Unmet Medical Need: An Introduction to Definitions and Stakeholder Perceptions.

Background: Despite increasing informal and formal use of unmet medical need (UMN) in drug development, regulation, and assessment, there is no insight into its definitions in use. This study aims to provide insight into the current definitions in use and to provide a starting point for a multi-stakeholder discussion on alignment.

Methods: A scoping and a gray literature review were performed to locate definitions of UMN in literature and on stakeholder websites. These definitions were categorized and then discussed among the multi-stakeholder author group via semistructured group discussions and open session workshops with a broader stakeholder audience. Issues with the formation of a common definition and mechanisms for use were discussed.

Results: The reviews yielded 16 definitions. Differences were evident, but all included 1 or more of the following elements: (adequacy of) available treatments (16 of 16: 100%), disease severity or burden (6 of 16: 38%), and patient population size (1 of 16: 6%). The stakeholder discussions led to a suggestion for a definition including the first 2 items and, depending on context, population size. The discussions also showed that quantification of UMN is highly dependent on the scope and the value framework in which it is used based on different stakeholder preferences and responsibilities.

Conclusion: We encourage stakeholders that want to promote alignment on the concept of UMN to prospectively discuss the scope in which they want to apply the concept, what elements they find important for consideration in each case, and how they would measure UMN within the broader regulatory or value framework applicable.