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Page 2 of 15 Zanello et al. Rare Dis Orphan Drugs J 2023;2:9 https://dx.doi.org/10.20517/rdodj.2023.04

the sustainability of the repurposing approach for each of the selected cases.

Based on the collective experience of the members of the Task Force and the output from the
questionnaires/interviews, we have identified ten key factors that should be considered by those embarking on
repurposing projects. These factors include the identification of unmet patient needs and partnership with patients,
collection of evidence concerning disease prevalence, patient numbers, drug pharmacology and disease etiology,
drug industrial property status, off-label or compounding use, data from past clinical studies and needs for
extended non-clinical and clinical studies. The development of a collaborative funding framework and early
discussion with regulators and payers are additional factors to implement early in the development of sustainable
drug repurposing projects.
Keywords: Drug repurposing, rare diseases, orphan drugs, sustainable approaches, medicines development,
IRDiRC

INTRODUCTION
Drug repurposing is a hot topic in regulatory science and drug development. More than ever, the COVID-
19 pandemic has clearly shown the importance and potential pitfalls of repurposing existing molecules in
the therapeutic armamentarium .
[1,2]

In the context of rare diseases, a field where the majority of conditions have pediatric onset and the number
[3,4]
of therapies is limited , drug repurposing represents an opportunity for new therapeutic alternatives by
exploiting yet untapped pharmacological resources. While previous work done by the IRDiRC Data Mining
and Repurposing Task Force had exemplified that the rare disease field could benefit hugely from the
repurposing opportunities, the potential is not yet fully realized for a variety of reasons .
[5]
Repurposing is underused not because of the lack of opportunities, but because the additional resources
required to demonstrate the benefit-risk profile of a new indication and sometimes to adapt formulation,
posology, and mode of use, often do not translate into a sustainable return on investment via the traditional
pharmaceutical industry and healthcare reimbursement models. Indeed, these models are essentially built
[6-8]
around innovative, industrial property-protected molecules , which is defined as one of the two parts of
the intellectual property field and relates to the protection of inventions and industrial or commercial
creative work that includes patents for inventions, industrial designs, trademarks.

IRDiRC Task Force used the definition of drug repurposing established by the European expert group Safe
and Timely Access to Medicinal Products (STAMP) : “Process of identifying a new use for an existing drug/
[9]
active substance in an indication outside the scope of the original indication”. The Task Force looked at the
issue of the under-utilization of repurposing with the specific aim of considering which types of
development models could help to foster more successful cases of repurposing while keeping a balance
between attractiveness for developers and access to therapies for rare disease patients. The scope included
understanding key features of success criteria for the selected cases of repurposing projects and the
subsequent reflections of the Task Force on how to optimize these features.

APPROACH AND METHODS
Task Force members were selected based on their multi-stakeholder experience and knowledge of different
elements of repurposing programs. The Task Force conducted literature-based reviews to inform the
conclusions of this perspective paper. In order to help further inform expert opinions from the Task Force,
we selected different types of repurposed cases that would help us further identify key success factors for