergence of resistance-associated substitutions (RASs) that reduce the efficacy of antiviral drugs, but real-world studies assessing the clinical impact of RASs are limited. Here, an analysis of the impact of RASs on retreatment outcomes for different salvage regimens in patients nationally who failed first-line DAA therapy is reported.

Methods

We collected data from 363 Australian patients who failed first-line DAA therapy, including: age, sex, fibrosis stage, HCV genotype, NS3/NS5A/NS5B RASs, details of failed first-line regimen, subsequent salvage regimens, and treatment outcome.

Results

Of 240 patients who were initially retreated as per protocol, 210 (87.5%) achieved sustained virologic response (SVR) and 30 (12.5%) relapsed or did not respond. The SVR rate for salvage regimens that included sofosbuvir/velpatasvir/voxilaprevir was 94.3% (n = 140), sofosbuvir/velpatasvir 75.0% (n = 52), elbasvir/grazoprevir 81.6% (n = 38), and glecaprevir/pibrentasvir 84.6% (n = 13). NS5A RASs were present in 71.0% (n = 210) of patients who achieved SVR and in 66.7% (n = 30) of patients who subsequently relapsed. NS3 RASs were detected in 20 patients (20%) in the SVR group and 1 patient in the relapse group. NS5B RASs were observed in only 3 patients. Cirrhosis was a predictor of relapse after retreatment, as was previous treatment with sofosbuvir/velpatasvir.

Conclusions

In our cohort, the SVR rate for sofosbuvir/velpatasvir/voxilaprevir was higher than with other salvage regimens. The presence of NS5A, NS5B, or NS3 RASs did not appear to negatively influence retreatment outcomes.

Real-world effectiveness of voxilaprevir/velpatasvir/sofosbuvir in patients following DAA failure

Background & Aims

Voxilaprevir/velpatasvir/sofosbuvir (VOX/VEL/SOF) is highly effective for re-treatment of direct-acting antiviral (DAA)-experienced patients with chronic HCV infection. In the present study, predictors of virologic treatment response were analyzed in an integrative analysis of three large real-world cohorts.

Methods

Consecutive patients re-treated with VOX/VEL/SOF after DAA failure were enrolled between 2016 and 2021 in Austria, Belgium, Germany, Italy, Spain and Switzerland.

Results

A total of 746 patients were included: median age was 56 (16-88) years and 77% were male. Most patients were infected with HCV genotype 1 (56%) and 3 (32%). 86% of patients carried resistance-associated substitutions in the NS3, NS5A or NS5B regions. Overall, 95.4% (683/716) of patients achieved a sustained virologic response. Treatment effectiveness was significantly affected by advanced liver disease (p <0.001), hepatocellular carcinoma (p <0.001), higher baseline ALT levels (p = 0.02), HCV genotype 3 (p <0.001), and prior VEL/SOF treatment (p = 0.01). In a multivariate analysis, only HCV genotype 3, hepatocellular carcinoma and cirrhosis turned out to be independent predictors of treatment failure. Resistance-associated substitutions, as well as the presence of rare genotypes, did not impact treatment outcome. The effectiveness of rescue therapy with glecaprevir/pibrentasvir and SOF, with or without ribavirin, for 12 to 24 weeks was found to be high (100%).

Conclusions

Infection with HCV genotype 3, the presence of liver cancer and cirrhosis are independently associated with failure of VOX/VEL/SOF re-treatment. It is unclear whether the addition of ribavirin and/or extension of treatment duration may be effective to avoid virologic relapse on VOX/VEL/SOF. However, rescue treatment with glecaprevir/pibrentasvir+SOF seems to be effective.

Impact and implications

Representative data on the effectiveness of voxilaprevir/velpatasvir/sofosbuvir (VOX/VEL/SOF) in clinical practice are still scarce and the collection of a larger number of patients with difficult-to-treat cofactors including the assessment of resistance-associated substitution profiles is required before more specific recommendations for optimal re-treatment in these patients can be given. Thus, we aimed to analyze treatment effectiveness and predictors of virologic response to VOX/VEL/SOF in an integrative analysis of three large real-word cohorts. The study results, derived from a multicenter cohort consisting of 746 patients, demonstrated that re-treatment with VOX/VEL/SOF is an effective salvage therapy associated with an overall per protocol sustained virologic response rate of 95%. Hepatocellular carcinoma onset, cirrhosis and HCV genotype 3 were identified as independent negative predictors of treatment response, whereas resistance-associated substitutions, as well as rare genotypes and chimera, did not impact sustained virologic response rates following re-treatment with VOX/VEL/SOF.

