To focus IL-15 on the effectors of tumor immunity and minimize its off-target effects, Zekri et al. fused Fc-optimized CD19- or CD20-specific antibodies to an IL-15 moiety mutated to disable IL-15 binding to IL-15Rα+ cells and improve the specificity of IL-15 trans-stimulation of IL-15Rβγ+ cytotoxic cells. In vitro and in mouse models, the constructs induced superior (compared to Fc-optimized anti-CD19 or CD20 antibodies) CD19/CD20-dependent IL-15R activation, NK cell proliferation and survival, and human and mouse NK cell-mediated ADCC activity against CD19/CD20+ autologous and allogeneic B cells, lymphoma cells and patient ALL cells.
Contributed by Paula Hochman
ABSTRACT: Despite the advances in cancer treatment achieved, for example, by the CD20 antibody rituximab, an urgent medical need remains to optimize the capacity of such antibodies to induce antibody-dependent cellular cytotoxicity (ADCC) that determines therapeutic efficacy. The cytokine IL-15 stimulates proliferation, activation, and cytolytic capacity of NK cells, but broad clinical use is prevented by short half-life, poor accumulation at the tumor site, and severe toxicity due to unspecific immune activation. We here report modified immunocytokines consisting of Fc-optimized CD19 and CD20 antibodies fused to an IL-15 moiety comprising an L45E-E46K double mutation (MIC+ format). The E46K mutation abrogated binding to IL-15Rα, thereby enabling substitution of physiological trans-presentation by target binding and thus conditional IL-15Rβγ stimulation, whereas the L45E mutation optimized IL-15Rβγ agonism and producibility. In vitro analysis of NK activation, anti-leukemia reactivity, and toxicity using autologous and allogeneic B cells confirmed target-dependent function of MIC+ constructs. Compared with Fc-optimized CD19 and CD20 antibodies, MIC+ constructs mediated superior target cell killing and NK cell proliferation. Mouse models using luciferase-expressing human NALM-6 lymphoma cells, patient acute lymphoblastic leukemia (ALL) cells, and murine EL-4 lymphoma cells transduced with human CD19/CD20 as targets and human and murine NK cells as effectors, respectively, confirmed superior and target-dependent anti-leukemic activity. In summary, MIC+ constructs combine the benefits of Fc-optimized antibodies and IL-15 cytokine activity and mediate superior NK cell immunity with potentially reduced side effects. They thus constitute a promising new immunotherapeutic approach shown here for B cell malignancies.
Author Info: (1) Clinical Collaboration Unit Translational Immunology, German Cancer Consortium (DKTK), Department of Internal Medicine, University Hospital Tbingen, 72076 Tbingen, Germany. C
Author Info: (1) Clinical Collaboration Unit Translational Immunology, German Cancer Consortium (DKTK), Department of Internal Medicine, University Hospital Tbingen, 72076 Tbingen, Germany. Cluster of Excellence iFIT (EXC 2180) "Image-Guided and Functionally Instructed Tumor Therapies," University of Tbingen, 72076 Tbingen, Germany. Department of Immunology, Institute for Cell Biology, Eberhard Karls Universitt Tbingen, Germany. DKFZ Partner Site Tbingen, German Cancer Consortium (DKTK), 72076 Tbingen, Germany. (2) Clinical Collaboration Unit Translational Immunology, German Cancer Consortium (DKTK), Department of Internal Medicine, University Hospital Tbingen, 72076 Tbingen, Germany. Cluster of Excellence iFIT (EXC 2180) "Image-Guided and Functionally Instructed Tumor Therapies," University of Tbingen, 72076 Tbingen, Germany. (3) Clinical Collaboration Unit Translational Immunology, German Cancer Consortium (DKTK), Department of Internal Medicine, University Hospital Tbingen, 72076 Tbingen, Germany. Cluster of Excellence iFIT (EXC 2180) "Image-Guided and Functionally Instructed Tumor Therapies," University of Tbingen, 72076 Tbingen, Germany. (4) Clinical Collaboration Unit