Variable short duration treatment versus standard treatment, with and without adjunctive ribavirin, for chronic hepatitis C: the STOP-HCV-1 non-inferiority, factorial RCT
Authors: Cooke Graham S , Pett Sarah , McCabe Leanne , Jones Christopher , Gilson Richard , Verma Sumita , Ryder Stephen D , Collier Jane D , Barclay Stephen T , Ala Aftab , Bhagani Sanjay , Nelson Mark , Ch’Ng Chin Lye , Stone Benjamin , Wiselka Martin , Forton Daniel , McPherson Stuart , Halford Rachel , Nguyen Dung , Smith David , Ansari M Azim , Ainscough Helen , Dennis Emily , Hudson Fleur , Barnes Eleanor J , Walker Ann Sarah ,   the STOP-HCV trial team
Published: October 2021

Background
High cure rates with licensed durations of therapy for chronic hepatitis C virus suggest that many patients are overtreated. New strategies in individuals who find it challenging to adhere to standard treatment courses could significantly contribute to the elimination agenda.

Objectives
To compare cure rates using variable ultrashort first-line treatment stratified by baseline viral load followed by retreatment, with a fixed 8-week first-line treatment with retreatment with or without adjunctive ribavirin.

Design
An open-label, multicentre, factorial randomised controlled trial.

Randomisation
Randomisation was computer generated, with patients allocated in a 1 : 1 ratio using a factorial design to each of biomarker-stratified variable ultrashort strategy or fixed duration and adjunctive ribavirin (or not), using a minimisation algorithm with a probabilistic element.

Setting
NHS.

Participants
A total of 202 adults (aged ≥ 18 years) infected with chronic hepatitis C virus genotype 1a/1b or 4 for ≥ 6 months, with a detectable plasma hepatitis C viral load and no significant fibrosis [FibroScan® (Echosens, Paris, France) score F0–F1 or biopsy-proven minimal fibrosis], a hepatitis C virus viral load < 10,000,000 IU/ml, no previous exposure to direct-acting antiviral therapy for this infection and not pregnant. Patients co-infected with human immunodeficiency virus were eligible if human immunodeficiency virus viral load had been < 50 copies/ml for > 24 weeks on anti-human immunodeficiency virus drugs.

Interventions
Fixed-duration 8-week first-line therapy compared with variable ultrashort first-line therapy, initially for 4–6 weeks (continuous scale) stratified by screening viral load (variable ultrashort strategy 1, mean 32 days of treatment) and then, subsequently, for 4–7 weeks (variable ultrashort strategy 2 mean 39 days of duration), predominantly with ombitasvir, paritaprevir, ritonavir (Viekirax®; AbbVie, Chicago, IL, USA), and dasabuvir (Exviera®; AbbVie, Chicago, IL, USA) or ritonavir. All patients in whom first-line treatment was unsuccessful were immediately retreated with 12 weeks’ sofosbuvir, ledipasvir (Harvoni®, Gilead Sciences, Inc., Foster City, CA, USA) and ribavirin.

Main outcome measure
The primary outcome was overall sustained virological response (persistently undetectable) 12 weeks after the end of therapy (SVR12).

Results
A total of 202 patients were analysed. All patients in whom the primary outcome was evaluable achieved SVR12 overall [100% (197/197), 95% confidence interval 86% to 100%], demonstrating non-inferiority between fixed- and variable-duration strategies (difference 0%, 95% confidence interval –3.8% to 3.7%, prespecified non-inferiority margin 4%). A SVR12 following first-line treatment was achieved in 91% (92/101; 95% confidence interval 86% to 97%) of participants randomised to the fixed-duration strategy and by 48% (47/98; 95% confidence interval 39% to 57%) allocated to the variable-duration strategy. However, the proportion achieving SVR12 was significantly higher among those allocated to variable ultrashort strategy 2 [72% (23/32), 95% confidence interval 56% to 87%] than among those allocated to variable ultrashort strategy 1 [36% (24/66), 95% confidence interval 25% to 48%]. Overall, a SVR12 following first-line treatment was achieved by 72% (70/101) (95% confidence interval 65% to 78%) of patients treated with ribavirin and by 68% (69/98) (95% confidence interval 61% to 76%) of those not treated with ribavirin. A SVR12 with variable ultrashort strategies 1 and 2 was 52% (25/48) (95% confidence interval 38% to 65%) with ribavirin, compared with 44% (22/50) (95% confidence interval 31% to 56) without. However, at treatment failure, the emergence of viral resistance was lower with ribavirin [12% (3/26), 95% confidence interval 2% to 30%] than without [38% (11/29), 95% confidence interval 21% to 58%; p = 0.01]. All 10 individuals who became undetectable at day 3 of treatment achieved first-line SVR12 regardless of treatment duration. Five participants in the variable-duration arm and five in the fixed-duration arm experienced serious adverse events (p = 0.69), as did five participants receiving ribavirin and five participants receiving no ribavirin.

Conclusions
SVR12 rates were significantly higher when ultrashort treatment varied between 4 and 7 weeks, rather than between 4 and 6 weeks. We found no evidence of ribavirin significantly affecting first-line SVR12, with unsuccessful first-line short-course therapy also not compromising subsequent retreatment with sofosbuvir, ledipasvir and ribavirin.

Future work
A priority for future work needs to be the development and evaluation of robust predictive measures to identify those patients who can be cured with ultrashort courses of therapy.

Trial registration
Current Controlled Trials ISRCTN37915093, EudraCT 2015-005004-28 and CTA 19174/0370/001-0001.

Funding
This project was funded by the Efficacy and Mechanism Evaluation programme, a MRC and National Institute for Health Research (NIHR) partnership. This will be published in full in Efficacy and Mechanism Evaluation; Vol. 8, No. 17. See the NIHR Journals Library website for further project information.