Background and purpose: The p38 kinase regulates the release of proinflammatory cytokines including tumour-necrosis factor-a (TNFa) and is regarded as a potential therapeutic target in rheumatoid arthritis (RA). Using the novel p38 inhibitor Org 48762-0, we investigated the therapeutic potential of p38 inhibition and compared this to anti-mouse (m)TNFa antibody treatment in murine collagen-induced arthritis (CIA). Experimental approach: Pharmacological profiles of Org 48762-0 were characterized in kinase assays, cellular assays and in lipopolysaccharide (LPS)-induced inflammation in mice. The effects of Org 48762-0 and of mTNFa-neutralization on established arthritis were examined in murine CIA. Key results: Org 48762-0 potently inhibited p38a kinase with a high degree of kinase selectivity. In cellular assays, Org 48762-0 reduced LPS-induced TNFa release. Oral administration of Org 48762-0 in mice showed drug-like pharmacokinetic properties and inhibited LPS-induced cytokine production. These pharmacological characteristics of Org 48762-0 prompted a comparison of therapeutic efficacy with mTNFa-neutralization in CIA. Org 48762-0 and anti-mTNFa antibody treatment equally inhibited development of arthritis when evaluated macroscopically. Radiological analyses revealed protection against bone damage for both treatments, although statistical difference was reached with Org 48762-0 treatment only. Further, micro-computed tomographical and histopathological analyses confirmed the protective effects of Org 48762-0 on joint damage. Conclusions and implications: Pharmacological targeting of p38 kinase provided good protection against joint tissue damage in CIA. In our experiments, neutralization of mTNFa produced less prominent suppression of bone damage. Our data suggest a therapeutic potential for selective and potent p38 inhibitors in RA.

Human CXCR2 (hCXCR2) has been implicated in diverse inflammatory diseases. When roles of this receptor studied in animal models are extrapolated into men, large species differences in expression of the receptor and its ligands must be considered. These differences seriously weaken conclusions toward the role of hCXCR2 in the development of human diseases. It furthermore hampers straightforward testing of CXCR2 antagonists, especially when compounds discriminate between human and other species' receptors. Using gene targeting in embryonic stem cells, a hCXCR2 knockin mouse strain was generated in which endogenous murine CXCR2 (mCXCR2) sequences are replaced by the hCXCR2 gene. Correct targeting and expression on neutrophils were confirmed by Southern blot and immunohistochemical analyses. A phenotypic analysis of the hCXCR2 knockin mice, in comparison to wild-type and CXCR2 knockout mice, confirmed proper function of the hCXCR2 gene. In vivo migratory responses of neutrophils were intact in hCXCR2 knockin mice. Finally, an experiment with a CXCR2 antagonist demonstrated that the knockin model is indeed useful for in vivo evaluation of low-molecular weight compounds. In conclusion, our data unequivocally show that hCXCR2 can functionally replace mCXCR2, making this an attractive model to test novel pharmaceuticals designed to antagonize human CXCR2 in vivo.

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Simvastatin and fenofibrate are frequently co-prescribed at staggered intervals for the treatment of dyslipidemia. Since a drug-drug interaction has been reported when the two drugs are given simultaneously, it is of clinical interest to know whether the interaction differs between simultaneous and staggered combinations. A study, assessing the impact of both combinations on the interaction, was conducted with 7-day treatment regimens using simvastatin 40 mg and fenofibrate 145 mg: (A) simvastatin only (evening), (B) simvastatin and fenofibrate (both in evening), and (C) simvastatin (evening) and fenofibrate (morning). Eighty-five healthy subjects received the respective treatments in a randomized, 3-way cross-over study. The pharmacokinetics of simvastatin and the active metabolite simvastatin acid were determined. There was a limited reduction in the AUC0-24h of simvastatin acid of 21 and 29% for simultaneous and staggered combination, respectively. The geometric mean AUC0-24h ratio of simvastatin acid for the two combined dosing regimens (B/C) and 90% confidence interval were 111% (102-121). The interaction apparently had no impact on lipid markers. The findings imply that the observed pharmacokinetic interaction is unlikely clinically relevant, and support the combined use of simvastatin and fenofibrate not only given at staggered interval but also given simultaneously.

