1. Formation of 1-O-acyl-β-d-glucuronide conjugates is a significant pathway in the metabolism of drugs containing a carboxylic acid group. The formation of acyl glucuronides results in an increase ...in both the aqueous solubility and molecular mass of the conjugate in comparison to the parent drug and thus facilitates excretion in both urine and bile.
2. Acyl glucuronides are effectively esters, which undergo first order decomposition by both hydrolysis and the intra-migration of the acyl group around the glucuronide ring to yield 2-, 3- and 4-O-glucuronic acid esters which, unlike the metabolically formed 1-O-acyl-β-d-glucuronides, are not substrates for β-glucuronidase. The first order degradation half-life is therefore a composite value of these two reactions and a useful indicator of chemical reactivity and potential toxicity.
3. Intra-molecular migration is expected to be the predominant pathway due to entropic considerations.
4. Such conjugates, together with their isomeric ester derivatives, react with nucleophilic sites on proteins and small endogenous molecules, such as glutathione, which potentially contributes to the observed toxicity and adverse drug reactions associated with some drugs.
5. Examination of the stability of the 1-O-acyl-β-d-glucuronides of aryl acetic acid, α-carbon substituted aryl acetic acid, aliphatic and aromatic acids, as determined by their first order degradation half-lives, indicates the significance of electronic and steric features that contribute to conjugate stability under physiological conditions.
6. Examination of the of the electronic properties of the carbonyl carbon atom in acyl glucuronides, as measured by the pKa of the parent acid, together with the steric substituents about the acyl carbonyl provides insight into the reactivity of these conjugates.
7. The investigations reported herein on a large number of 1-O-acyl-β-d-glucuronides has allowed rationalisation of their physicochemical properties in relation to the structure of the parent drug and has the potential to contribute to the design of carboxylic acid containing drug molecules with increased stability of a major metabolite with potential reduction in toxicity and adverse drug reactions.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Hepcidin, a central regulator of iron homeostasis, is pathologically elevated in patients with non-dialysis-dependent chronic kidney disease (NDD-CKD) and anemia. Elevations in hepcidin contribute to ...the onset, maintenance, and severity of anemia. DISC-0974 is an investigational, first-in-class, monoclonal antibody that blocks hemojuvelin (HJV), a co-receptor in the bone morphogenetic protein-signaling pathway regulating hepcidin expression. In a healthy volunteer study, DISC-0974 demonstrated dose-dependent reductions in serum hepcidin, increases in serum iron with doses up to 56 mg administered subcutaneously (SC), and increasing trends in reticulocyte count, reticulocyte hemoglobin, mean corpuscular hemoglobin, total hemoglobin (Hgb), and red blood cell count. In a rat model of anemia in CKD, DISC-0974 decreased hepcidin, increased serum iron, and normalized hemoglobin (Wu et al., ASH 2022). DISC-0974-103 is a Phase 1b, double-blind, placebo-controlled, single-ascending dose study (NCT05745883) to assess the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of DISC-0974 in patients with NDD-CKD and anemia. Eligible participants include patients over 18 years of age with NDD-CKD, stages 2-5, hemoglobin (Hgb) <10.5 g/dL in women and <11.0 g/dL in men, serum ferritin ≥100 μg/L, and transferrin saturation (TSAT) ≤30%. Major exclusionary criteria include: concomitant treatment with therapeutic oral iron, intravenous iron, erythropoietin-stimulating agents, or blood transfusions; splenectomy; and nutritional, genetic, infectious, or autoimmune causes of anemia. Approximately 32 participants will be enrolled. On Day 1, participants will receive a single dose of DISC-0974 SC with evaluations for safety, PK, and PD through 57 days of follow-up. Dose escalation is planned across 4 cohorts consisting of 8 participants each, randomized 3:1 active treatment to placebo, treated at single doses of 28, 40, 60, and 90 mg SC DISC-0974. Safety Review Committee assessments are planned to gate escalation decisions. Primary endpoints include adverse events (AEs), clinical laboratory assessments, vital signs, physical examinations, and electrocardiograms. Secondary endpoints include changes in serum hepcidin-25, iron, TSAT, ferritin, Hgb, and other hematology biomarkers. Enrollment is currently ongoing, and available study results will be presented at the meeting.
