The CD40 agonist antibody CP-870,893 enhances dendritic cell and B-cell activity and promotes anti-tumor efficacy in SCID-hu mice.

CD40 is a member of the TNF family of receptors that has been shown to play a crucial role in enhancing dendritic cell activity and fostering anti-tumor immune responses. In this study, we demonstrate the in vitro properties and in vivo efficacious activity of the CD40 agonist antibody, CP-870,893. CP-870,893 is a fully human, IgG2 antibody that selectively interacts with CD40 at a site distinct from its ligand-binding region with a KD of 0.4 nM. It enhances the expression of MHC class II, CD54, CD86, and CD23 on human B cells in vitro. CP-870,893 also enhances dendritic cell activity as evidenced by cytokine secretion (IL-12, IL-23, IL-8), the upregulation of CD86 and CD83, and the ability to prime T cells to secrete IFNγ. In SCID-beige mice, a single parenteral injection of CP-870,893 was therapeutically effective against several CD40(pos) human tumors (B-cell lymphoma, breast, colon, and prostate) indicating direct effects on tumor cell survival and/or growth. When mice were co-implanted with human T cells and dendritic cells, the activity of CP-870,893 against CD40(pos) tumors increased, and efficacy was also observed against CD40(neg) and CD40(low) tumors demonstrating the ability of CP-870,893 to enhance anti-tumor immune function in vivo. These studies suggest that CP-870,893 has the potential to be efficacious against a wide range of tumor types through both direct and immune-mediated effects.

Phase I evaluation of the safety, pharmacokinetics and pharmacodynamics of CP-481,715.

BACKGROUND AND OBJECTIVES: The chemokine receptor CCR1 is believed to play a role in several inflammatory diseases, primarily by promoting the migration of leukocytes through the endothelial barrier. Thus, a possible strategy for treating inflammatory diseases is inhibition of leukocyte infiltration by antagonising CCR1. Recently, CP-481,715 has been described as a potent and specific antagonist of CCR1. The aims of this study were to assess the safety, pharmacokinetics and pharmacodynamics of CP-481,715 along with drug interactions with ciclosporin. SUBJECTS AND METHODS: This was a phase I randomised, double-blind, placebo-controlled study with CP-481,715 in 78 healthy male volunteers. Subjects were administered escalating CP-481,715 doses of up to 3000 mg with food and after fasting in the single-dose study. In the drug interaction study, which was a single-dose, two-way crossover study, 12 subjects received a 300 mg dose of CP-481,715 as a suspension of polymorph A under fasted conditions, both with and without prior administration of ciclosporin. RESULTS AND CONCLUSIONS: All doses of CP-481,715 were well tolerated, with linear pharmacokinetics up to the 300 mg dose. The pharmacodynamic activity of CP-481,715 was detected ex vivo by demonstrating a dose-related and linear increase in the amount of macrophage inflammatory protein-1alpha, CCL3, required to induce CD11b upregulation. Analysis of vital signs indicated no consistent clinical effects, and statistical analysis of ECG characteristics demonstrated no significant prolongation of the corrected QT interval. A drug-drug interaction study with ciclosporin demonstrated that CP-481,715 clearance was decreased by ciclosporin, consistent with its ability to compete with P-glycoprotein. Phase II studies may be warranted to see if CP-481,715 exhibits efficacy in treating inflammatory diseases such as rheumatoid arthritis, multiple sclerosis or transplant rejection.

CCR1 antagonists for the treatment of autoimmune diseases.

Chemokines are 8- to 10-kDa proteins that regulate leukocyte infiltration into inflammatory sites. The therapeutic potential of inhibiting these proteins is supported by their increased expression in human diseases, numerous studies in animal models of disease and, in some cases, by human genetic association studies. These findings, combined with the ability of chemokines to interact with 7-transmembrane G protein-coupled receptors, render them attractive drug discovery targets. This article reviews the evidence that supports a role for the chemokine receptor CCR1 in the pathogenesis of autoimmune diseases, progress made in identifying low molecular-weight antagonists and the current status of agents undergoing clinical evaluation.

CCR1 antagonists: what have we learned from clinical trials.

