Author ORCID Identifier
https://orcid.org/0000-0002-3912-5068
Date of Graduation
5-2018
Document Type
Dissertation (PhD)
Program Affiliation
Immunology
Degree Name
Doctor of Philosophy (PhD)
Advisor/Committee Chair
Jeffrey Molldrem MD
Committee Member
Gheath Al-Atrash DO, PhD
Committee Member
William Plunkett PhD
Committee Member
Michael Curran PhD
Committee Member
Wendy Woodward MD, PhD
Abstract
Despite substantial advances in the treatment of acute myeloid leukemia (AML), only 30% of AML patients survive more than 5 years. Therefore, new therapeutics are much needed. Here, we present novel therapeutic strategy targeting myeloid leukemia antigen, HLA-A2 restricted peptide PR1.Previously, we have conducted pre-clinical development and humanization of a T cell receptor-like monoclonal antibody (h8F4) that targets PR1/HLA-A2 and eliminates AML xenografts by antibody-dependent cellular cytotoxicity (ADCC) following repeat dosing. To improve the potency of h8F4, we have developed a bi-specific T cell-engaging antibody that targets PR1/HLA-A2 on leukemia and CD3 on neighboring T cells. Here we demonstrate successful production and purification of the h8F4 bi-specific antibody. Utilizing flow cytometry, we confirm PR1/HLA-A2 and CD3-specific binding characteristics, T cell activation in the presence of PR1/HLA-A2, and importantly AML target cell cytotoxicity after h8F4 bi-specific antibody engagement with healthy donor effector T cells. Cytotoxicity assays were performed with both AML cell lines and primary patient AML blasts serving as target cells and health donor PBMC as a source of effector T cells at an Effector: Target ratio of 2:1. Results indicate up to 50% leukemia-specific lysis with 0.2nM h8F4 bi-specific antibody after only 18 hours of incubation. In addition, in vivo data also confirms significant elimination of the leukemia cell line U937 (as evidenced by % leukemia cells detected in peripheral blood and bio-luminescence imaging) in an NSG-U937 AML xenograft mouse model when compared to control groups treated with effector cells alone. In conclusion, these studies demonstrate the therapeutic potential of a novel bi-specific antibody targeting the PR1/HLA-A2 leukemia-associated antigen. This bi-specific antibody appears to increase the potency of h8F4 with rapid elimination of AML and our studies justify potential development as a treatment option for patients with high-risk AML.
Keywords
Acute Myeloid Leukemia, bi-specific antibody, cancer immunotherapy, re-directed cytotoxicity