Emmanuel Pinard

Selective GlyT1 Inhibitors: Discovery of [4-(3-Fluoro-5-trifluoromethylpyridin-2-yl)piperazin-1-yl]-[5-methanesulfonyl-2-((S)-2,2,2-trifluoro-1-methylethoxy)phenyl]methanone (RG1678), a Promising Novel Medicine To Treat Schizophrenia

The GlyT1 transporter has emerged as a key novel target for the treatment of schizophrenia. Herein, we report on the optimization of the 2-alkoxy-5-methylsulfonebenzoylpiperazine class of GlyT1 inhibitors to improve hERG channel selectivity and brain penetration. This effort culminated in the discovery of compound 10a (RG1678), the first potent and selective GlyT1 inhibitor to have a beneficial effect in schizophrenic patients in a phase II clinical trial.

β-Secretase (BACE1) Inhibitors with High in Vivo Efficacy Suitable for Clinical Evaluation in Alzheimer’s Disease

An extensive fluorine scan of 1,3-oxazines revealed the power of fluorine(s) to lower the pKa and thereby dramatically change the pharmacological profile of this class of BACE1 inhibitors. The CF3 substituted oxazine 89, a potent and highly brain penetrant BACE1 inhibitor, was able to reduce significantly CSF Aβ40 and 42 in rats at oral doses as low as 1 mg/kg. The effect was long lasting, showing a significant reduction of Aβ40 and 42 even after 24 h. In contrast to 89, compound 1b lacking the CF3 group was virtually inactive in vivo.

Biochemical and behavioural characterization of EMPA, a novel high‐affinity, selective antagonist for the OX2 receptor

Background and purpose:  The OX2 receptor is a G‐protein‐coupled receptor that is abundantly found in the tuberomammillary nucleus, an important site for the regulation of the sleep‐wake state. Herein, we describe the in vitro and in vivo properties of a selective OX2 receptor antagonist, N‐ethyl‐2‐[(6‐methoxy‐pyridin‐3‐yl)‐(toluene‐2‐sulphonyl)‐amino]‐N‐pyridin‐3‐ylmethyl‐acetamide (EMPA).

Biochemical and Electrophysiological Characterization of Almorexant, a Dual Orexin 1 Receptor (OX1)/Orexin 2 Receptor (OX2) Antagonist: Comparison with Selective OX1 and OX2 Antagonists

Recent preclinical and clinical research has shown that almorexant promotes sleep in animals and humans without disrupting the sleep architecture. Here, the pharmacology and kinetics of [3H]almorexant binding to human orexin 1 receptor (OX1)- and human orexin 2 receptor (OX2)-human embryonic kidney 293 membranes were characterized and compared with those of selective OX1 and OX2 antagonists, including 1-(5-(2-fluoro-phenyl)-2-methyl-thiazol-4-yl)-1-((S)-2-(5-phenyl-(1,3,4)oxadiazol-2-ylmethyl)-pyrrolidin-1-yl)-methanone (SB-674042), 1-(6,8-difluoro-2-methyl-quinolin-4-yl)-3-(4-dimethylamino-phenyl)-urea (SB-408124), and N-ethyl-2-[(6-methoxy-pyridin-3-yl)-(toluene-2-sulfonyl)-amino]-N-pyridin-3-ylmethyl-acetamide (EMPA). The effect of these antagonists was also examined in vitro on the spontaneous activity of rat ventral tegmental area (VTA) dopaminergic neurons. [3H]Almorexant bound to a single saturable site on hOX1 and hOX2 with high affinity (Kd of 1.3 and 0.17 nM, respectively). In Schild analyses using the [3H]inositol phosphates assay, almorexant acted as a competitive antagonist at hOX1 and as a noncompetitive-like antagonist at hOX2. In binding kinetic analyses, [3H]almorexant had fast association and dissociation rates at hOX1, whereas it had a fast association rate and a remarkably slow dissociation rate at hOX2. In the VTA, orexin-A potentiated the basal firing frequency to 175 ± 17% of control in approximately half of the neurons tested. In the presence of 1 μM SB-674042 or SB-408124, the effect of orexin-A was only partially antagonized. However, in the presence of 1 μM EMPA or 1 μM almorexant, the effect of orexin-A was completely antagonized. In conclusion, almorexant exhibited a noncompetitive and long-lasting pseudo-irreversible mode of antagonism as a result of its very slow rate of dissociation from OX2. The electrophysiology data suggest that OX2 might be more important than OX1 in mediating the effect of orexin-A on slow-firing of VTA dopaminergic neurons.

