Success rates have dropped 10% during the period 2008–2009 compared with success rates in 2006–2007. A report published by the Centre for Medicines Research (a Thompson Reuters business) published in the April 2011 issue of Nature Reviews Drug Discovery, reported that the success rate from 2008–2009 was 18%, versus 28% in 2006–2007. Of 108 trials that failed in phase II, 87 reported the reason for failure. Around half (51%) failed for lack of efficacy, 19% for safety, and 29% for strategic reasons. An earlier report by the same group, found that the failure rate for phase III and submission between 2007–2010 was around 50%, most of which was due to lack of efficacy. Taken together, that’s a lot of compounds that make it to clinical trials but fail to demonstrate efficacy.
Efficacy failures in Phase II can occur for several reasons: the mechanism targeted is not a good therapeutic target; the mechanism is good but the drug doesn’t perform well; or, occasionally, the trial is just poorly designed and doesn’t meet its endpoints. It’s easy to write an alarming headline, such as “Failures on the rise!,” but for me, this report raised many more questions than it answered. What was different about the trials run between 2008–2009 and the years previously? Were more trials run in difficult therapeutic areas, such as cancer and CNS indications? The numbers reported from 2008–2009 indicate that 21% of the failures were in cancer, and 19% in neuroscience, but that information was not reported for the earlier timeframe, making it difficult to compare the two sets of data.
A finding that the report keys on is the failure rate of 29% due to strategic reasons. “Strategic reasons” may mean that the compound failed to differentiate itself from a competitor compound, or may mean a change in the risk-benefit profile for that class of drugs. Again, more information would be useful to make sense of this. Has the bar gotten higher, or is this a dropout rate that has remained fairly constant over the past few years?
Finally, the report gathers its data from 16 companies that represent approximately 60% of global research and development. It would be interesting to know if the success rate is different for small companies that have smaller pipelines and riskier targets. It seems like a lot of information could come out of a serious analysis of trial failures, but no one issues press releases about failures—only successes.