Sofosbuvir/velpatasvir/voxilaprevir: a highly effective option for retreatment of hepatitis C in difficult-to-treat patients

Kill or corrupt: Mechanisms of action and drug-resistance of nucleotide analogues against SARS-CoV-2

Nucleoside/tide analogues (NAs) have long been used in the fight against viral diseases, and now present a promising option for the treatment of COVID-19. Once activated to the 5'-triphosphate state, NAs act by targeting the viral RNA-dependent RNA-polymerase for incorporation into the viral RNA genome. Incorporated analogues can either 'kill' (terminate) synthesis, or 'corrupt' (genetically or chemically) the RNA. Against coronaviruses, the use of NAs has been further complicated by the presence of a virally encoded exonuclease domain (nsp14) with proofreading and repair capacities. Here, we describe the mechanism of action of four promising anti-COVID-19 NAs; remdesivir, molnupiravir, favipiravir and bemnifosbuvir. Their distinct mechanisms of action best exemplify the concept of 'killers' and 'corruptors'. We review available data regarding their ability to be incorporated and excised, and discuss the specific structural features that dictate their overall potency, toxicity, and mutagenic potential. This should guide the synthesis of novel analogues, lend insight into the potential for resistance mutations, and provide a rational basis for upcoming combinations therapies.

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.

Salvage Therapy with Sofosbuvir/Velpatasvir/Voxilaprevir in DAA-experienced Patients: Results from a Prospective Canadian Registry

BACKGROUND

Despite the current highly effective therapies with direct-acting antiviral agents (DAAs), some patients with chronic hepatitis C virus (HCV) infection still do not achieve sustained virological response (SVR) and require retreatment. Sofosbuvir/velpatasvir/voxilaprevir (SVV) is recommended as the first-line retreatment option for most patients. The aim of this study was to evaluate the efficacy of SVV as salvage therapy after at least one course of DAA.

METHODS

Data were collected on all HCV-infected patients who failed DAAs and were prescribed SVV from a prospective Canadian registry (CANUHC) including 17 sites across Canada. Factors associated with failure to achieve SVR with SVV therapy and the utility of RAS testing and ribavirin use were evaluated.

RESULTS

A total of 128 patients received SVV after non-SVR with DAA treatment: 80% male, median age 57.5 (31-86), 44% cirrhotic, and 17 patients post liver transplant. First line regimens included: sofosbuvir/velpatasvir (27.3%), sofosbuvir/ledipasvir (26.5%), grazoprevir/elbasvir (12.5%), other (33.5%). Ribavirin was added to SVV in 26 patients due to past sofosbuvir/velpatasvir use (n = 8), complex resistance associated substitution profiles (n = 16) and/or cirrhosis (n = 9). Overall SVR rate was 96% (123/128). Of 35 patients who previously failed sofosbuvir/velpatasvir, 31 (88.5%) achieved SVR compared to 92 of 93 (99%) among those receiving any other regimen (P = .01).

CONCLUSIONS

Similar to reports from phase 3 clinical trials, SVV proved highly effective as salvage therapy for patients who failed a previous DAA therapy. Those who failed SVV had at least 2 of the following factors: genotype 3, presence of cirrhosis, past liver transplantation, past exposure to sofosbuvir/velpatasvir and/or complex resistance profiles.

Broad spectrum antiviral nucleosides-Our best hope for the future

The current focus for many researchers has turned to the development of therapeutics that have the potential for serving as broad-spectrum inhibitors that can target numerous viruses, both within a particular family, as well as to span across multiple viral families. This will allow us to build an arsenal of therapeutics that could be used for the next outbreak. In that regard, nucleosides have served as the cornerstone for antiviral therapy for many decades. As detailed herein, many nucleosides have been shown to inhibit multiple viruses due to the conserved nature of many viral enzyme binding sites. Thus, it is somewhat surprising that up until very recently, many researchers focused more on "one bug one drug," rather than trying to target multiple viruses given those similarities. This attitude is now changing due to the realization that we need to be proactive rather than reactive when it comes to combating emerging and reemerging infectious diseases. A brief summary of prominent nucleoside analogues that previously exhibited broad-spectrum activity and are now under renewed interest, as well as new analogues, that are currently under investigation against SARS-CoV-2 and other viruses is discussed herein.

