Winfuran: Withdrawal of the marketing authorisation application

Winfuran is a medicine that contains the active substance nalfurafine. It was to be available as a concentrate for solution for infusion into a vein.

Winfuran was expected to be used for the treatment of patients with severe uraemic pruritus. Uraemic pruritus is a persisting form of itching that occurs in some patients whose kidneys are not functioning properly. Winfuran was to be used in patients with end-stage renal disease (when the kidneys have stopped working completely) and who are on dialysis (a technique for removing waste products from the blood).

Winfuran was designated an 'orphan medicine' (a medicine to be used in rare diseases) on 11 September 2002 for uraemic pruritus.

Although the exact cause of uraemic pruritus is not known it is thought that the itching is linked to an excessive activity of certain receptors called mu-opioid receptors in the brain and skin. Winfuran activates different opioid receptors, called kappa receptors, which block the activity of the mu-opioid receptors and therefore relieve the itching in patients with uraemic pruritus.

The effects of Winfuran were first tested in experimental models before being studied in humans.

The effects of Winfuran were compared with placebo (a dummy treatment) in one main study involving 339 patients with uraemic pruritus who were on regular dialysis. The main measure of effectiveness was the change in symptoms such as itching intensity and sleep disturbance after 4 weeks of treatment based on a standard scoring system.

The evaluation had finished and the CHMP had given a negative opinion.

Based on the review of the data, at the time of the withdrawal, the CHMP had given a negative opinion, recommending that the marketing authorisation be refused for Winfuran for the treatment of severe uraemic pruritus.

The CHMP's main concern was that the benefits of Winfuran in the treatment of uraemic pruritus had not been sufficiently shown. The main study failed to show that Winfuran was more effective than placebo at relieving itching. Although an additional analysis showed a modest benefit in a subpopulation of patients with a severe form of uraemic pruritus, the CHMP considered that the clinical relevance had not been shown. Therefore, at the time of the withdrawal, the CHMP was of the opinion that the benefits of Winfuran did not outweigh its risks and it concluded that the medicine could not have been approved on the basis of the data presented by the company.

In its official letter, the company stated that its decision to withdraw the application was based on the CHMP's view that the data provided do not allow the Committee to conclude on a positive benefit-risk balance.

The company informed the CHMP that there are no ongoing clinical trials or compassionate use programmes for Winfuran.