The Mitochondrial Effects of Small Organic Ligands of BCL-2 SENSITIZATION OF BCL-2-OVEREXPRESSING CELLS TO APOPTOSIS BY A PYRIMIDINE-2,4,6-TRIONE DERIVATIVE

We have investigated the mitochondrial effects of BH3I-2′, Chelerythrine, and HA14-1, small organic molecules that share the ability to bind the BH3 domain of BCL-2. All compounds displayed a biphasic effect on mitochondrial respiration with uncoupling at low concentrations and respiratory inhibition at higher concentrations, the relative uncoupling potency being BH3I-2′ (half-maximal uncoupling at about 80 nm) > Chelerythrine (half-maximal uncoupling at about 2 μm) > HA14-1 (half-maximal uncoupling at about 20 μm). At concentrations lower than required for uncoupling all compounds sensitized the permeability transition pore (PTP) to opening both in isolated mitochondria and intact cells. To assess whether the effects on BCL-2 binding, PTP induction and respiration could be due to different structural determinants we have tested a set of HA14-1 analogs from the Hoffmann-La Roche chemical library. We have identified 5-(6-chloro-2,4-dioxo-1,3,4,10-tetrahydro-2H-9-oxa-1,3-diaza-anthracen-10-yl)-pyrimidine-2,4,6-trione (EM20-25) as a molecule devoid of effects on respiration that is able to induce PTP opening, to disrupt the BCL-2/BAX interactions in situ and to activate caspase-9 in BCL-2-overexpressing cells. EM20-25 neutralized the antiapoptotic activity of overexpressed BCL-2 toward staurosporine and sensitized BCL-2-expressing cells from leukemic patients to the killing effects of staurosporine, chlorambucil, and fludarabine. These results provide a proof of principle that the potentially toxic effects of BCL-2 ligands on mitochondrial respiration are not essential for their antiapoptotic activity and represent an important step forward in the development of tumor-selective drugs acting on BCL-2.

A Real-World Perspective on Molecular Design.

We present a series of small molecule drug discovery case studies where computational methods were prospectively employed to impact Roche research projects, with the aim of highlighting those methods that provide real added value. Our brief accounts encompass a broad range of methods and techniques applied to a variety of enzymes and receptors. Most of these are based on judicious application of knowledge about molecular conformations and interactions: filling of lipophilic pockets to gain affinity or selectivity, addition of polar substituents, scaffold hopping, transfer of SAR, conformation analysis, and molecular overlays. A case study of sequence-driven focused screening is presented to illustrate how appropriate preprocessing of information enables effective exploitation of prior knowledge. We conclude that qualitative statements enabling chemists to focus on promising regions of chemical space are often more impactful than quantitative prediction.

4-Aminoquinolines as a novel class of NR1/2B subtype selective NMDA receptor antagonists.

Screening of the Roche compound library led to the identification of 4-aminoquinoline 4 as structurally novel NR1/2B subtype selective NMDA receptor antagonist. The SAR which was developed in this series resulted in the discovery of highly potent and in vivo active blockers.

BACE1 inhibitors: a head group scan on a series of amides.

A series of amides bearing a variety of amidine head groups was investigated as BACE1 inhibitors with respect to inhibitory activity in a BACE1 enzyme as well as a cell-based assay. Determination of their basicity as well as their properties as substrates of P-glycoprotein revealed that a 2-amino-1,3-oxazine head group would be a suitable starting point for further development of brain penetrating compounds for potential Alzheimers disease treatment.

Asymmetric total synthesis of (+)-pisatin, a phytoalexin from garden peas (Pisum sativum L.)

Abstract A short asymmetric total synthesis of (+)-pisatin is described involving a Sharpless asymmetric dihydroxylation and an “hydrogenative cyclisation” as key steps.

Discovery of benzoylpiperazines as a novel class of potent and selective GlyT1 inhibitors

Screening of the Roche compound library led to the identification of the benzoylpiperazine 7 as a structurally novel GlyT1 inhibitor. The SAR which was developed in this series resulted in the discovery of highly potent compounds displaying excellent selectivity against the GlyT2 isoform, drug-like properties, and in vivo efficacy after oral administration.