The characteristics and regulations of adaptive designs from 2008 to 2020: An overview of European Medicines Agency approvals.

Objective: The aim of this study was to identify and characterize all European Medicines Agency (EMA) approvals derived from adaptive designs in clinical trials and to provide an update of the current status of these drugs.

Materials and methods: Relevant files were identified in the EMA database for annual reports for the period between 2008 and 2020 using a list of suitable keywords related to adaptive designs. We recorded trial characteristics from drug approvals and used Fisher exact test to compare the characteristics.

Results: A total of 1,054 EMA approvals were identified, and the percentage of EMA approvals planned with adaptive trial designs increased from 1.85% in the period 2008 - 2012 to 6.19% in between 2017 - 2020. A total of 41 approvals were identified among 91 original EMA files that contained adaptive designs. The types of adaptive designs used in clinical trials increased after 2017 where the most common type used was the most common (17/41). Most approvals (32/41) comprised pivotal trials, and most assessments had not been accelerated (38/41). Of 32 confirmatory trials planned with adaptive designs, the proportion of those with additional monitoring (AM) increased significantly (p < 0.0001) from 0% in the 2008 - 2012 period to 90.48% in the 2017 - 2020 period. The percentage of approved antitumor drugs in approved drugs in ongoing clinical trials was 82.35%, compared to 20.83% in trials that were completed (p = 0.0001). The proportion of drug approved but where clinical trials were still ongoing in companies requiring post-authorization safety studies (PASSs) or post-authorization efficacy studies (PAESs) or who were granted conditional marketing authorization (CMA) significantly differed from the group of drugs approved where clinical trials were completed (p = 0.0230).

Conclusion: A trend showing an increased number of EMA approvals related to adaptive designs was observed for the period from 2008 to 2020. Different types of adaptive trial designs could be encouraged for the designation of clinical trials, especially for antitumor drugs; meanwhile, more stringent monitoring regulations seemed to be conducted for ongoing trials of antitumor drugs with adaptive design.