CP-105696 (Pfizer 105696)

Leveraging model-based study designs and serial micro-sampling techniques to understand the oral pharmacokinetics of the potent LTB4 inhibitor, CP-105696, for mouse pharmacology studies

1. Leukotriene B4 (LTB4) is a proinflammatory mediator important in the progression of a number of inflammatory diseases. Preclinical models can explore the role of LTB4 in pathophysiology using tool compounds, such as CP-105696, that modulate its activity. To support preclinical pharmacology studies, micro-sampling techniques and mathematical modeling were used to determine the pharmacokinetics of CP-105696 in mice within the context of systemic inflammation induced by a high-fat diet (HFD). 2. Following oral administration of doses > 35 mg/kg, CP-105696 kinetics can be described by a one-compartment model with first order absorption. The compound's half-life is 44-62 h with an apparent volume of distribution of 0.51-0.72 L/kg. Exposures in animals fed an HFD are within 2-fold of those fed a normal chow diet. Daily dosing at 100 mg/kg was not tolerated and resulted in a >20% weight loss in the mice. 3. CP-105696's long half-life has the potential to support a twice weekly dosing schedule. Given that most chronic inflammatory diseases will require long-term therapies, these results are useful in determining the optimal dosing schedules for preclinical studies using CP-105696.

The in vitro and in vivo pharmacologic activity of the potent and selective leukotriene B4 receptor antagonist CP-105696

CP-105696, (+)-1-(3S,4R)-[3-(4-phenyl-benzyl)-4-hydroxy-chroman-7-yl] cyclopentane carboxylic acid, is a structurally novel, selective and potent leukotriene B4 (LTB4) receptor antagonist. In vitro, CP-105696 inhibited [3H]LTB4 (0.3 nM) binding to high-affinity LTB4 receptors on human neutrophils with an IC50 value of 8.42 +/- 0.26 nM. Scatchard analyses of [3H]LTB4 binding to these high-affinity receptors indicated that CP-105696 acted as a noncompetitive antagonist. CP-105696 inhibited human neutrophil chemotaxis mediated by LTB4 (5 nM) in a noncompetitive manner with an IC50 value of 5.0 +/- 2.0 nM. Scatchard analyses of [3H]LTB4 binding to low-affinity receptors on neutrophils indicated that CP-105696 acted as a competitive antagonist at this receptor, and inhibition of LTB4-mediated CD11b upregulation on human neutrophils was competitively inhibited by CP-105696 (pA2 = 8.03 +/- 0.19). CP-105696 at 10 microM did not inhibit either human neutrophil chemotaxis or CD11b upregulation mediated through alternate (i.e., C5a, IL-8, PAF) G-protein coupled chemotactic factor receptors. In isolated human monocytes, LTB4 (5 nM)-mediated Ca++ mobilization was inhibited by CP-105696 with an IC50 value of 940 +/- 70 nM. In vivo, after oral administration, CP-105696 blocked neutrophil and eosinophil infiltration in cavine dermis mediated by either LTB4 or arachidonic acid with ED50 values of 0.3 +/- 0.1 mg/kg. 12(R)-Hydroxyeicosatetraenoic acid-mediated neutrophil infiltration was blocked by 76.4 +/- 14.8% at 3 mg/kg.(ABSTRACT TRUNCATED AT 250 WORDS)

Antagonizing leukotriene B4 receptors delays cardiac allograft rejection in mice

Background: Allograft rejection is a cellular immunological/inflammatory response that is, in part, directed by potent proinflammatory mediators. This study was designed to test the hypothesis that leukotriene B4 (LTB4) may have a role in graft rejection and that LTB4 receptor antagonists may be clinically useful in the treatment of allograft rejection.
Methods: We evaluated the potent and selective LTB4 receptor antagonist CP-105696 in a murine heterotopic cardiac allograft model with oral dosing daily for 28 days or in an induction protocol (day -1 to day 3).
Results: At a dose of 50 mg/kg/day (28 days), B10.BR (H2k) allografts transplanted into C57Bl/6 (H2b) recipients were significantly protected, as reflected by the mean survival time versus control grafts (27+/-20 days [n=10] vs. 12+/-6 days [n=14]; P=0.0146). Using an induction protocol (day -1 to day 3), CP-105696 at 100 mg/kg/day significantly prolonged allograft survival (33+/-23 days [n=9]; P=0.0026), but CP-105696 at 10 mg/kg/day did not (18+/-16 days [n=8]; P=0.1433). Syngeneic grafts survived indefinitely (n=11). Immunohistological evaluation of allografts at rejection revealed a mononuclear cell infiltrate composed primarily of CD3+ and CD11b+ (Mac-1+) cells, which were infrequent in syngeneic grafts. Allografts from mice treated with CP-105696 at 50 or 100 mg/kg/day demonstrated a selective reduction in beta2-integrin (Mac-1) expression on monocytes/macrophages, as demonstrated by CD11b staining density compared with allograft controls.
Conclusions: The results suggest that LTB4 or other potential ligands for LTB4 receptors may be important mediators of allograft rejection and support the clinical evaluation of LTB4 receptor antagonists in human organ transplantation.

