The low 5-year survival rate for patients with acute myeloid leukemia (AML), primarily caused due to disease relapse, emphasizes the need for better therapeutic strategies. Disease relapse is facilitated by leukemic stem cells (LSCs) that are resistant to standard chemotherapy and promote tumor growth. To target AML blasts and LSCs using natural killer (NK) cells, we have developed a trispecific killer engager (TriKETM) molecule containing a humanized anti-CD16 heavy chain camelid single-domain antibody (sdAb) that activates NK cells, an IL-15 molecule that drives NK-cell priming, expansion and survival, and a single-chain variable fragment (scFv) against human CLEC12A (CLEC12A TriKE). CLEC12A is a myeloid lineage antigen that is highly expressed by AML cells and LSCs, but not expressed by normal hematopoietic stem cells (HSCs), thus minimizing off-target toxicity. The CLEC12A TriKE induced robust NK-cell specific proliferation, enhanced NK-cell activation, and killing of both AML cell lines and primary patient-derived AML blasts in vitro while sparing healthy HSCs. Additionally, the CLEC12A TriKE was able to reduce tumor burden in preclinical mouse models. These findings highlight the clinical potential of the CLEC12A TriKE for the effective treatment of AML.
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Acknowledgements We would like to acknowledge the Translational Therapy Laboratory, Flow Cytometry, and Imaging cores at the University of Minnesota for their services. This work was supported in part by NCI P01 CA111412 (JSM, BRB, DAV, MF), NCI P01 65493 (JSM, BRB), R35 CA197292 (JSM), P30 CA077598 (JSM, MF), R01 HL56067 (BRB), Minnesota Masonic Charities, and the Killebrew-Thompson Memorial Fund. We would also like to thank Xianzheng Zhou, at New York Medical College, for use of his HL-60luc cells.
Funding This work was supported in part by DoD CA150085 (MF), NCI P01 CA111412 (MF and JSM), P01 CA65493 (MF and JSM), and R35 CA197292 (MF and JSM). The TriKE™ work was also supported in part by funding provided by GT Biopharma, Inc (MF, DAV, and JSM). The University of Minnesota has licensed the technology covered in this work to GT Biopharma. All conflicts have been declared and managed in accordance with the University’s conflict management plan.
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