Hepatitis C

Hepatitis C virus (HCV) is a hepatotropic RNA virus that can cause acute and chronic hepatitis, with progressive liver damage resulting in cirrhosis, decompensated liver disease, and hepatocellular carcinoma. In 2016, WHO called for the elimination of HCV infection as a public health threat by 2030. Despite some progress, an estimated 57 million people were living with HCV infection in 2020, and 300 000 HCV-related deaths occur per year. The development of direct-acting antiviral therapy has revolutionised clinical care and generated impetus for elimination, but simplified and broadened HCV screening, enhanced linkage to care, and higher coverage of treatment and primary prevention strategies are urgently required.

Virological characterization of treatment failures and retreatment outcomes in patients infected with "unusual" HCV genotype 1 subtypes

BACKGROUND AND AIMS

Suboptimal rates of sustained virological response have been reported in patients infected with an "unusual," non-1a/1b HCV genotype 1 subtype. The objectives of this study were to assess the proportion of non-1a/1b genotype 1 subtypes in a population of HCV-infected patients who failed to achieve sustained virological response after first-line direct-acting antiviral treatment, to virologically characterize their failures and to assess their outcomes on retreatment.

APPROACH AND RESULTS

Samples addressed between January 2015 and December 2021 to the French National Reference Center for Viral Hepatitis B, C, and D were prospectively analyzed by means of Sanger and deep sequencing. Among 640 failures, 47 (7.3%) occurred in patients infected with an "unusual" genotype 1 subtype. Samples were available in 43 of them; 92.5% of these patients were born in Africa. Our results show the presence at baseline and at treatment failure of NS3 protease and/or NS5A polymorphisms conferring inherent reduced susceptibility to direct-acting antivirals in these patients, together with the presence at failure of additional resistance-associated substitutions not naturally present as dominant species, but jointly selected by first-line therapy.

CONCLUSIONS

Patients infected with "unusual" HCV genotype 1 subtypes are over-represented among direct-acting antiviral treatment failures. Most of them were born and likely infected in sub-Saharan Africa. "Unusual" HCV genotype 1 subtypes naturally carry polymorphisms that confer reduced susceptibility to the drugs currently used to cure hepatitis C, in particular the NS5A inhibitors. Retreatment with sofosbuvir plus an NS3 protease and an NS5A inhibitor is generally efficacious.

Treatment Outcomes of Sofosbuvir/Velpatasvir/Voxilaprevir in Direct-Acting Antiviral-Experienced Hepatitis C Virus Patients: A Systematic Review and Meta-Analysis

About 5% of chronic hepatitis C (CHC) patients experienced treatment failure with direct-acting antiviral (DAA) treatment. The global data on the practice and treatment outcomes of Sofosbuvir/Velpatasvir/Voxilaprevir (SOF/VEL/VOX) in DAA-experienced CHC patients remains sparse. We performed a systematic review and meta-analysis to evaluate the efficacy and safety of SOF/VEL/VOX as a salvage treatment in DAA-experienced CHC patients. We searched five electronic databases from inception to 31 January 2023. The study outcomes were SVR12 and treatment-related adverse effects, with subgroup analysis performed based on genotype, cirrhosis, HCC, prior SOF/VEL exposure, and region. We identified and analyzed data from 24 studies (2877 DAA-experienced CHC patients); 17.2% had prior SOF/VEL exposure, 25% received ribavirin with SOF/VEL/VOX, and 42% had pre-treatment resistance-associated substitution (RAS) testing performed. Eastern Mediterranean had a higher pooled SVR12 than the America and Europe regions (p < 0.05). Predictors of SOF/VEL/VOX failure were genotype 3, active HCC, baseline cirrhosis, and prior SOF/VEL. Baseline RAS mutation and ribavirin supplementation were not associated with higher SVR12. Treatment discontinuation because of drug-related adverse events was uncommon (10 studies, 0.2%). In summary, SOF/VEL/VOX is efficacious and safe for retreatment in DAA-experienced CHC patients, even with RAS mutation. Our findings support SOF/VEL/VOX as a first-line rescue treatment for DAA-experienced CHC patients.

