Discovery of Novel Small-Molecule-Based Potential PD-L1/EGFR Dual Inhibitors with High Druggability for Glioblastoma Immunotherapy.

Based on the close relationship between programmed death protein ligand 1 (PD-L1) and epidermal growth factor receptor (EGFR) in glioblastoma (GBM), we designed and synthesized a series of small molecules as potential dual inhibitors of EGFR and PD-L1. Among them, compound EP26 exhibited the highest inhibitory activity against EGFR (IC50 = 37.5 nM) and PD-1/PD-L1 interaction (IC50 = 1.77 µM). In addition, EP26 displayed superior in vitro antiproliferative activities and in vitro immunomodulatory effects by promoting U87MG cell death in a U87MG/Jurkat cell coculture model. Furthermore, EP26 possessed favorable pharmacokinetic properties (F = 22%) and inhibited tumor growth (TGI = 92.0%) in a GBM mouse model more effectively than Gefitinib (77.2%) and NP19 (82.8%). Moreover, EP26 increased CD4+ cells and CD8+ cells in tumor microenvironment. Collectively, these results suggest that EP26 represents the first small-molecule-based PD-L1/EGFR dual inhibitor deserving further investigation as an immunomodulating agent for cancer treatment.

Identification of New EGFR Inhibitors by Structure-Based Virtual Screening and Biological Evaluation.

Epidermal growth factor receptor (EGFR) inhibitors have been used in clinical for the treatment of non-small-cell lung cancer for years. However, the emergence of drug resistance continues to be a major problem. To identify potential inhibitors, molecular docking-based virtual screening was conducted on ChemDiv and Enamine commercial databases using the Glide program. After multi-step VS and visual inspection, a total of 23 compounds with novel and varied structures were selected, and the predicted ADMET properties were within the satisfactory range. Further molecular dynamics simulations revealed that the reprehensive compound ZINC49691377 formed a stable complex with the allosteric pocket of EGFR and exhibited conserved hydrogen bond interactions with Lys 745 and Asp855 of EGFR over the course of simulation. All compounds were further tested in experiments. Among them, the most promising hit ZINC49691377 demonstrated excellent anti-proliferation activity against H1975 and PC-9 cells, while showing no significant anti-proliferation activity against A549 cells. Meanwhile, apoptosis analysis indicated that the compound ZINC49691377 can effectively induce apoptosis of H1975 and PC-9 cells in a dose-dependent manner, while having no significant effect on the apoptosis of A549 cells. The results indicate that ZINC49691377 exhibits good selectivity. Based on virtual screening and bioassays, ZINC4961377 can be considered as an excellent starting point for the development of new EGFR inhibitors.

A Side-Effect-Free Interventional Therapy for Precisely Eliminating Unresectable Cancer Pain.

Of patients bearing unresectable tumors at advanced stages, most undergo serious pain. For unresectable tumors adjacent to vital organs or nerves, eliminating local cancer pain without adverse effects remains a formidable challenge. Interventional ablative therapies (IATs), such as radio frequency ablation (RFA), microwave ablation, and irreversible electroporation, have been clinically adopted to treat various carcinomas. In this study, we established another palliative interventional therapy to eliminate local cancer pain, instead of relieving nociception temporarily. Here, we developed another interventional ablative therapy (termed nanoparticle-mediated microknife ablation) to locoregionally eliminate cancer pain and tumors. The IAT system was composed of self-assembled nanodrugs, infusion catheters, puncture needles, injection pump, and an empirical tumor ablation formula. Notably, the ablation formula established in the IAT system enables us to predict the essential nanoparticle (NP) numbers used for completely destroying tumors. In a mouse model of cancer pain, tumor-targeted nanodrugs made of Paclitaxel and Hematoporphyrin, which have an extremely high drug-loading efficiency (more than 60%), were infused into tumors through injection pumps under imaging guidance. In conclusion, when compared to classic chemotherapeutic agents, IAT showed significantly higher effectiveness in cancer pain removal. It also presented no damage to the nervous, sensory, and motor capabilities of the treated mice. All of these merits resulted from NPs' long-lasting retention, targeted ablation, and confined diffusion in tumor stroma. Therefore, this safe treatment modality has great potential to eradicate local cancer pain in the clinic.

