Joachim Blanz

Discovery of NVP-BYL719 a potent and selective phosphatidylinositol-3 kinase alpha inhibitor selected for clinical evaluation.

Phosphatidylinositol-3-kinase α (PI3Kα) is a therapeutic target of high interest in anticancer drug research. On the basis of a binding model rationalizing the high selectivity and potency of a particular series of 2-aminothiazole compounds in inhibiting PI3Kα, a medicinal chemistry program has led to the discovery of the clinical candidate NVP-BYL719.

Discovery and profiling of a selective and efficacious syk inhibitor.

We describe the discovery of selective and potent Syk inhibitor 11, which exhibited favorable PK profiles in rat and dog and was found to be active in a collagen-induced arthritis model in rats. Compound 11 was selected for further profiling, but, unfortunately, in GLP toxicological studies it showed liver findings in rat and dog. Nevertheless, 11 could become a valuable tool compound to investigate the rich biology of Syk in vitro and in vivo.

Syk inhibitors with high potency in presence of blood.

We describe two series of Syk inhibitors which potently abrogate Syk kinase function in enzymatic assays, cellular assays and in primary cells in the presence of blood. Introduction of a 7-aminoindole substituent led to derivatives with good kinase selectivity and little or no hERG channel inhibition (3b, 10c).

Benzimidazoles as Potent and Orally Active mGlu5 Receptor Antagonists with an Improved PK Profile.

A focused chemical optimization effort of compound 1 based on metabolite elucidation is described, resulting in 15i, a highly potent and selective mGlu5 receptor antagonist with an improved pharmacokinetic profile compared to 1. Characterization of 15i in vivo in the fear-potentiated startle (FPS) paradigm revealed a robust reduction of conditioned fear behavior. This effect nicely correlates with the rat brain pharmacokinetics.

Micropreparative isolation and NMR structure elucidation of metabolites of the drug candidate 1-isopropyl-4-(4-isopropylphenyl)-6-(prop-2-yn-1-yloxy) quinazolin-2(1H)-one from rat bile and urine.

LC-MS based drug metabolism studies are effective in the optimization stage of drug discovery for rapid partial structure identification of metabolites. However, these studies usually do not provide unambiguous structural characterization of all metabolites, due to the limitations of MS-based structure identification. LC-MS-SPE-NMR is a technique that allows complete structure identification, but is difficult to apply to complex in vivo samples (such as bile collected during in vivo drug metabolism studies) due to the presence, at high concentrations, of interfering endogenous components, and potentially also dosage excipient components (e.g. polyethylene glycols). Here, we describe the isolation and structure characterization of seven metabolites of the drug development candidate 1-isopropyl-4-(4-isopropylphenyl)-6-(prop-2-yn-1-yloxy) quinazolin-2(1H)-one from a routine metabolism study in a bile-duct cannulated rat by LC-MS-SPE. The metabolites were isolated from bile and urine by repeated automatic trapping of the chromatographic peak of each metabolite on separate Oasis HLB SPE columns. The micropreparative HPLC/MS was performed on an XBridge BEH130 C18 HPLC column using aqueous formic acid/acetonitrile/methanol as mobile phase for the gradient elution. Mass spectrometric detection was performed on a LTQ XL linear ion trap mass spectrometer using electrospray ionization. Desorption of each metabolite was performed after the separation sequence. NMR spectra ((1)H, (13)C, 2D ROESY, HSQC and HMBC were measured on a Bruker AVANCE III spectrometer (600 MHz proton frequency) equipped with a 1.7 mm (1)H{(13)C,(15)N} Bruker Biospins TCI MicroCryoProbe™.

Identification and optimisation of 4,5-dihydrobenzo[1,2-d:3,4-d]bisthiazole and 4,5-dihydrothiazolo[4,5-h]quinazoline series of selective phosphatidylinositol-3 kinase alpha inhibitors

A cyclisation within a 4,5-bisthiazole (S)-proline-amide-urea series of selective PI3Kα inhibitors led to a novel 4,5-dihydrobenzo[1,2-d:3,4-d]bisthiazole tricyclic sub-series. The synthesis and optimisation of this 4,5-dihydrobenzo[1,2-d:3,4-d]bisthiazole sub-series and the expansion to a related tricyclic 4,5-dihydrothiazolo[4,5-h]quinazoline sub-series are described. From this work analogues including 11, 12, 19 and 23 were identified as potent and selective PI3Kα inhibitor in vivo tool compounds.

Evaluation of relative MS response factors of drug metabolites for semi-quantitative assessment of chemical liabilities in drug discovery.

Drug metabolism studies are performed in drug discovery to identify metabolic soft spots, detect potentially toxic or reactive metabolites and provide an early insight into potential species differences. The relative peak area approach is often used to semi-quantitatively estimate the abundance of metabolites. Differences in the liquid chromatography-mass spectrometry responses result in an underestimation or overestimation of the metabolite and misinterpretation of results. The relative MS response factors (RF) of 132 structurally diverse drug candidates and their 233 corresponding metabolites were evaluated using a capillary-liquid chromatography/high-resolution mass spectrometry system. All of the synthesized metabolites discussed here were previously identified as key biotransformation products in discovery investigations or predicted to be formed. The most commonly occurring biotransformation mechanisms such as oxygenation, dealkylation and amide cleavage are represented within this dataset. However, relatively few phase II metabolites were evaluated because of the limited availability of authentic standards. Approximately 85% of these metabolites had a relative RF in the range between 0.2 (fivefold under-prediction) and 2.0 (twofold over-prediction), and the median MS RF was 0.6. Exceptions to this included very small metabolites that were hardly detectable. Additional experiments performed to understand the impact of the MS platform, flow rate and concentration suggested that these parameters do not have a significant impact on the RF of the compounds tested. This indicates that the use of relative peak areas to semi-quantitatively estimate the abundance of metabolites is justified in the drug discovery setting in order to guide medicinal chemistry efforts. Copyright

Orally bioavailable Syk inhibitors with activity in a rat PK/PD model.

Design and optimization of benzo- and pyrido-thiazoles/isothiazoles are reported leading to the discovery of the potent, orally bioavailable Syk inhibitor 5, which was found to be active in a rat PK/PD model. Compound 5 showed acceptable overall kinase selectivity. However, in addition to Syk it also inhibited Aurora kinase in enzymatic and cellular settings leading to findings in the micronucleus assay. As a consequence, compound 5 was not further pursued.

Exploring subtype selectivity and metabolic stability of a novel series of ligands for the benzodiazepine binding site of the GABAA receptor

A novel series of agonists at the benzodiazepine binding site of the GABA(A) receptor was prepared by functionalizing a known template. Adding substituents to the pyrazolone-oxygen of CGS-9896 led to a number of compounds with selectivities for either α2- or α1-containing GABA(A) receptor subtypes offering an entry into indications such as anxiety and insomnia. In this communication, structure-activity relationship and efforts to increase in vitro stabilities are discussed.

Increasing metabolic stability via the deuterium kinetic isotope effect: An example from a proline-amide-urea aminothiazole series of phosphatidylinositol-3 kinase alpha inhibitors

In vitro metabolic identification studies with a PI3K-α inhibitor lead molecule 1 identified a single predominant site of oxidative metabolism to be occurring within a tert.butyl moiety. Modification of the tert.butyl group within the lead molecule 1, to the corresponding d9-tert.butyl analogue 2, led to an increase in both the in vitro and in vivo metabolic stability. This increase in metabolic stability resulted in a 2-fold increase in the oral bioavailability measured in the rat, and a 3-fold increase in potency in a chronic in vivo study in the mouse, for 2 when compared to 1.