Merck KGaA has decided to cut its losses and will no longer seek approvals for its oral multiple sclerosis treatment cladribine, as attempting to satisfy regulators would require fresh long and costly trials.

The German firm says that the decision has been made based on discussions with the US Food and Drug Administration at an end-of-review meeting for cladribine. In March, the agency issued a complete response letter and asked for further information on the analyses submitted or for new studies to be carried out.

Merck believes that data from ongoing clinical trials "are very unlikely to address the FDA requirements and will not provide a basis for approval". The US regulator's feedback was consistent with that received from the European Medicines Agency, which confirmed its negative opinion on cladribine earlier this year.

Stefan Oschmann, head of the Darmstadt-based group's Merck Serono unit, said that "considering the time it would take to complete a new clinical trial programme and the significant risk" that such a study would not result in sufficient data". He added that "taking into account the changing competitive landscape, we have decided to not pursue further the worldwide approval process of cladribine", saying that the company will now focus on other projects "bringing benefit to patients with MS".

In Australia and Russia, where cladribine is already available under the tradename Movectro, Merck intends to withdraw the product from the market. The company added that it will take a one-off charge of 20 million euros in the second quarter in connection with the move.

The plug being pulled on cladribine is a further boost for Novartis' MS tablet Gilenya (fingolimod), which is already available in the USA and Europe.