- The ability, starting with an indication, to find what mechanisms, based on repurposing, are appropriate for that indication. ChemBL is mainly focussed on the primary associations, and not secondary ones. In DrugRepurposing Online you can not only find what these mechanisms are, but also one click go on to find other compounds that may be relevant based on that mechanism. If that second link is based on a mechanism which is not normally associated with the compound, e.g. if it, itself, is based on repurposing, there may well be interesting opportunities from the perspective of patenting. This comment derives from a philosophical concept, Swanson’s ABC model. This involves the general principle is that if concept A is related to concept B and B is related to concept C, then it is plausibly true that A is related to C (see below). However, from a patent perspective, not only is the inference of C to A novel, but also it may in certain circumstances be non-obvious (see Cavalla D, Oerton E, Bender A. (2017) Drug Repurposing Review. In: Comprehensive Medicinal Chemistry III. Elsevier; 11-47).
- Similar comments can be made regarding connections between indication and chemical class, which in DrugRepurposing Online are deliberately limited to those connections that are not the primary indication; or mechanism and chemical class, which do not involve the primary mode of action. To the limited extent ChemBL includes this information, it is in any case only a small component of the content in the ChemBL database, and difficult to separate from other content.
- DrugRepurposing Online owes this focus on the curation of references which involve repurposing rather than primary pharmacology or primary utility.
- The public databases may be comprehensive with respect to genes or targets and chemicals, but are quite weak with respect to connections between drugs and indications, and particularly weak with respect to secondary indications.
- The ability to search for dual mechanisms that may be involved with an indication, or dual mechanisms that may reside within one compound, are — as far as we can tell — completely absent from the capabilities of ChemBL. This capability of DrugRepurposing Online through the ‘Turbo Search’ button at the bottom of the Search Results page when you search for mechanisms appropriate for a particular indication or mechanisms resulting from a particular chemical class. This search capability is particularly useful for those interested in finding what combinations are likely to be useful for a particular indication.
There have been recent developments in databases of value to drug repurposing like ChemBL and DrugBank. These are vast, free sources of information that repurposing can benefit from. But Drug Repuposing Online is different, and we wanted to tell you how it is a unique, and in our opinion, a more focused resource for repurposing, built by people who do this for a living. ChemBL has recently changed the layout significantly and through a RESTful API make it available for remote searching, which adds quite a lot to its functionality. Nevertheless, there are some things we think would benefit researchers who want to find out what drugs can be repurposed for what, which are still not possible with ChemBL. For instance, neither ChemBL nor DrugBank offer: