Here we report a new drug design workflow that facilitates the transfer of structure-activity relationships (SARs) and recommends alternative fragments from SAR databases. We first prepare two collections of matched molecular series (MMS) comprising a query set of compounds with their SARs and a set derived from reference SAR databases. The second step detects MMS from the reference SAR sources, which identifies profiles similar to a query MMS according to integrated similarities of scaffold shapes and SAR trends. The third step enumerates new compounds with improved activity profiles compared with a query compound computed using a collaborative filtering algorithm. Our workflow detected direct and latent relationships between a query MMS and those derived from the reference SAR sources. Retrospective application of this workflow to the identification of factor Xa inhibitors yielded recommendations with higher predictive accuracy than a conventional quantitative SAR technique. Moreover, potent S1 binding elements were identified using SAR knowledge independent of information about ligand-protein complexes.
Trifluorothymidine (TFT) has antitumor activity, but it is easily metabolized to inert trifluorothymine by thymidine phosphorylase (TP). Accordingly, TFT alone cannot show satisfactory clinical antitumor effects. Human TP (HTP) is the main enzyme of pyrimidine nucleoside phosphorylase in human. Therefore, it has been necessary to develop a HTP inhibitor to maintain antitumor activity of TFT. Here we reveal the drug design process of HTP inhibitor based on SBDD and classical QSAR analysis. Thymine was selected as a seed compound and then 5-chlorouracil (3) was selected as a lead compound. The introduction of the imino moiety to C6 position of the lead compound (3) enhanced the inhibitory activity of TP. As a result, 5-chloro-6-[1-(2-iminopyrrolidinyl) methyl] uracil hydrochloride (TPI) was chosen as the candidate for the clinical trials. And TAS-102 (the combination of TFT and TPI in a 1:0.5 molar ratio) has been approved as Trifluridine/Tipiracil (Lonsurf) for the treatment of metastatic colorectal cancer in Japan, United States and EU.