Translational research and efficacy of biologics in Crohn's disease: a cautionary tale

Drug repurposing: a systematic review on root causes, barriers and facilitators

BACKGROUND

Repurposing is a drug development strategy receiving heightened attention after the Food and Drug Administration granted emergency use authorization of several repurposed drugs to treat Covid-19. There remain knowledge gaps on the root causes, facilitators and barriers for repurposing.

METHOD

This systematic review used controlled vocabulary and free text terms to search ABI/Informa, Academic Search Premier, Business Source Complete, Cochrane Library, EconLit, Google Scholar, Ovid Embase, Ovid Medline, Pubmed, Scopus, and Web of Science Core Collection databases for the characteristics, reasons and example of companies deprioritizing development of promising drugs and barriers, facilitators and examples of successful re-purposing.

RESULTS

We identified 11,814 articles, screened 5,976 for relevance, found 437 eligible for full text review, 115 of which were included in full analysis. Most articles (66%, 76/115) discussed why promising drugs are abandoned, with lack of efficacy or superiority to other therapies (n = 59), strategic business reasons (n = 35), safety problems (n = 28), research design decisions (n = 12), the complex nature of a studied disease or drug (n = 7) and regulatory bodies requiring more information (n = 2) among top reasons. Key barriers to repurposing include inadequate resources (n = 42), trial data access and transparency around abandoned compounds (n = 20) and expertise (n = 11). Additional barriers include uncertainty about the value of repurposing (n = 13), liability risks (n = 5) and intellectual property (IP) challenges (n = 26). Facilitators include the ability to form multi-partner collaborations (n = 38), access to compound databases and database screening tools (n = 32), regulatory modifications (n = 5) and tax incentives (n = 2).

CONCLUSION

Promising drugs are commonly shelved due to insufficient efficacy or superiority to alternate therapies, poor market prospects, and industry consolidation. Inadequate resources and data access and challenges negotiating IP are key barriers to repurposing reaching its full potential as a core approach in drug development. Multi-partner collaborations and the availability and use of compound databases and tax incentives are key facilitators for repurposing. More research is needed on the current value of repurposing in drug development and how to better facilitate resources to support it, where valuable, especially financial, staffing for out-licensing shelved products, and legal expertise to negotiate IP agreements in multi-partner collaborations.

TRIAL REGISTRATION

The protocol was registered on Open Science Framework ( https://osf.io/f634k/ ) as it was not eligible for registration on PROSPERO as the review did not focus on a health-related outcome.

Challenges in animal modelling of mesenchymal stromal cell therapy for inflammatory bowel disease

Utilization of mesenchymal stromal cells (MSCs) for the treatment of Crohn’s disease and ulcerative colitis is of translational interest. Safety of MSC therapy has been well demonstrated in early phase clinical trials but efficacy in randomized clinical trials needs to be demonstrated. Understanding MSC mechanisms of action to reduce gut injury and inflammation is necessary to improve current ongoing and future clinical trials. However, two major hurdles impede the direct translation of data derived from animal experiments to the clinical situation: (1) limitations of the currently available animal models of colitis that reflect human inflammatory bowel diseases (IBD). The etiology and progression of human IBD are multifactorial and hence a challenge to mimic in animal models; and (2) Species specific differences in the functionality of MSCs derived from mice versus humans. MSCs derived from mice and humans are not identical in their mechanisms of action in suppressing inflammation. Thus, preclinical animal studies with murine derived MSCs cannot be considered as an exact replica of human MSC based clinical trials. In the present review, we discuss the therapeutic properties of MSCs in preclinical and clinical studies of IBD. We also discuss the challenges and approaches of using appropriate animal models of colitis, not only to study putative MSC therapeutic efficacy and their mechanisms of action, but also the suitability of translating findings derived from such studies to the clinic.