Razuprotafib, a sulphamic acid-containing phosphatase inhibitor, is shown in vivo to undergo enzymatic oxidation and methylation to form a major metabolite in monkey and human excreta with an m/z
-
...value of 633.
LC-MS/MS analysis of samples derived from incubations of razuprotafib with human liver microsomes and recombinant CYP2C8 enzyme has elucidated the metabolic pathway for formation of the thiol precursor to the S-methyl metabolite MS633 (m/z
-
633).
Under in vitro conditions, the major pathway of razuprotafib metabolism involves extensive oxidation of the thiophene and phenyl rings.
A single oxidation takes place at one of the phenyl groups. Multiple oxidations occur at the thiophene moiety: initial oxidation results in the formation of a thiolactone followed by a second oxidation giving rise to an S-oxide of the thiolactone, which is further metabolised to the ring-opened form and ultimate formation of a thiol (m/z
-
619).
An additional mono-oxidation pathway involves epoxidation of the thiophene followed by hydrolysis to a diol.
The thiol and diol metabolites are trapped by the addition of a nucleophilic trapping agent, 3-methoxyphenacyl bromide (MPB), giving adducts with m/z
-
767.
The thiol is a likely precursor to the major in vivo razuprotafib metabolite, MS633.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Abstract
Aims
Receptor-type vascular endothelial protein tyrosine phosphatase (VE-PTP) dephosphorylates Tie-2 as well as CD31, VE-cadherin, and vascular endothelial growth factor receptor 2 (VEGFR2). ...The latter form a signal transduction complex that mediates the endothelial cell response to shear stress, including the activation of the endothelial nitric oxide (NO) synthase (eNOS). As VE-PTP expression is increased in diabetes, we investigated the consequences of VE-PTP inhibition (using AKB-9778) on blood pressure in diabetic patients and the role of VE-PTP in the regulation of eNOS activity and vascular reactivity.
Methods and results
In diabetic patients AKB-9778 significantly lowered systolic and diastolic blood pressure. This could be linked to elevated NO production, as AKB increased NO generation by cultured endothelial cells and elicited the NOS inhibitor-sensitive relaxation of endothelium-intact rings of mouse aorta. At the molecular level, VE-PTP inhibition increased the phosphorylation of eNOS on Tyr81 and Ser1177 (human sequence). The PIEZO1 activator Yoda1, which was used to mimic the response to shear stress, also increased eNOS Tyr81 phosphorylation, an effect that was enhanced by VE-PTP inhibition. Two kinases, i.e. abelson-tyrosine protein kinase (ABL)1 and Src were identified as eNOS Tyr81 kinases as their inhibition and down-regulation significantly reduced the basal and Yoda1-induced tyrosine phosphorylation and activity of eNOS. VE-PTP, on the other hand, formed a complex with eNOS in endothelial cells and directly dephosphorylated eNOS Tyr81 in vitro. Finally, phosphorylation of eNOS on Tyr80 (murine sequence) was found to be reduced in diabetic mice and diabetes-induced endothelial dysfunction (isolated aortic rings) was blunted by VE-PTP inhibition.
Conclusions
VE-PTP inhibition enhances eNOS activity to improve endothelial function and decrease blood pressure indirectly, through the activation of Tie-2 and the CD31/VE-cadherin/VEGFR2 complex, and directly by dephosphorylating eNOS Tyr81. VE-PTP inhibition, therefore, represents an attractive novel therapeutic option for diabetes-induced endothelial dysfunction and hypertension.
