Merck & Co’s once-daily oral hepatitis C virus (HCV) combination therapy grazoprevir/elbasvir looks on course for regulatory filing later this year after showing efficacy in a phase II/III trial.
While Merck is coming somewhat late to the all-oral HCV therapy market – with rival therapies from Gilead and AbbVie already firmly established as more patient-friendly alternatives to injectable interferon-based regimens – grazoprevir/elbasvir could find a lucrative niche among HCV patients who also have kidney disease.
The results of the C-SURFER trial showed that a 12-week course of NS3/4A protease inhibitor grazoprevir and NS5A replication complex inhibitor elbasvir achieved a sustained virologic response – considered a clinical cure – in 99% of patients.
The study enrolled both treatment-naïve patients and those who had been given interferon in the past – with and without cirrhosis – all of whom had genotype 1 HCV and advanced chronic kidney disease.
Merck suffered a setback in its development plans to the combination therapy after the FDA decided to rescind breakthrough status for genotype 1 HCV, on the grounds that there are now other drugs on the market which address this medical need.
Earlier this month, however, the US regulator restored some of the lustre to the programme and awarded grazoprevir/elbasvir breakthrough status in two other indications – chronic genotype 1 HCV with end-stage renal disease and chronic genotype 4 HCV.
Despite the lead for rival oral HCV therapies such as Gilead’s Sovaldi (sofosbuvir) and Harvoni (sofosbuvir and ledipasvir) and AbbVie’s Viekira Pak (ombitasvir/paritaprevir/ritonavir and dasabuvir), consensus analyst predictions cited by Thomson Reuters suggest Merck’s combination could achieve sales of $2bn-plus in 2019, assuming a launch early next year.
Merck is also developing an HCV polymerase inhibitor – called MK-3682 – that it is testing alongside grazoprevir/elbasvir and other double therapies in phase II studies. It is planning to start a phase III programme for MK-3682 before the end of the year.