Discovery and characterization of a selective IKZF2 glue degrader for cancer immunotherapy.

Malignant tumors can evade destruction by the immune system by attracting immune-suppressive regulatory T cells (Treg) cells. The IKZF2 (Helios) transcription factor plays a crucial role in maintaining function and stability of Treg cells, and IKZF2 deficiency reduces tumor growth in mice. Here we report the discovery of NVP-DKY709, a selective molecular glue degrader of IKZF2 that spares IKZF1/3. We describe the recruitment-guided medicinal chemistry campaign leading to NVP-DKY709 that redirected the degradation selectivity of cereblon (CRBN) binders from IKZF1 toward IKZF2. Selectivity of NVP-DKY709 for IKZF2 was rationalized by analyzing the DDB1:CRBN:NVP-DKY709:IKZF2(ZF2 or ZF2-3) ternary complex X-ray structures. Exposure to NVP-DKY709 reduced the suppressive activity of human Treg cells and rescued cytokine production in exhausted T-effector cells. In vivo, treatment with NVP-DKY709 delayed tumor growth in mice with a humanized immune system and enhanced immunization responses in cynomolgus monkeys. NVP-DKY709 is being investigated in the clinic as an immune-enhancing agent for cancer immunotherapy.

Risk-Based Pharmacokinetic and Drug-Drug Interaction Characterization of Antibody-Drug Conjugates in Oncology Clinical Development: An International Consortium for Innovation and Quality in Pharmaceutical Development Perspective.

Antibody-drug conjugates (ADCs) represent a rapidly evolving area of drug development and hold significant promise. To date, nine ADCs have been approved by the US Food and Drug Administration (FDA). These conjugates combine the target specificity of monoclonal antibodies with the anticancer activity of small-molecule therapeutics (also referred to as payload). Due to the complex structure, three analytes, namely ADC conjugate, total antibody, and unconjugated payload, are typically quantified during drug development; however, the benefits of measuring all three analytes at later stages of clinical development are not clear. The cytotoxic payloads, upon release from the ADC, are considered to behave like small molecules. Given the relatively high potency and low systemic exposure of cytotoxic payloads, drug-drug interaction (DDI) considerations for ADCs might be different from traditional small molecule therapeutics. The International Consortium for Innovation and Quality in Pharmaceutical Development (IQ Consortium) convened an ADC working group to create an IQ ADC database that includes 26 ADCs with six unique payloads. The analysis of the ADC data in the IQ database, as well as nine approved ADCs, supports the strategy of pharmacokinetic characterization of all three analytes in early-phase development and progressively minimizing the number of analytes to be measured in the late-phase studies. The systemic concentrations of unconjugated payload are usually too low to serve as a DDI perpetrator; however, the potential for unconjugated payloads as a victim still exists. A data-driven and risk-based decision tree was developed to guide the assessment of a circulating payload as a victim of DDI.

Promoter-Driven Overexpression in Chromobacterium vaccinii Facilitates Access to FR900359 and Yields Novel Low Abundance Analogs.

Access to the cyclic depsipeptide FR900359 (FR), a selective Gq/11 protein inhibitor of high pharmacological interest and a potential lead molecule for targeted therapy of cancers with oncogenic GNAQ or GNA11 mutations (encoding Gq and G11 respectively), has been challenging ever since its initial discovery more than three decades ago. The recent discovery of Chromobacterium vaccinii as a cultivable FR producer enables the development of approaches leading to a high-yielding, scalable and sustainable biotechnological process for production of FR, thereby removing this bottleneck. Here we characterize different promoters in exchange of the native promoter of the FR assembly line, resulting in an overexpression mutant with significantly increased production of FR. Thereby, the isolation and structure elucidation of novel FR analogs of low abundance is enabled. Further, we explore the antiproliferative activities of fifteen chromodepsins against uveal melanoma cell lines harboring Gq/11 mutations and characterize the major metabolite of FR formed in plasma.

An IMiD-inducible degron provides reversible regulation for chimeric antigen receptor expression and activity.

The recent development of successful CAR (chimeric antigen receptor) T cell therapies has been accompanied by a need to better control potentially fatal toxicities that can arise from adverse immune reactions. Here we present a ligand-controlled CAR system, based on the IKZF3 ZF2 ß-hairpin IMiD-inducible degron, which allows for the reversible control of expression levels of type I membrane proteins, including CARs. Testing this system in an established mouse xenotransplantation model for acute lymphoblastic leukemia, we validate the ability of the CAR19-degron to target and kill CD19-positive cells displaying complete control/clearance of the tumor. We also demonstrate that the activity of CAR19-degron can be regulated in vivo when dosing a US Food and Drug Administration-approved drug, lenalidomide.

