Translation of rare disease research into orphan drug development: disease matters.

More than 25 years of orphan drug regulations have yielded several new treatments for patients with rare diseases. Here, we show that successful translation of rare disease research into an orphan drug discovery and development programme is dependent on the disease class, its prevalence and the disease-specific scientific output. Our findings indicate that current orphan drug legislation alone is not sufficient to stimulate orphan drug development for diseases with a very low prevalence. Consequently, additional incentives should focus on stimulating the specific needs of rare disease research at disease class level.