Discovery of novel 2-aminopyridine derivatives as ROS1 and ALK dual inhibitors to combat drug-resistant mutants including ROS1G2032R and ALKG1202R.

Clinical treatment by FDA-approved ROS1/ALK inhibitor Crizotinib significantly improved the therapeutic outcomes. However, the emergence of drug resistance, especially driven by acquired mutations, have become an inevitable problem and worsened the clinical effects of Crizotinib. To combat drug resistance, some novel 2-aminopyridine derivatives were designed rationally based on molecular simulation, then synthesised and subjected to biological test. The preferred spiro derivative C01 exhibited remarkable activity against CD74-ROS1G2032R cell with an IC50 value of 42.3 nM, which was about 30-fold more potent than Crizotinib. Moreover, C01 also potently inhibited enzymatic activity against clinically Crizotinib-resistant ALKG1202R, harbouring a 10-fold potency superior to Crizotinib. Furthermore, molecular dynamic disclosed that introducing the spiro group could reduce the steric hindrance with bulky side chain (Arginine) in solvent region of ROS1G2032R, which explained the sensitivity of C01 to drug-resistant mutant. These results indicated a path forward for the generation of anti Crizotinib-resistant ROS1/ALK dual inhibitors.

A Novel and Highly Selective Epidermal Growth Factor Receptor Inhibitor, SMUZ106, for the Treatment of Glioblastoma.

Targeting the epidermal growth factor receptor (EGFR) is one of the potential ways to treat glioblastoma (GBM). In this study, we investigate the anti-GBM tumor effects of the EGFR inhibitor SMUZ106 in both in vitro and in vivo conditions. The effects of SMUZ106 on the growth and proliferation of GBM cells were explored through MTT and clone formation experiments. Additionally, flow cytometry experiments were conducted to study the effects of SMUZ106 on the cell cycle and apoptosis of GBM cells. The inhibitory activity and selectivity of SMUZ106 to the EGFR protein were proved by Western blotting, molecular docking, and kinase spectrum screening methods. We also conducted a pharmacokinetic analysis of SMUZ106 hydrochloride following i.v. or p.o. administration to mice and assessed the acute toxicity level of SMUZ106 hydrochloride following p.o. administration to mice. Subcutaneous and orthotopic xenograft models of U87MG-EGFRvIII cells were established to assess the antitumor activity of SMUZ106 hydrochloride in vivo. SMUZ106 could inhibit the growth and proliferation of GBM cells, especially for the U87MG-EGFRvIII cells with a mean IC50 value of 4.36 µM. Western blotting analyses showed that compound SMUZ106 inhibits the level of EGFR phosphorylation in GBM cells. It was also shown that SMUZ106 targets EGFR and presents high selectivity. In vivo, the absolute bioavailability of SMUZ106 hydrochloride was 51.97%, and its LD50 exceeded 5000 mg/kg. SMUZ106 hydrochloride significantly inhibited GBM growth in vivo. Furthermore, SMUZ106 inhibited the activity of U87MG-resistant cells induced by temozolomide (TMZ) (IC50: 7.86 µM). These results suggest that SMUZ106 hydrochloride has the potential to be used as a treatment method for GBM as an EGFR inhibitor.

Structure Modification of Ginsenoside Rh2 and Cytostatic Activity on Cancer Cells.

