Abstract 4: Discovery of novel and highly potent small molecule inhibitors of chemokine receptor CXCR4

Abstract

Introduction: CXCR4 is a member of chemokine receptor and G protein coupled receptor (GPCR) families. Its interaction with the chemotactic ligand stromal cell-derived factor 1 (SDF-1 or CXCL12) plays important roles in physiological and pathological processes. Recent studies have showed that the blockade of CXCL12-CXCR4 interaction by small molecules can be used in several clinical applications, including sensitizing cancer cells to chemotherapy, mobilizing hematopoietic stem cells (HSCs) to the blood for HSC collection, and inhibiting the tumor metastasis. To date, AMD3100 (Plerixafor) is the only clinically approved drug used in combination with G-CSF for mobilizing HSCs. Here, we report the discovery and development of a new class of highly potent small molecule CXCR4 inhibitors which can strongly antagonize CXCL12-CXCR4 interaction and mobilizing HSCs. Methods: Based on the crystal structures of CXCR4 showing a major and minor subpockets, we applied a fragment-based combinatorial design (FBCD) strategy to design a new class of hybrid molecules to recognize these two subpockets. A series of designed compounds were chemically synthesized and tested in a panel of biological assays including competitive CXCR4 binding, chemotaxis, calcium mobilization and CXCR4 internalization to characterize their biological activities. Furthermore, site-directed mutagenesis coupled with molecular docking simulation was carried out to determine the binding modes of the most potent compounds. Results: More than 30 compounds were synthesized and characterized. Among them, compound HFX51116 showed the most potent CXCR4 binding activity (IC50 = 12.2 nM), which was more potent than AMD3100 tested in parallel (IC50 = 325.3 nM). Furthermore, HFX51116 displayed remarkable inhibition of calcium mobilization (IC50 = 1.478 nM) and chemotaxis activity (IC50 = 252.7 nM), both of which are better than those of AMD3100. In addition, mutational studies and molecular docking simulation suggested that HFX51116 recognizes the minor subpocket mainly and major subpocket partially. Conclusions: Our findings have demonstrated that HFX51116 is a promising novel lead compound for developing a new class of small molecule therapeutics targeting CXCR4. Citation Format: Xiong Fang, Qian Meng, Xiao Fang, Siyu Zhu, Yazi Huang, Jing An, Yan Xu, Ziwei Huang. Discovery of novel and highly potent small molecule inhibitors of chemokine receptor CXCR4 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4.

A novel small molecule CXCR4 antagonist potently mobilizes hematopoietic stem cells in mice and monkeys

“…1 a). HF51116 binds strongly to CXCR4 with the IC 50 of 12 nM in competitive binding with 12G5 [ 25 ]. We examined the compositions and dynamics of different PB cells in mice following subcutaneous injection of HF51116.…”

“…Blocking the SDF-1α/CXCR4 axis can elicit rapid mobilization of HSCs from the BM to the PB in clinical practice [ 35 ], as demonstrated by the clinically approved CXCR4 antagonist AMD3100 [ 29 ]. Our recent efforts in developing new CXCR4 antagonists led to the discovery of HF51116 [ 25 ], a novel small molecule which strongly and specifically binds CXCR4 and effectively blocks SDF-1α-induced CXCR4 + cell migration and calcium influx (unpublished results).…”

“…In the present study, we report the in vivo HSC mobilization efficacy of HF51116 [ 24 ], a novel CXCR4 antagonist developed recently by our laboratories. HF51116 possesses a very high CXCR4 binding affinity (IC 50 = 12 nM) [ 25 ] and potently mobilizes HSCs from the bone marrow (BM) to the peripheral blood (PB). We have evaluated the efficacy of HF51116 in mice and monkeys, which demonstrates its potential as a new promising CXCR4 antagonist for clinical application in HSC transplantation.…”

A novel small molecule CXCR4 antagonist potently mobilizes hematopoietic stem cells in mice and monkeys

“…On the basis of our representative compound HF50731 (29), we have developed a new highly potent small molecule analog named HF51116, which features an unsymmetrical polyamine ( Figure 1A). HF51116 binds strongly to CXCR4 with the IC50 of 12 nM in competitive binding with 12G5 (26). We examined the compositions and dynamics of different PB cells in mice following subcutaneous injection of HF51116.…”

“…In the present study, we report the in vivo HSC mobilization e cacy of HF51116 (25), a novel CXCR4 antagonist developed recently by our laboratories. HF51116 possesses very high CXCR4 binding a nity (IC 50 = 12 nM) (26) and potently mobilizes HSCs from the bone marrow (BM) to the peripheral blood (PB).…”