Pharmacokinetics and pharmacodynamics of the leukotriene B4 receptor antagonist CP-105,696 in man following single oral administration

Aims: CP-105,696, (+)-1-(3S,4R)-[3-(4-phenylbenzyl)-4-hydroxy-chroman-7-yl] cyclopropane carboxylic acid is a potent, novel LTB4 receptor antagonist advanced to clinical trials to determine its efficacy in inflammatory diseases. The pharmacokinetics and pharmacodynamics of CP-105,696 were investigated in healthy male volunteers following oral administration of single doses of 5 to 640 mg.
Methods: Forty-eight subjects participated in a randomized, double-blind, parallel group study. Plasma and urine concentrations of CP-105,696 were determined at intervals after drug administration. As an indication of LTB4 receptor antagonism following oral administration of CP-105,696, the inhibiton of LTB4-induced upregulation of the neutrophil cell surface complement receptor (CR3), CD11b/CD18, was monitored at 4 h following drug administration using an ex vivo whole blood flow cytometry assay.
Results: Cmax and AUC(0, infinity) increased in a dose-related manner. Respective mean Cmax values were 0.54 to 30.41 microg ml(-1) following doses of 5 to 640 mg. Respective mean AUC(0, infinity) values were 1337 to 16819 microg ml(-1) h for the 40 to 640 mg dose groups. Plasma concentrations declined in a monoexponential manner, with terminal elimination half-lives ranging from 289 to 495 h. Group mean terminal elimination half-lives were dose-independent. Urinary excretion of unchanged drug accounted for < 1% of the administered dose. A linear relationship was observed between CP-105,696 plasma concentrations and inhibition of LTB4-mediated CD11b upregulation on human neutrophils in whole blood. CP-105,696 plasma concentrations of 5-6 microg ml(-1) were necessary to elicit a two-fold shift to the right of the LTB4 concentration response curve for CD11b upregulation.
Conclusions: These studies demonstrate pharmacologically significant LTB4-receptor antagonism following a single dose of CP-105,696 and pharmacokinetics consistent with once-daily dosing.

In vitro and in vivo effects of leukotriene B4 antagonism in a primate model of asthma

To test the hypothesis that leukotriene (LT) B4 antagonists may be clinically useful in the treatment of asthma, CP-105,696 was evaluated in vitro, using chemotaxis and flow cytometry assays, and in vivo, using a primate asthma model. CP-105,696 inhibited LTB4-mediated monkey neutrophil chemotaxis (isolated cells, LTB4 = 5 nM) and CD11b upregulation (whole blood, LTB4 = 100 nM) with IC50 values of 20 nM and 16.5 microM, respectively. Using a modification of a previously described in vivo protocol (Turner et al. Am. J. Respir. Crit. Care Med. 1994. 149: 1153-1159), we observed that treatment with CP-105,696 inhibited the acute increase in bronchoalveolar lavage (BAL) levels of IL-6 and IL-8 by 56.9 +/- 13.2% and 46.9 +/- 14.5%, respectively, 4 h after challenge with Ascaris suum antigen (Ag). CP-105,696 tended to reduce the increase in BAL protein levels 0.5 h after Ag challenge by 47.5 +/- 18.3%, but this was not statistically significant. In addition, CP-105,696 prevented the significant 11-fold increase in airway responsiveness to methacholine after multiple Ag challenge. These results suggest that LTB4 partially mediates acute and chronic responses to antigen in an experimental primate asthma model and support the clinical evaluation of LTB4 antagonists in human asthma.