Applied Clinical Trials
Only one in 10 self-originated drugs targeting diseases of the central nervous system (CNS) that entered clinical testing between 2002 and 2007 were approved. As such, CNS drugs have a success rate that is half that of the overall clinical approval success rate. Drug developers face numerous challenges in developing treatments targeting complex chronic illnesses in CNS including very demanding protocol designs and substantially longer development and regulatory review times. The clinical phase through approval duration for CNS drugs, for example, was 32 months longer than that of non-CNS drugs. Mean clinical phase duration for CNS drugs was 40% longer and the regulatory review and approval duration was 13% longer. CNS drugs are also far less likely to receive priority review status: between 1996 and 2010, non-CNS drugs were two-and-a-half times more likely to receive a priority review rating from the US Food and Drug Administration. The CNS new product pipeline, however, is among the richest, accounting for 11% of all drug development projects worldwide and growing by 6% annually.
Phase transition probabilities for self-originated CNS drugs and the benchmark for all TAs (2002-2007).
—Tufts Center for the Study of Drug Development, http://csdd.tufts.edu.