Efficacy of ultra-short, response-guided sofosbuvir and daclatasvir therapy for hepatitis C in a single-arm mechanistic pilot study

Background

World Health Organization has called for research into predictive factors for selecting persons who could be successfully treated with shorter durations of direct-acting antiviral (DAA) therapy for hepatitis C. We evaluated early virological response as a means of shortening treatment and explored host, viral and pharmacokinetic contributors to treatment outcome.

Methods

Duration of sofosbuvir and daclatasvir (SOF/DCV) was determined according to day 2 (D2) virologic response for HCV genotype (gt) 1- or 6-infected adults in Vietnam with mild liver disease. Participants received 4- or 8-week treatment according to whether D2 HCV RNA was above or below 500 IU/ml (standard duration is 12 weeks). Primary endpoint was sustained virological response (SVR12). Those failing therapy were retreated with 12 weeks SOF/DCV. Host IFNL4 genotype and viral sequencing was performed at baseline, with repeat viral sequencing if virological rebound was observed. Levels of SOF, its inactive metabolite GS-331007 and DCV were measured on days 0 and 28.

Results

Of 52 adults enrolled, 34 received 4 weeks SOF/DCV, 17 got 8 weeks and 1 withdrew. SVR12 was achieved in 21/34 (62%) treated for 4 weeks, and 17/17 (100%) treated for 8 weeks. Overall, 38/51 (75%) were cured with first-line treatment (mean duration 37 days). Despite a high prevalence of putative NS5A-inhibitor resistance-associated substitutions (RASs), all first-line treatment failures cured after retreatment (13/13). We found no evidence treatment failure was associated with host IFNL4 genotype, viral subtype, baseline RAS, SOF or DCV levels.

Conclusions

Shortened SOF/DCV therapy, with retreatment if needed, reduces DAA use in patients with mild liver disease, while maintaining high cure rates. D2 virologic response alone does not adequately predict SVR12 with 4-week treatment.

Funding

Funded by the Medical Research Council (Grant MR/P025064/1) and The Global Challenges Research 70 Fund (Wellcome Trust Grant 206/296/Z/17/Z).

Universal testing for hepatitis B and hepatitis C in the emergency department: a cost-effectiveness and budget impact analysis of two urban hospitals in the United Kingdom

Background

Numerous studies have shown the effectiveness of testing for hepatitis B (HBV) and hepatitis C (HCV) in emergency departments (ED), due to the elevated prevalence amongst attendees. The aim of this study was to conduct a cost-effectiveness analysis of universal opt-out HBV and HCV testing in EDs based on 2 long-term studies of the real-world effectiveness of testing in 2 large ED’s in the UK.

Methods

A Markov model was used to evaluate ED-based HBV and HCV testing versus no ED testing, in addition to current testing practice. The two EDs had a HBV HBsAg prevalence of 0.5–0.9% and an HCV RNA prevalence of 0.9–1.0%. The analysis was performed from a UK health service perspective, over a lifetime time horizon. Costs are reported in British pounds (GBP), and outcomes as quality adjusted life years (QALYs), with both discounted at 3.5% per year. Incremental cost-effectiveness ratios (ICER) are calculated as costs per QALY gained. A willingness-to-pay threshold of £20,000/QALY was used. The cost-effectiveness was estimated for both infections, in both ED’s.

Results

HBV and HCV testing were highly cost-effective in both settings, with ICERs ranging from £7,177 to £12,387 per QALY gained. In probabilistic analyses, HBV testing was 89–94% likely to be cost-effective at the threshold, while HCV testing was 94–100% likely to be cost-effective, across both settings. In deterministic sensitivity analyses, testing remained cost-effective in both locations at ≥ 0.25% HBsAg prevalence, and ≥ 0.49% HCV RNA prevalence. This is much lower than the prevalence observed in the two EDs included in this study.

Conclusions

HBV and HCV testing in urban EDs is highly cost-effective in the UK, and can be cost-effective at relatively low prevalence. These results should be reflected in UK and European hepatitis testing guidelines.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12962-022-00388-7.

