Improved Activity against Acute Myeloid Leukemia with Chimeric Antigen Receptor (CAR)-NK-92 Cells Designed to Target CD123.

Michael A Morgan,Axel Schambach,Maximilian Keisker,Daniela Lenz,Juliette Nowak,Arnold Kloos,Marco Bentele,Martin Sauer,Nadine Kattre,Katharina Zimmermann,Julia Dahlke,Michael Heuser

doi:10.3390/v13071365

Michael A Morgan, Axel Schambach + Show 10 more

Open Access

https://doi.org/10.3390/v13071365

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Abstract

Anti-cancer activity can be improved by engineering immune cells to express chimeric antigen receptors (CARs) that recognize tumor-associated antigens. Retroviral vector gene transfer strategies allow stable and durable transgene expression. Here, we used alpharetroviral vectors to modify NK-92 cells, a natural killer cell line, with a third-generation CAR designed to target the IL-3 receptor subunit alpha (CD123), which is strongly expressed on the surface of acute myeloid leukemia (AML) cells. Alpharetroviral vectors also contained a transgene cassette to allow constitutive expression of human IL-15 for increased NK cell persistence in vivo. The anti-AML activity of CAR-NK-92 cells was tested via in vitro cytotoxicity assays with the CD123+ AML cell line KG-1a and in vivo in a patient-derived xenotransplantation CD123+ AML model. Unmodified NK-92 cells or NK-92 cells modified with a truncated version of the CAR that lacked the signaling domain served as controls. Alpharetroviral vector-modified NK-92 cells stably expressed the transgenes and secreted IL-15. Anti-CD123-CAR-NK-92 cells exhibited enhanced anti-AML activity in vitro and in vivo as compared to control NK-92 cells. Our data (1) shows the importance of IL-15 expression for in vivo persistence of NK-92 cells, (2) supports continued investigation of anti-CD123-CAR-NK cells to target AML, and (3) points towards potential strategies to further improve CAR-NK anti-AML activity.

Highlights

Retroviral vectors are commonly used to generate stably modified cells for preclinical and clinical applications
We show that a self-inactivating (SIN) alpharetroviral vector system can be successfully used to deliver and stably express a chimeric antigen receptors (CARs) designed to recognize the acute myeloid leukemia (AML) target antigen CD123, human IL-15 (hIL-15), and enhanced green fluorescent protein (EGFP)
NK-92 cells modified with the full-length CAR exhibited greater anti-AML activity in in vitro cytotoxicity assays and in an in vivo AML-patientderived xenotransplantation (PDX) model as compared to unmodified or

Summary

Introduction

Retroviral vectors are commonly used to generate stably modified cells for preclinical and clinical applications. CARs are synthetic receptors that can be designed to target specific antigens (e.g., neoantigens or tumor-associated antigens). These artificial receptors typically consist of an antigen-binding domain, a hinge region, a transmembrane sequence, and an internal signaling domain that drives the cellular response upon recognition of the target antigen. The successful use of CAR-T and CAR-NK cells to treat CD19+ lymphoid cancers has served as the proof-of-concept to expand CAR therapies to treat other types of cancers. The majority of CAR-T-cell therapies is applied in autologous settings due to the risk of graft versus host disease (GVHD). As NK cells do not seem to cause GVHD even after mismatched allogeneic transplantation, CAR-NK cells may be more amenable to generation of off-the-shelf cell therapies [8]

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