Discovery of Novel 5,6-Dihydro-4H-pyrido[2,3,4-de]quinazoline Irreversible Inhibitors Targeting Both Wild-Type and A775_G776insYVMA Mutated HER2 Kinases.

HER2 mutations were seen in 4% of non-small-cell lung cancer (NSCLC) patients. Most of these mutations (90%) occur as an insertion mutation within the exon 20 frame, leading to the downstream activation of the PI3K-AKT and RAS/MAPK pathways. However, no targeted therapies have yet been approved worldwide. Here a novel series of highly potent HER2 inhibitors with a pyrido[2,3,4-de]quinazoline core were designed and developed. The derivatives with the pyrido[2,3,4-de]quinazoline core displayed superior efficacy of antiproliferation in BaF3 cells harboring HER2insYVMA mutation compared with afatinib and neratinib. Rat studies showed that 8a and 9a with the newly developed core have good pharmacokinetic properties with an oral bioavailability of 41.7 and 42.0%, respectively. Oral administration of 4a and 10e (30 mg/kg, QD) displayed significant antitumor efficacy in an in vivo xenograft model. We proposed promising strategies for the development of HER2insYVMA mutant inhibitors in this study.

Integrated molecular modeling and dynamics approaches revealed the mechanism of selective inhibition of HDAC6/8.

The high structural homology of histone deacetylases 6 and 8 (HDAC6/8) poses a challenge in achieving isoform selectivity and has resulted in adverse side effects due to pan-inhibition in clinical applications. Additionally, the rational design of dual-target inhibitors, centered on HDAC6/8, demands a profound understanding of their selectivity mechanisms. Addressing the urgent need for enhanced specificity in the development of inhibitors targeting specific isoforms, we elucidate the mechanism underpinning the selective inhibition of HDAC6/8 inhibitors through in-silico strategies. The hydrogen bonding interaction with Asp101 and Tyr306 is a key factor that enables compound 12b to selectively inhibit HDAC8. Its favorable spatial orientation places the Cap group of 12b between Tyr306 and Tyr100, resulting in an overall L-shaped conformation. These two factors significantly contribute to the selective inhibitory activity of 12b against HDAC8. The zinc binding group (ZBG) of compound NN-390 forms a hydrogen bond with His610, a key residue of HDAC6, facilitating stable chelation with zinc ions. In addition, the Cap group of NN-390 interacts with Phe620 and Phe680 via van der Waals forces, leading to an overall Y-shaped conformation. The aforementioned factors are the main reasons for the selective inhibition of HDAC6 by NN-390. Furthermore, whether the Cap group is in the para or meta-position will influence the selective inhibition of either HDAC6 or HDAC8. We believe these clues can offer valuable insights for the rational design of selective inhibitors targeting HDAC6/8 and pave the way for rational design of dual-target HDAC6/8-based inhibitors.Communicated by Ramaswamy H. Sarma.

Design, synthesis and biological evaluation of 2,3-dihydro-[1,4]dioxino[2,3-f]quinazoline derivatives as EGFR inhibitors.

Epidermal growth factor receptor (EGFR) is the most attractive target for drug research in non-small cell lung cancer (NSCLC). The first-generation EGFR tyrosine kinase inhibitors (TKIs) Gefetinib and Elotinib showed good clinical efficacy on lung adenocarcinoma tumors, but almost all patients developed resistance to these inhibitors over time. Quinazoline and quinoline derivatives are common targeted inhibitors of EGFR kinase, and their structural optimization is an important direction for the development of effective targeted anticancer drugs. Based on these facts, a series of heterocyclic 2,3-dihydro-[1,4]dioxino[2,3-f]quinazoline derivatives have been designed and synthesized and their structures were confirmed by spectral analyses. The cytotoxic activity of the newly synthesized compounds was evaluated against the human kidney epithelial T293 cell line, normal lung cell lines WI-38, non-small cell lung cancer A549 and NCI-H157 cell lines using MTT. The tested compounds showed an evident anticancer activity against the tested cell lines, especially compound 13c, which was the most potent anticancer agent with half maximal inhibitory concentrations (IC50) between 8.82 and 10.24 µM. Docking study showed that compound 13b could be nicely bound to the ATP binding pocket of EGFR. In addition, the inhibitory activity of the target compounds against epidermal growth factor receptor tyrosine kinase (EGFR-TK) was evaluated. Results indicated the ability of the target compounds to inhibit EGFR-TK with half maximal inhibitory concentrations (IC50) in the range of 10.29 nM to 652.3 nM. In view of the reported compound activity, the structure deserves further optimization as cancer treatment agents.

Discovery of Dioxino[2,3-f]quinazoline derivative VEGFR-2 inhibitors exerting significant antipro-liferative activity in HUVECs and mice.

Twelve 2,3-dihydro-[1,4]-dioxino[2,3-f]quinazoline derivatives were designed and evaluated as vascular endothelial growth factor receptor 2 (VEGFR-2) inhibitors. The most half-maximal inhibitory concentration (IC50) values of them were less than 10 nM. Among these compounds, 13d displayed highly effective inhibitory activity against VEGFR-2 (IC50 = 2.4 nM) and excellent antiproliferative activities against human umbilical vein endothelial cells (HUVECs) (IC50 = 1.2 nM). When anti-tumor animal experiments were carried out in mice, the tumor almost disappeared (TGI = 133.0%) after six days of administration of 13d. Therefore, 13d was a potential and effective anticancer agent. The binding conformations were respectively compared between VEGFR-2 with 13d and leading compound lenvatinib, and shows that they have similar binding modes.

