A convenient transesterification method for synthesis of AT2 receptor ligands with improved stability in human liver microsomes.

A series of AT2R ligands have been synthesized applying a quick, simple, and safe transesterification-type reaction whereby the sulfonyl carbamate alkyl tail of the selective AT2R antagonist C38 was varied. Furthermore, a limited number of compounds where acyl sulfonamides and sulfonyl ureas served as carboxylic acid bioisosteres were synthesized and evaluated. By reducing the size of the alkyl chain of the sulfonyl carbamates, ligands 7a and 7b were identified with significantly improved in vitro metabolic stability in both human and mouse liver microsomes as compared to C38 while retaining the AT2R binding affinity and AT2R/AT1R selectivity. Eight of the compounds synthesized exhibit an improved stability in human microsomes as compared to C38.

Development and evaluation of 4-(pyrrolidin-3-yl)benzonitrile derivatives as inhibitors of lysine specific demethylase 1.

As part of our ongoing efforts to develop reversible inhibitors of LSD1, we identified a series of 4-(pyrrolidin-3-yl)benzonitrile derivatives that act as successful scaffold-hops of the literature inhibitor GSK-690. The most active compound, 21g, demonstrated a Kd value of 22nM and a biochemical IC50 of 57nM. In addition, this compound displayed improved selectivity over the hERG ion channel compared to GSK-690, and no activity against the related enzymes MAO-A and B. In human THP-1 acute myeloid leukaemia cells, 21g was found to increase the expression of the surrogate cellular biomarker CD86. This work further demonstrates the versatility of scaffold-hopping asa method to develop structurally diverse, potent inhibitors of LSD1.

Development of 5-hydroxypyrazole derivatives as reversible inhibitors of lysine specific demethylase 1.

A series of reversible inhibitors of lysine specific demethylase 1 (LSD1) with a 5-hydroxypyrazole scaffold have been developed from compound 7, which was identified from the patent literature. Surface plasmon resonance (SPR) and biochemical analysis showed it to be a reversible LSD1 inhibitor with an IC50 value of 0.23µM. Optimisation of this compound by rational design afforded compounds with Kd values of <10nM. In human THP-1 cells, these compounds were found to upregulate the expression of the surrogate cellular biomarker CD86. Compound 11p was found to have moderate oral bioavailability in mice suggesting its potential for use as an in vivo tool compound.

Mechanistic characterization of a copper containing thiosemicarbazone with potent antitumor activity.

BACKGROUND: The thiosemicarbazone CD 02750 (VLX50) was recently reported as a hit compound in a phenotype-based drug screen in primary cultures of patient tumor cells. We synthesized a copper complex of VLX50, denoted VLX60, and characterized its antitumor and mechanistic properties. MATERIALS AND METHODS: The cytotoxic effects and mechanistic properties of VLX60 were investigated in monolayer cultures of multiple human cell lines, in tumor cells from patients, in a 3-D spheroid cell culture system and in vivo and were compared with those of VLX50. RESULTS: VLX60 showed ≥ 3-fold higher cytotoxic activity than VLX50 in 2-D cultures and, in contrast to VLX50, retained its activity in the presence of additional iron. VLX60 was effective against non-proliferative spheroids and against tumor xenografts in vivo in a murine model. In contrast to VLX50, gene expression analysis demonstrated that genes associated with oxidative stress were considerably enriched in cells exposed to VLX60 as was induction of reactive oxygen. VLX60 compromised the ubiquitin-proteasome system and was more active in BRAF mutated versus BRAF wild-type colon cancer cells. CONCLUSIONS: The cytotoxic effects of the copper thiosemicarbazone VLX60 differ from those of VLX50 and shows interesting features as a potential antitumor drug, notably against BRAF mutated colorectal cancer.

Development of (4-Cyanophenyl)glycine Derivatives as Reversible Inhibitors of Lysine Specific Demethylase 1.

Inhibition of lysine specific demethylase 1 (LSD1) has been shown to induce the differentiation of leukemia stem cells in acute myeloid leukemia (AML). Irreversible inhibitors developed from the nonspecific inhibitor tranylcypromine have entered clinical trials; however, the development of effective reversible inhibitors has proved more challenging. Herein, we describe our efforts to identify reversible inhibitors of LSD1 from a high throughput screen and subsequent in silico modeling approaches. From a single hit (12) validated by biochemical and biophysical assays, we describe our efforts to develop acyclic scaffold-hops from GSK-690 (1). A further scaffold modification to a (4-cyanophenyl)glycinamide (e.g., 29a) led to the development of compound 32, with a Kd value of 32 nM and an EC50 value of 0.67 µM in a surrogate cellular biomarker assay. Moreover, this derivative does not display the same level of hERG liability as observed with 1 and represents a promising lead for further development.

Iron chelators target both proliferating and quiescent cancer cells.

Poorly vascularized areas of solid tumors contain quiescent cell populations that are resistant to cell cycle-active cancer drugs. The compound VLX600 was recently identified to target quiescent tumor cells and to inhibit mitochondrial respiration. We here performed gene expression analysis in order to characterize the cellular response to VLX600. The compound-specific signature of VLX600 revealed a striking similarity to signatures generated by compounds known to chelate iron. Validation experiments including addition of ferrous and ferric iron in excess, EXAFS measurements, and structure activity relationship analyses showed that VLX600 chelates iron and supported the hypothesis that the biological effects of this compound is due to iron chelation. Compounds that chelate iron possess anti-cancer activity, an effect largely attributed to inhibition of ribonucleotide reductase in proliferating cells. Here we show that iron chelators decrease mitochondrial energy production, an effect poorly tolerated by metabolically stressed tumor cells. These pleiotropic features make iron chelators an attractive option for the treatment of solid tumors containing heterogeneous populations of proliferating and quiescent cells.