The eyes of the beholder: Perceived barriers to successful drug repurposing

Despite tremendous advances in new drug development over recent decades, the medical needs of an ever increasing and ageing global population are still significantly unmet. Drug repurposing (DR)-finding new therapeutic uses for existing medicinal substances and products-offers a promising strategy by potentially reducing development time, costs and risk. However, currently, significant hurdles restrict broader application of DR. This study was conducted within the European Commission funded REMEDi4ALL consortium to systematically identify and analyse the key policy obstacles perceived to be hindering the success of DR. A systematic literature review was conducted using PubMed and Embase, supplemented by grey literature searches and expert interviews within the consortium. The extracted data underwent thematic analysis. A barrier tree was developed and validated through five workshops with 80 experts from seven stakeholder groups. From 4059 hits, 192 were included for data extraction, resulting in the identification of 33 key barriers grouped into nine main themes: perception of off-patent medicines, business case for on-patent DR, business case for off-patent DR, non-industry-funded DR, ecosystem for non-profit or small and medium-sized enterprise-driven repurposing, market authorisation, exclusivity rights, health technology assessment and pricing. This comprehensive analysis provides a foundation for prioritizing the main areas for future interventions. Surprisingly, there were considerable differences in how different stakeholders perceived the importance of a number of key barriers. Such multidimensional aspects of DR barriers will need to inform future development of actionable policy recommendations to enhance the DR ecosystem and facilitate broader access to repurposed medicines.