Ginsenoside Rh2 (Rh2) is one of the most effective anticancer components extracted from red ginseng, but the poor solubility limits its clinical application. In this paper, ginsenoside Rh2 was modified with maleimidocaproic acid or maleimidoundecanoic acid with functional groups at both ends. The structures of derivatives were determined by analysis of 1D and 2D nuclear magnetic resonance, Fourier transform infrared, and high-resolution mass spectrometry. Antiproliferative cell experiments showed that Rh2 modified with maleimidocaproic acid (C-Rh2) displayed higher cytostatic activity against different tumor cells compared with Rh2, while Rh2 modified with maleimidoundecanoic acid (U-Rh2) did not exhibit obvious cytotoxicity. The results suggest that the length of the spacer arm may play an important role in the cytostatic activity of the Rh2 derivatives.

Mechanism of anti-hyperuricemia of isobavachin based on network pharmacology and molecular docking.

BACKGROUND: Hyperuricemia is a more popular metabolic disease caused by a disorder of purine metabolism. Our previous study firstly screened out a natural product Isobavachin as anti-hyperuricemia targeted hURAT1 from a Chinese medicine Haitongpi (Cortex Erythrinae). In view of Isobavachin's diverse pharmacological activities, similar to the Tranilast (as another hURAT1 inhibitor), our study focused on its potential targets and molecular mechanisms of Isobavachin anti-hyperuricemia based on network pharmacology and molecular docking. METHODS: First of all, the putative target genes of compounds were screen out based on the public databases with different methods, such as SwissTargetPerdiction, PharmMapper and TargetNet,etc. Then the compound-pathways were obtained by the compounds' targets gene from David database for Gene Ontology (GO) function enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways enrichment analysis. The cross pathways of compound-pathways and the diseases pathways of hyperuricemia from Comparative Toxicogenomics Database were be considered as the compound-disease pathways. Next, based on the compound-disease pathways and the PPI network, the core targets were identified based on the retrieved disease-genes. Finally, the compound-target-pathway-disease network was constructed by Cytoscape and the mechanism of isobavachin anti-hyperuricemia was discussed based on the network analysis. RESULTS: Our study demonstrated that there were five pathways involved in Isobavachin against hyperuricemia, including Drug metabolism-other enzymes, Metabolic pathways, Bile secretion, Renin-angiotensin system and Renin secretion. Among the proteins involved in these pathways, HPRT1, REN and ABCG2 were identified as the core targets associated with hyperuricemia, which regulated the five pathways mentioned above. It is quite different from that of Tranilast, which involved in the same pathways except Bile secretion instead of purine metabolism. CONCLUSION: This study revealed Isobavachin could regulate the pathways including Drug metabolism-other enzymes, Metabolic pathways, Bile secretion, Renin-angiotensin system, Renin secretion by core targets HPRT1, REN and ABCG2, in the treatment of hyperuricemia effect. Among them, the Bile secretion regulated by ABCG2 probably would be a novel pathway. Our work provided a theoretical basis for the pharmacological study of Isobavachin in lowering uric acid and further basic research.

Discovery and Computational Studies of Potent Covalent Kinase Inhibitors with α-Substituent Electrophiles Targeting Cysteine.

Both reversible noncovalent inhibitors and irreversible covalent inhibitors targeting tyrosine kinases have their disadvantages. The reversible covalent inhibitors with electrophilic group cyanoacrylamide as warheads reacting with cysteine residues could solve the dilemmas. However, there are still several unresolved issues regarding the electrophilic groups. In this manuscript, a series of EGFR inhibitors with double electron-withdrawing substituents introduced into the Cα position on the olefin bond were designed and synthesized. The binding structures and characteristics of inhibitors with the kinase in both the first noncovalent binding phase and the second covalent binding step were explored and combined with molecular docking and molecular dynamics simulations. Then, the reverse ß-elimination reactions of the thiol-Michael adducts were investigated by applying density functional theory calculations. In addition, the effects of different electrophilic substituents of Cα on the binding between the inhibitors and kinase were elucidated. The results suggested that the electrophilicity and size of the electron-withdrawing groups play an important role in the specific interactions during the reaction. The compounds with the electron-withdrawing groups that had medium electrostatic and steric complementarity to the kinase active site could cooperatively stabilize the complexes and showed relatively good potent activities in the kinase assay experiment. The mechanical and structural information in this study could enhance our understanding of the functioning of the electron-withdrawing groups in the covalent inhibitors. The results might help to design efficient cysteine targeting inhibitors in the future.

