Merck KGaA and its development partner, Newron, say that a late-stage study of their experimental therapy for Parkinson’s failed to demonstrate any significant effect. But the two developers refuse to walk away from safinamide. Researchers are planning to mount new trials with lower doses to find the right formula.

“The primary endpoint, time to intervention, did not reach statistical significance when data from both safinamide dose groups were pooled,” the companies said, after reviewing 18 months of combined data from patients taking the 50-100 mg and 120-200 mg doses. But researchers said that a lack of response among patients taking the highest dose could have skewed the data. Adding safinamide to dopamine agonist therapy at 50-100 mg daily could delay the time to therapeutic adjustment.