Drug rediscovery in gastroenterology: from off-label to on-label use of thioguanine in inflammatory bowel disease.

Drug rediscovery refers to the principle of using 'old' drugs outside the indications mentioned in the summary of product characteristics. In the past decades, several drugs were rediscovered in a wide variety of medical fields. One of the most recent examples is the unconditional registration of thioguanine (TG), a thiopurine derivative, in patients with inflammatory bowel disease in the Netherlands. In this paper, we aim to visualise potential hurdles that hamper drug rediscovery in general, emphasise the global need for optimal use and development of potentially useful drugs, and provide an overview of the registration process for TG in the Netherlands. With this summary, we aim to guide drug rediscovery trajectories in the near future.
Competing Interests: Competing interests: NdB served as a speaker for AbbVie and MSD and as consultant and principal investigator for TEVA Pharma BV and Takeda; and received an unrestricted research grant from Dr Falk, TEVA Pharma BV, MLDS and Takeda. MS received unrestricted research grants from TEVA Pharma BV. BM has nothing to declare. MN served as an adviser to Boehringer, MSD, AbbVie, Celgene, Pentax, Takeda, Janssen, Giuliani and PPM. AAvB received speaker, consultancy or advisory board fees from AbbVie, BMS, Galapagos, Ferring, Janssen and TEVA Pharma BV. Galapagos, Ferring and Janssen supported educational programmes. TEVA Pharma BV and Pfizer supported research projects. CM served as an adviser to TEVA UK, Arega Belgium and Douglas Pharma NZ.
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