BACKGROUND:
GB004 is a small molecule prolyl hydroxylase inhibitor (PHDi) that stabilizes hypoxia inducible factors (HIF-α), key transcription factors involved in the adaptive and protective cellular ...responses at the intersection of hypoxia and inflammation. GB004 is being developed as a therapy for inflammatory bowel disease (IBD). For diseases such as IBD, an ideal profile for a PHDi is a molecule that has a gut targeted PK profile and preferentially activates tissue specific protective mechanisms to a greater extent than other pathways where HIF transcription factors have a role (e.g., erythropoietin (EPO) production). GB004 was selected to meet this profile, and consistent with it, orally administered GB004 in animal models of colitis demonstrated a significant reduction in disease activity, an improvement in histology, greater exposure in GI tissue relative to plasma, and no increase in systemic EPO or hematocrit. This single ascending dose (SAD) study is the first-in-human study to evaluate the safety, tolerability, and PK of GB004 in healthy subjects. This study also determined the pharmacodynamic (PD) effects of GB004 on plasma EPO and vascular endothelial growth factor (VEGF).
METHODS:
This was a randomized, double-blind, placebo-controlled, single-ascending dose, Phase 1a study conducted at a single site in Canada. Single oral solution doses were investigated in 5 sequential cohorts (20, 60, 120, and 240 mg in 50 ml solution, and 240 mg in 100 ml solution), consisting of 2 placebo and 6 GB004 male subjects per cohort. PK and safety were evaluated through follow-up on day 8. EPO and VEGF levels were collected at baseline, 4, 8, and 12 hours post dose.
RESULTS:
40 subjects were randomized. The mean age and BMI were 36.2 yrs and 25.61 kg/m2, respectively. All subjects completed the study. GB004 was rapidly absorbed with a median Tmax of 0.5 hour for all doses. Cmax of GB004 increased in a dose proportional manner while AUC of GB004 increased slightly larger than dose proportional. GB004 was rapidly eliminated from systemic circulation. No dose related changes were observed in plasma EPO or VEGF at any dose level. There were no adverse events (AEs) leading to discontinuation, serious adverse events (SAEs) or deaths. The incidence of AEs in the 30 GB004-treated subjects was 46.7% vs 50.0% in the 10 placebo-treated subjects. AEs with an incidence of >=10% in GB004-treated subjects and higher than in placebo were: nausea (20.0% GB004 vs 0% placebo), vomiting (13.3% vs 0%), feeling cold (13.3% vs 10.0%), and somnolence (10.0% vs 0%). All AEs reported in GB004-treated subjects were mild, and the incidence of AEs for GB004 240 mg in 100 ml was lower than 240 mg or 120 mg in 50 ml.
CONCLUSION(S):
This study demonstrated that single doses of GB004 solution were generally well tolerated, with no effects observed on serum EPO or VEGF levels, consistent with the intended PK profile and animal model data. Clinical studies of GB004 are ongoing in patients with ulcerative colitis to explore PK and PD both systemically and within colonic tissue (NCT03860896). A tablet formulation is being developed.
The disposition of radioactivity following subcutaneous
14
C-razuprotafib, a Tie2 activator, was explored in multiple species.
The absorption and clearance of razuprotafib and total radioactivity in ...human plasma are rapid and pharmacokinetics support razuprotafib as primary circulating component. Radioactivity is distributed greater to human plasma than whole blood (B:P = 0.36).
In pigmented rats, radioactivity distributes to whole-body tissues rapidly and, within 24 h, is localised to elimination pathway end organs and injection site.
Overall recovery of radioactivity across species is >93%, with the majority recovered within 24-48 h, and >80% in faeces.
The CYP2C8 enzyme contributes significantly to razuprotafib metabolism.
A hydrolysis product of razuprotafib (m/z
−
380) is the main component in rat plasma at 2 h (49% peak area radioactivity), while razuprotafib (m/z
−
585) is the main component in plasma for dog (58%), monkey (99.3%), and human (100%).
Razuprotafib is present in dog, monkey, and human faeces, with the greatest percentage of radioactivity as metabolites. The major metabolite (>25%) in monkey and human, m/z
−
633, is an S-methylated oxidised derivative of razuprotafib and is localised in faeces.
