Synthesis, in Vitro Covalent Binding Evaluation, and Metabolism of ¹⁴C‑Labeled Inhibitors of 11β-HSD1

In this letter, we reported the design and synthesis of three potent, selective, and orally bioavailable 11β-HSD1 inhibitors labeled with ¹⁴C: AMG 456 (<b>1</b>), AM-6949 (<b>2</b>), and AM-7715 (<b>3</b>). We evaluated the covalent protein binding of the labeled inhibitors in human liver microsomes in vitro and assessed their potential bioactivation risk in humans. We then studied the in vitro mechanism of <b>2</b> in human hepatocytes and the formation of reactive intermediates. Our study results suggest that <b>1</b> and <b>3</b> have low potential for metabolic bioactivation in humans, while <b>2</b> has relatively high risk

Linker Immolation Determines Cell Killing Activity of Disulfide-Linked Pyrrolobenzodiazepine Antibody–Drug Conjugates

Disulfide bonds could be valuable linkers for a variety of therapeutic applications requiring tunable cleavage between two parts of a molecule (e.g., antibody–drug conjugates). The in vitro linker immolation of β-mercaptoethyl-carbamate disulfides and DNA alkylation properties of associated payloads were investigated to understand the determinant of cell killing potency of anti-CD22 linked pyrrolobenzodiazepine (PBD-dimer) conjugates. Efficient immolation and release of a PBD-dimer with strong DNA alkylation properties were observed following disulfide cleavage of methyl- and cyclobutyl-substituted disulfide linkers. However, the analogous cyclopropyl-containing linker did not immolate, and the associated thiol-containing product was a poor DNA alkylator. As predicted from these in vitro assessments, the related anti-CD22 ADCs showed different target-dependent cell killing activities in WSU-DLCL2 and BJAB cell lines. These results demonstrate how the in vitro immolation models can be used to help design efficacious ADCs

Immolation of <i>p</i>‑Aminobenzyl Ether Linker and Payload Potency and Stability Determine the Cell-Killing Activity of Antibody–Drug Conjugates with Phenol-Containing Payloads

The valine-citrulline (Val-Cit) dipeptide and <i>p</i>-aminobenzyl (PAB) spacer have been commonly used as a cleavable self-immolating linker in ADC design including in the clinically approved ADC, brentuximab vedotin (Adcetris). When the same linker was used to connect to the phenol of the cyclopropabenzindolone (CBI) (<b>P1</b>), the resulting <b>ADC1</b> showed loss of potency in CD22 target-expressing cancer cell lines (e.g., BJAB, WSU-DLCL2). In comparison, the conjugate (<b>ADC2</b>) of a cyclopropapyrroloindolone (CPI) (<b>P2</b>) was potent despite the two corresponding free drugs having similar picomolar cell-killing activity. Although the corresponding spirocyclization products of <b>P1</b> and <b>P2</b>, responsible for DNA alkylation, are a prominent component in buffer, the linker immolation was slow when the PAB was connected as an ether (PABE) to the phenol in <b>P1</b> compared to that in <b>P2</b>. Additional immolation studies with two other PABE-linked substituted phenol compounds showed that electron-withdrawing groups accelerated the immolation to release an acidic phenol-containing payload (to delocalize the negative charge on the anticipated anionic phenol oxygen during immolation). In contrast, efficient immolation of <b>LD4</b> did not result in an active <b>ADC4</b> because the payload (<b>P4</b>) had a low potency to kill cells. In addition, nonimmolation of <b>LD5</b> did not affect the cell-killing potency of its <b>ADC5</b> since immolation is not required for DNA alkylation by the center-linked pyrrolobenzodiazepine. Therefore, careful evaluation needs to be conducted when the Val-Cit-PAB linker is used to connect antibodies to a phenol-containing drug as the linker immolation, as well as payload potency and stability, affects the cell-killing activity of an ADC

Aminopyrazole–Phenylalanine Based GPR142 Agonists: Discovery of Tool Compound and in Vivo Efficacy Studies

Herein, we report the lead optimization of amrinone–phenylalanine based GPR142 agonists. Structure–activity relationship studies led to the discovery of aminopyrazole–phenylalanine carboxylic acid <b>22</b>, which exhibited good agonistic activity, high target selectivity, desirable pharmacokinetic properties, and no cytochrome P450 or hERG liability. Compound <b>22</b>, together with its orally bioavailable ethyl ester prodrug <b>23</b>, were found to be suitable for in vivo proof-of-concept studies. Compound <b>23</b> displayed good efficacy in a mouse oral glucose tolerance test (OGTT). Compound <b>22</b> showed GPR142 dependent stimulation of insulin secretion in isolated mouse islets and demonstrated a statistically significant glucose lowering effect in a mouse model bearing transplanted human islets

Potent and Orally Bioavailable GPR142 Agonists as Novel Insulin Secretagogues for the Treatment of Type 2 Diabetes

GPR142 is a G protein-coupled receptor that is predominantly expressed in pancreatic β-cells. GPR142 agonists stimulate insulin secretion in the presence of high glucose concentration, so that they could be novel insulin secretagogues with reduced or no risk of hypoglycemia. We report here the optimization of HTS hit compound <b>1</b> toward a proof of concept compound <b>33</b>, which showed potent glucose lowering effects during an oral glucose tolerance test in mice and monkeys

Scaffold-Hopping Approach To Discover Potent, Selective, and Efficacious Inhibitors of NF-κB Inducing Kinase

NF-κB-inducing kinase (NIK) is a protein kinase central to the noncanonical NF-κB pathway downstream from multiple TNF receptor family members, including BAFF, which has been associated with B cell survival and maturation, dendritic cell activation, secondary lymphoid organ development, and bone metabolism. We report herein the discovery of lead chemical series of NIK inhibitors that were identified through a scaffold-hopping strategy using structure-based design. Electronic and steric properties of lead compounds were modified to address glutathione conjugation and amide hydrolysis. These highly potent compounds exhibited selective inhibition of LTβR-dependent p52 translocation and transcription of NF-κB2 related genes. Compound <b>4f</b> is shown to have a favorable pharmacokinetic profile across species and to inhibit BAFF-induced B cell survival in vitro and reduce splenic marginal zone B cells in vivo

Scaffold-Hopping Approach To Discover Potent, Selective, and Efficacious Inhibitors of NF-κB Inducing Kinase

NF-κB-inducing kinase (NIK) is a protein kinase central to the noncanonical NF-κB pathway downstream from multiple TNF receptor family members, including BAFF, which has been associated with B cell survival and maturation, dendritic cell activation, secondary lymphoid organ development, and bone metabolism. We report herein the discovery of lead chemical series of NIK inhibitors that were identified through a scaffold-hopping strategy using structure-based design. Electronic and steric properties of lead compounds were modified to address glutathione conjugation and amide hydrolysis. These highly potent compounds exhibited selective inhibition of LTβR-dependent p52 translocation and transcription of NF-κB2 related genes. Compound <b>4f</b> is shown to have a favorable pharmacokinetic profile across species and to inhibit BAFF-induced B cell survival in vitro and reduce splenic marginal zone B cells in vivo