PKPD Assessment of the Anti-CD20 Antibody Obinutuzumab in Cynomolgus Monkey is Feasible Despite Marked Anti-Drug Antibody Response in This Species.

The pharmacokinetics (PK) of the anti-CD20 monoclonal antibody obinutuzumab was assessed after single intravenous dosing to cynomolgus monkeys. In addition, the pharmacokinetic-pharmacodynamic (PKPD) relationship for B-cell depletion was characterized. The PKPD model was used to estimate the B-cell repopulation during the recovery phase of chronic toxicology studies, thereby supporting the study design, in particular planning the recovery phase duration. Marked immunogenicity against obinutuzumab was observed approximately 10 days after single dose, leading to an up to ∼30-fold increase in obinutuzumab clearance in the affected monkeys. Despite this accelerated clearance, the PK could be characterized, either by disregarding the clearance in noncompartmental PK analysis or by capturing it explicitly as an additional time-dependent clearance process in compartmental modeling. This latter step was crucial to model the PKPD of B-cells as an indirect response to obinutuzumab exposure, showing that-without immune response-the limiting factor is obinutuzumab elimination with concentrations below 0.02 µg/mL required for initiation of B-cell recovery. Overall, the results demonstrate that despite a marked anti-drug antibody response in the nonclinical animal species, the PK and PKPD of obinutuzumab could be characterized successfully by appropriately addressing the immune-modulated clearance pathway in data analysis and modeling.

Oral administration of the 11ß-hydroxysteroid-dehydrogenase type 1 inhibitor RO5093151 to patients with glaucoma: an adaptive, randomised, placebo-controlled clinical study.

BACKGROUND/AIMS: Cortisol is involved in the regulation of intraocular pressure (IOP). This study aimed to assess the effect of 11ß-hydroxysteroid-dehydrogenase type 1 (11ßHSD1) inhibition by oral administration of RO5093151 on IOP. METHODS: The exposure of key ocular compartments following oral administration was assessed in rabbits. An adaptive, randomised, placebo-controlled study gated by a Bayesian decision criterion was performed in 35 patients with primary open angle glaucoma (POAG) or ocular hypertension (OHT). Following a 7-day placebo-controlled run-in period, 200 mg twice daily RO5093151 or placebo (4:1) were administered for 7 days. The extent of 11ßHSD1 inhibition was assessed by the ratio of urinary tetrahydrocortisol (5α and 5ß)/tetrahydrocortisone (THF/THE). Time-matched IOP assessments were performed. RESULTS: A high distribution of RO5093151 into the rabbit eye was observed. In humans, a high and sustained inhibition of 11ßHSD1 was shown by the decrease of THF/THE from 0.9 at baseline to 0.18 on day 7. There was no statistically significant difference in change of IOP from baseline. In the 'worse eye', the adjusted least square mean change from baseline was -2.7 mm Hg (95% CI -4.2 to -1.2) and -2.9(95% CI -5.9 to 0.1) in the RO5093151 and placebo group, respectively. CONCLUSIONS: Despite high inhibition of 11ßHSD1 and expected moderate to high tissue distribution in ocular tissues, a 7-day treatment with a high oral dose of RO5093151 did not result in a clinically meaningful effect on IOP in patients with POAG or OHT.

Effects of Cytochrome P450 3A4 Inhibitors-Ketoconazole and Erythromycin-on Bitopertin Pharmacokinetics and Comparison with Physiologically Based Modelling Predictions.

