Drug Repurposing: Opportunities for Developing Drugs Faster, Safer, Cheaper in New Therapeutic Areas
Drug discovery and the translation of research findings into new therapies require significant investments and resources by biopharmaceutical companies. Analyses across all therapeutic areas indicate that the development of a new medicine, from target identification through marketing authorization, takes over 12 years and often much longer (DiMasi 2010).
An attractive alternate development strategy is the repurposing of known drugs. The basic idea works as follows: Marketed drugs are approved for certain uses and have been tested in humans, so detailed information is available on their pharmacology, formulation and potential toxicity. The repurposing builds on these available data and previous research and development efforts, which facilitates the identification, design and development of new therapies and which can speed up the review by agencies and, if approved, the integration of the product into the healthcare system.
A comparison between conventional development strategies (i.e. for novel drugs and generics) and the repurposing development approach is presented in Exhibit 1. A more detailed view on the development process for novel and repurposed drugs is shown in Exhibit 2. In the literature, the estimated benefits of the repurposing development strategy slightly differ depending on the product type and target indication, however, it is obvious that drug repurposing is less risky, cheaper and faster than the development of novel drugs.
EXHIBIT 1 | Positioning of development strategies of biopharmaceutical companies.
EXHIBIT 2 | Comparison of drug development process for (a) novel drugs and for (b) repurposed drugs (Ashburn 2004).
Repurposing of established drugs can be defined as “studying drugs that are already approved to treat one disease or condition to see if they are safe and effective for treating other diseases” (National Center for Advancing Translational Sciences).
All repurposing programs contain two key elements:
taking existing scientific or medical knowledge and technology that is “approved” for human use in one disease or condition; and
applying this knowledge and technology to another disease or condition.
Exhibit 3 summarizes various examples of repurposed drugs for small molecules and biologicals. The opportunities of drug repurposing have been also discovered for the creation of totally new treatment regimens, e.g. combination therapies in oncology (Exhibit 4, Bertolini 2015).
EXHIBIT 3 | Examples of drugs repurposed for orphan indications in the US.
EXHIBIT 4 | Repurposing of drugs used in the development of new combination therapies for cancer treatment (Bertolini 2015).
The concept of drug repurposing is known to regulators, and applicable regulatory frameworks have been defined in the EU and the US (Exhibit 5). As for the development and registration of new molecule entities (NMEs), similar incentives exist for repurposed drugs, e.g. for orphan drugs or pediatric development programs. Combining the advantages of the drug repurposing approach with a sound development and regulatory strategy (avoiding pitfalls) provides enormous opportunities for biopharmaceutical companies.
EXHIBIT 5 | Overview of relevant regulatory frameworks for drug repurposing in the EU and in the US (Papakrivos 2011).
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DiMasi J.A., Feldman L., Seckler A., Wilson A. (2010): Trends in risks associated with new drug development: success rates for investigational drugs. Clin Pharmacol Ther. 87, 272–277.
Ashburn et al. (2004): Nat Rev Drug Disc 3 , 673-683
Bertolini F., Sukhatme V.P., Bouche G. (2015): Drug repurposing in oncology - patient and health systems opportunities. Nat Rev Clin Once 12, 732–742.
Papakrivos J. (2011): Regulatory Strategy for the Development of Known Drugs in New Therapeutic Areas, Rheinische Friedrich-Wilhelms-Universität Bonn