FDA's Flexibility in Subpart H Approvals: Assessing Quantum of Effectiveness Evidence

Area of Science:

• Pharmaceutical Sciences
• Regulatory Science
• Clinical Research

Background:

• The US Food and Drug Administration (FDA) utilizes the Accelerated Approval pathway, including Subpart H, for serious conditions.
• Subpart H allows approval based on surrogate or intermediate clinical endpoints reasonably likely to predict clinical benefit.
• This pathway has been in existence for twenty-four years, with nineteen non-AIDS, non-cancer approvals analyzed.

Purpose of the Study:

• To examine the scientific and clinical evidence supporting FDA's nineteen non-AIDS, non-cancer Subpart H approval determinations.
• To assess the application of FDA's four key factors for expedited programs in past Subpart H approvals.
• To understand the extent of regulatory flexibility exercised by the FDA under Subpart H.

Main Methods:

• Review of nineteen FDA Subpart H approval determinations for non-AIDS, non-cancer indications.
• Analysis of the evidence base for each approval against the four key factors outlined in FDA's 2014 Expedited Programs Guidance.
• Evaluation of the quantum and quality of evidence for surrogate or intermediate clinical endpoints used in these approvals.

Main Results:

• Significant variability was observed in the quantity and quality of evidence across the four key factors for the nineteen Subpart H precedents.
• A deficiency in evidence for any single factor did not preclude approval, indicating substantial regulatory flexibility.
• FDA's application of Subpart H demonstrates considerably more flexibility than explicitly stated in its foundational statutes and 2014 guidance.

Conclusions:

• The FDA exercises considerable regulatory flexibility under Subpart H, often exceeding the explicit stipulations in its guidelines.
• The findings suggest that Subpart H should be further investigated and utilized, especially considering advancements in personalized medicine and translational sciences.
• A detailed analysis of established precedents provides a foundation for understanding and potentially expanding the use of this expedited approval pathway.