1. Expression of a Recombinant High Affinity IgG Fc Receptor by Engineered NK Cells as a Docking Platform for Therapeutic mAbs to Target Cancer Cells
- Author
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Snyder, Kristin M, Hullsiek, Robert, Mishra, Hemant K, Mendez, Daniel C, Li, Yunfang, Rogich, Allison, Kaufman, Dan S, Wu, Jianming, and Walcheck, Bruce
- Subjects
Biotechnology ,Immunization ,Prevention ,Vaccine Related ,Cancer ,5.1 Pharmaceuticals ,Development of treatments and therapeutic interventions ,5.2 Cellular and gene therapies ,Antibodies ,Monoclonal ,Antibody-Dependent Cell Cytotoxicity ,Cell Culture Techniques ,Cell Line ,Humans ,Immunotherapy ,Induced Pluripotent Stem Cells ,Killer Cells ,Natural ,Neoplasms ,Protein Engineering ,Receptors ,IgG ,Recombinant Fusion Proteins ,FcR ,ADCC ,NK cell ,immunotherapy ,antibody ,Immunology ,Medical Microbiology - Abstract
Anti-tumor mAbs are the most widely used and characterized cancer immunotherapy. Despite having a significant impact on some malignancies, most cancer patients respond poorly or develop resistance to this therapy. A known mechanism of action of these therapeutic mAbs is antibody-dependent cell-mediated cytotoxicity (ADCC), a key effector function of human NK cells. CD16A on human NK cells has an exclusive role in binding to tumor-bound IgG antibodies. Though CD16A is a potent activating receptor, it is also a low affinity IgG Fc receptor (FcγR) that undergoes a rapid downregulation in expression by a proteolytic process involving ADAM17 upon NK cell activation. These regulatory processes are likely to limit the efficacy of tumor-targeting therapeutic mAbs in the tumor environment. We sought to enhance NK cell binding to anti-tumor mAbs by engineering these cells with a recombinant FcγR consisting of the extracellular region of CD64, the highest affinity FcγR expressed by leukocytes, and the transmembrane and cytoplasmic regions of CD16A. This novel recombinant FcγR (CD64/16A) was expressed in the human NK cell line NK92 and in induced pluripotent stem cells from which primary NK cells were derived. CD64/16A lacked the ADAM17 cleavage region in CD16A and it was not rapidly downregulated in expression following NK cell activation during ADCC. CD64/16A on NK cells facilitated conjugation to antibody-treated tumor cells, ADCC, and cytokine production, demonstrating functional activity by its two components. Unlike NK cells expressing CD16A, CD64/16A captured soluble therapeutic mAbs and the modified NK cells mediated tumor cell killing. Hence, CD64/16A could potentially be used as a docking platform on engineered NK cells for therapeutic mAbs and IgG Fc chimeric proteins, allowing for switchable targeting elements and a novel cancer cellular therapy.
- Published
- 2018