Design,Synthesis And Antitumor Study Of A Series Of Erlotinib Derivatives As Novel Dual Inhibitors Of EGFR And Indoleamine 2,3-dioxygenase 1 (IDO1)

BackgroundEGFR tyrosine kinase inhibitors(TKI)are emerging at the vanguard of therapy for non-small-cell lung cancer(NSCLC)patients with EGFR-activating mutations,which were observed in approximately 15%-20%NSCLC patients.However,the increasing therapeutic resistance caused by novel second mutations or activated bypass pathways has impeded the efficiency as well as utilization of EGFR TKIs.1,2,3-triazole ring is an eminent pharmacophore that widely occurs in different compounds characterized by various bioactivities,such as antitumor,antimicrobial,and antidiabetic effects.Indoleamine 2,3-dioxygenase-1(IDO1)is a promising cancer therapy target activated in many human cancers.Especially in lung cancer,IDO1 is a driver of disease progression and metastasis,thus associated with pool prognosis.Therefore,EGFR-TKI derivatives containing 1,2,3-triazole ring are probably dual inhibitors of EGFR and IDO1 with therapeutic potential for NSCLC.MethodsIn this study,one of the commercial EGFR TKIs,erlotinib was linked with different azides compounds to synthesize a novel class of erlotinib derivatives containing 1,2,3-triazole ring through copper-catalyzed azidealkyne cycloaddition(CuAAC)reaction.We evaluated the EGFR phosphorylation inhibitory activities of these erlotinib derivatives by enzyme-linked immunosorbent assay(ELISA),and screened the inhibitory activity of these compounds against IDO1 in Hela cells.We further tested the in vitro antitumor activity of these compounds by CCK-8 assay in NSCLC cells including A549,H460,H1299,H1975 and PC-9,as well as the correlation between cytotoxicity and apoptosis or cell cycle arrest.We used western blotting to examine the EGFR activities and its downstream signal in NSCLC cells treated with compounds e4 and e12.In vivo antitumor activity of compound e4 was evaluated in a H460 murine xenograft model.ResultsWe discovered that most of the erlotinib-1,2,3-triazole compounds are capable of suppressing EGFR phosphorylation,and also potent inhibitors of Indoleamine 2,3dioxygenase-1(IDO1).Besides,a few of the new compounds demonstrated robust cytotoxicity against diverse NSCLC cells in vitro including A549,H460,H1299,H1975 and PC-9.Remarkably,two of the most potent compounds e4 and e12 which were more efficient than erlotinib in all five NSCLC cell lines except PC-9,significantly induced apoptosis and cell cycle arrests in A549 and H460.Furthermore,Western blotting demonstrated that compounds e4 and e12 effectively suppressed the EGFR activity and its downstream signaling.Minor but nonsignificant antitumor activity of compound e4 was detected in the H460 murine xenograft model,and further investigation is needed.ConclusionsTherefore,we presume these erlotinib-1,2,3-triazole compounds with EGFR tyrosine kinase and IDO1 dual inhibitory activities probably are potential novel antitumor agents against NSCLC.