Protective Effect of CXCR4 Antagonist DBPR807 against Ischemia-Reperfusion Injury in a Rat and Porcine Model of Myocardial Infarction: Potential Adjunctive Therapy for Percutaneous Coronary Intervention.

CXCR4 antagonists have been claimed to reduce mortality after myocardial infarction in myocardial infarction (MI) animals, presumably due to suppressing inflammatory responses caused by myocardial ischemia-reperfusion injury, thus, subsequently facilitating tissue repair and cardiac function recovery. This study aims to determine whether a newly designed CXCR4 antagonist DBPR807 could exert better vascular-protective effects than other clinical counterparts (e.g., AMD3100) to alleviate cardiac damage further exacerbated by reperfusion. Consequently, we find that instead of traditional continuous treatment or multiple-dose treatment at different intervals of time, a single-dose treatment of DBPR807 before reperfusion in MI animals could attenuate inflammation via protecting oxidative stress damage and preserve vascular/capillary density and integrity via mobilizing endothelial progenitor cells, leading to a desirable fibrosis reduction and recovery of cardiac function, as evaluated with the LVEF (left ventricular ejection fraction) in infarcted hearts in rats and mini-pigs, respectively. Thus, it is highly suggested that CXCR4 antagonists should be given at a single high dose prior to reperfusion to provide the maximal cardiac functional improvement. Based on its favorable efficacy and safety profiles indicated in tested animals, DBPR807 has a great potential to serve as an adjunctive medicine for percutaneous coronary intervention (PCI) therapies in acute MI patients.

A highly selective and potent CXCR4 antagonist for hepatocellular carcinoma treatment.

The CXC chemokine receptor type 4 (CXCR4) receptor and its ligand, CXCL12, are overexpressed in various cancers and mediate tumor progression and hypoxia-mediated resistance to cancer therapy. While CXCR4 antagonists have potential anticancer effects when combined with conventional anticancer drugs, their poor potency against CXCL12/CXCR4 downstream signaling pathways and systemic toxicity had precluded clinical application. Herein, BPRCX807, known as a safe, selective, and potent CXCR4 antagonist, has been designed and experimentally realized. In in vitro and in vivo hepatocellular carcinoma mouse models it can significantly suppress primary tumor growth, prevent distant metastasis/cell migration, reduce angiogenesis, and normalize the immunosuppressive tumor microenvironment by reducing tumor-associated macrophages (TAMs) infiltration, reprogramming TAMs toward an immunostimulatory phenotype and promoting cytotoxic T cell infiltration into tumor. Although BPRCX807 treatment alone prolongs overall survival as effectively as both marketed sorafenib and anti-PD-1, it could synergize with either of them in combination therapy to further extend life expectancy and suppress distant metastasis more significantly.

Protective Effect of CXCR4 Antagonist CX807 in a Rat Model of Hemorrhagic Stroke.

Intracerebral hemorrhage (ICH) is a major cause of stroke, with high mortality and morbidity. There is no effective pharmacological therapy for ICH. Previous studies have indicated that CXCR4 antagonists reduced microglia activation, attenuated infiltration of T cells, and improved functional recovery in ischemic stroke animals. The interaction of CXCR4 antagonists and ICH has not been characterized. The purpose of this study is to examine the neuroprotective action of a novel CXCR4 antagonist CX807 against ICH. In primary cortical neuronal and BV2 microglia co-culture, CX807 reduced glutamate-mediated neuronal loss and microglia activation. Adult rats were locally administered with collagenase VII to induce ICH. CX807 was given systemically after the ICH. Early post-treatment with CX807 improved locomotor activity in ICH rats. Brain tissues were collected for qRTPCR and histological staining. ICH upregulated the expression of CXCR4, CD8, TNFα, IL6, and TLR4. The immunoreactivity of IBA1 and CD8, as well as TUNEL labeling, were enhanced in the perilesioned area. CX807 significantly mitigated these responses. In conclusion, our data suggest that CX807 is neuroprotective and anti-inflammatory against ICH. CX807 may have clinical implications for the treatment of hemorrhagic stroke.

Development of Stem-Cell-Mobilizing Agents Targeting CXCR4 Receptor for Peripheral Blood Stem Cell Transplantation and Beyond.

The function of the CXCR4/CXCL12 axis accounts for many disease indications, including tissue/nerve regeneration, cancer metastasis, and inflammation. Blocking CXCR4 signaling with its antagonists may lead to moving out CXCR4+ cell types from bone marrow to peripheral circulation. We have discovered a novel series of pyrimidine-based CXCR4 antagonists, a representative (i.e., 16) of which was tolerated at a higher dose and showed better HSC-mobilizing ability at the maximal response dose relative to the approved drug 1 (AMD3100), and thus considered a potential drug candidate for PBSCT indication. Docking compound 16 into the X-ray crystal structure of CXCR4 receptor revealed that it adopted a spider-like conformation striding over both major and minor subpockets. This putative binding mode provides a new insight into CXCR4 receptor-ligand interactions for further structural modifications.

