Journal
BLOOD
Volume 138, Issue 25, Pages 2655-2669Publisher
AMER SOC HEMATOLOGY
DOI: 10.1182/blood.2020010477
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Funding
- German Research Council (DFG) [SU197/3-1, SFB 1243]
- Bavarian Elite Graduate School i-target
- Wilhelm-Sander Stiftung [2018.087.1]
- European Research Council [681524]
- Italian Ministry of Health [RF-201102348034]
- Associazione Italiana per la Ricerca sul Cancro [14162]
- DKMS Mechtild Harf Foundation
- Roche
- European Research Council (ERC) [681524] Funding Source: European Research Council (ERC)
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The novel T-cell bispecific (TCB) antibody targets intracellular antigens, recognizing multiple leukemia-associated targets. WT1-TCB demonstrates potent killing of AML cells through various methods, with enhanced cytotoxicity when combined with immunomodulatory drugs.
Antibody-based immunotherapy is a promising strategy for targeting chemoresistant leukemic cells. However, classical antibody-based approaches are restricted to targeting lineage-specific cell surface antigens. By targeting intracellular antigens, a large number of other leukemia-associated targets would become accessible. In this study, we evaluated a novel T-cell bispecific (TCB) antibody, generated by using CrossMAb and knob-into-holes technology, containing a bivalent T-cell receptor-like binding domain that recognizes the RMFPNAPYL peptide derived from the intracellular tumor antigen Wilms tumor protein (WT1) in the context of HLA-A*02. Binding to CD3(epsilon) recruits T cells irrespective of their T-cell receptor specificity. WT1-TCB elicited antibody-mediated T-cell cytotoxicity against AML cell lines in a WT1- and HLA-restricted manner. Specific lysis of primary acute myeloid leukemia (AML) cells was mediated in ex vivo long-term cocultures by using allogeneic (mean +/- standard error of the mean [SEM] specific lysis, 67 +/- 6% after 13-14 days; n = 18) or autologous, patient-derived T cells (mean +/- SEM specific lysis, 54 +/- 12% after 11-14 days; n = 8). WT1-TCB-treated T cells exhibited higher cytotoxicity against primary AML cells than an HLA-A*02 RMF-specific T-cell clone. Combining WT1-TCB with the immunomodulatory drug lenalidomide further enhanced antibody-mediated T-cell cytotoxicity against primary AML cells (mean +/- SEM specific lysis on days 3-4, 45.4 +/- 9.0% vs 70.8 +/- 8.3%; P = .015; n = 9-10). In vivo, WT1-TCB-treated humanized mice bearing SKM-1 tumors exhibited a significant and dose-dependent reduction in tumor growth. In summary, we show that WT1-TCB facilitates potent in vitro, ex vivo, and in vivo killing of AML cell lines and primary AML cells; these results led to the initiation of a phase 1 trial in patients with relapsed/refractory AML (#NCT04580121).
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