Discovery of 4-amino-3-arylsulfoquinolines, a novel non-acetylenic chemotype of metabotropic glutamate 5 (mGlu5) receptor negative allosteric modulators.

Negative allosteric modulators of metabotropic glutamate receptor 5 (mGlu5) showed efficacy in a number of animal models of different CNS diseases including anxiety and depression. Virtually all of the compounds which reached the clinic belong to the same chemotype having an acetylenic linker that connects (hetero)cyclic moieties. Searching for new chemotypes we identified a morpholino-sulfoquinoline derivative (1) by screening our corporate compound deck. The HTS hit showed reasonable affinity and selectivity towards mGlu5 receptors, however, its inferior metabolic stability prevented its testing in vivo. In a chemical program we aimed to improve the affinity, physicochemical properties and metabolic stability exploring three regions of the hit. Systematic variation of different amines at position 4 (region I) led to the identification of 4-methyl-piperidinyl analogues. Substituents of the quinoline core (region II) and the phenylsulfonyl moiety (region III) were mapped by parallel synthesis. Evaluation of both morpholino- and 4-methyl-piperidinyl-sulfoquinoline libraries of about 270 derivatives revealed beneficial substituent combinations in regions II and III. Blood levels of optimized 4-methyl-piperidinyl-sulfoquinolines, however, were still insufficient for robust in vivo efficacy. Finally, introducing 4-hydoxymethyl-piperidinyl substituent to region I resulted in new sulfoquinolines with greatly improved solubility and reasonable affinity coupled with affordable metabolic stability. The most promising analogues (24 and 25) showed high blood levels and demonstrated significant efficacy in the experimental model of anxiety.

Discovery and Preclinical Characterization of 3-((4-(4-Chlorophenyl)-7-fluoroquinoline-3-yl)sulfonyl)benzonitrile, a Novel Non-acetylenic Metabotropic Glutamate Receptor 5 (mGluR5) Negative Allosteric Modulator for Psychiatric Indications.

Negative allosteric modulators (NAM) of metabotropic glutamate receptor 5 (mGluR5) have been implicated as a potential pharmacotherapy for a number of psychiatric diseases, including anxiety and depression. Most of the mGluR5 NAM clinical candidates can be characterized by the central acetylenic moiety that connects the terminal pharmacophores. Identification of a sulfoquinoline hit via high throughput screening (HTS) followed by optimization provided a 4-phenyl-3-aryl-sulfoquinoline lead compound with the minimal pharmacophore. Optimization of the core and aryl appendages was performed by scanning and matrix libraries synthesized by the multiple parallel synthesis approach. Biological evaluation of matrix libraries provided a number of potent, metabolically stable, and in vivo active compounds. One of these compounds, 25 showed high efficacy and safety in preclinical in vivo models; this allowed its nomination as a novel, nonacetylenic mGluR5 NAM clinical candidate. Compound 25 was advanced to first-in-man trials for the treatment of psychiatric conditions.

4-Aryl-3-arylsulfonyl-quinolines as negative allosteric modulators of metabotropic GluR5 receptors: From HTS hit to development candidate.

High throughput screening of our corporate compound library followed by hit-to-lead development resulted in a 4-aryl-3-arylsulfonyl-quinoline derivative lead (2) with mGluR5 negative allosteric modulator activity. During the lead optimization process, our objective was to improve affinity and metabolic stability. Modifications at the three targeted regions of the lead structure resulted in compounds with nanomolar affinity and acceptable metabolic stability. One of the most promising compounds (3), showing excellent in vivo efficacy, was selected for preclinical development and subsequent phase I clinical studies.

Thieno[2,3-b]pyridines as negative allosteric modulators of metabotropic GluR5 receptors: Lead optimization.

An HTS campaign of our corporate compound library, and hit-to lead development resulted in thieno[2,3-b]pyridine derivative leads with mGluR5 negative allosteric modulator effects. During the lead optimization process, our objective was to improve affinity and metabolic stability. Modification of the first two targeted regions resulted in compounds with nanomolar affinity, then optimal substitution of the third region improved metabolic stability. One of the most promising compounds showed excellent in vivo efficacy and is a potential development candidate.

Carbamoyloximes as novel non-competitive mGlu5 receptor antagonists.

Hit-to-lead optimization of a HTS hit led to new carbamoyloxime derivatives. After identification of an advanced hit (8d) the CYP enzyme inhibitory activity of this class of compounds was successfully eliminated. Systematic exploration of different parts of the advanced hit led us to some promising lead compounds with mGluR5 affinities comparable to that of MPEP.