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Cell Therapy & Immunotherapy
CD20 and CD37 antibodies synergize to activate complement by Fc-mediated clustering
Ferrata Storti Foundation
Haematologica 2019 Volume 104(9):1841-1852
Simone C. Oostindie,1,2 Hilma J. van der Horst,3 Margaret A. Lindorfer,4 Erika M. Cook,4 Jillian C. Tupitza,4 Clive S. Zent,5 Richard Burack,5
Karl R. VanDerMeid,5 Kristin Strumane,1 Martine E. D. Chamuleau,3 Tuna Mutis,3 Rob N. de Jong,1 Janine Schuurman,1 Esther C. W. Breij,1 Frank J. Beurskens,1 Paul W. H. I. Parren2,6 and Ronald P. Taylor4
1Genmab, Utrecht, the Netherlands; 2Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, the Netherlands; 3Department
of Hematology, Amsterdam University Medical Center, Amsterdam, the Netherlands; 4Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, Virginia, USA; 5Wilmot Cancer Institute, University of Rochester Medical Center, Rochester, NY, USA and 6Lava Therapeutics, Utrecht,
the Netherlands
ABSTRACT
CD20 monoclonal antibody therapies have significantly improved the outlook for patients with B-cell malignancies. However, many patients acquire resistance, demonstrating the need for new and improved drugs. We previously demonstrated that the natural process of antibody hexamer formation on targeted cells allows for optimal induc- tion of complement-dependent cytotoxicity. Complement-dependent cytotoxicity can be potentiated by introducing a single point mutation such as E430G in the IgG Fc domain that enhances intermolecular Fc-Fc interactions between cell-bound IgG molecules, thereby facilitating IgG hexamer formation. Antibodies specific for CD37, a target that is abun- dantly expressed on healthy and malignant B cells, are generally poor inducers of complement-dependent cytotoxicity. Here we demonstrate that introduction of the hexamerization-enhancing mutation E430G in CD37-specific antibodies facilitates highly potent complement-depen- dent cytotoxicity in chronic lymphocytic leukemia cells ex vivo. Strikingly, we observed that combinations of hexamerization-enhanced CD20 and CD37 antibodies cooperated in C1q binding and induced superior and synergistic complement-dependent cytotoxicity in patient-derived cancer cells compared to the single agents. Furthermore, CD20 and CD37 anti- bodies colocalized on the cell membrane, an effect that was potentiated by the hexamerization-enhancing mutation. Moreover, upon cell surface binding, CD20 and CD37 antibodies were shown to form mixed hexam- eric antibody complexes consisting of both antibodies each bound to their own cognate target, so-called hetero-hexamers. These findings pro- vide novel insights into the mechanisms of synergy in antibody-mediated complement-dependent cytotoxicity and provide a rationale to explore Fc-engineering and antibody hetero-hexamerization as a tool to enhance the cooperativity and therapeutic efficacy of antibody combinations.
Introduction
Monoclonal antibodies (mAbS) have become the backbone of treatment regimens for several cancer indications. The chimeric immunoglobulin (Ig)G1 CD20 mAb rit- uximab was the first mAb approved for clinical use in cancer therapy. CD20 is expressed on more than 90% of mature B cells and rituximab is widely used to treat B-cell malignancies.1-3 However, many patients do not experience complete remis- sion or acquire resistance to rituximab treatment, thereby demonstrating the need for improved mAb therapeutics or alternative tumor-targeting strategies.4-6
Correspondence:
SIMONE C. OOSTINDIE
sio@genmab.com
RONALD P. TAYLOR
rpt@virginia.edu
Received: October 2, 2018. Accepted: February 19, 2019. Pre-published: February 21, 2019.
doi:10.3324/haematol.2018.207266
Check the online version for the most updated information on this article, online supplements, and information on authorship & disclosures: www.haematologica.org/content/104/9/1841
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