Knowledge of the rates and causes of drug candidate attrition by clinical development phase and by therapeutic area is valuable in assessing the impact of changes in development strategy and research area focus by the pharmaceutical industry. Two years ago, we published brief reports on failures in Phase III and submission from 2007 to 2010 (Nature Rev. Drug Discov. 10. 87; 2011) and failures in Phase II from 2008 to 2010 (Nature Rev. Drug Discov. 10. 328-329; 2011). Here. using data gathered from Drugs of Today, as in the previous analyses, we have conducted a similar analysis for 2011 and 2012.

During this period. there were a total of 148 failures between Phase II and submission (also including Phase I/II studies in patients and major new indications of already marketed drugs). Of these. 105 had reported reasons for failure. The majority were due to a lack of efficacy (56%) or to safety issues (28%); here. safety includes those failures that were due to an insufficient therapeutic index (FIG. 1a).