Wyeth has suffered another blow to its pipeline after it was revealed by partner ViroPharma that the firms have discontinued development of a hepatitis C drug that was in mid-stage trials.

The firms said that studies of HCV-796 have been halted “due to the previously announced safety issue that emerged in the ongoing Phase II trial” in patients with hepatitis C. ViroPharma chief executive Vincent Milano, said “clearly, this is a disappointing outcome” and while “significant activities were undertaken to determine a clear path forward for HCV-796”, the risk associated with potential hepatotoxicity “ultimately posed too high of a hurdle to merit further development."

The firms said that patients enrolled in the Phase II study will continue to receive the current standard of care, but they will not collaborate on future development of hepatitis C treatment candidates.

The news came as no great surprise seeing as how Wyeth and Viropharma discontinued dosing patients in the Phase II trial of HCV-796 last August. That decision followed a review by a joint safety review board which found that around 8% of patients receiving HCV-796 in combination with pegylated interferon and ribavirin had elevated liver enzymes.

Wyeth has seen a number of other drugs fail to make the grade of late. Most recently, it voluntarily withdrew an application for European marketing authorisation for Pristiq (desvenlafaxine) for the treatment of hot flushes, associated with menopause. It also presented disappointing late-stage data, along with Progenics Pharmaceuticals, from a trial of their investigational bowel drug methylnaltrexone.

Meantime, Wyeth and partner Elan Corp have suspended a mid-stage clinical trial of their vaccine for Alzheimer’s disease after one patient suffered a skin lesion which was potentially a serious side effect.

ACC-001 is a jab which creates antibodies against beta amyloid, which in turn forms plaques in the brain believed to play a key role in Alzheimer’s disease. Elan spokesman Jonathan Birt told Reuters that the Phase II study was halted after a single patient was hospitalised with what was described as a "skin lesion, possibly vasculitis,” though this later proved not to be the case. The patient has been treated and discharged.

The companies noted that the trial has not been permanently halted and will not affect their Phase III clinical programme for AAB-001 (bapineuzumab) for the treatment of patients with mild to moderate Alzheimer's disease.