TCR-mimic bispecific antibodies targeting LMP2A show potent activity against EBV malignancies
Mahiuddin Ahmed, … , Cheng Liu, Nai-Kong V. Cheung
Mahiuddin Ahmed, … , Cheng Liu, Nai-Kong V. Cheung
Published February 22, 2018
Citation Information: JCI Insight. 2018;3(4):e97805. https://doi.org/10.1172/jci.insight.97805.
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Research Article Oncology Therapeutics

TCR-mimic bispecific antibodies targeting LMP2A show potent activity against EBV malignancies

Abstract

EBV infection is associated with a number of malignancies of clinical unmet need, including Hodgkin lymphoma, nasopharyngeal carcinoma, gastric cancer, and posttransplant lymphoproliferative disease (PTLD), all of which express the EBV protein latent membrane protein 2A (LMP2A), an antigen that is difficult to target by conventional antibody approaches. To overcome this, we utilized phage display technology and a structure-guided selection strategy to generate human T cell receptor–like (TCR-like) monoclonal antibodies with exquisite specificity for the LMP2A-derived nonamer peptide, C426LGGLLTMV434 (CLG), as presented on HLA-A*02:01. Our lead construct, clone 38, closely mimics the native binding mode of a TCR, recognizing residues at position P3–P8 of the CLG peptide. To enhance antitumor potency, we constructed dimeric T cell engaging bispecific antibodies (DiBsAb) of clone 38 and an affinity-matured version clone 38-2. Both DiBsAb showed potent antitumor properties in vitro and in immunodeficient mice implanted with EBV transformed B lymphoblastoid cell lines and human T cell effectors. Clone 38 DiBsAb showed a stronger safety profile compared with its affinity-matured variant, with no activity against EBV– tumor cell lines and a panel of normal tissues, and was less cross-reactive against HLA-A*02:01 cells pulsed with a panel of CLG-like peptides predicted from a proteomic analysis. Clone 38 was also shown to recognize the CLG peptide on other HLA-A*02 suballeles, including HLA-A*02:02, HLA-A*02:04, and HLA-A*02:06, allowing for its potential use in additional populations. Clone 38 DiBsAb is a lead candidate to treat EBV malignancies with one of the strongest safety profiles documented for TCR-like mAbs.

Authors

Mahiuddin Ahmed, Andres Lopez-Albaitero, Dmitry Pankov, Brian H. Santich, Hong Liu, Su Yan, Jingyi Xiang, Pei Wang, Aisha N. Hasan, Annamalai Selvakumar, Richard J. O’Reilly, Cheng Liu, Nai-Kong V. Cheung

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Figure 2

Biochemical analysis of top antibody clones show distinct binding epitopes and affinities.

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Biochemical analysis of top antibody clones show distinct binding epitop...
(A) Epitope mapping of top 4 clones (26, 38, 40, 61) based on Ala-substituted CLG peptides at positions P3–P8. Clones were tested in a human IgG1 format for their ability to bind to pulsed T2 cells, as measured by flow cytometry. T2 cells were loaded with either WT CLG peptide or Ala-substituted CLG peptides at positions P3–P8. (B) SPR sensorgrams showing the binding kinetics of top 4 clones (26, 38, 40, 61) in a human IgG1 format. Each sensorgram shows the association and dissociation kinetic curves at the following antibody concentrations: 50 (red), 100 (green), 200 (purple), 400 (black), and 800 (brown) nM. Calculated affinity constants (KD) are displayed in each graph.