OBJECTIVE: To assess the effect of strong and moderate cytochrome P450 (CYP) 3A4 inhibition on exposure of bitopertin, a glycine reuptake inhibitor primarily metabolized by CYP3A4, and to compare the results with predictions based on physiologically based pharmacokinetic (PBPK) modelling. METHODS: The effects of ketoconazole and erythromycin were assessed in two male volunteer studies with open-label, two-period, fixed-sequence designs. Twelve subjects were enrolled in each of the studies. In period 1, a single dose of bitopertin was administered; in period 2, 400 mg ketoconazole was administered once daily for 17 days or 500 mg erythromycin was administered twice daily for 21 days. A single dose of bitopertin was coadministered on day 5. Pharmacokinetic parameters were derived by non-compartmental methods. Simulated bitopertin profiles using dynamic PBPK modelling for a typical healthy volunteer in GastroPlus(®) were used to predict changes in pharmacokinetic parameters. RESULTS: In healthy volunteers, coadministration of ketoconazole increased the bitopertin area under the plasma concentration-time curve (AUC) from 0 to 312 h (AUC0-312h) 4.2-fold (90 % confidence interval [CI] 3.5-5.0) and erythromycin increased the AUC from time zero to infinity (AUC0-inf) 2.1-fold (90 % CI 1.9-2.3). The peak concentration (C max) increased by <25 % in both studies. Simulated bitopertin profiles using PBPK modelling showed good agreement with the observed AUC ratios in both studies. The predicted AUC0-inf ratios for the interaction with ketoconazole and erythromycin were 7.7 and 1.9, respectively. CONCLUSION: Strong CYP3A4 inhibitors increase AUC0-inf of bitopertin 7- to 8-fold and hence should not be administered concomitantly with bitopertin. Moderate CYP3A4 inhibitors double AUC0-inf.

An ex vivo potency assay to assess active drug levels of a GLP-1 agonistic peptide during preclinical safety studies.

BACKGROUND: During development of biologics, safety and efficacy assessments are often hampered by immune responses to the treatment. To assess active exposure of a drug peptide in a toxicology study, we developed an ex vivo potency assay which complemented the total drug quantification assay. METHODOLOGY: Compound activity was assessed in samples of treated monkeys by cell-based cAMP measurements. For each animal, activity was compared with its predose sample to which the compound has been added at the postdose concentration as determined by a total LC-MS/MS assay. CONCLUSION: We were able to show that despite a high total test compound level, activity was reduced tremendously in antidrug-antibody-positive monkeys. Therefore, the applied ex vivo potency assay supplements drug quantification methods to determine active exposures.

Physiologically based absorption modelling to predict the impact of drug properties on pharmacokinetics of bitopertin.

Bitopertin (RG1678) is a glycine reuptake inhibitor in phase 3 trials for treatment of schizophrenia. Its clinical oral pharmacokinetics is sensitive to changes in drug substance particle size and dosage form. Physiologically based pharmacokinetic (PBPK) absorption model simulations of the impact of changes in particle size and dosage form (either capsules, tablets, or an aqueous suspension) on oral pharmacokinetics was verified by comparison to measured plasma concentrations. Then, a model parameter sensitivity analysis was applied to set limits on the particle sizes included in tablets for the market. The model was also used to explore the in vitro to in vivo correlation. Simulated changes in oral pharmacokinetics caused by differences in particle size and dosage form were confirmed in two separate relative bioavailability studies. Model parameter sensitivity analyses predicted that AUCinf was hardly reduced as long as particle diameter (D50) remained smaller than 30 µm, and >20% reduced Cmax is anticipated only when particle diameter exceeds 15 µm. An exploration of the sensitivity to the presence of larger particles within a polydisperse distribution showed that simulated Cmax is again more affected than AUC but is less than 20% reduced as long as D50 is less than 8 µm and D90 is smaller than 56 µm. PBPK absorption modelling can contribute to a quality by design (QbD) approach for clinical formulation development and support the setting of biorelevant specifications for release of the product.

Preparation and characterization of albumin conjugates of a truncated peptide YY analogue for half-life extension.

Recombinant human serum albumin (HSA) conjugates of a 15-amino-acid truncated peptide YY (PYY) analogue were prepared using three heterobifunctional linkers [succinimidyl 4-[N-maleimidomethyl]cyclohexane-1-carboxylate (SMCC), 6-maleimidohexanoic acid N-hydroxysuccinimide ester (MHS), and N-[γ-maleimidobutyryloxy]sulfosuccinimide ester (GMBS)] in 2 synthetic steps involving (1) reaction of succinimidyl ester on linker with ε-amine of Lys2 on the peptide and (2) reaction of maleimide on peptide linker with free thiol of Cysteine 34 (Cys34) on albumin. In-process controls using ESI LC-MS were used to follow reactions and identify reaction products. Proteolytic digests of the conjugate revealed that peptide conjugation occurs at Cys34 on HSA. Conjugates were assayed in cell-based assays to determine potency at the human Y2-receptor, and selectivity at the human Y1-, Y4-, and Y5-receptors using a calcium flux assay. All three conjugates assayed were selective agonists of the Y2-receptor, and displayed nanomolar potencies. MCC and MH conjugates were selected for acute PK/PD studies in DIO mice. Significant reduction in food intake was observed with the MH conjugate, which lasted for 24 h at the 10 mg (or 4 µmol)/kg dose. While the MCC conjugate exhibited greater potency in vitro, it was slightly less effective than the MH conjugate in vivo with respect to reduction in food intake. Both conjugates were significantly less active than the peptide coupled to a 30 kDa PEG. The observed T1/2 (8-9 h) for both conjugates was significantly lower than that observed for the PEGylated peptide (∼25 h). These results suggest that, as compared with the unmodified and PEGylated peptide, the extended circulation half-life of albumin conjugates is mediated through uptake and recirculation by FcRn, and allometric scaling methods are necessary to account for interspecies variation in pharmacokinetic properties.