Discovery of 4-methyl-3-(pyridin-2-ylamino)benzamide derivatives as C-Abl inhibitors with potential neuroprotective effect.

C-Abl is involved in various biological processes and plays an important role in neurodegenerative diseases, especially Parkinson's disease (PD). Previous studies have found that nilotinib shows a neuroprotective effect in cell and animal models of PD by inhibiting the activation of c-Abl. But the low blood-brain barrier permeability and potential toxicity limit the further use of nilotinib in PD. Based on molecular modeling studies, a series of 4-methyl-3-(pyridin-2-ylamino)benzamide derivatives were designed and synthesized. In particular, compound 9a exhibited significant inhibitory activity against c-Abl and a potent neuroprotective effect against MPP+-induced SH-SY5Y cell death. Moreover, 9a not only displayed lower cell toxicity compared with nilotinib, but also showed higher oral bioavailability and proper permeability of the blood-brain barrier. This paper provides 4-methyl-3-(pyridin-2-ylamino)benzamide derivatives as a new scaffold for c-Abl inhibitor with potential neuroprotective effect.

Design and synthesis of proteolysis targeting chimeras (PROTACs) as an EGFR degrader based on CO-1686.

Epidermal growth factor receptor (EGFR) inhibitors represent the first-line treatment of non-small-cell lung cancer (NSCLC). However, the emergence of acquired drug resistance and side effects largely encumbered their application in clinic. The emerging technology proteolysis targeting chimera (PROTAC) could be an alternative strategy to overcome these problems. Herein, we reported the discovery of EGFRL858R/T790M degraders based on CO-1686. Promising PROTAC 1q could effectively and selectively inhibit the growth of PC-9 (EGFRDel 19) and H1975 (EGFRL858R/T790M) cells, but not that of A549 (EGFRWT) cells. In addition, 1q could time- and dose-dependently induce degradation of EGFRL858R/T790M in H1975 cells with a DC50 value of 355.9 nM, while did not show obvious effect on the EGFRDel 19 and EGFRWT protein. Preliminary mechanism study demonstrated that the protein degradation was mediated through ubiquitin-proteasome system (UPS). Furthermore, 1q could significantly induce the apoptosis of H1975 cells and arrest the cells in G0/G1 phase. These findings demonstrated that compound 1q could be used as initial lead compound for the development of new EGFRL858R/T790M degraders based therapy.

Molecular mechanism study of EGFR allosteric inhibitors using molecular dynamics simulations and free energy calculations.

ABTRACTThe epidermal growth factor receptor (EGFR) kinase inhibitors Gefitinib, Erlotinib, Afatinib and Osimertinib have been approved for the treatments of non-small cell lung cancer patients harboring sensitive EGFR mutations, but resistance arises rapidly. To date all approved EGFR inhibitors are ATP-competitive inhibitors, highlighting the need for therapeutic agents with alternative mechanisms of action. Allosteric kinase inhibitors offer a promising new therapeutic strategy to ATP-competitive inhibitors. The mutant-selective allosteric EGFR inhibitors EAI045 exhibited higher potency for EGFRL858R&T790M compared to WT, which was also effective in EGFR-mutant models including those harboring the C797S mutation. However, it was not effective as a single-agent inhibitor, and require the co-administration of the anti-EGFR antibody Cetuximab. Further efforts produced a more potent analog JBJ-04-125-02, which can inhibit cell proliferation as a single-agent inhibitor. In the present study, molecular dynamics simulations and free energy calculations were performed and revealed the detailed inhibitory mechanism of JBJ-04-125-02 as more potent EGFR inhibitor. Moreover, the energy difference between HOMO and LUMO calculated by DFT implied the higher interaction of JBJ-04-125-02 than EAI045 in the active site of the EGFR. The identified key features obtained from the molecular modeling enabled us to design novel EGFR allosteric inhibitors.Communicated by Ramaswamy H. Sarma.

