Raising orphans: how clinical development programs of drugs for rare and common diseases are different.

We compared clinical trials described in package inserts from noncancer orphan and nonorphan drugs from 1 January 2001 to 31 December 2011. Among the 37 orphan and 58 nonorphan drugs approved by the US Food and Drug Administration (US FDA) during this period, orphans had fewer clinical trials (2.8 vs. 3.5, P < 0.05) and fewer total participants (390 vs. 2,566, P < 0.001), but proportions with randomization, blinding, and placebo-controlled clinical end points were similar, as were development times. We conclude that small studies of appropriate design can support US FDA approval of new medicines for rare diseases.