ABSTRACT
BACKGROUND AIMS: Natural killer (NK) cell transfer is a promising cellular immunotherapy for cancer. Previously, we developed a robust method to generate large NK cell numbers from CD34+ hematopoietic stem and progenitor cells (HSPCs), which exhibit strong anti-tumor activity. However, since these cells express low levels of the Fc receptor CD16a in vitro, antibody-dependent cellular cytotoxicity (ADCC) by these cells is limited. To broaden clinical applicability of our HSPC-NK cells toward less NK-sensitive malignancies, we aimed to improve ADCC through CD16a transduction. METHODS: Using wildtype and S197P mutant greater-affinity (both with V158) CD16a retroviral transgenes (i.e., a cleavable and noncleavable CD16a upon stimulation), we generated CD16a HSPC-transduced NK cells, with CD34+ cells isolated from umbilical cord blood (UCB) or peripheral blood after G-CSF stem cell mobilization (MPB). CD16a expressing NK cells were enriched using flow cytometry-based cell sorting. Subsequently, phenotypic analyses and functional assays were performed to investigate natural cytotoxicity and ADCC activity. RESULTS: Mean transduction efficiency was 34% for UCB-derived HSPCs and 20% for MPB-derived HSPCs, which was enriched by flow cytometry-based cell sorting to >90% for both conditions. Expression of the transgene remained stable during the entire NK expansion cell generation process. Proliferation and differentiation of HSPCs were not hampered by the transduction process, resulting in effectively differentiated CD56+ NK cells after 5 weeks. Activation of the HSPC-derived NK cells resulted in significant shedding of wildtype CD16a transcribed from the endogenous gene, but not of the noncleavable mutant CD16a protein expressed from the transduced construct. The mean increase of CD107+IFNγ+ expressing NK cells after inducing ADCC was tenfold in enriched noncleavable CD16a HSPC-NK cells. Killing capacity of CD16a-transduced NK cells was significantly improved after addition of a tumor-targeting antibody in tumor cell lines and primary B-cell leukemia and lymphoma cells compared to unmodified HSPC-NK cells. CONCLUSIONS: Together, these data demonstrate that the applicability of adoptive NK cell immunotherapy may be broadened to less NK-sensitive malignancies by upregulation of CD16a expression in combination with the use of tumor-targeting monoclonal antibodies.
Subject(s)
Antibody-Dependent Cell Cytotoxicity , Receptors, IgG , Cell Adhesion Molecules/metabolism , Cell Line, Tumor , Killer Cells, Natural , Receptors, Fc/metabolism , HumansABSTRACT
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.
Subject(s)
Immunotherapy/methods , Interleukin-15/metabolism , Killer Cells, Natural/immunology , Lectins, C-Type/immunology , Leukemia, Myeloid, Acute/therapy , Receptors, IgG/immunology , Receptors, Mitogen/immunology , Single-Domain Antibodies/pharmacology , Animals , Apoptosis , Cell Proliferation , Female , GPI-Linked Proteins/immunology , Humans , Lectins, C-Type/antagonists & inhibitors , Leukemia, Myeloid, Acute/immunology , Leukemia, Myeloid, Acute/metabolism , Leukemia, Myeloid, Acute/pathology , Mice , Mice, Inbred NOD , Mice, SCID , Prognosis , Receptors, Mitogen/antagonists & inhibitors , Tumor Cells, Cultured , Xenograft Model Antitumor AssaysABSTRACT
Multinodular goitre is the most common thyroid gland disorder. It can cause hyperthyroidism and mechanical complaints such as tracheal compression or dysphagia. We report a unique case of a patient with a toxic multinodular goitre presenting with a deep venous thrombosis of the left arm due to direct local compression of blood flow. LEARNING POINTS: Multinodular goitre can cause deep venous thrombosis of the upper extremity due to local compression of blood flow.Hyperthyroidism causes a hypercoagulable and hypofibrinolytic state which, if left untreated, is a risk factor for venous thrombosis.A diagnostic algorithm combining the Constans clinical score, D-dimer testing and, when indicated, ultrasonography is a safely and effectively approach for investigating suspected deep venous thrombosis of the upper extremity.