Targeting intracellular WT1 in AML with a novel RMF-peptide-MHC-specific T-cell bispecific antibody

Abstract

Antibody-based immunotherapy is a promising strategy for targeting chemo-resistant 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 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 1 (WT1) in the context of human leukocyte antigen (HLA) A*02. Binding to CD3ε 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 AML cells was mediated in ex vivo long-term co-cultures utilizing allogenic (mean specific lysis: 67±6% after 13-14 days; ±SEM; n=18) or autologous, patient-derived T cells (mean specific lysis: 54±12% after 11-14 days; ±SEM; 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 specific lysis on day 3-4: 45.4±9.0% vs 70.8±8.3%; p=0.015; ±SEM; n=9-10). In vivo, WT1-TCB-treated humanized mice bearing SKM-1 tumors showed 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 I trial in patients with r/r AML (NCT04580121).

Molecular-Targeted Therapy of Pediatric Acute Myeloid Leukemia

“…The results of the AAML0531 phase III clinical trial have proven that Gemtuzumab ozogamicin (GO), an anti-CD33-calicheamicin drug-antibody conjugate, is effective in treating KMT2Amutated pediatric AML. The 5-year EFS was significantly higher in the GO-receiving group (48%) in comparison to the placebo (29%), with both cohorts being administered conventional chemotherapy [32].…”

Identification of CD8+ T-cell epitope from multiple myeloma-specific antigen AKAP4

“…The specific lysis of the AKAP4 + HLA-A*0201 + MM cell line provided strong evidence that AKAP4 630–638 (VLMLIQKLL) is a real antigenic epitope. Therefore, it is promising that the VLMLIQKLL epitope can be used as another myeloma antigen peptide to develop DC vaccine ( 28 ), TCR-T ( 29 , 30 ), TCR-mimic antibody ( 31 ), or T-cell bispecific antibody ( 32 ) against myeloma.…”

An in silico Model of T Cell Infiltration Dynamics Based on an Advanced in vitro System to Enhance Preclinical Decision Making in Cancer Immunotherapy

“…A tool HLA-restricted T cell bispecific antibody (hereafter toxic TCB), D66-ESK, known to result in broad T-cell mediated killing of HLA-A2-expressing target cells ( Augsberger et al, 2021 ) is used to test whether recreating the cellular and architectural complexity of an immune-responsive intestinal mucosa would allow us to recapitulate the damaging apoptotic effects and investigate the resulting influence on T cell infiltration. A non-targeting, CD3-only binding TCB (hereafter control TCB), DP47, was used as a control expected to yield no toxicity.…”