The identification of chemokines and their receptors as potent mediators of leukocyte infiltration raised interest in the potential role of these proteins on disease pathogenesis. This is exemplified by the chemokine receptor, CCR1, which has been shown to be up-regulated in a number of human diseases, the implications of which have been suggested by animal models where inhibition of CCR1 or its ligands have shown beneficial effects. These data support the possibility that a CCR1 antagonist will provide therapeutic benefit to patients with inflammatory diseases. Over the last several years, several of these antagonists entered clinical trials, including CP-481,715 (Pfizer) and MLN3897 (Millennium) for rheumatoid arthritis, BX471 (Berlex / Scherring AG) for multiple sclerosis, and AZD-4818 (Astra-Zeneca) for COPD. This review will describe the evidence that supported the role of CCR1 in these diseases, the results from clinical trials, and provide perspectives on what has been learned from these trials for potential application / consideration to other studies with chemokine receptor antagonists.

CCR2 receptor blockade alters blood monocyte subpopulations but does not affect atherosclerotic lesions in apoE(-/-) mice.

OBJECTIVE: The CCR2 receptor plays a crucial role in monocyte recruitment and has been implicated as a contributing factor to atherosclerosis. CCR2 receptor deletion leads to significant inhibition of lesion development. Our objective was to determine if CCR2 receptor blockade with a small molecule would have a beneficial effect of decreasing established lesions. METHODS AND RESULTS: We demonstrated that CCR2 blockade had no significant effect on advanced lesions or the progression of fatty streaks. CCR2 blockade in mice resulted in elevations in plasma CCL2 levels and a significant reduction in the plasma Ly-6C(hi) subpopulations of monocytes expressing the CCR2 receptor. Neither CCL2 elevation nor margination of the Ly-6C(hi) population was observed in CCR2(-/-) mice. CONCLUSIONS: CCR2 receptor blockade with a small molecule antagonist at dose levels showing efficacy in several inflammatory models did not show a beneficial effect in murine models of atherosclerosis. Elevations in CCL2 and margination of Ly-6C(hi) cells demonstrate that the role of CCR2 in controlling monocyte levels goes beyond the control of monocyte emigration.

Essential role of CCR6 in directing activated T cells to the skin during contact hypersensitivity.

CCR6 is expressed in a number of dermatological inflammatory diseases. Here, we report that mice sensitized with the hapten oxazolone had increased numbers of CCR6+ T cells in the draining lymph nodes. Using CCR6-/- mice, we assessed the role of CCR6 on the development of contact hypersensitivity. After hapten sensitization and re-challenge, ear swelling in CCR6-/- animals was reduced 80% as compared with wild-type (WT) control mice. This decreased level of inflammation was not related to an inhibition in T-cell activation, because CCR6-/- lymph node cells from sensitized mice produced threefold higher levels of IFN-gamma in culture than cells from sensitized WT mice and, when these cells were directly injected into the site of hapten challenge, induced a robust inflammatory response. However, intravenous injection of CCR6-/- lymph node cells from sensitized mice were unable to prime naive mice to re-challenge whereas cells from primed WT mice were able to sensitize animals. These results suggest that CCR6 plays an important role in directing the trafficking of activated T cells into the skin and suggests that a CCR6 antagonist could be useful to treat skin-mediated inflammatory reactions.

CXCR3-dependent recruitment of antigen-specific T lymphocytes to the liver during murine cytomegalovirus infection.

Innate inflammatory events promoting antiviral defense in the liver against murine cytomegalovirus (MCMV) infection have been characterized. However, the mechanisms that regulate the selective recruitment of inflammatory T lymphocytes to the liver during MCMV infection have not been defined. The studies presented here demonstrate the expression of monokine induced by gamma interferon (IFN-gamma; Mig/CXCL9) and IFN-gamma-inducible protein 10 (IP-10/CXCL10) in liver leukocytes and correlate their production with the infiltration of MCMV-specific CD8 T cells into the liver. Antibody-mediated neutralization of CXCL9 and CXCL10 and studies using mice deficient in CXCR3, the primary known receptor for these chemokines, revealed that CXCR3-dependent mechanisms promote the infiltration of virus-specific CD8 T cells into the liver during acute infection with MCMV. Furthermore, CXCR3 functions augmented the hepatic accumulation of CD8 T-cell IFN-gamma responses to MCMV. Evaluation of protective functions demonstrated enhanced pathology that overlapped with transient increases in virus titers in CXCR3-deficient mice. However, ultimate viral clearance and survival were not compromised. Thus, CXCR3-mediated signals support the accumulation of MCMV-specific CD8 T cells that contribute to, but are not exclusively required for, protective responses in a virus-infected tissue site.