Translational Immunology, German Cancer Consortium (DKTK), Department of Internal Medicine, University Hospital Tbingen, 72076 Tbingen, Germany. Cluster of Excellence iFIT (EXC 2180) "Image-Guided and Functionally Instructed Tumor Therapies," University of Tbingen, 72076 Tbingen, Germany. (5) School of Medical Sciences, University of Sydney, 2050 NSW, Australia. (6) Department of Immunology, Institute for Cell Biology, Eberhard Karls Universitt Tbingen, Germany. DKFZ Partner Site Tbingen, German Cancer Consortium (DKTK), 72076 Tbingen, Germany. (7) Clinical Collaboration Unit Translational Immunology, German Cancer Consortium (DKTK), Department of Internal Medicine, University Hospital Tbingen, 72076 Tbingen, Germany. Department of Immunology, Institute for Cell Biology, Eberhard Karls Universitt Tbingen, Germany. DKFZ Partner Site Tbingen, German Cancer Consortium (DKTK), 72076 Tbingen, Germany. (8) Clinical Collaboration Unit Translational Immunology, German Cancer Consortium (DKTK), Department of Internal Medicine, University Hospital Tbingen, 72076 Tbingen, Germany. Cluster of Excellence iFIT (EXC 2180) "Image-Guided and Functionally Instructed Tumor Therapies," University of Tbingen, 72076 Tbingen, Germany. Department of Immunology, Institute for Cell Biology, Eberhard Karls Universitt Tbingen, Germany. DKFZ Partner Site Tbingen, German Cancer Consortium (DKTK), 72076 Tbingen, Germany. (9) Clinical Collaboration Unit Translational Immunology, German Cancer Consortium (DKTK), Department of Internal Medicine, University Hospital Tbingen, 72076 Tbingen, Germany. Cluster of Excellence iFIT (EXC 2180) "Image-Guided and Functionally Instructed Tumor Therapies," University of Tbingen, 72076 Tbingen, Germany. (10) Cluster of Excellence iFIT (EXC 2180) "Image-Guided and Functionally Instructed Tumor Therapies," University of Tbingen, 72076 Tbingen, Germany. Department for Preclinical Imaging and Radiopharmacy, Werner Siemens Imaging Center, Eberhard Karls University Tbingen, 72076 Tbingen, Germany. (11) Cluster of Excellence iFIT (EXC 2180) "Image-Guided and Functionally Instructed Tumor Therapies," University of Tbingen, 72076 Tbingen, Germany. Department for Preclinical Imaging and Radiopharmacy, Werner Siemens Imaging Center, Eberhard Karls University Tbingen, 72076 Tbingen, Germany. (12) Department of Immunology, Institute for Cell Biology, Eberhard Karls Universitt Tbingen, Germany. DKFZ Partner Site Tbingen, German Cancer Consortium (DKTK), 72076 Tbingen, Germany. (13) Clinical Collaboration Unit Translational Immunology, German Cancer Consortium (DKTK), Department of Internal Medicine, University Hospital Tbingen, 72076 Tbingen, Germany. Cluster of Excellence iFIT (EXC 2180) "Image-Guided and Functionally Instructed Tumor Therapies," University of Tbingen, 72076 Tbingen, Germany. (14) Childrens University Hospital, University Hospital Tbingen, 72076 Tbingen, Germany. (15) Cluster of Excellence iFIT (EXC 2180) "Image-Guided and Functionally Instructed Tumor Therapies," University of Tbingen, 72076 Tbingen, Germany. Department of Immunology, Institute for Cell Biology, Eberhard Karls Universitt Tbingen, Germany. DKFZ Partner Site Tbingen, German Cancer Consortium (DKTK), 72076 Tbingen, Germany. (16) Cluster of Excellence iFIT (EXC 2180) "Image-Guided and Functionally Instructed Tumor Therapies," University of Tbingen, 72076 Tbingen, Germany. Department of Immunology, Institute for Cell Biology, Eberhard Karls Universitt Tbingen, Germany. DKFZ Partner Site Tbingen, German Cancer Consortium (DKTK), 72076 Tbingen, Germany. (17) Clinical Collaboration Unit Translational Immunology, German Cancer Consortium (DKTK), Department of Internal Medicine, University Hospital Tbingen, 72076 Tbingen, Germany. Cluster of Excellence iFIT (EXC 2180) "Image-Guided and Functionally Instructed Tumor Therapies," University of Tbingen, 72076 Tbingen, Germany.