Overall disposition of
14
C-razuprotafib in human is best modelled by monkey over lower order species.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Pathologic elevations in hepcidin, a key regulator of iron homeostasis, contribute to anemia of inflammation in chronic disease. DISC-0974 is a monoclonal antibody that binds to hemojuvelin and ...blocks bone morphogenetic protein signaling, thereby suppressing hepcidin production. Reduction of systemic hepcidin levels is predicted to increase iron absorption and mobilize stored iron into circulation, where it may be utilized by red blood cell (RBC) precursors in the bone marrow to improve hemoglobin levels and to potentially alleviate anemia of inflammation. We conducted a first-in-human, double-blind, placebo-controlled, single-ascending dose study to evaluate safety, pharmacokinetics, and pharmacodynamics of DISC-0974 in healthy participants. Overall, 42 participants were enrolled and received a single dose of placebo or DISC-0974 at escalating dose levels (7-56 mg), administered intravenously (IV) or subcutaneously (SC). DISC-0974 was well tolerated, with a safety profile comparable to that of placebo. Pharmacokinetic data was dose and route related, with a terminal half-life of approximately 7 days. The bioavailability of SC dosing was ∼50%. Pharmacodynamic data showed dose-dependent decreases in serum hepcidin, with reductions of nearly 75% relative to baseline at the highest dose level tested, and corresponding increases in serum iron in response to DISC-0974 administration. Dose-dependent changes in serum ferritin and hematology parameters were also observed, indicating mobilization of iron stores and downstream effects of enhanced hemoglobinization and production of RBCs. Altogether, these data are consistent with the mechanism of action of DISC-0974 and support the selection of a biologically active dose range for evaluation in clinical trials for individuals with anemia of inflammation.
Hepcidin, a central regulator of iron homeostasis, is pathologically elevated in patients with myelofibrosis (MF) and anemia. Chronic elevations in hepcidin contribute to the onset and severity of ...anemia. DISC-0974 is an investigational, first-in-class, monoclonal antibody that blocks hemojuvelin, a co-receptor in the bone morphogenetic protein-signaling pathway driving hepcidin expression. Preclinical studies have shown that DISC-0974 suppresses hepcidin and increases serum iron. A healthy volunteer study has demonstrated dose-dependent reductions in serum hepcidin, increases in serum iron with doses up to 56 mg administered subcutaneously, and increasing trends in reticulocyte count, reticulocyte hemoglobin, mean corpuscular hemoglobin, total hemoglobin (Hgb), and red blood cell count. In this Phase 1b/2a, open-label, multiple-ascending dose study (NCT05320198), we are assessing the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of DISC-0974 in patients with MF and anemia. Eligible participants include patients over 18 years of age with intermediate-2 or higher-risk MF and anemia. MF is required to be confirmed using the World Health Organization 2016 criteria. Anemia is defined per protocol as Hgb < 10 g/dL or transfusion dependence, as defined by the International Working Group for Myelofibrosis Research and Treatment (IWG-MRT). A stable dose of hydroxyurea and/or Janus kinase (JAK) inhibitor is allowed on trial. Major exclusion criteria include: liver iron concentration ≥ 7 mg/g dry weight; splenectomy; nutritional, genetic, infectious, or autoimmune causes of anemia. Dose escalation is based on a Bayesian optimal interval design with accelerated titration. Safety Review Committee assessments gate escalation decisions. Dosing occurs monthly for a total of 6 doses. Primary endpoints include safety and tolerability assessments of adverse events (AEs), clinical laboratory assessments, vital signs, physical examinations, and electrocardiograms. Secondary endpoints include anemia response as defined by the IWG-MRT, transfusion response as defined by a decrease of 50% in transfusion requirement over any 8-week period, standard PK parameters and PD metrics including serum hepcidin-25, iron, transferrin saturation, ferritin, and hematology biomarkers. All data are summarized using descriptive statistics. Initial data show a dose-related increase in pharmacokinetic parameters. DISC-0974 treatment led to dose-dependent reductions in serum hepcidin-25 and increases in serum iron levels. There have been no serious AEs or AEs leading to study withdrawal. Most AEs were mild, transient, and unrelated to DISC-0974. As of August 1, 2023, enrollment and dose escalation are ongoing. Safety, PK, and PD data from at least the first two cohorts will be presented.
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