Decisions on Non-oncology Breakthrough Therapy Designation Requests in 2017-2019.

Background: The US Food and Drug Administration's Breakthrough Therapy Designation (BTD) program is intended to facilitate and expedite development of investigational drugs to address unmet medical needs. The objective of this study is to provide an update on FDA's process for review of BTD requests.

Methods: We reviewed Center for Drug Evaluation and Research (CDER) decisions to grant or deny breakthrough therapy designation requests for non-oncology drugs or biological products ("drugs") from January 1, 2017, through December 31, 2019. Data collection included characteristics of the corresponding drug and condition, reasons for granting or denying breakthrough therapy status, reasons for rescinding or withdrawing breakthrough therapy status after a request was granted (if applicable), and subsequent marketing approval status through 2022.

Results: Among 240 requests, 93 (39%) requests were granted and 147 (61%) requests were denied. Granting of requests was more common for conditions where no therapy was available or for orphan diseases. Common reasons for denial included data-related issues, insufficient treatment effect, inadequate study design, endpoint attributes, safety issues, and reliance on post hoc analyses. Among 28 drugs receiving marketing approval as of the end of 2022 for the indication for which BTD was previously granted, 21 (75%) involved a first-in-class mechanism of action.

Conclusions: This analysis describes CDER's decision-making process related to review of requests for breakthrough therapy designations and enhances public awareness regarding efforts to expedite drug development.