Annals of Internal Medicine JUNE 18, 2015

Grazoprevir–Elbasvir in Treatment-Naïve Patients with Hepatitis C Genotype 1, 4, or 6 Infection (C-EDGE Treatment-Naïve)

Stefan Zeuzem, et al.

Bottom Line

The phase 3 C-EDGE Treatment-Naïve trial demonstrated that a 12-week regimen of the fixed-dose combination elbasvir/grazoprevir achieved a high rate of sustained virologic response (SVR12) in patients with chronic HCV genotypes 1, 4, or 6.

Key Findings

1. The primary endpoint of SVR12 was achieved by 95% (299/316) of patients in the immediate-treatment group.

2. Efficacy was high across genotypes: 95% for GT1, 100% for GT4, and 80% for GT6.

3. The regimen maintained efficacy in patients with compensated cirrhosis, with 96% (67/70) achieving SVR12.

4. Adverse events were generally mild, with headache, fatigue, and nausea being the most frequent reported, and the frequency of serious adverse events was low (3%).

Study Design

Design

RCT

Double-Blind

Sample

421

Patients

Duration

12 wk

Median

Setting

Multicenter, Global

Population Treatment-naïve patients (≥18 years) with chronic HCV genotype 1, 4, or 6 infection, with or without compensated cirrhosis

Intervention Fixed-dose combination of elbasvir (50 mg) and grazoprevir (100 mg) once daily for 12 weeks

Comparator Placebo for 12 weeks, followed by open-label treatment with elbasvir/grazoprevir

Outcome Sustained virologic response 12 weeks after the end of treatment (SVR12), defined as HCV RNA <15 IU/mL

Study Limitations

• The study included a relatively small number of patients with genotype 6 infection, limiting the robustness of results for this specific subgroup.

• The trial excluded patients with decompensated cirrhosis, meaning the findings cannot be generalized to more advanced liver disease.

• The study did not evaluate shorter treatment durations (e.g., 8 weeks) which have been explored in subsequent research.

• The trial was conducted in a controlled environment which may not fully reflect real-world adherence and patient comorbidities.

Clinical Significance

This trial provided critical evidence for the approval of the elbasvir/grazoprevir fixed-dose combination as an effective, interferon-free, and ribavirin-free treatment option for patients with chronic HCV genotypes 1, 4, and 6, significantly improving the treatment landscape for HCV.

Historical Context

The C-EDGE program was part of a larger clinical development effort to address the need for simplified, potent, and tolerable all-oral direct-acting antiviral (DAA) therapies, following the paradigm-shifting introduction of earlier DAAs that replaced interferon-based regimens.

Guided Discussion

High-yield insights from every perspective

Med Student

Medical Student

The C-EDGE trial utilizes a combination of elbasvir and grazoprevir; explain the specific viral targets for these two drugs and why inhibiting multiple points in the HCV life cycle is a fundamental principle of Direct-Acting Antiviral (DAA) therapy.

Key Response

Elbasvir is an NS5A inhibitor (involved in viral replication and assembly), while grazoprevir is an NS3/4A protease inhibitor (responsible for cleavage of the viral polyprotein). Using two different classes prevents the selection of resistance-associated substitutions (RASs), as the probability of a single virus acquiring simultaneous mutations against two distinct pathways is significantly lower than for monotherapy.

Resident

Based on the safety profile and drug classes used in the C-EDGE trial, which specific patient population with chronic HCV is elbasvir/grazoprevir strictly contraindicated in, and why?

Key Response

It is contraindicated in patients with Child-Pugh B or C (moderate to severe) hepatic impairment. Grazoprevir is a protease inhibitor, and this class is associated with significantly increased drug concentrations in patients with advanced liver disease, which can lead to further hepatotoxicity and potential clinical decompensation.

Fellow

In the C-EDGE trial, genotype 1a patients with baseline NS5A resistance-associated substitutions (RASs) showed lower SVR12 rates. How does the presence of these polymorphisms change the recommended duration and components of an elbasvir/grazoprevir regimen in current clinical practice?

Key Response

While the standard trial duration was 12 weeks, current clinical guidelines (AASLD/IDSA) recommend that GT1a patients with baseline NS5A RASs (at positions 28, 30, 31, or 93) being treated with elbasvir/grazoprevir should have their treatment extended to 16 weeks and include weight-based ribavirin to overcome the reduced susceptibility of the virus.