1. The metabolism of dydrogesterone was investigated in human liver cytosol (HLC) and human liver microsomes (HLM). Enzymes involved in dydrogesterone metabolism were identified and their relative contributions were estimated. 2. Dydrogesterone clearance was clearly higher in HLC compared to HLM. The major active metabolite 20α-dihydrodydrogesterone (20α-DHD) was only produced in HLC. 3. The formation of 20α-DHD by cytosolic aldo-keto reductase 1C (AKR1C) was confirmed with isoenzyme-specific AKR inhibitors. 4. Using recombinantly expressed human cytochrome P450 (CYP) isoenzymes, dydrogesterone was shown to be metabolically transformed by CYP3A4 and CYP2C19. 5. A clear contribution of CYP3A4 to microsomal metabolism of dydrogesterone was demonstrated with HLM and isoenzyme-specific CYP inhibitors, and confirmed by a significant correlation between dydrogesterone clearance and CYP3A4 activity. 6. Contribution of CYP2C19 was shown to be clearly less than CYP3A4 and restricted to a small group of human individuals with very high CYP2C19 activity. Therefore, it is expected that CYP2C19 genetic variations will not affect dydrogesterone pharmacokinetics in man. 7. In conclusion, dydrogesterone metabolism in the liver is dominated primarily by cytosolic enzymes (particularly AKR1C) and secondarily by CYP3A4, with the former exclusively responsible for 20α-DHD formation.

Background: Covalent Bruton’s tyrosine kinase (BTK) inhibitors such as ibrutinib are approved for treating patients with B-cell malignancies, but their long-term efficacy is limited due to their toxicity (i.e., on-target and off-target inhibition of kinases) and acquired resistance (i.e., BTK C481 mutation). AS-1763 is a potent, highly selective, orally active, non-covalent inhibitor of both wild-type and C481S-mutant BTK. AS-1763 strongly inhibits the proliferation of B cell lymphoma cell line OCI-LY10 carrying wild-type and C481S-mutatant BTK in vitro and in vivo. AS-1763, therefore, is expected to be a promising BTK inhibitor for patients who have failed or are intolerant to a covalent BTK inhibitor. This study reports the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) in healthy volunteers who received single, ascending doses of AS-1763 in an alternating cohort design. Methods: This is a first-in-human, double-blind, placebo-controlled, randomized, single-center, single-ascending dose Phase I study of AS-1763. Two cohorts of 8 healthy male and female subjects were alternately dosed with AS-1763 (5, 25, 100, 300, 500, and 600 mg) or placebo orally under fasted condition. Intensive blood sampling for PK (up to 72 h) and PD (up to 24 h) was conducted before and post-dosing to allow a successful PK/PD correlation. For the PD assessment, whole blood was stimulated ex vivo with an anti-IgD antibody, and CD69 upregulation on B cells was assessed by flow cytometry. Results: Single doses of up to 600 mg AS-1763 were well-tolerated. No serious adverse events (AE) were reported during the trial. All treatment-emerged AEs reported were of mild intensity and showed no apparent dose-relationship in frequency. No clinically relevant changes from baseline were observed in all other safety parameters assessed (clinical laboratory, ECGs, vital signs, or physical examinations). AS-1763 was rapidly absorbed with a median time to maximum plasma concentrations (tmax) of 0.5-2.0 h post-dose and thereafter gradually decreased with mean elimination half-time (t1/2) of 8.5-12 h. Overall, mean plasma concentrations of AS-1763 increased with dose up to 500 mg. AS-1763 at 100 mg or higher induced >80% inhibition of B cell activation (%CD69 upregulation in naïve B cells normalized to baseline) at 1-2 h post-dose and the duration of inhibitory effect increased with dose. PK/PD analysis demonstrated that the IC50 and IC90 (90% CI) values for inhibition of CD69 upregulation in naïve B cells were 10.5 ng/mL (9.7-11.2 ng/mL) and 34.6 ng/mL (28.8-40.4 ng/mL), respectively. Conclusions: Single doses of AS-1763 up to 600 mg were well-tolerated and showed encouraging pharmacodynamics (inhibition of CD69 upregulation) with a favorable safety profile. The data support continued development of AS-1763 for patients with B-cell malignancies. Citation Format: Akinori Arimura, Kyoko Miyamoto, Maria Velinova, Marieke van den Dobbelsteen, Katsuhiro Mihara, Robert M. Miller, Masaaki Sawa. Safety, pharmacokinetics, and pharmacodynamics of AS-1763, a highly selective, orally bioavailable, non-covalent BTK inhibitor, in healthy volunteers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT137.