Most of the papers Practical Fragments cover are limited in scope: a new chemical probe, say, or an NMR method. Even in our annual review of reviews, most of the publications have a focus, such as a particular technique. But a paper just published in Drug Discovery Today, by Iwan de Esch (VU University Amsterdam) and an international group of collaborators (including FragNet scholar Angelo Romasanta), is a rather different beast.
The (open access) paper is a bibliometric analysis of FBDD. The researchers first assembled all papers in Thomson-Reuter’s Web of Science which had “fragment” and one of several other terms as a keyword. If you try this at home you will find all sorts of irrelevant topics (such as antibody fragments), so these were manually removed, leaving 2781 publications. But many early papers did not refer to fragments, so all references that had been cited at least ten times were added, resulting in a total of 3642 papers published between 1953 and 2016. What can be learned with such a data set?
For one thing, the term “fragment-based drug discovery” didn’t appear until 2002. In the early 2000s “fragment-based lead discovery” was more common, though for roughly the past decade the former term and “fragment-based drug design” have co-dominated.
The researchers also examined the number of citations each paper has received to reveal interesting trends. For example, in the early years (1996-2001), industry dominated. Indeed, 9 of the 10 most cited papers of all time come from industry, and the sole outlier describes the protein data bank (PDB). In the past decade academics have become significant contributors, which is not surprising given their stronger incentive to publish.
Moving beyond raw citations, the researchers manually classified papers into scientific disciplines (methods, molecular basis, applications, and crystallography) to explore the diffusion of knowledge. This reveals the centrality of the 1996 “SAR by NMR” article, which was the first to cite theoretical and computational approaches and also bring in biophysics. Deservedly, this is the most highly-cited paper (454 citations within the set of articles, and currently >2100 total according to Google Scholar).
Our most recent poll of fragment-finding methods revealed a spike in crystallography, driven both by higher hit rates as well as technical advances, and this is also seen in the paper, where the 2011-2016 period shows a significant increase in crystallography over earlier five-year periods. As we’ve also noted, there has been a shift in content: while many earlier publications focused on techniques, medicinal chemistry has become a much more common subject in recent years.
There is plenty more here, and the paper is fun reading for anyone in FBDD, whether you have lived through the history or are new to the field. My one quibble is that the list of 3642 papers is not provided as supplementary material. Indeed, it is the open nature of the PDB that has made it such a valuable resource. Hopefully the authors will release their underlying data so others can build upon it.