Utilization of Structure-Based Design to Identify Novel, Irreversible Inhibitors of EGFR Harboring the T790M Mutation

Allosteric inhibition of tRNA synthetase Gln4 by N-pyrimidinyl-β-thiophenylacrylamides exerts highly selective antifungal activity

Candida species are among the most prevalent causes of systemic fungal infections, which account for ∼1.5 million annual fatalities. Here, we build on a compound screen that identified the molecule N-pyrimidinyl-β-thiophenylacrylamide (NP-BTA), which strongly inhibits Candida albicans growth. NP-BTA was hypothesized to target C. albicans glutaminyl-tRNA synthetase, Gln4. Here, we confirmed through in vitro amino-acylation assays NP-BTA is a potent inhibitor of Gln4, and we defined how NP-BTA arrests Gln4's transferase activity using co-crystallography. This analysis also uncovered Met496 as a critical residue for the compound's species-selective target engagement and potency. Structure-activity relationship (SAR) studies demonstrated the NP-BTA scaffold is subject to oxidative and non-oxidative metabolism, making it unsuitable for systemic administration. In a mouse dermatomycosis model, however, topical application of the compound provided significant therapeutic benefit. This work expands the repertoire of antifungal protein synthesis target mechanisms and provides a path to develop Gln4 inhibitors.

Advances in covalent kinase inhibitors

This comprehensive review details recent advances, challenges and innovations in covalent kinase inhibition within a 10 year period (2007–2018).

Discovery of Potent Irreversible Pan-Fibroblast Growth Factor Receptor (FGFR) Inhibitors

Fibroblast growth factor receptors (FGFR1-4) are promising therapeutic targets in many cancers. With the resurgence of interest in irreversible inhibitors, efforts have been directed to the discovery of irreversible FGFR inhibitors. Currently, several selective irreversible inhibitors are being evaluated in clinical trials that could covalently target a conserved cysteine in the P-loop of FGFR. In this article, we used a structure-guided approach that is rationalized by a computer-aided simulation to discover the novel and irreversible pan-FGFR inhibitor, 9g, which provided superior FGFR in vitro activities and decent selectivity over VEGFR2 (vascular endothelia growth factor receptor 2). In in vivo studies, 9g displayed clear antitumor activities in NCI-H1581 and SNU-16 xenograft mice models. Additionally, the diluting method confirmed the irreversible binding of 9g to FGFR.

Allenamide as a bioisostere of acrylamide in the design and synthesis of targeted covalent inhibitors

The success of acrylamide-containing drugs in treating cancers has spurred a passion to search for acrylamide bioisosteres. In our endeavour, we have identified that an allenamide group can be a reactive bioisostere of the acrylamide group. In our development of allenamide-containing compounds, we found that the most potent compound, 14, inhibited the kinase activities of both T790M/L858R double mutant and wild type EGFR in a low nM range. 14 also inhibited the growth of NCI-H1975 lung cancer cells at IC₅₀ = 33 nM, which is comparable to that of acrylamide-containing osimertinib. The western blot analysis showed that the phosphorylation of EGFR, AKT, and ERK1/2 was simultaneously inhibited in a dose-dependent manner when NCI-H1975 cells were treated with 14. By measuring the conjugate addition product formed by 14 and GSH, we obtained a reaction rate constant of 302.5 × 10^-3 min^-1, which is about 30-fold higher than that of osimertinib. Taken together, our data suggest that the allenamide-containing compounds inhibited EGFR kinases through covalent modifications. Our study indicates that the allenamide group could serve as an alternative electrophilic warhead in the design of targeted covalent inhibitors, and this bioisostere replacement may have broad applications in medicinal chemistry.