CXCR4 Chemokine Receptor Antagonists Research Articles

Efficacy and safety of a reduced dose of plerixafor in combination with granulocyte colony-stimulating factor in healthy haploidentical stem cell donors.

Implementation of the technique of immunomagnetic selection requires the procurement of a large number of CD34+ cells from haploidentical donors within a single apheresis procedure. The release of stem cells with granulocyte colony-stimulating factor (G-CSF) alone is unsatisfactory in a number of donors, and plerixafor, a CXCR4 chemokine receptor antagonist, could be used as an additional mobilization agent. The aim of our study was to examine whether a lower dose of plerixafor (0.12 mg/kg) can provide sufficient increase in CD34+ cells in the peripheral blood of allogeneic healthy donors in comparison with a historical control group. In addition, we assessed the risk of inability to provide the recipient with a transplant containing the optimal dose of 8-10 × 106 CD34+ cells/kg body weight of the recipient. In a prospective, single-arm study, we examined the results of 105 mobilizations in healthy adult haploidentical donors with G-CSF and plerixafor at a dose of 0.12 mg/kg. The historical control group consisted of 106 mobilizations with G-CSF and plerixafor at 0.24 mg/kg. The median increase in the number of CD34+ cells from day 4 to day 5 of mobilization was 69 cells/μl (range, 28-240) versus 77 cells/μl (24-217) in the groups of 0.12 and 0.24 mg/kg of plerixafor, respectively (p-value 0.255). The apheresis products contained a median of 14.4 × 106 /kg recipient body weight CD34+ cells versus 12.9 × 106 /kg in the groups that received 0.12 and 0.24 mg/kg of plerixafor, respectively (p-value 0.118). The obtained differences were not significant, which means the application of a decreased dose of plerixafor did not affect the results of mobilization. The obtained differences in collection were not significant, and thus the application of a decreased dose of plerixafor did not affect the results of mobilization.

Oncostatin M Is a Novel Niche Factor That Restrains Hematopoietic Stem Cell Mobilization in Response to G-CSF and CXCR4 Antagonist Plerixafor

