Study shows CNS drugs take longer than others to develop, receive approval

The time from investigational new drug application filing to NDA/BLA approval by FDA of drugs for central nervous system (CNS) disorders and the subsequent regulatory approval can take 35% longer than other therapeutic categories, according to a recent analysis published in the March/April Tufts Center for the Study of Drug Development Impact Report.

“Although I expected that CNS drug development and approval times were longer than average, I was somewhat surprised at the extent to which they were longer,” said Joseph A. DiMasi, PhD, director of economic analysis, Tufts Center for the Study of Drug Development (CSDD), and principal investigator. “I also found it surprising that non-CNS drugs were two-and-one half times more likely to receive a priority review rating from the FDA than were CNS drugs.”

Dr DiMasi and colleagues analyzed data from FDA and Tufts CSDD databases of approved and investigational drugs. To assess clinical approval success rates and clinical phase transition rates for CNS drugs and biologics, the researchers obtained data for the top 50 pharmaceutical firms in 2006 on self-originated investigational drugs and biologics first tested in humans between 1994 and 2007.

During a 15-year period spanning 1996 to 2010, the investigators found that the mean clinical phase plus approval time for CNS drugs was 32 months longer than that for non-CNS drugs. The mean time for CNS drugs to complete the clinical trial process was 102.2 months, which equates to 40% longer than non-CNS drugs. The mean approval time for CNS drugs during that same time period was then 20.3 months, which equates to 13% longer than the non-CNS counterparts.

CNS drugs with standard review ratings took a mean 28 months longer than non-CNS drugs to get through the clinical-plus-approval phase, while CNS drugs with priority review ratings took a mean 56 months longer than non-CNS drugs.

The CNS new product pipeline is the richest among therapeutic categories, growing 6% annually over the past decade to account for 11% of current drug development projects, Dr DiMasi and colleagues noted. However, they found that the estimated clinical approval success rate for self-originated CNS drugs entering clinical trials between 1993 and 2004 was about 1 in 10, compared to 1 in 6 for all self-originated drugs.

“Given the high risks and lengthy development times for drugs often intended to treat serious conditions that affect many people, it is imperative that developers, regulators, and academics find ways to improve productivity and shorten time to market for compounds that can make significant contributions in this therapeutic area,” Dr DiMasi said.