Premarket Pivotal Trial End Points and Postmarketing Requirements for FDA Breakthrough Therapies.

Importance: The US Food and Drug Administration (FDA) awards the breakthrough therapy designation to expedite development and review of therapeutics intended to treat serious conditions when preliminary clinical evidence demonstrates potential substantial improvement over existing therapies on clinically significant end points. Under the 21st Century Cures Act of 2016, the FDA is required to publish and routinely update a list of surrogate markers to provide industry sponsors with indication-specific information about end points that were or may be considered for approval. Therapeutics that are granted breakthrough therapy designation can receive accelerated or traditional approval; however, little is known about those approved through the latter pathway, where postmarketing confirmatory studies are typically not required, regardless of the end point used. Objective: To evaluate the primary end points used in premarket pivotal trials supporting FDA breakthrough therapy-designated approvals and to determine whether postmarketing studies confirming efficacy were required for approvals based on pivotal trials using surrogate markers as primary end points. Design, Setting, and Participants: This cross-sectional study used data from the Drugs@FDA database for all original breakthrough therapy-designated approvals from inception to December 31, 2023, in the US. The first designation was approved on November 1, 2013. Data analysis was performed in January 2024. Main Outcomes and Measures: Descriptive analyses were used to characterize the breakthrough therapy-designated indication approval pathways, the primary end points of pivotal efficacy trials, and their postmarketing requirements or commitments. Results: From 2013 to 2023, the FDA approved 157 original indications with breakthrough therapy designation. Of these, 52 (33%) were granted accelerated approval and 105 (67%) were granted traditional approval. All accelerated approvals were based on pivotal trials using surrogate markers as primary end points and had FDA-required postmarketing studies to confirm efficacy. Of these 52 indications, 51 (98%) were approved based on surrogate end points listed in the FDA table of surrogate end points for the same indication. Among traditional approvals, 61 (58%) were based on pivotal trials using surrogate markers as primary end points, of which 4 (7%) had FDA-required postmarketing studies to confirm efficacy and 39 (64%) were approved based on surrogate end points listed in the FDA table for the same indication. Conclusions and Relevance: In this cross-sectional study of original FDA breakthrough therapy-designated approvals from 2013 to 2023, trials supporting these approvals often used surrogate markers as primary end points (even when not approved via accelerated approval) and lacked FDA-required postmarketing studies to verify clinical benefit. These findings suggest that requiring postmarketing studies for breakthrough therapy-designated indications approved based on surrogate markers, regardless of approval pathway, may increase patient and clinician certainty of the expected clinical benefit.