Biased action of the CXCR4-targeting drug plerixafor is essential for its superior hematopoietic stem cell mobilization

Astrid S Jørgensen,Mette M Rosenkilde,Jon Våbenø,Viktorija Daugvilaite,Katia De Filippo,Masa Mavri,Tau Benned-Jensen,Sara Rankin,Christian Berg,Goda Juzenaite,Gertrud Hjortø

doi:10.1038/s42003-021-02070-9

Abstract

Following the FDA-approval of the hematopoietic stem cell (HSC) mobilizer plerixafor, orally available and potent CXCR4 antagonists were pursued. One such proposition was AMD11070, which was orally active and had superior antagonism in vitro; however, it did not appear as effective for HSC mobilization in vivo. Here we show that while AMD11070 acts as a full antagonist, plerixafor acts biased by stimulating β-arrestin recruitment while fully antagonizing G protein. Consequently, while AMD11070 prevents the constitutive receptor internalization, plerixafor allows it and thereby decreases receptor expression. These findings are confirmed by the successful transfer of both ligands’ binding sites and action to the related CXCR3 receptor. In vivo, plerixafor exhibits superior HSC mobilization associated with a dramatic reversal of the CXCL12 gradient across the bone marrow endothelium, which is not seen for AMD11070. We propose that the biased action of plerixafor is central for its superior therapeutic effect in HSC mobilization.

Highlights

Following the FDA-approval of the hematopoietic stem cell (HSC) mobilizer plerixafor, orally available and potent CXC chemokine receptor 4 (CXCR4) antagonists were pursued
CXCR4 internalized in the presence of phorbol-ester, suggesting that protein kinase C (PKC) phosphorylation is involved in the internalization process[28]
It is thought that plerixafor acts as a mobilizer by reversing the gradient of CXC chemokine ligand 12 (CXCL12) formed across the bone marrow (BM) and blood through its blockage of a CXCR4-mediated CXCL12 transport across the endothelium[10,24,64,65]

Summary

Introduction

Following the FDA-approval of the hematopoietic stem cell (HSC) mobilizer plerixafor, orally available and potent CXCR4 antagonists were pursued. The bicyclam CXCR4 antagonist plerixafor (known in the literature as AMD3100) was originally developed to inhibit cell entry of HIV X4-strains via CXCR4; initial in vivo preclinical tests revealed a massive leukocytosis following plerixafor administration[15]. This observation resulted in the launch of plerixafor (trade name Mozobil) as a first-in-class HSC mobilizing compound for the autologous transplantation of bone marrow (BM) cells in patients with Non-Hodgkin’s lymphoma and multiple myeloma[15]. Clinical trials of AMD11070 ( known as X4P-001 and mavorixafor) have been conducted for certain types of cancers, e.g., clear cell renal cell carcinoma and melanoma (ClinicalTrials. gov Identifiers: NCT02667886 and NCT02823405, respectively), as well as for WHIM syndrome, where it currently is in Phase 3 (ClinicalTrials.gov Identifier: NCT03995108)

Methods

Results

Conclusion