Merck & Co’s single-pill hepatitis C regimen grazoprevir/elbasvir has picked up two breakthrough designations from the US Food and Drug Administration.

The move comes just two months after the regulator issued a notice of intent to rescind the therapy’s breakthrough status for hepatitis C (HCV) genotype 1 (though hasn't actually been revoked), because of the increasingly crowded market place for new effective treatments for this patient group.

On the back of new clinical data, the FDA has now issued new breakthrough designations for patients with hepatitis genotype 4 and those with genotype 1 infection in patients with end-stage renal disease on haemodialysis. 

Merck said it intends to report a range of mid- and late-stage clinical data for grazoprevir/elbasvir at the International Liver Congress later this year, and that it remains on track to file the treatment with the USA in the next couple of months.