Effectiveness and Safety of Sofosbuvir/Velpatasvir/Voxilaprevir as a Hepatitis C Virus Infection Salvage Therapy in the Real World: A Systematic Review and Meta-analysis

Introduction

Sofosbuvir/Velpatasvir/Voxilaprevir (SOF/VEL/VOX) is the first direct-acting antiviral (DAA) therapy approved for patients who have previously failed a DAA-containing regimen including NS5A inhibitors. In clinical trials, SOF/VEL/VOX was associated with high rates of sustained virologic response at post-treatment week 12 (SVR12) and was well tolerated. However, the effectiveness and safety of SOF/VEL/VOX in the real world remained uncertain. We aimed to perform a systematic review and meta-analysis to assess the real world effectiveness and safety of SOF/VEL/VOX.

Methods

We systematically searched the PubMed, Embase, Cochrane Library, Web of Science, and ClinicalTrials.gov databases for relevant real world studies published before January 28, 2022. Patients with previous treatment failure who received SOF/VEL/VOX were included. The primary outcome was the percentage of patients achieving SVR12. Secondary outcome included adverse events (AEs) during treatment.

Results

Fifteen studies with a total of 1796 HCV-infected patients with previous treatment failure were included. SVR12 rates were 93% (95% CI 91–95) in the ITT populations (n = 1517, 11 cohorts) and 96% (95% CI 95–97) in the PP populations (n = 1187, 10 cohorts). SVR12 rates were significantly higher in non-GT3-infected patients (OR = 2.29, 95% CI 1.23–4.27, P = 0.009) and non-cirrhotic patients (OR = 2.22, 95% CI 1.07–4.60, P = 0.03) than in GT3-infected patients and cirrhotic patients. Furthermore, the SVR12 rates of previous treatment of SOF/VEL were significantly lower than those of other regimens in both ITT and PP populations (P ≤ 0.001). Adverse events (AEs) were reported in 30% (228/760) of patients. Serious AEs (SAEs) were reported in 3.82% (29/760) of patients. The most frequently reported AEs were headache, asthenia, nausea, fatigue, and diarrhea, which were mostly mild in severity. AE-related treatment discontinuations were reported in 0.66% (5/760) of patients.

Conclusions

Consistent with clinical trials, the real world evidence indicates that SOF/VEL/VOX is a well-tolerated and highly effective salvage therapy for HCV-infected patients with previous treatment failure. However, there may still be a risk of treatment failure for patients with GT3 infection, cirrhosis, or SOF/VEL treatment failure. The protocol of this study was registered at PROSPERO, registration no. CRD 42022306828.

Implementation of a controlled human infection model for evaluation of HCV vaccine candidates

Hepatitis C virus (HCV) remains a major global health concern. Directly acting antiviral (DAA) drugs have transformed the treatment of HCV. However, it has become clear that, without an effective HCV vaccine, it will not be possible to meet the World Health Organization targets of HCV viral elimination. Promising new vaccine technologies that generate high magnitude antiviral T and B cell immune responses and significant new funding have recently become available, stimulating the HCV vaccine pipeline. In the absence of an immune competent animal model for HCV, the major block in evaluating new HCV vaccine candidates will be the assessment of vaccine efficacy in humans. The development of a controlled human infection model (CHIM) for HCV could overcome this block, enabling the head-to-head assessment of vaccine candidates. The availability of highly effective DAA means that a CHIM for HCV is possible for the first time. In this review, we highlight the challenges and issues with currently available strategies to assess HCV vaccine efficacy including HCV "at-risk" cohorts and animal models. We describe the development of CHIM in other infections that are increasingly utilized by trialists and explore the ethical and safety concerns specific for an HCV CHIM. Finally, we propose an HCV CHIM study design including the selection of volunteers, the development of an infectious inoculum, the evaluation of host immune and viral parameters, and the definition of study end points for use in an HCV CHIM. Importantly, the study design (including number of volunteers required, cost, duration of study, and risk to volunteers) varies significantly depending on the proposed mechanism of action (sterilizing/rapid viral clearance vs. delayed viral clearance) of the vaccine under evaluation. We conclude that an HCV CHIM is now realistic, that safety and ethical concerns can be addressed with the right study design, and that, without an HCV CHIM, it is difficult to envisage how the development of an HCV vaccine will be possible.

