Improved Leukemia Clearance After Adoptive Transfer of NK Cells Expressing the Bone Marrow Homing Receptor CXCR4R334X

Two-layered immune escape in AML is overcome by Fcγ receptor activation and inhibition of PGE2 signaling in NK cells

ABSTRACT

Loss of anticancer natural killer (NK) cell function in patients with acute myeloid leukemia (AML) is associated with fatal disease progression and remains poorly understood. Here, we demonstrate that AML blasts isolated from patients rapidly inhibit NK cell function and escape NK cell-mediated killing. Transcriptome analysis of NK cells exposed to AML blasts revealed increased CREM expression and transcriptional activity, indicating enhanced cyclic adenosine monophosphate (cAMP) signaling, confirmed by uniform production of the cAMP-inducing prostanoid prostaglandin E2 (PGE2) by all AML-blast isolates from patients. Phosphoproteome analysis disclosed that PGE2 induced a blockade of lymphocyte-specific protein tyrosine kinase (LCK)-extracellular signal-regulated kinase signaling that is crucial for NK cell activation, indicating a 2-layered escape of AML blasts with low expression of NK cell-activating ligands and inhibition of NK cell signaling. To evaluate the therapeutic potential to target PGE2 inhibition, we combined Fcγ-receptor-mediated activation with the prevention of inhibitory PGE2 signaling. This rescued NK cell function and restored the killing of AML blasts. Thus, we identify the PGE2-LCK signaling axis as the key barrier for NK cell activation in 2-layered immune escape of AML blasts that can be targeted for immune therapy to reconstitute anticancer NK cell immunity in patients with AML.

Current status and future prospects of molecular imaging in targeting the tumor immune microenvironment

Molecular imaging technologies have significantly transformed cancer research and clinical practice, offering valuable tools for visualizing and understanding the complex tumor immune microenvironment. These technologies allow for the non-invasive examination of key components within the tumor immune microenvironment, including immune cells, cytokines, and stromal cells, providing crucial insights into tumor biology and treatment responses. This paper reviews the latest advancements in molecular imaging, with a focus on its applications in assessing interactions within the tumor immune microenvironment. Additionally, the challenges faced by molecular imaging technologies are discussed, such as the need for highly sensitive and specific imaging agents, issues with data integration, and difficulties in clinical translation. The future outlook emphasizes the potential of molecular imaging to enhance personalized cancer treatment through the integration of artificial intelligence and the development of novel imaging probes. Addressing these challenges is essential to fully realizing the potential of molecular imaging in improving cancer diagnosis, treatment, and patient outcomes.

Investigational CXCR4 inhibitors in early phase development for the treatment of hematological malignancies

INTRODUCTION

CXCR4/CXCL12 axis regulates cell proliferation, survival, and differentiation, as well as the homing and mobilization of hematopoietic stem cells (HSCs) from bone marrow niches to the peripheral blood. Furthermore, CXCR4 and CXCL12 are key mediators of cross-talk between hematological malignancies and their microenvironments. CXCR4 overexpression drives disease progression, boosts tumor cell survival, and promotes chemoresistance, leading to poor prognosis.

AREAS COVERED

In light of these discoveries, scientific investigations, and clinical trials have underscored the therapeutic promise found in small-molecule antagonists like plerixafor, peptides/peptidomimetics, such as BKT140, monoclonal antibodies like PF-06747143 and ulocuplumab, as well as microRNAs. Their efficacy is evident in reducing tumor burden, inducing apoptosis and sensitizing malignant cells to conventional chemotherapies. This overview delves into the pathogenic role of the CXC4/CXCL12 axis in hematological neoplasms and examines the clinical application of key CXCR4 antagonists.

EXPERT OPINION

The information collectively emphasizes the potential of CXCR4 antagonists as a therapeutic strategy for hematologic malignancies, showcasing advancements in preclinical and clinical studies. As these therapeutic strategies progress through clinical trials, their potential to reshape the prognosis of hematologic malignancies will become increasingly apparent.

Harnessing upregulated E-selectin while enhancing SDF-1α sensing redirects infused NK cells to the AML-perturbed bone marrow

Increased bone marrow (BM) homing of NK cells is associated with positive outcome in patients with acute myeloid leukemia (AML) treated within adoptive NK cell transfer trials. While most efforts to further improve the efficacy focus on augmenting NK cell persistence and cytotoxicity, few address their ability to home to the tumor. Here, we decipher how AML growth alters the BM niche to impair NK cell infiltration and how insights can be utilized to resolve this issue. We show that AML development gradually impairs the BM homing capacity of infused NK cells, which was tightly linked to loss of SDF-1α in this environment. AML development also triggered up-regulation of E-selectin on BM endothelial cells. Given the poor E-selectin-binding capacity of NK cells, introduction of fucosyltransferase-7 (FUT7) to the NK cells per mRNA transfection resulted in potent E-selectin binding and stronger adhesion to E-selectin+ endothelial cells. Co-introduction of FUT7 and gain-of-function CXCR4 (CXCR4R334X) redirected NK cell homing to the BM of AML-bearing mice nearly to the levels in AML-free mice. This work shows how impaired NK cell homing caused by AML-induced microenvironmental changes can be overcome by genetic engineering. We speculate our insights can help further advance future NK cell immunotherapies.