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

Available for download on Friday, May 03, 2019

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