Generation of CD20-specific TCRs for TCR gene therapy of CD20low B-cell malignancies insusceptible to CD20-targeting antibodies

Abstract

Immunotherapy of B-cell leukemia and lymphoma with CD20-targeting monoclonal antibodies (mAbs) has demonstrated clinical efficacy. However, the emergence of unresponsive disease due to low or absent cell surface CD20 urges the need to develop additional strategies. In contrast to mAbs, T-cells via their T-cell receptor (TCR) can recognize not only extracellular but also intracellular antigens in the context of HLA molecules. We hypothesized that T-cells equipped with high affinity CD20-targeting TCRs would be able to recognize B-cell malignancies even in the absence of extracellular CD20. We isolated CD8+ T-cell clones binding to peptide-MHC-tetramers composed of HLA-A*02:01 and CD20-derived peptide SLFLGILSV (CD20SLF) from HLA-A*02:01neg healthy individuals to overcome tolerance towards self-antigens such as CD20. High avidity T-cell clones were identified that readily recognized and lysed primary HLA-A2pos B-cell leukemia and lymphoma in the absence of reactivity against CD20-negative but HLA-A2pos healthy hematopoietic and nonhematopoietic cells. The T-cell clone with highest avidity efficiently lysed malignant cell-lines that had insufficient extracellular CD20 to be targeted by CD20 mAbs. Transfer of this TCR installed potent CD20-specificity onto recipient T-cells and led to lysis of CD20low malignant cell-lines. Moreover, our approach facilitates the generation of an off-the-shelf TCR library with broad applicability by targeting various HLA alleles. Using the same methodology, we isolated a T-cell clone that efficiently lysed primary HLA-B*07:02pos B-cell malignancies by targeting another CD20-derived peptide. TCR gene transfer of high affinity CD20-specific TCRs can be a valuable addition to current treatment options for patients suffering from CD20low B-cell malignancies.

T-Cell Receptor–Based Immunotherapy for Hematologic Malignancies

“…Transfer of an HLA-B*07:02restricted CD20 epitope-specific TCR enabled recognition of CD20-positive malignant cell lines and primary tumors (CLL, ALL, and mantle cell lymphoma) and suggested that TCR-based approaches may be effective in low-expression CD20-positive B-cell malignancies. 53 T cells transduced with a different TCR specific for an HLA-B*07:02-restricted CD22 epitope killed primary B-cell leukemia cells, but also killed healthy dendritic cells and macrophages, 54 illustrating both the potential promise and limitation of targeting lineage-restricted antigens.…”

T cell receptor-engineered T cells for leukemia immunotherapy

“…B cell-specific transcription factor BOB1-HLA-B*07:02-TCR-engineered T cells was efficiently shown to lyse primary B-cell leukemia, mantle cell lymphoma, and multiple myeloma in vitro and had in vivo antitumor reactivity in a multiple myeloma xenograft mouse model. This strategy may provide a novel target cellular treatment option for patients with B cell malignancies [41]. HMMR/Rhamm is overexpressed in numerous types of cancer, including ALL and AML.…”

Designer T-cells and T-cell receptors for customized cancer immunotherapies

“…Thymic deletion can also be bypassed by using HLA-mismatched donors to generate allo-TCRs specific for a given peptide-MHC [27]. Allogenic TCRs are sensitive enough to target antigens expressed at a very low copy number that cannot be targeted by antibody-based therapies [28]. However, it is crucial to ensure that TCRs procured from allogeneic HLA donors are truly peptidespecific rather that recognising allo-HLA irrespective of the peptide cargo.…”