Piperazinyl CCR1 antagonists--optimization of human liver microsome stability.

The synthesis, biological activity, and pharmacokinetic profile of CCR1 antagonists are described.

The human specific CCR1 antagonist CP-481,715 inhibits cell infiltration and inflammatory responses in human CCR1 transgenic mice.

We previously described the in vitro characteristics of the potent and selective CCR1 antagonist, CP-481,715. In addition to being selective for CCR1 vs other chemokine receptors, CP-481,715 is also specific for human CCR1 (hCCR1), preventing its evaluation in classical animal models. To address this, we generated mice whereby murine CCR1 was replaced by hCCR1 (knockin) and used these animals to assess the anti-inflammatory properties of CP-481,715. Cells isolated from hCCR1 knockin mice were shown to express hCCR1 and migrate in response to both murine CCR1 and hCCR1 ligands. Furthermore, this migration is inhibited by CP-481,715 at dose levels comparable to those obtained with human cells. In animal models of cell infiltration, CP-481,715 inhibited CCL3-induced neutrophil infiltration into skin or into an air pouch with an ED50 of 0.2 mg/kg. CP-481,715 did not inhibit cell infiltration in wild-type animals expressing murine CCR1. In a more generalized model of inflammation, delayed-type hypersensitivity, CP-481,715 significantly inhibited footpad swelling and decreased the amount of IFN-gamma and IL-2 produced by isolated spleen cells from sensitized animals. It did not, however, induce tolerance to a subsequent challenge. These studies illustrate the utility of hCCR1 knockin animals to assess the activity of human specific CCR1 antagonists; demonstrate the ability of the CCR1 antagonist CP-481,715 to inhibit cell infiltration, inflammation, and Th1 cytokine responses in these animals; and suggest that CP-481,715 may be useful to modulate inflammatory responses in human disease.

Identification of a histamine H4 receptor on human eosinophils--role in eosinophil chemotaxis.

Eosinophils are recruited to sites of inflammation via the action of a number of chemical mediators, including PAF, leukotrienes, eotaxins, ECF-A and histamine. Although many of the cell-surface receptors for these mediators have been identified, histamine-driven chemotaxis has not been conclusively attributed to any of the three known histamine receptor subtypes, suggesting the possibility of a 4th histamine-responsive receptor on eosinophils. We have identified and cloned a novel G protein-coupled receptor (GPCR), termed Pfi-013, from an IL-5 stimulated eosinophil cDNA library which is homologous to the human histamine H3 receptor, both at the sequence and gene structure level. Expression data indicates that Pfi-013 is predominantly expressed in peripheral blood leukocytes, with lower expression levels in spleen, testis and colon. Ligand-binding studies using Pfi-013 expressed in HEK-293Galpha15 cells, demonstrates specific binding to histamine with a Kd of 3.28 +/- 0.76 nM and possesses a unique rank order of potency against known histaminergic compounds in a competitive ligand-binding assay (histamine > clobenpropit > iodophenpropit > thioperamide > R-alpha-methylhistamine > cimetidine > pyrilamine). We have therefore termed this receptor human histamine H4. Chemotaxis studies on isolated human eosinophils have confirmed that histamine is chemotactic and that agonists of the known histamine receptors (H1, H2, and H3) do not induce such a response. Furthermore, studies employing histamine-receptor antagonists have shown an inhibition of chemotaxis only by the H3 antagonists clobenpropit and thioperamide. Since these compounds are also antagonists of hH4 we postulate that the receptor mediating histaminergic chemotaxis is this novel histamine H4 receptor.

The discovery of structurally novel CCR1 antagonists derived from a hydroxyethylene peptide isostere template.

The present manuscript details the discovery and early fundamental structure-activity relationship studies involving compound 3, a novel hydroxyethylene peptide isostere derived molecule that provides micromolar inhibition of CCL3 binding to its receptor CCR1. Initial studies established this screening hit as a legitimate lead for further medicinal chemistry optimization.