Granulocyte colony-stimulating factor (G-CSF) and the CXCR4 chemokine receptor antagonist Plerixafor are used to mobilize hematopoietic stem and progenitor cells (HSPC). However, in the autologous setting, prior chemotherapy and radiotherapy impair HSPC mobilizing response to G-CSF and Plerixafor thereby precluding autologous HSC transplantation. We now demonstrate in mice that oncostatin M (OSM) production in the bone marrow (BM) is dramatically increased in response to G-CSF and that OSM counteracts the mobilizing effect of G-CSF and Plerixafor indirectly through the BM stroma. Indeed, by immunohistochemistry, a 4-day G-CSF treatment strongly increased OSM protein expression in cell clusters containing F4/80+ macrophages in the endosteal and central region of the mobilized BM. OSM concentration was 7-fold higher in BM fluids of G-CSF mobilized mice compared to control mice as measured by ELISA. To investigate OSM effects on HSPC mobilization, C57BL/6 mice (WT) and mice lacking the OSM receptor gene (OSMR-/-) were treated with 125 μg/kg human G-CSF bidaily for 2-6 days and/or Plerixafor (10 mg/kg) one hour before harvest. Absence of OSMR increased HSPC mobilization with a 4-fold increase in colony forming cells (CFC), phenotypic Lin-Kit+Sca1+ HSPC (LKS+ cells) and LKS+Flt3-CD48-CD150+ HSC into the blood at days 2 and 4 of G-CSF treatment and increased accumulation of HSPC and HSC in the spleen of OSMR-/- mice at day 6 of G-CSF treatment. In a competitive repopulation assay with serial dilutions of mobilized blood, deletion of OSMR gene enhanced ≈4-fold mobilization of functional reconstituting HSC in response to G-CSF as shown by Poisson's distribution analysis. HSPC mobilization in response to Plerixafor was also significantly enhanced with a doubling of CFC, HSPC and HSC into the blood of OSMR-/- mice compared to WT. OSMR gene deletion also significantly enhanced HSPC mobilization (3-fold) in response to G-CSF plus Plerixafor combination, the most effective mobilization regimen currently approved. To further demonstrate that endogenous OSM restrains HSPC mobilization in response to G-CSF, we produced a recombinant mouse OSM-trap, a dimeric protein chimera made of the extracellular domain of mouse OSMR and mouse gp130 fused with a mutant Fc fragment of mouse IgG2a. Co-administration of this OSM-trap together with G-CSF also increased HSPC and HSC mobilization into the blood in response to G-CSF compared to mice treated with G-CSF and control trap construct. This negative effect of endogenous OSM on HSPC mobilization was indirectly mediated by BM stromal cells. qRT-PCR on BM myeloid and stromal cells sorted from steady-state or mobilized mice showed that Osm mRNA is mostly expressed by CD11b+F4/80+CD169+VCAM1+ macrophages and CD11b+F4/80-Ly6G+ neutrophils. In sharp contrast, Osmr mRNA was undetectable in any sorted BM leukocyte population, but abundantly expressed by CD45-Lin-CD31+Sca1+CD105+ endothelial and CD45-Lin-CD31-CD51+PDGFRα+/-Sca-1+/- mesenchymal progenitor cells. OSMR protein was expressed by vascular beds in the BM as detected by IHC. Confirming the indirect effect of OSM, we found that recombinant OSM had no effect on HSPC chemotaxis in response to CXCL12, or HSPC adhesion to immobilized VCAM-1 or selectins in vitro. However, HSPC freshly isolated from the BM of OSMR-/- mice had enhanced chemotaxis in response to CXCL12 compared to HSPC isolated from WT mice. In conclusion, G-CSF increases OSM expression in the BM, and this appears to restrain HSPC mobilization in response to G-CSF via OSMR-expressing endothelial and mesenchymal cells that decreases HSPC responsiveness to CXCL12 gradient. Disclosures Winkler: GlycoMimetics: Patents & Royalties. Levesque:GlycoMimetics: Equity Ownership.

Structure-based exploration and pharmacological evaluation of N-substituted piperidin-4-yl-methanamine CXCR4 chemokine receptor antagonists

Using the available structural information of the chemokine receptor CXCR4, we present hit finding and hit exploration studies that make use of virtual fragment screening, design, synthesis and structure-activity relationship (SAR) studies. Fragment 2 was identified as virtual screening hit and used as a starting point for the exploration of 31 N-substituted piperidin-4-yl-methanamine derivatives to investigate and improve the interactions with the CXCR4 binding site. Additionally, subtle structural ligand changes lead to distinct interactions with CXCR4 resulting in a full to partial displacement of CXCL12 binding and competitive and/or non-competitive antagonism. Three-dimensional quantitative structure-activity relationship (3D-QSAR) and binding model studies were used to identify important hydrophobic interactions that determine binding affinity and indicate key ligand-receptor interactions.

Lower Doses of Plerixafor Use Is Sufficient to Effectively Mobilize PBSC (Peripheral Blood Hematopoetic Stem Cells) When Compared to Standard Administration

