Final Report

1. Project objectives

The overall objective was to screen a Takeda’s new set of diversity and focused collection to identify progressable hit series for Chagas disease meeting GHIT/DNDi hit criteria. A total of 26,400 compounds were selected focusing on diversity from the parts of the Takeda’s compound library previously not tested, with acceptable physicochemical, ADME, and cytotoxicity properties. Substructures, which are likely to yield known types of inhibitors (CYP51, etc.), were avoided.

2. Project design

The activities were conducted as below.

Step 1: Selection of 26,400 compounds from the Takeda’s compound library

Step 2: Single-point T. cruzi screen

Step 3: Dose-response T. cruzi screen

Step 4: T. cruzi hit confirmation and CYP51 inhibition testing

Step 5: Resynthesis of 10 most promising and representative hits

Step 6: T. cruzi hit confirmation in at least two T. cruzi assays following by mechanism of action (MoA) assaying (proteasome inhibition, tRNA synthase inhibition and cytochrome bc1 inhibition)

Step 7: ADME profiling of hit compounds including solubility, metabolic stability in mouse and human microsomes, logD, permeability

Step 8: Data review - new progressable series identified

3. Results, lessons learned

A total of 267 hits were identified from T. cruzi high-throughput screening conducted at IPK. Of which, 260 compounds passed QC criteria. A total of 173 physically available compounds were sent to the University of Dundee (DDU) for T. cruzi hit confirmation and CYP51 inhibition testing. A cluster analysis of the combined data resulted in identification of 9 scaffolds meeting DNDi T. cruzi hit activity and selectivity criteria and demonstrating a higher than 10-fold selectivity window over CYP51 inhibition. Only 2 scaffolds are not singletons although identified analogues appear to display either borderline or suboptimal selectivity with regard to host cell toxicity. Furthermore, 3 of the identified singletons were deprioritized due to presence of reactive groups or ugly fragments. The remaining 6 scaffolds are novel to our discovery program for Chagas disease. The resynthesis of 9 compounds (6 initial hits representing 6 distinct scaffolds as well as 3 analogues) was completed at TCG Lifesciences. We experienced a delay in the resynthesis of one hit due to the complexity of the synthetic route, but this compound was finally obtained. All compounds were sent to DDU for T. cruzi activity confirmation and MoA profiling. These investigations are currently ongoing and will be completed outside the GHIT funding support.