Novel natural scaffold as hURAT1 inhibitor identified by 3D-shape-based, docking-based virtual screening approach and biological evaluation.

As a promising therapeutic target for gout, hURAT1 has attracted increasing attention. In this work, we identified a novel scaffold of hURAT1 inhibitors from a personal natural product database of verified herb-treated gout. First, we constructed more than 800 natural compounds from Chinese medicine that were verified to treat gout. Following the application of both shape-based and docking-based virtual screening (VS) methods, taking into account the shape similarity and flexibility of the target, we identified isopentenyl dihydroflavones that might inhibit hURAT1. Specifically, 9 compounds with commercial availability were tested with biochemical assays for the inhibition of 14C-uric acid uptake in high-expression hURAT1 cells (HEK293-hURAT1), and their structure-activity relationship was evaluated. As a result, 8-isopentenyl dihydroflavone was identified as a novel scaffold of hURAT1 inhibitors since isobavachin (DHF3) inhibited hURAT1 with an IC50 value of 0.39 ± 0.17 µM, which was comparable to verinurad with an IC50 value of 0.32 ± 0.23 µM. Remarkably, isobavachin also displayed an eminent effect in the decline of serum uric acid in vivo experiments. Taken together, isobavachin is a promising candidate for the treatment of hyperuricemia and gout.

Identification of imidazo[4,5-c]pyridin-2-one derivatives as novel Src family kinase inhibitors against glioblastoma.

Glioblastoma multiforme (GBM) is the most common and malignant primary brain tumour in the central nervous system (CNS). As the ideal targets for GBM treatment, Src family kinases (SFKs) have attracted much attention. Herein, a new series of imidazo[4,5-c]pyridin-2-one derivatives were designed and synthesised as SFK inhibitors. Compounds 1d, 1e, 1q, 1s exhibited potential Src and Fyn kinase inhibition in the submicromolar range, of which were next tested for their antiproliferative potency on four GBM cell lines. Compound 1s showed effective activity against U87, U251, T98G, and U87-EGFRvIII GBM cell lines, comparable to that of lead compound PP2. Molecular dynamics (MDs) simulation revealed the possible binding patterns of the most active compound 1s in ATP binding site of SFKs. ADME prediction suggested that 1s accord with the criteria of CNS drugs. These results led us to identify a novel SFK inhibitor as candidate for GBM treatment.

Molecular dynamics simulation and free energy calculation studies of the binding mechanism of allosteric inhibitors with TrkA kinase.

Tropomyosin receptor kinase A (Trk A) is a receptor tyrosine kinase activated by nerve growth factor (NGF). TrkA plays an important role in pain sensation, which leads to significant interest in the development of small molecule inhibitors of TrkA. However, TrkA and the other two highly homologous isoforms, TrkB and TrkC, are highly conserved in the ATP binding site, which suggests that achieving TrkA subtype selectivity over TrkB and TrkC in this site may be extremely challenging. Allosteric inhibitors without making any interactions with the conserved ATP binding site may present a more promising approach. Recently, selective TrkA inhibitors 1 and 2 were reported to be allosteric inhibitors targeting the DFG-out allosteric pocket. In the present study, molecular dynamics simulations and free energy calculations were carried out on TrkA in complex with ligands 1 and 2, which was expected to provide a basis for the rational drug design of TrkA allosteric inhibitors.

Mibefradil and Flunarizine, Two T-Type Calcium Channel Inhibitors, Protect Mice against Lipopolysaccharide-Induced Acute Lung Injury.

