title: Retargeting NK-92 cells by means of CD19- and CD20-specific chimeric antigen receptors compares favorably with antibody-dependent cellular cytotoxicity.
abstract: Multiple natural killer (NK) cell-based anticancer therapies are currently under development. Here, we compare the efficiency of genetically modified NK-92 cells expressing chimeric antigen receptors (CARs) at killing NK cell-resistant B-lymphoid leukemia cells to the antibody-dependent cell-mediated cytotoxicity (ADCC) of NK-92 cells expressing a high affinity variant of the IgG Fc receptor (FcγRIII). First, we compared in vitro the abilities of NK-92 cells expressing CD20-targeting CARs to kill primary chronic lymphocytic leukemia (CLL) cells derived from 9 patients with active, untreated disease to the cytotoxicity of NK-92 cells expressing FcγRIII combined with either of the anti-CD20 monoclonal antibodies (mAbs) rituximab or ofatumumab. We found that CAR-expressing NK-92 cells effectively kill NK cell-resistant primary CLL cells and that such a cytotoxic response is significantly stronger than that resulting from ADCC. For studying CAR-expressing NK cell-based immunotherapy in vivo, we established xenograft mouse models of residual leukemia using the human BCR-ABL1+cell lines SUP-B15 (CD19+CD20-) and TMD-5 (CD19+CD20+), two acute lymphoblastic leukemia (ALL) lines that are resistant to parental NK-92 cells. Intravenous injection of NK-92 cells expressing CD19-targeting CARs eliminated SUP-B15 cells, whereas they had no such effect on TMD-5 cells. However, the intrafemoral injection of NK-92 cells expressing CD19-targeting CAR resulted in the depletion of TMD-5 cells from the bone marrow environment. Comparative studies in which NK-92 cells expressing either CD19- or CD20-targeting CARs were directly injected into subcutaneous CD19+CD20+Daudi lymphoma xenografts revealed that CD20-targeting CAR is superior to its CD19-specific counterpart in controlling local tumor growth. In summary, we show here that CAR-expressing NK-92 cells can be functionally superior to ADCC (as mediated by anti-CD20 mAbs) in the elimination of primary CLL cells. Moreover, we provide data demonstrating that the systemic administration of CAR-expressing NK-92 cells can control lymphoblastic leukemia in immunocompromised mice. Our results also suggest that the direct injection of CAR-expressing NK-92 cells to neoplastic lesions could be an effective treatment modality against lymphoma.
authors.affiliation: Molecular Oncology Research Institute; Tufts Medical Center; Boston, MA USA.
authors.forename: Laurent
authors.initials: L
authors.lastname: Boissel
authors.affiliation: Molecular Oncology Research Institute; Tufts Medical Center; Boston, MA USA.
authors.forename: Monica
authors.initials: M
authors.lastname: Betancur-Boissel
authors.affiliation: Molecular Oncology Research Institute; Tufts Medical Center; Boston, MA USA ; Division of Hematology/Oncology; Tufts Medical Center; Boston, MA USA.
authors.forename: Weiquan
authors.initials: W
authors.lastname: Lu
authors.affiliation: Center for Regenerative Medicine and Cancer Center; Massachusetts General Hospital; Boston, MA USA.
authors.forename: Daniela S
authors.initials: DS
authors.lastname: Krause
authors.affiliation: Molecular Oncology Research Institute; Tufts Medical Center; Boston, MA USA ; Division of Hematology/Oncology; Tufts Medical Center; Boston, MA USA.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Van Etten
authors.affiliation: Chemotherapeutisches Forschungsinstitut Georg-Speyer-Haus; Frankfurt am Main, Germany.
authors.forename: Winfried S
authors.initials: WS
authors.lastname: Wels
authors.affiliation: Molecular Oncology Research Institute; Tufts Medical Center; Boston, MA USA ; Division of Hematology/Oncology; Tufts Medical Center; Boston, MA USA.
authors.forename: Hans
authors.initials: H
authors.lastname: Klingemann
keywords: CAR; NK cells; NK-92; lentiviral vector; lymphoid malignancies