by Michael Firgens
The development of new drugs requires high investments from biopharmaceutical companies and takes a significant amount of time until a drug is marketed. Drug repurposing is an alternative cost-effective approach to drug development which uses already approved drugs and compounds for the treatment of a different disease (see also our article “Drug repurposing – a smart development strategy to make drug development cheaper, faster, safer and more successful”. The advantages of repurposing strategies in terms of dossier data requirements are illustrated in Figure 1. Prominent examples include Pfizer’s Viagra (sildenafil) for erectile dysfunction and Celgene’s Thalomid (thalidomide) for the treatment of erythema nodosum leprosum (ENL) and multiple myeloma. Further advances and future trends in drug repurposing are expected by new technologies such as artificial intelligence (AI) and big data analysis tools [1-3].
Although drug repurposing provides opportunities for shelved or abandoned drugs, it can be expected that the repurposed drug faces strong competitive challenges from generics and other products with the same active pharmaceutical ingredient (API). Therefore, the actual commercial success of a repurposed drug depends on achieving effective protection against competitors through a combination of intellectual property (IP) and regulatory exclusivities.
The IP exclusivity refers to the protection granted by patents such as composition of matter and process or method of use patents. The filing of the composition of matter and formulation patents usually occurs early during the development of a new drug and, for repurposed drugs, the remaining patent life may be short or none. A new composition of matter patent could be issued for repurposed drugs if the product includes a new chemical entity or formulation, delivery mechanism or combination of APIs. Method of use patents are effective if the API is only approved for the newly patented indication. However, in clinical practice, generic products with the same API can still be used off-label. Overall, for repurposed drugs, a full protection from generic competition may be difficult to achieve by patents.
The exclusivity granted by the regulatory framework is the second pillar for effective protection of repurposed drugs that obtain the marketing authorization. These legislations are different in the EU and US, and the exclusivity granted to the repurposed drug depends on the chosen regulatory registration pathway (Art. 8(3) or Art. 10(3) in the EU; 505(b)(2) in the US) and whether the drug is intended for the treatment of pediatric patients or an orphan condition. In summary, the exclusivities are directed to prevent (1) that a drug manufacturer uses the safety and efficacy data from another marketing authorization application (data protection) or (2) that the same drug is registered for the same indication which is specifically applicable to orphan drugs. Importantly, the regulatory strategy and its impact on the exclusivities must be aligned early on during the development process to secure all competitive advantages of the repurposed drug. In particular, the potential for obtaining market exclusivity by an orphan drug designation should be carefully assessed in the context of the intneded clinical-regulatory strategy and competitive landscape.
Biopharma Excellence is experienced in developing smart integrated regulatory and repurposing strategies, including tailored strategies for orphan medicinal products. If you wish to learn more, please contact us.
 Tae-Wan Kim, Drug Repositioning Approaches for the Discovery of New Therapeutics for Alzheimer’s Disease, Neurotherapeutics, January 2015
[2 ]Beste Turanli et al, Drug Repositioning for Effective Prostate Cancer Treatment, Front. Physiol., 15 May 2018
 Andrii Buvailo, 2018: AI Is Surging In Drug Discovery Market, Biopharma Trend