Recent studies have illuminated that blocking Ca2+ influx into effector cells is an attractive therapeutic strategy for lung injury. We hypothesize that T-type calcium channel may be a potential therapeutic target for acute lung injury (ALI). In this study, the pharmacological activity of mibefradil (a classical T-type calcium channel inhibitor) was assessed in a mouse model of lipopolysaccharide- (LPS-) induced ALI. In LPS challenged mice, mibefradil (20 and 40 mg/kg) dramatically decreased the total cell number, as well as the productions of TNF-α and IL-6 in bronchoalveolar lavage fluid (BALF). Mibefradil also suppressed total protein concentration in BALF, attenuated Evans blue extravasation, MPO activity, and NF-κB activation in lung tissue. Furthermore, flunarizine, a widely prescripted antimigraine agent with potent inhibition on T-type channel, was also found to protect mice against lung injury. These data demonstrated that T-type calcium channel inhibitors may be beneficial for treating acute lung injury. The important role of T-type calcium channel in the acute lung injury is encouraged to be further investigated.

Computational studies of potent covalent inhibitors on wild type or T790M/L858R mutant epidermal growth factor receptor.

In this paper, we designed and synthesized two analog compounds M1 and T1 that have a Michael acceptor warhead. Although only slightly diversity existed in the structures of M1 and T1, their inhibitory activities against wild type epidermal growth factor receptor (EGFRWT) and T790M/L858R mutant epidermal growth factor receptor (EGFRT790M/L858R) were significant different. Thus, multiple computational approaches were applied to investigate the interactions between the compounds with EGFRWT and EGFRT790M/L858R in order to explore the effect of different compounds. The molecular docking and MD simulations were performed to study the intermolecular interactions between compounds and EGFR. The binding free energy revealed that M1-EGFRWT and M1-EGFRT790M/L858R complexes have stronger binding affinity compared with the corresponding T1-EGFRWT and T1-EGFRT790M/L858R complexes, respectively. And the binding free energy decompositions for each residue analysis indicated that the van der Waals interactions are the major contributor to enhance the compounds to bind with EGFR. In addition, covalent binding complexes of M1-EGFRWT and M1-EGFRT790M/L858R were constructed and studied. Moreover, quantum mechanics method was applied to investigate the reaction mechanism of covalent binding of the compound and EGFR. The results will provide the details of structural and energetic information to develop potent covalent EGFR inhibitors in the future.

The cytochrome P450 metabolic profiling of SMU-B in vitro, a novel small molecule tyrosine kinase inhibitor.

A novel small molecule tyrosine kinase inhibitor 6-[6-Amino-5-[(1R)-1-(2,6-dichloro-3-fluorophenyl)ethoxy]-3-pyridyl]-1'-methylspiro[indoline-3,4'-piperidine]-2-one (SMU-B) had good activity against ALK (anaplastic lymphoma kinase) and ROS1 (c-ros oncogene 1) targets in non-small-cell lung cancer. The excellent bioactivity of SMU-B highlights the importance of determining its metabolic traits, which could provide meaningful information for further pharmacokinetic studies of SMU-B. In this work, we studied the metabolism of SMU-B in human liver microsomes. Three metabolites of SMU-B were identified by a quadrupole-time of flight tandem mass spectrometer (Q-TOF-MS), and the metabolic pathways of SMU-B were demethylation, dehydrogenation and oxidation. CYP3A4/5 was the principal isoform involved in SMU-B metabolism, as shown by chemical inhibition and recombination human enzyme studies. Additionally, a predication with a molecular docking model confirmed that SMU-B could interact with the active sites of CYP3A4 and CYP3A5. This study illuminates the metabolic profile of the anti-tumor drug SMU-B, which will accelerate its clinical use.

Design, synthesis and biological evaluations of 2-amino-4-(1-piperidine) pyridine derivatives as novel anti crizotinib-resistant ALK/ROS1 dual inhibitors.