Background: Plerixafor (CXCR4 chemokine receptor antagonist), is indicated to mobilize hematopoietic stem cells (HSCs) to the peripheral blood for collection and subsequent autologous transplantation in patients who are poor mobilizers. In this retrospective analysis, we compared the efficacy of plerixafor 0.24 mg/kg by subcutaneous (SC) injection (1-2 doses) versus plerixafor (3-4 doses) 0.24 mg/kg by SC injection in terms of their effect on the hematopoietic recovery in hematopoietic cell transplantation (HCT).Methods: We retrospectively reviewed the peripheral blood stem cell (PBSC) collections of 40 consecutive lymphoma and multiple myeloma patients who underwent autologous HCT, who had previously mobilized poorly and were given plerixafor for mobilization. Twenty-six patients received 1-2 doses of plerixafor and 14 patients received 3-4 doses. All patients gave written informed consent for the procedure. Successful engraftment time was defined as neutrophils >0.5x 109 cells/L, platelets>20 x109 cells/L for three consecutive days. SPSSincver. 20 is used for statistics.Results: All of the 40 patients were mobilized promptly after plerixafor administration without any problem. The mean amount of autologous CD34+ PBSC was 3,8 x 10(6)/kg versus 3,2 x 10(6)/kg, for 1-2 doses of plerixafor administration ve3-4 doses, respectively(p=0,4). Median times to the neutrophil engraftment to >0,5x 109/L were 12 and 10 days for the 1-2 doses and 3-4 doses, respectively (p=0,2). Additionally, median times to the platelet engraftment to >20x 109/L were 14 and 15 days for the 1-2 doses and 3-4 doses, respectively (p=0,6).Conclusions: These data show that the lower doses, i.e. 1-2 days of plerixafor administration evaluated in this study are sufficient to mobilize HSCs. This retrospective comparison suggest that larger prospective studies comparing two days vs. four days of plerixafor should be performed in order to further elucidate the role of two days of plerixafor use in HSC mobilization, and hence would a relatively cost effective way of mobilization in poor mobilizing patients. DisclosuresNo relevant conflicts of interest to declare.

CXCR4 chemokine receptor antagonists: nickel(ii) complexes of configurationally restricted macrocycles

Tetraazamacrocyclic complexes of transition metals provide useful units for incorporating multiple coordination interactions into a single protein binding molecule. They can be designed with available sites for protein interactions via donor atom-containing amino acid side chains or labile ligands, such as H(2)O, allowing facile exchange. Three configurationally restricted nickel(II) cyclam complexes with either one or two macrocyclic rings were synthesised and their ability to abrogate the CXCR4 chemokine receptor signalling process was assessed (IC(50) = 8320, 194 and 14 nM). Analogues were characterised crystallographically to determine the geometric parameters of the acetate binding as a model for aspartate. The most active nickel(II) compound was tested in several anti-HIV assays against representative viral strains showing highly potent EC(50) values down to 13 nM against CXCR4 using viruses, with no observed cytotoxicity (CC(50) > 125 μM).

Plerixafor

Plerixafor (Mozobil®) is a CXCR4 chemokine receptor antagonist that is indicated for use in combination with granulocyte colony-stimulating factor (G-CSF) to mobilize stem cells to the peripheral blood for collection and subsequent autologous stem-cell transplantation in patients who have non-Hodgkin's lymphoma (NHL) or multiple myeloma (MM) [US] and in patients who have lymphoma or MM and are poor mobilizers (EU). This article reviews the clinical efficacy and tolerability of subcutaneous plerixafor for stem-cell mobilization in patients with lymphoma or MM, as well as summarizing its pharmacological properties. Pharmacoeconomic analyses of plerixafor and decision-making algorithms intended to optimize its use are also discussed. Plerixafor plus G-CSF mobilized stem cells more efficiently than placebo plus G-CSF in adults with NHL or MM, according to the results of two randomized, double-blind, multicentre trials. In these trials, significantly more plerixafor plus G-CSF recipients than placebo plus G-CSF recipients reached primary apheresis targets in significantly fewer apheresis days. In the trial in patients with NHL, significantly more plerixafor plus G-CSF than placebo plus G-CSF recipients proceeded to transplantation. Results of compassionate-use studies in patients with lymphoma or MM demonstrated that plerixafor plus G-CSF successfully mobilized stem cells in the majority of patients who were poor mobilizers (i.e. sufficient CD34+ cells had not been collected during apheresis or apheresis had not occurred because of low peripheral blood CD34+ cell counts). Results of compassionate-use studies and additional studies in patients with lymphoma or MM also demonstrated that plerixafor plus G-CSF successfully mobilized stem cells in predicted poor mobilizers, such as heavily pretreated patients considered to be at high risk of mobilization failure. In addition, a small study showed mobilization with pre-emptive plerixafor to be effective. Subcutaneous plerixafor was generally well tolerated during stem-cell mobilization in patients with NHL or MM; the most commonly occurring treatment-related adverse events in plerixafor plus G-CSF recipients included injection-site reactions and gastrointestinal adverse events. Preliminary results of a US cost-effectiveness analysis suggest that plerixafor plus G-CSF is a cost-saving option compared with cyclophosphamide plus G-CSF. A retrospective US cost analysis found no significant difference between plerixafor plus G-CSF and cyclophosphamide plus G-CSF recipients in the median total cost of initial mobilization, suggesting that the cost of plerixafor may be offset by increased utilization of other resources in patients receiving alternative mobilization regimens. Additional cost analyses examined the use of pre-emptive plerixafor; institutions have developed decision-making algorithms, mainly relating to the use of pre-emptive plerixafor, to help optimize its use. In conclusion, plerixafor is a valuable stem-cell mobilizer for use in combination with G-CSF in patients with lymphoma or MM, particularly in patients who are poor mobilizers or predicted poor mobilizers.

