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International audience; During our search for topically-active Caspase-1 inhibitors, we identified a novel class of potent in-hibitors based on a 1,3,5-trisubstituted uracil motif equipped with an L-aspartate semi-aldehyde derived warhead. In the literature, the majority of Caspase-1 inhibitors possessing the same warhead have been designed and evaluated for oral administration as the ethyl acetal pro-drug form. For our topical program , the pro-drug acetal form was not fully hydrolysed in the skin and was unstable in many of our standard topical excipients, therefore, we were obliged to focus on the actual hemiacetal drug form of the molecule during our drug discovery program. Our work focuses on both the synthesis and achiral and chiral stability of the final drug molecules in topical excipients.

The use of an interleukin β antibody is currently being investigated in the clinic for the treatment of acne, a dermatological disorder affecting 650M persons globally. Inhibiting the protease responsible for the cleavage of inactive pro-IL1β into active IL-1β, caspase-1, could be an alternative small molecule approach. This report describes the discovery of uracil 20, a potent (38 nM in THP1 cells assay) caspase-1 inhibitor for the topical treatment of inflammatory acne. The uracil series was designed according to a published caspase-1 pharmacophore model involving a reactive warhead in P1 for covalent reversible inhibition and an aryl moiety in P4 for selectivity against the apoptotic caspases. Reversibility was assessed in an enzymatic dilution assay or by using different substrate concentrations. In addition to classical structure-activity-relationship exploration, topical administration challenges such as phototoxicity, organic and aqueous solubility, chemical stability in solution, and skin metabolic stability are discussed and successfully resolved.

Virtual fragmentation of a library of 12,000 compounds inspired by natural products led to a dataset of 153,000 fragments that was used as a source to identify effective P2-P3 scaffold replacement solutions for peptidic Caspase-1 inhibitors. Our strategy led to the identification of an original 2-azabicyclo-octane scaffold (2-ABO) that was further elaborated into the potent Caspase-1 inhibitor CD10847 (IC 50 = 17 nM). The crystal structure of Caspase-1 in complex with CD10847 was obtained, and its binding mode was shown to be similar to the one predicted by docking and in good agreement with other known inhibitors.

In our hands, access to 2 novel peptidomimetic scaffolds, based on N-alkylated pyrroldin-2,5-diones and piperidin-2,6-diones, proved to be much more challenging than anticipated. In this short communication, we disclose the strategies that we explored and our final route choices to the desired scaffolds with control of both stereocenters.

ATAD2 (ANCCA) is an epigenetic regulator and transcriptional cofactor, whose overexpression has been linked to the progress of various cancer types. Here, we report a DNA-encoded library screen leading to the discovery of BAY-850, a potent and isoform selective inhibitor that specifically induces ATAD2 bromodomain dimerization and prevents interactions with acetylated histones in vitro, as well as with chromatin in cells. These features qualify BAY-850 as a chemical probe to explore ATAD2 biology.

The preparation of a simple 1-oxa-spiro[2.4]heptane derivative is described. Observations made in the course of the synthesis show again that apparently minor structural modifications of the dienic substrate exert a strong influence on the ring-closing metathesis outcome and that the efficient construction of even simple but highly substituted systems by RCM may constitute a synthetic challenge.

[reaction: see text] Enantioselective deprotonation of 4-substituted cyclohexanones and highly stereoselective conjugate addition of higher order mixed cuprates were the key steps in a concise synthesis of fumagalone-related molecules. The origin of the (low) biological activity of the new compounds as compared to fumagalone is briefly discussed.

The preparation of a series of new fumagillin-derived MetAP-2 inhibitors is described. The synthetic approach was designed so as to permit modification of the fumagillin backbone at sites inaccessible through semisynthesis or previously existing total syntheses. An Evans aldolization and a ring-closing metathesis allowed the preparation of a pivotal intermediate which could then be functionalized in various ways using already established or newly developed methodologies.