Physiologically based pharmacokinetic modelling to predict single- and multiple-dose human pharmacokinetics of bitopertin.

BACKGROUND: Bitopertin (RG1678) is a glycine reuptake inhibitor currently in phase 3 trials for treatment of schizophrenia. This paper describes the use of physiologically based pharmacokinetic (PBPK) modelling and preclinical data to gain insights into and predict bitopertin clinical pharmacokinetics. METHODS: Simulations of pharmacokinetics were initiated early in the drug discovery stage by integrating physicochemical properties and in vitro measurements into a PBPK rat model. Comparison of pharmacokinetics predicted by PBPK modelling with those measured after intravenous and oral dosing in rats and monkeys showed a good match and thus increased confidence that a similar approach could be applied for human prediction. After comparison of predicted plasma concentrations with those measured after single oral doses in the first clinical study, the human model was refined and then applied to simulate multiple-dose pharmacokinetics. RESULTS: Clinical plasma concentrations measured were in good agreement with PBPK predictions. Predicted area under the plasma concentration-time curve (AUC) was within twofold of the observed mean values for all dose levels. Maximum plasma concentration (C max) at higher doses was well predicted but approximately twofold below observed values at the lower doses. A slightly less than dose-proportional increase in both AUC and C max was observed, and model simulations indicated that when the dose exceeded 50 mg, solubility limited the fraction of dose absorbed. Refinement of the absorption model with additional solubility and permeability measurements further improved the match of simulations to observed single-dose data. Simulated multiple-dose pharmacokinetics with the refined model were in good agreement with observed data. CONCLUSIONS: Clinical pharmacokinetics of bitopertin can be well simulated with a mechanistic PBPK model. This model supports further clinical development and provides a valuable repository for pharmacokinetic knowledge gained about the molecule.

Pre-clinical characterization of [11C]R05013853 as a novel radiotracer for imaging of the glycine transporter type 1 by positron emission tomography.

A specific positron emission tomography (PET) radiotracer for the glycine transporter type 1 (GlyT1) would constitute an imaging biomarker to investigate the distribution of GlyT1 in normal individuals and those with neuropsychiatric disorders. In addition it could demonstrate the ability of a novel drug to reach its target in the brain and enable receptor occupancy studies, thus facilitating drug development. In this article we describe the evaluation in non-human primates of two candidate PET radiotracers ([(11)C]RO5013852 and [(11)C]RO5013853) previously characterized in the rat. Both radiotracers showed acceptable uptake in the baboon brain and heterogeneous distribution consistent with that reported for GlyT1. In vivo blockade studies with two specific glycine reuptake inhibitors (GRIs), RO5013853 and bitopertin (RG1678, reduced uptake of both tracers to homogenous levels across brain regions and demonstrated specificity of the signal. [(11)C]RO5013853 showed a larger specific signal and slightly higher brain uptake and was therefore selected for further characterization. Quantitative compartmental analysis of PET data showed that the 2-tissue compartment model with 5 parameters was the most appropriate to describe the kinetics of [(11)C]RO5013853. Two additional methods were used: a) the Logan graphical analysis using plasma input and, b) a linear parametric imaging approach with the 2-tissue compartmental model. These produced VT estimates of comparable magnitude, namely, pons, thalamus and cerebellum>caudate, putamen and cortical regions. High resolution autoradiography with tritiated RO5013853 was used to confirm the binding pattern observed by PET. In vivo metabolism studies in the baboon demonstrated the formation of a single, radiolabeled metabolite more polar than the parent compound. Finally, [(11)C]RO5013853 was used to quantify the degree of cerebral GlyT1 occupancy observed in the baboon following oral administration of bitopertin, a selective GRI presently in Phase III clinical trial. Plasma concentrations of approximately 150-300 ng/mL were estimated to produce 50% GlyT1 occupancy in the thalamus, the cerebellum and the pons. [(11)C]RO5013853 is a promising radiotracer for in vivo imaging of the GlyT1. It can be easily radiolabeled, exhibits moderate metabolism, displays a good specific signal, and is suitable for receptor occupancy studies of therapeutic compounds that target the GlyT1. The successful characterization of [(11)C]RO5013853 in healthy volunteers is presented in this NeuroImage issue (Wong et al., 2013).