Novel strategies for blood stem cell mobilization: special focus on plerixafor

Introduction:More than 98% of autologous stem cell transplants are now performed with the support of mobilized blood stem cells, and the proportion of allogeneic blood stem cell transplants has risen to more than 70%. Blood stem cell mobilization strategies are therefore important components of all transplant programs.Areas covered:Stem cell mobilization strategies are evaluated based on current literature, with special focus on the use of plerixafor, a CXCR4 chemokine receptor antagonist. Mobilization methods in autologous settings include the use of G-CSF alone or following chemotherapy (chemomobilization), and the use of G-CSF alone in allogeneic transplants. A combination of G-CSF + plerixafor has been shown to be effective in patients who have failed a previous mobilization. This combination has also been found to be superior to G-CSF alone in Phase III studies in myeloma and non-Hodgkin lymphoma patients as the first-line mobilization.Expert opinion:Addition of plerixafor to chemomobilization or G-CSF mobilization may be more cost-effective than its routine use, and it is worth considering in predicted or proven poor mobilizers. Novel mobilization strategies have allowed more successful stem cell collection in autologous setting, although the effect of plerixafor on graft content and long-term patient outcomes needs further investigation.

Discovery of Novel Small Molecule Orally Bioavailable C−X−C Chemokine Receptor 4 Antagonists That Are Potent Inhibitors of T-Tropic (X4) HIV-1 Replication

The redesign of azamacrocyclic CXCR4 chemokine receptor antagonists resulted in the discovery of novel, small molecule, orally bioavailable compounds that retained T-tropic (CXCR4 using, X4) anti-HIV-1 activity. A structure-activity relationship (SAR) was determined on the basis of the inhibition of replication of X4 HIV-1 NL4.3 in MT-4 cells. As a result of lead optimization, we identified (S)-N'-((1H-benzo[d]imidazol-2-yl)methyl)-N'-(5,6,7,8-tetrahydroquinolin-8-yl)butane-1,4-diamine (AMD070) 2 as a potent and selective antagonist of CXCR4 with an IC(50) value of 13 nM in a CXCR4 125I-SDF inhibition binding assay. Compound 2 inhibited the replication of T-tropic HIV-1 (NL4.3 strain) in MT-4 cells and PBMCs with an IC(50) of 2 and 26 nM, respectively, while remaining noncytotoxic to cells at concentrations exceeding 23 microM. The pharmacokinetics of 2 was evaluated in rat and dog, and good oral bioavailability was observed in both species. This compound represents the first small molecule orally bioavailable CXCR4 antagonist that was developed for the treatment of HIV-1 infection.

