Germany’s Merck KGaA and Italian partner Newron Pharmaceuticals have presented some disappointing late-stage data for their novel Parkinson’s disease drug safinamide but the firms hope it is only a question of getting the dosage right.

Preliminary results of a 12-month extension study of a 6-month Phase III trial of safinamide as an add-on treatment to dopamine agonist therapy in patients with early stage Parkinson's disease reveal that it failed to reach statistical significance when data from both safinamide dose groups (50-100 mg and 150-200 mg) were pooled. Also, only 187 patients out of 227 completed the 12-month extension study, with the rest discontinuing due to side effects, lack of efficacy and withdrawal of consent.

However the firms said that the analysis showed that the lower dose range of safinamide alongside dopamine seemed to significantly reduce the number of patients who experienced an intervention, maintained improvement in motor symptoms and improved quality of life compared with dopamine agonist monotherapy.

"These 18-month data suggest that, at a dose of 50-100 mg once daily, safinamide may delay the time to intervention for therapeutic adjustment and provide sustained improvement of Parkinson's disease symptoms when added to dopamine agonist therapy," said study investigator Anthony Schapira. He added that “additional Phase III studies are planned to further assess the efficacy of this dose". he added in the statement on Wednesday.

Commenting on the news, Benjamin Yeoh at Dresdner Kleinwort said that the result is disappointing “but does not necessarily kill the drug” as the original six-month study already suggested the lower dose could be a better treatment option. He noted that does not have anything factored into its model for safinamide but said the news would be a trading negative for Merck during the day. The Darmstadt-based company’s shares actually ended up 0.7% to 91.95 euros, but Newron, which is listed on the SWX stock exchange, slipped 2.25% to 67 Swiss francs.

Merck signed a development and commercialisation deal with Newron last October for safinamide, which is also being investigated as a treatment for Alzheimer’s disease, restless leg syndrome and other cognitive disorders.