Attending

The C-EDGE trial demonstrated high efficacy in treatment-naive patients across genotypes 1, 4, and 6. Given the shift toward 'pangenotypic' regimens like glecaprevir/pibrentasvir or sofosbuvir/velpatasvir, what is the remaining clinical niche or strategic advantage of using a genotype-specific regimen like elbasvir/grazoprevir in modern practice?

Key Response

Elbasvir/grazoprevir remains a highly cost-effective and potent option for genotype 1b and genotype 4, often requiring only a single tablet daily for 12 weeks without the need for RAS testing (in 1b). Its use is also well-validated in patients with severe renal impairment or end-stage renal disease (ESRD), where some other DAA components were historically more restricted.

Scholarly Review

Critical appraisal through the lens of expert reviewers and guideline development

PhD

The C-EDGE trial utilized a deferred-treatment randomized control group. Critically evaluate the choice of a placebo-controlled deferred-start design over an active-comparator design in the context of the rapid evolution of HCV therapies during the mid-2010s.

Key Response

The deferred-start design provided a rigorous safety control group while ensuring all participants eventually received effective treatment, which was ethically necessary given the curative potential of DAAs. However, the lack of an active comparator (e.g., ledipasvir/sofosbuvir) limited the study's ability to provide head-to-head comparative effectiveness data, which is often more valuable for health economics and relative efficacy modeling in a crowded therapeutic market.

Journal Editor

The C-EDGE trial reports an overall SVR12 of 95%, yet the inclusion criteria excluded patients with HIV/HCV co-infection and those with a history of intravenous drug use within 6 months. How does this impact the generalizability of the results to the 'real-world' HCV epidemic, and what would a reviewer flag as a potential threat to external validity?

Key Response

The strict inclusion/exclusion criteria create a 'highly curated' cohort that likely overestimates real-world adherence and underestimates biological complexity (like drug-drug interactions in HIV patients). A reviewer would flag that the trial population may not represent the highest-burden groups—specifically people who inject drugs (PWID)—where social determinants of health and reinfection risks significantly influence long-term outcomes.

Guideline Committee

Does the evidence from C-EDGE justify the use of elbasvir/grazoprevir as a first-line agent for treatment-naive genotype 1a patients without baseline resistance testing, and how does this align with the AASLD/IDSA simplified treatment algorithms?

Key Response

No, it does not justify use without testing. Because SVR12 rates drop significantly (to ~70%) in GT1a patients with specific NS5A RASs, guidelines explicitly require baseline RAS testing if this regimen is selected. Under current AASLD/IDSA 'simplified' algorithms, pangenotypic options that do not require baseline resistance testing are often preferred to reduce the diagnostic burden and expedite treatment initiation.

Clinical Landscape

Noteworthy Related Trials

2014

C-WORTHY Trial

n = 471 · NEJM

Tested

Grazoprevir and elbasvir with or without ribavirin

Population

Treatment-naive or experienced patients with HCV genotype 1

Comparator

Placebo or different treatment durations

Endpoint

Sustained virologic response at 12 weeks (SVR12)

Key result: High rates of SVR12 were achieved across various study arms, proving the potency of this combination therapy.

2015

C-EDGE CO-INFECTION Trial

n = 218 · Lancet

Tested

Elbasvir (50mg) / Grazoprevir (100mg) once daily

Population

HCV genotype 1, 4, or 6 patients co-infected with HIV

Comparator

None (single-arm)

Endpoint

Sustained virologic response at 12 weeks (SVR12)

Key result: The treatment achieved an SVR12 rate of 96% in patients with HIV and HCV co-infection.

2015

C-EDGE TN Trial

n = 316 · Annals of Internal Medicine

Tested

Elbasvir (50mg) / Grazoprevir (100mg) once daily for 12 weeks

Population

Treatment-naive patients with HCV genotype 1, 4, or 6

Comparator

Delayed treatment (placebo)

Endpoint

Sustained virologic response at 12 weeks (SVR12)

Key result: 95% of patients achieved SVR12, demonstrating the high efficacy and safety of the regimen.

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