Date of Award

2-27-2026

Embargo Period

2-27-2031

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Molecular and Cellular Pharmacology and Experimental Therapeutics

College

College of Graduate Studies

Additional College

College of Medicine

First Advisor

Nathan Dolloff

Second Advisor

Joe Blumer

Third Advisor

Peggi Angel

Fourth Advisor

Dennis Guttridge

Fifth Advisor

Richard O'Neil

Abstract

The development of a successful targeted immunotherapeutic for pediatric acute myeloid leukemia (pAML) has remained a challenge due to disease heterogeneity, leaving conventional chemotherapy as the standard of care (SOC). Although novel agents have been incorporated into modern treatment plans, these drugs have typically been developed for adult AML (aAML), with their application to pAML considered retrospectively. Therapeutic strategies are needed that account for the distinct genetic and clinical features of pAML. Sialic acid-binding immunoglobulin-like lectin 3 (CD33) has been a key target in AML immunotherapy research due to its overexpression in 90% of AML cases. However, 50% of these patients harbor a single nucleotide polymorphism that generates a CD33 splice variant lacking the antibody-binding epitope for existing CD33-targeted therapeutics. These limitations highlight the need for a novel approach for pAML that is effective across all CD33-positive patient populations.

In this dissertation, we describe the development and evaluation of an MHC class II (MHCII)-targeted immunotherapy, M2T-CD33, which delivers CD33 to antigen-presenting cells for enhanced presentation to the immune system. We initially established that M2T-CD33 confers protection against AML and optimized construct design and in vivo evaluation strategies through binding and aggregation analyses, humoral response quantification, and survival assessment in a syngeneic mouse model. We next validated anti-AML efficacy in a prophylactic model and demonstrated a survival benefit in combination with SOC chemotherapy, cytarabine. In a therapeutic model, combination with an immune checkpoint inhibitor further prolonged survival, implicating T cell involvement in M2T-CD33 efficacy.

We further characterized the adaptive immune response elicited by M2T-CD33, showing contributions of the anti-CD33 humoral response and dependence on both CD4+ and CD8+ T cells through in vitro and in vivo studies. Importantly, we observed no evidence of toxicity at concentrations 40-fold higher than the efficacious dose, as determined by cytokine levels, body weight, blood cell counts, plasma chemistry, and myeloid progenitor analysis. Finally, binding assays showed that M2T-CD33 should be applicable to patients regardless of splice variant status and HLA haplotype. Collectively, these studies demonstrate the preclinical potential of M2T-CD33 for the treatment of pAML and emphasize the importance of MHCII for cancer immunotherapy.

Rights

Copyright is held by the author. All rights reserved.

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