Targeting Tumor Associated Phosphatidylserine with New Zinc Dipicolylamine-Based Drug Conjugates.

A series of zinc(II) dipicolylamine (ZnDPA)-based drug conjugates have been synthesized to probe the potential of phosphatidylserine (PS) as a new antigen for small molecule drug conjugate (SMDC) development. Using in vitro cytotoxicity and plasma stability studies, PS-binding assay, in vivo pharmacokinetic studies, and maximum tolerated dose profiles, we provided a roadmap and the key parameters required for the development of the ZnDPA based drug conjugate. In particular, conjugate 24 induced tumor regression in the COLO 205 xenograft model and exhibited a more potent antitumor effect with a 70% reduction of cytotoxic payload compared to that of the marketed irinotecan when dosed at the same regimen. In addition to the validation of PS as an effective pharmacodelivery target for SMDC, our work also provided the foundation that, if applicable, a variety of therapeutic agents could be conjugated in the same manner to treat other PS-associated diseases.

Stem cell mobilizers targeting chemokine receptor CXCR4: renoprotective application in acute kidney injury.

We have discovered a novel series of quinazoline-based CXCR4 antagonists. Of these, compound 19 mobilized CXCR4(+) cell types, including hematopoietic stem cells and endothelial progenitor cells, more efficiently than the marketed 1 (AMD3100) with subcutaneous administration at the same dose (6 mg/kg) in mice. This series of compounds thus provides a set of valuable tools to study diseases mediated by the CXCR4/SDF-1 axis, including myocardial infarction, ischemic stroke, and cancer metastasis. More importantly, treatment with compound 19 significantly lowered levels of blood urea nitrogen and serum creatinine in rats with renal ischemia-reperfusion injury, providing evidence for its therapeutic potential in preventing ischemic acute kidney injury. CXCR4 antagonists such as 19 might also be useful to increase circulating levels of adult stem cells, thereby exerting beneficial effects on damaged and/or inflamed tissues in diseases that currently are not treated by standard approaches.

Function-oriented development of CXCR4 antagonists as selective human immunodeficiency virus (HIV)-1 entry inhibitors.

Motivated by the pivotal role of CXCR4 as an HIV entry co-receptor, we herein report a de novo hit-to-lead effort on the identification of subnanomolar purine-based CXCR4 antagonists against HIV-1 infection. Compound 24, with an EC50 of 0.5 nM against HIV-1 entry into host cells and an IC50 of 16.4 nM for inhibition of radioligand stromal-derived factor-1α (SDF-1α) binding to CXCR4, was also found to be highly selective against closely related chemokine receptors. We rationalized that compound 24 complementarily interacted with the critical CXCR4 residues that are essential for binding to HIV-1 gp120 V3 loop and subsequent viral entry. Compound 24 showed a 130-fold increase in anti-HIV activity compared to that of the marketed CXCR4 antagonist, AMD3100 (Plerixafor), whereas both compounds exhibited similar potency in mobilization of CXCR4(+)/CD34(+) stem cells at a high dose. Our study offers insight into the design of anti-HIV therapeutics devoid of major interference with SDF-1α function.

Discovery of 2-[5-(4-chloro-phenyl)-1-(2,4-dichloro-phenyl)-4-ethyl-1H-pyrazol-3-yl]-1,5,5-trimethyl-1,5-dihydro-imidazol-4-thione (BPR-890) via an active metabolite. A novel, potent and selective cannabinoid-1 receptor inverse agonist with high antiobesity efficacy in DIO mice.

By using the active metabolite 5 as an initial template, further structural modifications led to the identification of the titled compound 24 (BPR-890) as a highly potent CB1 inverse agonist possessing an excellent CB2/1 selectivity and remarkable in vivo efficacy in diet-induced obese mice with a minimum effective dose as low as 0.03 mg/kg (po qd) at the end of the 30-day chronic study. Current SAR studies along with those of many existing rimonabant-mimicking molecules imply that around the pyrazole C3-position, a rigid and deep binding pocket should exist for CB1 receptor. In addition, relative to the conventional carboxamide carbonyl, serving as a key hydrogen-bond acceptor during ligand-CB1 receptor interaction, the corresponding polarizable thione carbonyl might play a more critical role in stabilizing the Asp366-Lys192 salt bridge in the proposed CB1-receptor homology model and inducing significant selectivity for CB1R over CB2R.