Expression of rat I-TAC/CXCL11/SCYA11 during central nervous system inflammation: comparison with other CXCR3 ligands.

The chemokines are a large gene superfamily with critical roles in development and immunity. The chemokine receptor CXCR3 appears to play a major role in the trafficking of activated Th1 lymphocytes. There are at least three major ligands for CXCR3: mig/CXCL9, IP-10/CXCL10 and I-TAC/CXCL11, and of these three ligands, CXCL11 is the least well-characterized. In this study, we have cloned a rat ortholog of CXCL11, evaluated its function, and examined its expression in the Th-1-mediated disease, experimental autoimmune encephalomyelitis (EAE) in the rat. Based on its predicted primary amino-acid sequence, rat I-TAC/CXCL11 was synthesized and shown to induce chemotaxis of activated rat T lymphocytes in vitro and the in vivo migration of T lymphocytes when injected into the skin. I-TAC/CXCL11 expression, as determined by RT-PCR, increased in lymph node and spinal cord tissue collected from rats in which EAE had been actively induced, and in spinal cord tissue from rats in which EAE had been passively induced. The kinetics of expression were similar to that of CXCR3 and IP-10/CXCL10, although expression of both CXCR3 and IP-10/CXCL10 was more intense than that of I-TAC/CXCL11 and increased more rapidly in both lymph nodes and the spinal cord. Only minor levels of expression of the related chemokine mig/CXCL9 were observed. Immunohistochemistry revealed that the major cellular source of I-TAC/CXCL11 in the central nervous system (CNS) during EAE is likely to be the astrocyte. Together, these data indicate that I-TAC/CXCL11 is expressed in the CNS during the clinical phase of EAE. However, the observation that I-TAC/CXCL11 is expressed after receptor expression is detected suggests that it is not essential for the initial migration of CXCR3-bearing cells into the CNS.

Potent small molecule CCR1 antagonists.

The present manuscript details structure-activity relationship studies of lead structure 1, which led to the discovery of CCR1 antagonists >100-fold more potent than 1.

Novel CCR1 antagonists with improved metabolic stability.

The synthesis, biological activity, and pharmacokinetic profile of novel CCR1 antagonists are described.

CP-481,715, a potent and selective CCR1 antagonist with potential therapeutic implications for inflammatory diseases.

The chemokines CCL3 and CCL5, as well as their shared receptor CCR1, are believed to play a role in the pathogenesis of several inflammatory diseases including rheumatoid arthritis, multiple sclerosis, and transplant rejection. In this study we describe the pharmacological properties of a novel small molecular weight CCR1 antagonist, CP-481,715 (quinoxaline-2-carboxylic acid [4(R)-carbamoyl-1(S)-(3-fluorobenzyl)-2(S),7-dihydroxy-7-methyloctyl]amide). Radiolabeled binding studies indicate that CP-481,715 binds to human CCR1 with a Kd of 9.2 nm and displaces 125I-labeled CCL3 from CCR1-transfected cells with an IC50 of 74 nm. CP-481,715 lacks intrinsic agonist activity but fully blocks the ability of CCL3 and CCL5 to stimulate receptor signaling (guanosine 5'-O-(thiotriphosphate) incorporation; IC50 = 210 nm), calcium mobilization (IC50 = 71 nm), monocyte chemotaxis (IC50 = 55 nm), and matrix metalloproteinase 9 release (IC50 = 54 nm). CP-481,715 retains activity in human whole blood, inhibiting CCL3-induced CD11b up-regulation and actin polymerization (IC50 = 165 and 57 nm, respectively) on monocytes. Furthermore, it behaves as a competitive and reversible antagonist. CP-481,715 is >100-fold selective for CCR1 as compared with a panel of G-protein-coupled receptors including related chemokine receptors. Evidence for its potential use in human disease is suggested by its ability to inhibit 90% of the monocyte chemotactic activity present in 11/15 rheumatoid arthritis synovial fluid samples. These data illustrate that CP-481,715 is a potent and selective antagonist for CCR1 with therapeutic potential for rheumatoid arthritis and other inflammatory diseases.