Retreatment for hepatitis C virus direct acting antiviral therapy virological failure in primary and tertiary settings: the REACH-C cohort

Virological failure occurs in a small proportion of people treated for hepatitis C virus (HCV) with direct-acting antiviral (DAA) therapies. This study assessed retreatment for virological failure in a large real-world cohort. REACH-C is an Australian observational study (n=10843) evaluating treatment outcomes of sequential DAA initiations across 33 health services between March 2016 to June 2019. Virological failure retreatment data were collected until October 2020. Of 408 people with virological failure (81% male; median age 53; 38% cirrhosis; 56% genotype 3), 213 (54%) were retreated once; 15 were retreated twice. A range of genotype specific and pangenotypic DAAs were used to retreat virological failure in primary (n=56) and tertiary (n=157) settings. Following sofosbuvir/velpatasvir/voxilaprevir availability in 2019, the proportion retreated in primary care increased from 21% to 40% and median time to retreatment initiation declined from 294 to 152 days. Per-protocol (PP) sustained virological response (SVR12) was similar for people retreated in primary and tertiary settings (80% vs 81%; p=1.000). In regression analysis, sofosbuvir/velpatasvir/voxilaprevir (vs. other regimens) significantly decreased likelihood of second virological failure (PP SVR12 88% vs. 77%; adjusted odds ratio [AOR] 0.29; 95%CI 0.11-0.81); cirrhosis increased likelihood (PP SVR12 69% vs. 91%; AOR 4.26; 95%CI 1.64-11.09). Indigenous Australians had lower likelihood of retreatment initiation (AOR 0.36; 95%CI 0.15-0.81). Treatment setting and prescriber type were not associated with retreatment initiation or outcome. Virological failure can be effectively retreated in primary care. Expanded access to simplified retreatment regimens through decentralised models may increase retreatment uptake and reduce HCV-related mortality.

The Role of RASs /RVs in the Current Management of HCV

The approval of combination therapies with direct-acting antiviral (DAA) regimens has led to significant progress in the field of hepatitis C virus (HCV) treatment. Although most patients treated with these agents achieve a virological cure, resistance to DAAs is a major issue. The rapid emergence of resistance-associated substitutions (RASs), in particular in the context of incomplete drug pressure, has an impact on sustained virological response (SVR) rates. Several RASs in NS3, NS5A and NS5B have been linked with reduced susceptibility to DAAs. RAS vary based on HCV characteristics and the different drug classes. DAA-resistant HCV variant haplotypes (RVs) are dominant in cases of virological failure. Viruses with resistance to NS3-4A protease inhibitors are only detected in the peripheral blood in a time frame ranging from weeks to months following completion of treatment, whereas NS5A inhibitor-resistant viruses may persist for years. Novel agents have been developed that demonstrate promising results in DAA-experienced patients. The recent approval of broad-spectrum drug combinations with a high genetic barrier to resistance and antiviral potency may overcome the problem of resistance.

Using host genetics to infer the global spread and evolutionary history of HCV subtype 3a

Studies have shown that hepatitis C virus subtype 3a (HCV-3a) is likely to have been circulating in South Asia before its global spread. However, the time and route of this dissemination remain unclear. For the first time, we generated host and virus genome-wide data for more than 500 patients infected with HCV-3a from the UK, North America, Australia, and New Zealand. We used the host genomic data to infer the ancestry of the patients and used this information to investigate the epidemic history of HCV-3a. We observed that viruses from hosts of South Asian ancestry clustered together near the root of the tree, irrespective of the sampling country, and that they were more diverse than viruses from other host ancestries. We hypothesized that South Asian hosts are more likely to have been infected in South Asia and used the inferred host ancestries to distinguish between the location where the infection was acquired and where the sample was taken. Next, we inferred that three independent transmission events resulted in the spread of the virus from South Asia to the UK, North America, and Oceania. This initial spread happened during or soon after the end of World War II. This was subsequently followed by many independent transmissions between the UK, North America, and Oceania. Using both host and virus genomic information can be highly informative in studying the virus epidemic history, especially in the context of chronic infections where migration histories need to be accounted for.