Potentiating CD20 monoclonal antibody therapy by targeting complement C3 fragments covalently deposited on lymphoma cells
Abstract
Abstract Monoclonal antibodies (mAbs) improve survival of patients with mature B-cell malignancies. Fcγ receptor–dependent effector mechanisms kill tumor cells but can promote antigen loss through trogocytosis, contributing to treatment failures. Cell-bound mAbs trigger the complement cascade to deposit C3 activation fragments and lyse cells. Within 24 hours after ofatumumab administration to patients with chronic lymphocytic leukemia (CLL), circulating tumor cells had lost CD20 and were opsonized with C3d, the terminal covalently bound form of complement protein C3. We hypothesized that C3d provides a target to eliminate residual CD20− tumor cells. To test this hypothesis, we generated C8xi, a mouse/human chimeric immunoglobulin G1 (IgG1) that reacts with human but not mouse C3d. C8xi was effective in a patient-derived xenograft model against CD20−, C3d opsonized CLL cells from patients treated with ofatumumab. We also generated rabbit mAbs, 2 of which were chosen because they bound mouse and human C3d with low nanomolar affinity but were minimally cross-reactive with full-length C3. Anti-C3d rabbit/human chimeric IgG1 in combination with ofatumumab or rituximab prolonged survival of xenografted mice that model 3 different types of non-Hodgkin lymphoma (NHL). For example, in a diffuse large B-cell lymphoma model (SU-DHL-6), median survival with single-agent CD20 mAb was 114 days but was not reached for mAb combination treatment (P = .008). In another NHL model (SU-DHL-4), single-agent and combination mAb therapy eradicated lymphoma in most mice. In long-term survivors from both cohorts, there was no evidence of adverse effects. We propose that C3d mAbs combined with complement-fixing CD20 mAbs can overcome antigen-loss escape and increase efficacy of mAb-based therapy.
Article Details
Authors (22)
Sivasubramanian Baskar
1Hematology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
Haiyong Peng
Erika M. Gaglione
1Hematology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
Elizabeth J. Carstens
Margaret A. Lindorfer
3Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA
Inhye E. Ahn
1Laboratory of Lymphoid Malignancies, Hematology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
Sarah E. M. Herman
1Hematology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
Martin Skarzynski
1Hematology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
Jing Chang
Keyvan Keyvanfar
1Hematology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
Vicent Butera
1Hematology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
Amy Blackburn
1Hematology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
Bérengère Vire
1Hematology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
Irina Maric
5Department of Laboratory Medicine, Clinical Center, National Institutes of Health, Bethesda, MD
Maryalice Stetler-Stevenson
5Flow Cytometry Unit, Laboratory of Pathology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
Constance M. Yuan
2Laboratory of Pathology, National Cancer Institute, National Institutes of Health, Bethesda, MD
Michael A. Eckhaus
6Division of Veterinary Resources, Office of Research Services, National Institutes of Health, Bethesda, MD
Susan Soto
1Laboratory of Lymphoid Malignancies, Hematology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
Mohammed Z. H. Farooqui
1Laboratory of Lymphoid Malignancies, Hematology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
Ronald P. Taylor
3Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA
Christoph Rader
Adrian Wiestner
1Laboratory of Lymphoid Malignancies, Hematology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD