New drug products are tested for safety and efficacy in clinical trials
before being approved for use in medical practice. Clinical trial data are often misreported or underreported to ClinicalTrials.gov and in the medical literature. There is limited research on clinical trial characteristics for Food and Drug Administration (FDA) approved drugs, particularly examining differences in characteristics across different approval pathways or therapeutic indications.
Data from the Aggregate Analysis of ClinicalTrials.gov (AACT) were used to compare the characteristics of completed clinical trials
for drugs approved by the FDA in 2015 and 2016 across different approval pathways (expedited vs. nonexpedited) and therapeutic indications (oncology vs. nononcology).
There were 59 novel therapeutic drugs approved by the FDA in 2015 and 2016. A search of the AACT database yielded 955 studies that were associated with these 59 drugs. Median Phase 2 trial enrollment was smaller for drugs granted expedited approval compared with drugs without expedited approval (60 vs. 94; P
=0.0079) and for oncology drugs compared with nononcology drugs (53 vs. 92; P
<0.001). In general, trials across all phases were less likely to be blinded for drugs that received expedited approval compared with drugs without expedited approval and for oncology drugs compared with nononcology drugs.
The characteristics of clinical trials
differ across different approval pathways and therapeutic indications. More research is needed to determine whether the information from clinical trials
of approved drugs is sufficient to adequately inform the public regarding their potential benefits and harms.