Efficacy and Safety of Glecaprevir/Pibrentasvir in HCV Patients With Previous Direct-Acting Antiviral Therapy Failures: A Meta-Analysis

Background: Since a greater number of hepatitis C virus (HCV) patients have access to direct-acting antiviral (DAA) based therapies, the number of patients not properly responding to prior DAA regimens is increasing. The objective of this comprehensive analysis was to assess the efficacy and safety of glecaprevir/pibrentasvir (GLE/PIB) in HCV patients who experienced previous DAA therapy failures.

Methods: Bibliographic databases were systematically searched for relevant articles published by November 2020. The main endpoints were sustained viral response after 12 weeks (SVR12), adverse events (AEs; any grade) and severe adverse events (SAEs). Publication bias assessment was performed using funnel plots and the Egger's test.

Results: Fourteen studies consisting of a total of 1,294 subjects were included in this study and the pooled estimate of SVR12, AEs and SAEs rates were 96.8% (95%CI: 95.1–98.2), 47.1% (95%CI: 26.0–69.3), and 1.8% (95%CI: 0.7–3.4), respectively. Subgroup analysis showed that pooled SVR12 rates were 97.9% (95%CI: 96.7–98.9) for Japan and 91.1% (95%CI: 87.3–94.3) for the United States; 95.8% (95%CI: 93.9–97.4) for genotype (GT)1 and 100.0% (95%CI: 99.6–100.0) for GT2; 95.3% (95%CI: 92.4–97.2) for cirrhosis and 96.3% (95%CI: 94.2–97.7) for non-cirrhosis cases. There was no publication bias included this study.

Conclusion: This comprehensive analysis revealed that GLE/PIB is an effective and secure retreatment option for patients who did not optimally respond to DAA treatment, especially the Asian population with GT1-2.

A pilot study of safety and efficacy of HCV retreatment with sofosbuvir/velpatasvir/voxilaprevir in patients with or without HIV (RESOLVE STUDY)

BACKGROUND & AIMS

Cure rates in response to retreatment with sofosbuvir/velpatasvir/voxilaprevir (SOF/VEL/VOX) are high, but this regimen has not been studied in patients with a history of poor adherence or treatment interruption, nor in patients with HIV/HCV coinfection. Herein, we aimed to assess the safety and efficacy of this combination in patients with genotype 1 HCV infection who had relapsed following combination direct-acting antiviral (DAA) therapy, regardless of HIV infection or previous treatment course.

METHODS

The RESOLVE study was a multicenter, open-label, phase IIb study investigating the safety, tolerability and efficacy of SOF/VEL/VOX in 77 patients with virologic rebound following combination DAA therapy. Efficacy was defined as HCV RNA below the lower limit of detection 12 weeks after the end of treatment (SVR12), while safety endpoints included the incidence of grade 3 and 4 adverse events (AEs) following treatment, and the proportion of patients who stopped treatment prematurely due to AEs.

RESULTS

In an intent-to-treat analysis, 70/77 (90.9%, 95% CI 82.1-95.8%) patients achieved SVR12, including 14/17 (82.4%) HIV coinfected participants and 18/22 (81.8%) of those with previous non-completion of DAA therapy. In an analysis of all patients who completed 12 weeks of study medication, 70/71 patients (99%) achieved SVR12. One patient experienced a grade 3 AE, and 4 experienced a grade 4 AE, all unrelated to study participation. Reported AEs were similar in HIV-coinfected patients, and patients receiving dolutegravir-based antiretroviral treatment experienced no clinically significant increases in aminotransferases.

CONCLUSION

Retreatment with 12 weeks of SOF/VEL/VOX was safe and effective in patients with relapsed HCV following initial combination DAA-based treatment. Treatment response was not affected by HIV coinfection or previous treatment course.

LAY SUMMARY

Twelve weeks of the combination of direct-acting antivirals (SOF/VEL/VOX) was safe and effective in patients with relapsed hepatitis C virus infection who had previously received combination therapy with direct-acting antivirals. Treatment response was not diminished by HIV coinfection, or non-completion of previous direct-acting antiviral-based therapy.