Synthesis and anti-tumor activity of [1,4] dioxino [2,3-f] quinazoline derivatives as dual inhibitors of c-Met and VEGFR-2.

Both c-Met and VEGFR-2 were important targets for cancer therapies. In order to develop reversible and non-covalent c-Met and VEGFR-2 dual inhibitors, a series of [1,4]dioxino[2,3-f]quinazoline derivatives were designed and synthesized. The enzyme assay demonstrated that most target compounds had inhibition potency on both c-Met and VEGFR-2 with IC50 values in nanomolar range especially compounds 7m and 7k. Based on further cell proliferation assay in vitro, compound 7k showed significantly anti-tumor activity in vivo on a hepatocellular carcinoma (MHCC97H cells) xenograft mouse model. We docked the compound 7m with c-Met and VEGFR-2 kinases, and interpreted the SAR of these analogues. All results indicated that the target compounds were dual inhibitors of c-Met and VEGFR-2 kinases that held promising potential in cancer therapy.

Design, synthesis, and biological activity of 4-(imidazo[1,2-b]pyridazin-3-yl)-1H-pyrazol-1-yl-phenylbenzamide derivatives as BCR-ABL kinase inhibitors.

A series of 4-((pyrazolo[1,5-a]pyrimidin-6-yl)-1H-pyrazol-1-yl)phenyl-3-benzamide derivatives and 4-((imidazo[1,2-b]pyridazin-3-yl)-1H-pyrazol-1-yl-)phenyl-3-benzamide derivatives were designed, synthesized as new BCR-ABL tyrosine kinase inhibitors by using combinational strategies of scaffold hopping and conformational constraint. These new compounds were screened for BCR-ABL1 kinase inhibitory activity, and most of them appeared good inhibitory activity against BCR-ABL1 kinase. One of the most potent compounds 16a strongly suppressed BCR-ABL1 kinase with IC50 value of 8.5nM. The tested compounds 16a and 16i showed strong inhibitory activities against K562 with IC50 value of less than 2nM. Molecular docking studies indicated that these compounds fitted well with the active site of BCR-ABL1 protein. The results showed these inhibitors may serve as lead compounds for further developing new drugs targeted BCR-ABL kinase.

Discovery of new [1,4]dioxino[2,3-f]quinazoline-based inhibitors of EGFR including the T790M/L858R mutant.

A novel series of 2,3-dihydro-[1,4]dioxino[2,3-f]quinazoline derivatives were designed, synthesized and evaluated as reversible and noncovalent epidermal growth factor receptor (EGFR) inhibitors. Most of the compounds exhibited good potency against EGFR(wt) and some showed moderate to excellent potency against EGFR(T790M/L858R) mutant. The half-maximal inhibitory concentration (IC50) values of twenty-one compounds against EGFR(wt) were less than 50nM, and those of six compounds were less than 10nM. The IC50 values of eleven compounds against EGFR(T790M/L858R) were less than 100nM. Among these, compound b1 displayed the most potent inhibitory activity against EGFR(wt) (IC50=2.0nM) and EGFR(T790M/L858R) (IC50=6.9nM). Compounds with excellent inhibitory activities against EGFR(wt) and EGFR(T790M/L858R) kinase inhibitory activities showed good antiproliferative activities against H358 and A549 cells. Docking study was performed to position compound b1 into the EGFR active pocket to determine the probable binding conformation.

Novel morpholin-3-one fused quinazoline derivatives as EGFR tyrosine kinase inhibitors.

A series of novel morpholin-3-one-fused quinazoline derivatives were designed, synthesized and evaluated as EGFR tyrosine kinase inhibitors. Nineteen compounds showed significant inhibitory activities against EGFR(wt) kinase (IC50<1 µM). Compound a8 demonstrated the most potent inhibitory activity toward EGFR(wt) (IC50=53.1 nM). Compound a7 and a8 showed excellent inhibitory activities against mutant EGFR(T790M/L858R) and strong antiproliferative activity against H358 and A549 cell lines. Finally, molecular docking studies were performed to predict the possible binding mode of the target compounds. It is believed that this work would be very useful for designing a new series of tyrosine kinase inhibitors targeting EGFR.

Synthesis of polyhydroxylated aromatics having amidation of piperazine nitrogen as HIV-1 integrase inhibitor.

(E)-N-[3-(4-cinnamoylpiperazin-1-yl)propyl]-3,4-dihydroxybenzamide and (E)-N-[3-(4-cinnamoylpiperazin-1-yl)propyl]-3,4,5-trihydroxybenzamide were designed and synthesized as potential HIV-1 integrase inhibitors and evaluated their inhibition to the strand transfer process of HIV-1 integrase. The result indicates that 3,4,5-trihydroxylated aromatic derivatives exhibit good inhibition to HIV-1 integrase, however, corresponding 3,4-dihydroxylated aromatic derivatives appear little inhibition of HIV-1 integrase.