Second-generation epidermal growth factor tyrosine kinase inhibitors in non-small cell lung cancer

Design, Synthesis, and Antitumor Activity of Erlotinib Derivatives

Nineteen erlotinib derivatives bearing different 1,2,3-triazole moieties were designed, synthesized, and evaluated for their potential against different cancer cell lines. The structures of the synthesized compounds were confirmed via 1H NMR, 13C NMR, and HR MS. Preliminary antitumor activity assay results suggested that some compounds showed remarkable inhibitory activity against different cancer cell lines including the corresponding drug-resistant ones. Among these compounds, 3d was the most promising one with an IC50 of 7.17 ± 0.73 μM (KYSE70TR), 7.91 ± 0.61 μM (KYSE410TR), 10.02 ± 0.75 μM (KYSE450TR), 5.76 ± 0.3 3 μM (H1650TR), and 2.38 ± 0.17 μM (HCC827GR). A preliminary mechanism study suggested that compound 3d suppressed cancer cell proliferation through the EGFR-TK pathway.

Activation of multiple ERBB family receptors mediates glioblastoma cancer stem-like cell resistance to EGFR-targeted inhibition

Epidermal growth factor receptor (EGFR) signaling is strongly implicated in glioblastoma (GBM) tumorigenesis. However, molecular agents targeting EGFR have demonstrated minimal efficacy in clinical trials, suggesting the existence of GBM resistance mechanisms. GBM cells with stem-like properties (CSCs) are highly efficient at tumor initiation and exhibit therapeutic resistance. In this study, GBMCSC lines showed sphere-forming and tumor initiation capacity after EGF withdrawal from cell culture media, compared with normal neural stem cells that rapidly perished after EGF withdrawal. Compensatory activation of related ERBB family receptors (ERBB2 and ERBB3) was observed in GBM CSCs deprived of EGFR signal (EGF deprivation or cetuximab inhibition), suggesting an intrinsic GBM resistance mechanism for EGFR-targeted therapy. Dual inhibition of EGFR and ERBB2 with lapatinib significantly reduced GBM proliferation in colony formation assays compared to cetuximab-mediated EGFR-specific inhibition. Phosphorylation of downstream ERBB signaling components (AKT, ERK1/2) and GBM CSC proliferation were inhibited by lapatinib. Collectively, these findings show that GBM therapeutic resistance to EGFR inhibitors may be explained by compensatory activation of EGFR-related family members (ERBB2, ERBB3) enabling GBM CSC proliferation, and therefore simultaneous blockade of multiple ERBB family members may be required for more efficacious GBM therapy.

Strategies for discovering and derisking covalent, irreversible enzyme inhibitors

This article presents several covalent inhibitors, including examples of successful drugs, as well as highly selective, irreversible inhibitors of emerging therapeutic targets, such as fatty acid amide hydolase. Covalent inhibitors have many desirable features, including increased biochemical efficiency of target disruption, less sensitivity toward pharmacokinetic parameters and increased duration of action that outlasts the pharmacokinetics of the compound. Safety concerns that must be mitigated include lack of specificity and the potential immunogenicity of protein-inhibitor adduct(s). Particular attention will be given to recent technologies, such as activity-based protein profiling, which allow one to define the proteome-wide selectivity patterns for covalent inhibitors in vitro and in vivo. For instance, any covalent inhibitor can, in principle, be modified with a 'clickable' tag to generate an activity probe that is almost indistinguishable from the original agent. These probes can be applied to any living system across a broad dose range to fully inventory their on and off targets. The substantial number of drugs on the market today that act by a covalent mechanism belies historical prejudices against the development of irreversibly acting therapeutic small molecules. Emerging proteomic technologies offer a means to systematically discriminate safe (selective) versus deleterious (nonselective) covalent inhibitors and thus should inspire their future design and development.

Activity-based proteome profiling of potential cellular targets of Orlistat--an FDA-approved drug with anti-tumor activities

Orlistat, or tetrahydrolipstatin (THL), is an FDA-approved antiobesity drug with potential antitumor activities. Cellular off-targets and potential side effects of Orlistat in cancer therapies, however, have not been extensively explored thus far. In this study, we report the total of synthesis of THL-like protein-reactive probes, in which extremely conservative modifications (i.e., an alkyne handle) were introduced in the parental THL structure to maintain the native biological properties of Orlistat, while providing the necessary functionality for target identification via the bio-orthogonal click chemistry. With these natural productlike, cell-permeable probes, we were able to demonstrate, for the first time, this chemical proteomic approach is suitable for the identification of previously unknown cellular targets of Orlistat. In addition to the expected fatty acid synthase (FAS), we identified a total of eight new targets, some of which were further validated by experiments including Western blotting, recombinant protein expression, and site-directed mutagenesis. Our findings have important implications in the consideration of Orlistat as a potential anticancer drug at its early stages of development for cancer therapy. Our strategy should be broadly useful for off-target identification against quite a number of existing drugs and/or candidates, which are also covalent modifiers of their biological targets.

(1)H,(13)C and (19)F NMR data of N-substituted 6-(4-methoxyphenyl)-7H-pyrrolo[2,3-d]pyrimidin-4-amines in DMSO-d(6)

Chemical shift assignment of seven N-substituted 6-(4-methoxyphenyl)-7H-pyrrolo[2, 3-d]pyrimidin-4-amines, six of which are fluorinated, have been performed based on (1)H, (13)C, (19)F, and 2D COSY, HMBC and HSQC experiments.

Synthesis and biological evaluation of p38alpha kinase-targeting dialkynylimidazoles

Based on the mild, thermal rearrangement of 1,2-dialkynylimidazoles to reactive carbene or diradical intermediates, a series of 1,2-dialkynylimidazoles were designed as potential irreversible p38 MAP kinase alpha-isoform (p38alpha) inhibitors. The synthesis of these dialkynylimidazoles and their kinase inhibition activity is reported. The 1-ethynyl-substituted dialkynylimidazole 14 is a potent (IC(50)=200 nM) and selective inhibitor of p38alpha. Moreover, compound 14 covalently modifies p38alpha as determined by ESI-MS after 12h incubation at 37 degrees C. The unique kinase inhibition, covalent kinase adduct formation, and minimal CYP450 2D6 inhibition by compound 14 demonstrate that dialkynylimidazoles are a new, promising class of p38alpha inhibitors.