Novartis has pulled the plug on its hepatitis C collaboration with Enanta Pharmaceuticals and will be spending its research dollars in other therapeutic areas.

The Swiss major has returned the rights to EDP-239, an NS5A inhibitor currently in Phase I for HCV. The companies began collaborating in February 2012 (in a deal worth up to $440 million) developing the drug as monotherapy and in combination with alisporivir, a cyclophilin inhibitor licensed by Novartis from Debiopharm.

However Novartis has had problems with alisporivir and three cases of acute pancreatitis, one fatal, led the US Food and Drug Administration to put a clinical hold on a trial of the treatment in 2012.

The news was broken by Enanta chief executive Jay Luly who said its partner had notified him that “as part of an ongoing portfolio transformation, HCV research would no longer be a strategic focus for Novartis”. He praised the Basel-headquartered group’s contributions to the development of EDP-239 “and its ready agreement to return the NS5A programme to us”.

Enanta is also in partnership with AbbVie, having developed the protease inhibitor ABT-450, one of three antivirals in the latter’s all-oral, interferon-free regimen for chronic genotype 1 HCV infection which was filed in Europe in May.