CXCR4 Chemokine Receptor Antagonists from Ultra-rigid Metal Complexes Profoundly Inhibit HIV-1 Replication, and also AMD3100-resistant Strains

CXCR4 Chemokine Receptor Antagonists from Ultra-rigid Metal Complexes Profoundly Inhibit HIV-1 Replication, and also AMD3100-resistant Strains

CXCR4 chemokine receptor antagonists: perspectives in SCLC

Small-cell lung cancer (SCLC) is a particularly aggressive form of lung cancer characterized by early and widespread metastases and the ability to rapidly develop resistance against chemotherapeutic agents. Tumor cell migration and metastasis share many similarities with leukocyte trafficking, which is critically regulated by chemokine receptors and adhesion molecules. SCLC cells express high levels of CXCR4 (CD184), a seven-transmembrane G-protein-coupled chemokine receptor. Stromal cells within the bone marrow microenvironment and at extramedullary sites constitutively secrete stromal cell-derived factor-1 (CXCL12), the ligand for CXCR4. Activation of CXCR4 induces SCLC cell migration and adhesion to stromal cells that secrete CXCL12, which in turn provides growth- and drug resistance-signals to the tumor cells. CXCR4 antagonists, such as Plerixafor (AMD3100) and T140 analogues (TN14003/ BKT140), disrupt CXCR4-mediated SCLC cell-adhesion to stromal cells. In stromal cell co-cultures, CXCR4 antagonists also sensitize SCLC cells to cytotoxic drugs, such as etoposide, and thereby antagonize cell adhesion-mediated drug resistance. Therefore, targeting the CXCR4–CXCL12 axis is a novel, attractive therapeutic approach in SCLC. Here, we summarize preclinical data about CXCR4 in SCLC, and the current status of the preclinical and clinical development of CXCR4 antagonists.

Binding Optimization through Coordination Chemistry: CXCR4 Chemokine Receptor Antagonists from Ultrarigid Metal Complexes

A new copper(II) containing bis-macrocyclic CXCR4 chemokine receptor antagonist is shown to have improved binding properties to the receptor protein in comparison to the drug AMD3100 (Plerixafor, Mozobil). The interaction of the metallodrug has been optimized by using ultrarigid chelator units that offer an equatorial site for coordination to the amino acid side chains of the protein. Binding competition assays with anti-CXCR4 antibodies show that the new compound stays bound longer and it has improved anti-HIV potency in vitro (EC(50) = 4.3 nM). X-ray structural studies using acetate as a model for carboxylate amino acid side chains indicate the nature of the coordination interaction.

Plerixafor approved for autologous hematopoietic stem-cell transplantation

Genzyme Corporation announced December15 that FDA has approved the marketing of plerixafor injection, or Mozobil, for use in patients with non-Hodgkin’s lymphoma or multiple myeloma who will undergo autologous hematopoietic stem-cell transplantation. According to the product’s FDA-approved labeling, plerixafor is indicated, in combination with granulocyte colony-stimulating factor (G-CSF), to increase the number of circulating hematopoietic stem cells available for collection and subsequent autologous transplantation. Plerixafor is a CXCR4 chemokine-receptor antagonist that blocks the binding of stromal-cell-derived factor 1-alpha and interferes with the sequestering of hematopoietic stem cells in the bone marrow, the labeling states. According to Genzyme, the use of plerixafor in combination with G-CSF may potentially reduce the number of times a patient needs to undergo apheresis before autologous hematopoietic stem-cell transplantation. The use of plerixafor causes an increase in circulating leukocytes and may cause a decrease in platelets. The labeling warns that white blood cell and platelet counts should be monitored in patients treated with the drug.

AMD070, a CXCR4 Chemokine Receptor Antagonist: Practical Large-Scale Laboratory Synthesis

An efficient and convergent four-step synthetic route to the CXCR4 chemokine receptor antagonist AMD070 (1) has been developed which employs only a single chromatographic step in the entire sequence. Novel reductive amination methods have been developed for the coupling of 2 and 3 in which a dehydrative imine formation is followed by reduction with an attenuated borohydride reagent (zinc chloride and sodium borohydride). Selective extraction methods were employed to purify synthetic intermediates and remove reagents and impurities. A procedure has also been developed to isolate 1 in a pure crystalline form.