ALK and ROS1 kinases have become promising therapeutic targets since Crizotinib was used to treat non-small-cell lung cancer clinically. Aiming to explore new potent inhibitors, a series of 2-amino-4-(1-piperidine) pyridine derivatives that stabilized a novel DFG-shifted conformation in the kinase domain of ALK were designed and synthesized on the base of lead compound A. Biological evaluation highlighted that most of these new compounds could also potently inhibit ROS1 kinase, leading to the promising inhibitors against both ROS1 and ALK. Among them, the representative compound 2e stood out potent anti-proliferative activity against ALK-addicted H3122 and ROS1-addicted HCC78 cell lines (IC50 = 6.27 µM and 10.71 µM, respectively), which were comparable to that of Crizotinib. Moreover, 2e showed impressive enzyme activity against clinically Crizotinib-resistant ALKL1196M with an IC50 value of 41.3 nM, which was about 2-fold more potent than that of Crizotinib. 2e also showed potent inhibitory activity in about 6-fold superior to Crizotinib (IC50: 104.7 nM vs. 643.5 nM) in Ba/F3 cell line harboring ROS1G2032R. Furthermore, molecular modeling disclosed that all the representative inhibitors could dock into the active site of ALK and ROS1, which gave a probable explanation of anti Crizotinib-resistant mutants. These results indicated that our work has established a path forward for the generation of anti Crizotinib-resistant ALK/ROS1 dual inhibitors.

Protective effects of S-carvedilol on doxorubicin-induced damages to human umbilical vein endothelial cells and rats.

Doxorubicin (DOX) is a highly active anticancer drug with severe cytotoxicity, which is strongly associated with oxidative stress. Carvedilol (CAR), used as its racemate with S-CAR and R-CAR (1:1), has been previously reported to ameliorate the DOX-induced cytotoxicity. However, the main contributor from CAR of its protective effects has not been clear. Therefore, in this study, we aimed to investigate further the different effects of CAR enantiomers on DOX-induced cytotoxicity in human umbilical vein endothelial cells and rats, respectively. Results indicated that S-CAR could significantly attenuate DOX-induced cell death, apoptotic morphological changes, decrease the mitochondrial membrane potential and oxidative stress responses by increasing the superoxide dismutase and catalase activities, and decreasing malondialdehyde contents and reactive oxygen species levels via the phosphoinositide 3-kinase/AKT/endothelial nitric oxide synthase pathway in vitro. Consistent with the in vitro study, the protective effects of S-CAR on the myocardial tissues and hemodynamics were also detected in rats suffering because of DOX treatment. With the obtained results, we can first conclude that S-CAR provides superior protection to injury induced by DOX relative to that of racemic CAR and R-CAR.

Insight into binding mechanisms of EGFR allosteric inhibitors using molecular dynamics simulations and free energy calculations.

Lung cancer is the leading cause of cancer death, and epidermal growth factor receptor (EGFR) kinase domain mutations are a common cause of non-small-cell lung cancer (NSCLC), a major subtype of lung cancers. Patients harboring most of these mutations respond well to the EGFR inhibitors Gefitinib and Erlotinib initially, but soon develop resistance to them due to the emergence of the gatekeeper mutation T790M. The new-generation inhibitors such as AZD9291, HM61713, CO-1686 and WZ4002 can overcome T790M through covalent binding to Cys 797, but ultimately lose their efficacy upon the emergence of the C797S mutation that abolishes the covalent bonding. Allosteric inhibitors EAI001 and EAI045 are a new type of EGFR inhibitors that bind to EGFR away from the ATP-binding site and not relying on Cys 797. In this study, molecular dynamics simulations and free energy calculations were carried out on EAI001 and EAI045 in complex with EGFR, revealing the detailed inhibitory mechanism of EAI001 and EAI045 as EGFR allosteric inhibitor, which was expected to provide a basis for rational drug design of the EGFR allosteric inhibitors. Communicated by Ramaswamy H. Sarma.