Glycine reuptake inhibitor RG1678: a pharmacologic characterization of an investigational agent for the treatment of schizophrenia.

Dysfunctional N-methyl-d-aspartate (NMDA) receptor neurotransmission has been implicated in the pathophysiology of schizophrenia. It is thought that this abnormal functioning can be corrected by increasing availability of the NMDA co-agonist glycine through inhibition of glycine transporter type 1 (GlyT1). Herein is described the pharmacologic profile of RG1678, a potent and noncompetitive glycine reuptake inhibitor. In vitro, RG1678 noncompetitively inhibited glycine uptake at human GlyT1 with a concentration exhibiting half-maximal inhibition (IC(50)) of 25 nM and competitively blocked [(3)H]ORG24598 binding sites at human GlyT1b in membranes from Chinese hamster ovary cells. In hippocampal CA1 pyramidal cells, RG1678 enhanced NMDA-dependent long-term potentiation at 100 nM but not at 300 nM. In vivo, RG1678 dose-dependently increased cerebrospinal fluid and striatal levels of glycine measured by microdialysis in rats. Additionally RG1678 attenuated hyperlocomotion induced by the psychostimulant d-amphetamine or the NMDA receptor glycine site antagonist L-687,414 in mice. RG1678 also prevented the hyper-response to d-amphetamine challenge in rats treated chronically with phencyclidine, an NMDA receptor open-channel blocker. In the latter experiment, a decrease in ex vivo striatal [(3)H]raclopride binding was also measured. These data demonstrate that RG1678 is a potent, noncompetitive glycine reuptake inhibitor that can modulate both glutamatergic and dopaminergic neurotransmission in animal experiments that model aspects of schizophrenia. This article is part of a Special Issue entitled 'Post-Traumatic Stress Disorder'.

Discovery of benzoylisoindolines as a novel class of potent, selective and orally active GlyT1 inhibitors.

Benzoylisoindolines were discovered as a novel structural class of GlyT1 inhibitors. SAR studies and subsequent lead optimization efforts focused primarily on addressing hERG liability and on improving in vivo efficacy resulted in the identification of potent GlyT1 inhibitors displaying excellent selectivity and in vivo PD and PK profiles.

Pyrido pyrimidinones as selective agonists of the high affinity niacin receptor GPR109A: optimization of in vitro activity.

Pyrido pyrimidinones are selective agonists of the human high affinity niacin receptor GPR109A (HM74A). They show no activity on the highly homologous low affinity receptor GPR109B (HM74). Starting from a high throughput screening hit the in vitro activity of the pyrido pyrimidinones was significantly improved providing lead compounds suitable for further optimization.

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.

Design, synthesis and structure-activity relationship of simple bis-amides as potent inhibitors of GlyT1.

Several novel classes of potent and small amide-type inhibitors of glycine transport (GlyT1) were developed through sequential simplification of a benzodiazepinone-lead structure identified from a high-throughput screening. The most potent compounds of these structurally simple classes show low nanomolar inhibition at the GlyT1 target.

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.

Discovery of 4-substituted-8-(2-hydroxy-2-phenyl-cyclohexyl)-2,8-diaza-spiro[4.5]decan-1-one as a novel class of highly selective GlyT1 inhibitors with improved metabolic stability.

A novel class of 4-aryl-8-(2-hydroxy-2-phenyl-cyclohexyl)-2,8-diaza-spiro[4.5]decan-1- ones have been discovered and developed as potent and selective GlyT1 inhibitors. The molecules are devoid of activity at the GlyT2 isoform and display excellent selectivities against the mu-opioid receptor as well as the Nociceptin/Orphanin FQ peptide (NOP) receptor. In particular these novel compounds 4 as well as the 4-substituted-8-(2-phenyl-cyclohexyl)-2,8-diaza-spiro[4.5]decan-1-one 3 show improved metabolic stability and pharmacokinetic profiles in rodents compared to previous triazaspiropiperidine series 1 and 2. We have also identified within these diazaspiropiperidine series a key relationship between reducing basicity of the piperidine nitrogen and reducing hERG affinity.