Indazole-Based Covalent Inhibitors To Target Drug-Resistant Epidermal Growth Factor Receptor

Abstract

The specific targeting of oncogenic mutant epidermal growth factor receptor (EGFR) is a breakthrough in targeted cancer therapy and marks a drastic change in the treatment of non-small cell lung cancer (NSCLC). The recurrent emergence of resistance to these targeted drugs requires the development of novel chemical entities that efficiently inhibit drug-resistant EGFR. Herein, we report the optimization process for a hit compound that has emerged from a phenotypic screen resulting in indazole-based compounds. These inhibitors are conformationally less flexible, target gatekeeper mutated drug-resistant EGFR-L858R/T790M, and covalently alkylate Cys797. Western blot analysis, as well as characterization of the binding kinetics and kinase selectivity profiling, substantiates our approach of targeting drug-resistant EGFR-L858R/T790M with inhibitors incorporating the indazole as hinge binder.

Overcoming EGFRG724S-mediated osimertinib resistance through unique binding characteristics of second-generation EGFR inhibitors

“…Interestingly, we also identified an aminoindazole-based inhibitor with low nanomolar activity against the double-mutant kinase that would not be classified as a second-generation EGFR inhibitor but indeed exhibits a different binding mode than osimertinib (Fig. 4b , Supplementary Table 2 ) 35 .…”

Recent Advances in the Development of Indazole‐based Anticancer Agents

“…In light of the poor cellular potencya nd slow rate of covalent bond formation of compound 2,t he research group continued to prepare as et of indazole-based derivatives by reducing molecular flexibility and optimizing spatial arrangemento f the acrylamide to covalently target the reactive cysteinei nt he binding site ( Figure 2). [20] Aromatic extensions in the 6-or 5-positions of the indazole were aimed to extend toward the binding site or interactw ith the methionine gatekeeper.At ertiary amine side chain wasi ntroduced to increase solubility.A mong these derivatives, compounds bearing substituents on the 6positiono ft he indazole ring (such as 3 and 4)e xhibited striking selectivity over wild-type EGFR, being active against the L858R/T790M double-mutated EGFR with IC 50 values below 5nm biochemically and below 500 nm against the corresponding cells. It is interesting to notethat compound 5,with aflexible secondary amine-bridged meta-fluorobenzene moiety,w as found to be the most potent EGFRi nhibitor,w ith IC 50 values in the sub-nanomolar range against all of the forms tested biochemically and cellular activity below 200 nm in the drug-resistant H1975 cell line.…”

Advances of small molecule targeting of kinases

“…Another covalent EGFR inhibitor, osimertinib, was approved in 2015 for the treatment of non-small-cell lung cancer (NSCLC) characterized by the EGFR T790M mutation [36,37]. Novel covalent inhibitors of EGFR-T790M based on pyrazolopyrimidines[38] and indazoles[39] have been reported recently, and other inhibitors such as rociletinib are in late phase clinical trials for non-small cell lung cancer (NSLCL) [40]. Gray and colleagues developed novel covalent inhibitors to target specific kinase isoforms including JAK3 of the JAK family [41], as well as CDK7 [42,43] and CDK12 [44] which are critical for the transcriptional machinery to sustain the oncogenic state.…”