Original Research ARTICLE
CD38-specific biparatopic heavy chain antibodies display potent complement-dependent cytotoxicity against multiple myeloma cells
- 1Universitätsklinikum Hamburg-Eppendorf, Germany
- 2Ablynx (Belgium), Belgium
CD38 is overexpressed by multiple myeloma cells and has emerged as a target for therapeutic antibodies. Nanobodies are soluble single domain antibody fragments derived from the VHH variable domain of heavy chain antibodies naturally occurring in camelids. We previously identified distinct llama nanobodies that recognize three non-overlapping epitopes of the extracellular domain of CD38. Here, we fused these VHH domains to the hinge, CH2, and CH3 domains of human IgG1, yielding highly soluble chimeric llama/human heavy chain antibodies (hcAbs). We analyzed the capacity of these hcAbs to mediate complement dependent cytotoxicity (CDC) to CD38-expressing human multiple myeloma and Burkitt lymphoma cell lines. Combinations of two hcAbs that recognize distinct, non-overlapping epitopes of CD38 mediated potent CDC, in contrast to the hcAb monotherapy with only weak CDC capacity. Similarly, combining daratumumab with a hcAb that recognizes a non-overlapping epitope resulted in dramatically enhanced CDC. Further, introducing the E345R HexaBody mutation into the CH3 domain strongly enhanced the CDC potency of hcAbs to CD38-expressing cells. Harnessing their high solubility, we genetically fused two distinct nanobodies into heteromeric dimers via a flexible peptide linker and then fused these nanobody dimers to the hinge, CH2 and CH3 domains of human IgG1, yielding highly soluble, biparatopic hcAbs. These biparatopic hcAbs elicited CDC toward CD38-expressing myeloma cells more effectively than daratumumab. Our results underscore the advantage of nanobodies vs. pairs of VH and VL domains for constructing bispecific antibodies. Moreover, the CD38-specific biparatopic heavy chain antibodies described here represent potential new powerful therapeutics for treatment of multiple myeloma.
Keywords: complement dependent cytotoxicity (CDC), CD38, Multiple Myeloma, Nanobody, Heavy chain antibody, Antibody engineering, biparatopic/bispecific binding domain
Received: 30 Jul 2018;
Accepted: 17 Oct 2018.
Edited by:Nicola Giuliani, Università degli Studi di Parma, Italy
Reviewed by:Torben Plesner, Vejle Sygehus, Denmark
Paul W. Parren, Lava Therapeutics B.V., Netherlands
Copyright: © 2018 Schütze, Petry, Hambach, Fumey, Schuster, Schriewer, Röckendorf, Menzel, Albrecht, Haag, Stortelers, Bannas and Koch-Nolte. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Dr. Peter Bannas, Universitätsklinikum Hamburg-Eppendorf, Hamburg, 20246, Hamburg, Germany, firstname.lastname@example.org
Prof. Friedrich Koch-Nolte, Universitätsklinikum Hamburg-Eppendorf, Hamburg, 20246, Hamburg, Germany, email@example.com