ATAD2 (ATPase family AAA-domain containing protein 2, also called ANCCA) is an epigenetic regulator that binds to chromatin through its bromodomain (BD), a motif specialized for acetyl-lysine recognition. ATAD2 directly associates with multiple transcription factors such as ERα, AR, E2F, and Myc; hence, ATAD2 has been proposed to act as a co-factor for oncogenic transcription factors. Furthermore, we have recently reported a novel role for ATAD2 during DNA replication, uncovering interactions between ATAD2 and histone acetylation marks on newly synthesized histone H4. High expression of ATAD2 strongly correlates with poor patient prognosis in multiple tumor types, including gastric, endometrial, hepatocellular, ovarian, breast and lung cancers. However, the exact function of ATAD2 in these tumor types remains unclear. A more thorough validation of ATAD2 as a therapeutic target is hampered by the lack of isoform-selective, potent and cellularly active ATAD2 inhibitors. A systematic assessment of crystal structures of BD-containing protein family predicted that development of selective inhibitors of ATAD2 would be challenging. In line with this prediction, only limited progress in developing lead compounds targeting ATAD2 has been reported so far. A few notable exceptions relied on fragments as starting points, however, their weak potency, insufficient selectivity against other BDs, permeability limitations or modest cellular activity have curbed their further development towards drug candidates. Here we embarked on a novel strategy to identify ATAD2 inhibitors: 11 different DNA-encoded libraries adding up to 67 billion unique encoded compounds were combined and incubated with ATAD2 BD followed by two rounds of affinity-mediated selection. This approach provided with several series of binders, for which specific target engagement of their SMOL moiety upon off-DNA synthesis was confirmed in biochemical and biophysical assays. Several rounds of potency optimization led to the identification of BAY-850, a highly potent and ATAD2 (isoform A) mono-selective inhibitor, which holds an amine substituted 3-(2-furyl)benzamide core. This compound shows - as revealed by size exclusion chromatography and native mass spectrometry - a novel mode of action for a BD inhibitor based on specific target dimerization. In a cellular fluorescence recovery after photobleaching (FRAP) assay BAY-850 displaced wild-type ATAD2 from the chromatin to the same extent as the genetic mutagenesis of ATAD2 BD. In contrast, chemically very similar inactive control compounds showed no major effects on ATAD2 association with the chromatin. These results qualify BAY-850 as the first biologically active ATAD2 isoform A-specific chemical probe, which will enable further elucidation of the cancer biology of this intriguing protein. Citation Format: Amaury E. Fernández-Montalván, Markus Berger, Benno Kuropka, Seong Joo Koo, Volker Badock, Joerg Weiske, Simon J. Holton, Apirat Chaikuad, Laura Díaz-Sáez, James Bennett, Oleg Federov, Kilian Huber, Paolo Centrella, Matthew A. Clark, Christoph E. Dumelin, Eric A. Sigel, Holly S. Soutter, Dawn M. Troast, Ying Zhang, John W. Cuozzo, Anthony D. Keefe, Didier Roche, Vincent Rodeschini, Jan Hübner, Hilmar Weinmann, Ingo V. Hartung, Matyas Gorjanacz. Potent and isoform-selective ATAD2 bromodomain inhibitor with unprecedented chemical structure and mode of action [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5084. doi:10.1158/1538-7445.AM2017-5084

[Structure: see text] A concise synthesis of the polyprenylated acylphloroglucinol natural product, clusianone, in racemic form, is described. An Effenburger cyclization generated a core bicyclo[3.3.1]nonane-trione structure, which was then elaborated by means of regioselective lithiation reactions.

The synthesis of an unnatural polyprenylated acylphloroglucinol (PPAP), regioisomeric with nemorosone and clusianone, has been accomplished. The separated enantiomers of this new PPAP, along with those of nemorosone and clusianone, have been screened for activity against HeLa (cervix carcinoma), MIA-PaCa-2 (pancreatic carcinoma), and MCF7 (mamma carcinoma) cancer cell lines. All of the isomers examined gave surprisingly similar results in the screens.

Aqueous glyoxal solution Phenylmagnesium chloride 1 R--(+)-Phenylethylamine 1(S),2(S)-Diphenyl-N,N′-bis[1-R-phenyl-ethyl]-ethane-1,2-diamine Chlorohexanedicarboxylic anhydride 2-(3,4-Dimethoxyphenyl)ethylamine (3a,S,7aR)-2-[2-(3,4-Dimethoxyphenyl)-ethyl]hexahydro-isoindole-1,3-dione Butyl lithium Methyl cyanoformate (3aS, 7aS)-2-[2-(3,4-Dimethoxyphenyl)-ethyl]-1,3-diox-octahydroisoindole-3a-carboxylic acid methyl ester Keywords: chiral lithium amide bases; desymmetrization; ring fused imide; prochiral cyclic imide; enantioselectivities; waste disposal

A chiral base kinetic resolution of an advanced bicyclic intermediate enabled access to the polyprenylated phloroglucinol natural product (+)-clusianone in enantiomerically pure form. X-ray structure determination of another product obtained by the same method then allowed the absolute stereochemistry of (+)-clusianone to be assigned.

Bridgehead lithiations have successfully been carried out on substrates derived from catechinic acid, which possess the core bicyclo[3.3.1]nonane-1,3,5-trione structure present in garsubellin A. Using an external quench method, various electrophiles have been incorporated at the C-5 bridgehead position in a one-step process that appears to be sensitive to the substitution pattern on the bicyclic system. Regioselective lithiation at the C-3 sp(2) centre was achieved by changing the base used from LDA to LTMP. Following the introduction of a prenyl substituent by bridgehead substitution, annulation of a THF ring, analogous to that in garsubellin A, was possible via an epoxidation-ring opening sequence. Oxidative modification of the catechol substituent of the catechinic acid core was possible to give systems with muconic acid, ortho-quinone or furan 2-carboxylic acid side chains.