Clinuvel Pharmaceuticals (ASX:CUV) said the European Medicines Agency (EMA) has proposed evaluating the company's Scenesse drug for the treatment of systemic vitiligo based on a "totality of evidence" regulatory approach, according to a Friday filing with the Australian bourse.

Vitiligo is a chronic skin condition that results in patches of skin turning white.

Following the EMA's final advice on the design of a planned phase 3 study of Scenesse, Clinuvel said the proportion of patients who achieve 50% or more repigmentation of the total body, excluding hands and feet, will be the study's primary endpoint.

Photographic evidence of change from baseline will be used to assess primary and secondary endpoints in the study, which is scheduled to start in the second half of this year.

The EMA also advised that patients with darker skin would benefit from systemic treatment first, as the visibility of the disease is more pronounced in such patient groups, Clinuvel said.