Fluorescent CXCR4 chemokine receptor antagonists: metal activated binding

The copper(II) complex of a novel rhodamine-azamacrocycle conjugate binds to the CXCR4 chemokine receptor and competes effectively against anti-CXCR4 monoclonal antibodies. The copper macrocycle unit adopts a trans-II configuration in the solid state.

Configurationally Restricted Bismacrocyclic CXCR4 Receptor Antagonists

A zinc(II) containing configurationally restricted analogue of bismacrocyclic cyclam-type CXCR4 chemokine receptor antagonists has been synthesized and shown to adopt only one configuration in solution. The single crystal X-ray structure reveals favorable binding to acetate via a bidentate chelation that can be related to the proposed interaction with aspartate on the receptor protein surface. The zinc(II) complex is highly active against HIV infection in vitro.

Mechanism for Complement-Mediated, Antibody-Dependent Enhancement of Human Immunodeficiency Virus Type 1 Infection in MT2 Cells Is Enhanced Entry through CD4, CD21, and CXCR4 Chemokine Receptors

Some antibodies neutralize Human Immunodeficiency Virus (HIV). However, antibody to HIV and complement can enhance HIV replication if cells express both complement receptors and CD4, a phenomenon described as complement-mediated, antibody-dependent enhancement (C'ADE). Although increased binding of opsonized virions has been reported, the mechanism by which C'ADE enhances HIV replication remains unproven. In this study, real-time polymerase chain reaction to detect HIV cDNA indicates that complement and anti-HIV antibodies enhance HIV entry 8- to 30- fold with similar increases in integrated provirus. Thus, complement increases HIV replication through a mechanism of enhanced entry. To further refine the mechanism of C'ADE, chemokine receptor antagonists were employed. JM2987, a CXCR4 chemokine receptor antagonist, blocked HIV infection and C'ADE; thus CD4, complement receptors, and CXCR4 chemokine receptors are required for enhanced entry of HIV into MT2 cells. Finally, anti-HIV immunoglobulin enhanced replication of not only group M clade B HIV but also group M clade D and group O isolates. These data demonstrate that antibodies mediating C'ADE of HIV infection are broadly reactive.

Stereoselective Synthesis of 3,6-Disubstituted-3,6-dihydropyridin-2-ones as Potential Diketopiperazine Mimetics Using Organocopper-Mediated anti-SN2‘ Reactions and Their Use in the Preparation of Low-Molecule CXCR4 Antagonists

Organocopper-mediated anti-SN2' reactions of gamma-phosphoryloxy-alpha,beta-unsaturated-delta-lactams were used to prepare highly functionalized diketopiperazine mimetics. The substrate phosphates 24, 32, and 47 were prepared from alpha-amino acid-derived allylic alcohols 10 by a sequence of reactions that included ring-closing metathesis. In the reactions of phosphates with organocopper reagents, the addition of LiCl dramatically improved anti-SN2' selectivity, indicating that an organocopper cluster containing lithium chloride plays an important role in the determination of regioselectivity. This reaction system was applied to the preparation of novel low molecular weight CXCR4-chemokine receptor antagonists.

Recent Progress in the Discovery of New CCR5 and CXCR4 Chemokine Receptor Antagonists as Inhibitors of HIV-1 Entry. Part 2*

This review addresses key medicinal chemistry issues relevant in the discovery and development of CCR5 and CXCR4 antagonists as anti-HIV drugs. Recent progress in the discovery and development of such antagonists, SAR and clinical status are reviewed. Keywords: chemotherapy, transcriptase inhibitors, aids, ccr5 receptor, probe, chemokine, allosteric modulator