# Effective imaging and treatment of Acute Myeloid Leukemia with radiotheranostics targeting the activated conformation of integrin-βeta2

## TL;DR

This study shows that targeting the active form of integrin-β2 with radiopharmaceuticals can effectively image and treat Acute Myeloid Leukemia in preclinical models.

## Contribution

The study introduces aITGB2 as a novel, tumor-selective target for AML and develops a theranostic pair for imaging and therapy.

## Key findings

- aITGB2 is widely expressed on AML cells but minimally on healthy tissues.
- The [89Zr]DFO*-7065 radiopharmaceutical showed high tumor uptake and reduced binding to normal marrow.
- The [225Ac]Macropa-PEG4-7065 therapy improved survival in AML models compared to existing treatments.

## Abstract

There remains an unmet clinical need for improved treatment strategies in Acute Myeloid Leukemia (AML). Although radiopharmaceutical therapies targeting non-cancer-selective antigens have shown promise in AML, their clinical utility is often limited by prolonged bone marrow suppression. Using a unique proteomics-based strategy, we recently identified the active conformation of integrin-β2 (aITGB2) as a novel, tumor-selective target for AML. Importantly, this conformational epitope is expressed widely on AML cells but minimally on normal marrow progenitors/healthy tissues. Here we first confirmed widespread aITGB2 expression on AML tumors that was largely independent of tumor genotype or prior therapeutic regimen. We developed diagnostic and therapeutic radiopharmaceuticals targeting aITGB2 utilizing a conformation-specific antibody (clone 7065). PET/CT imaging with 89Zr and 134Ce-labeled 7065 in AML models revealed high target-mediated uptake, greater than that compared to standard of care [18F]-FDG. PET/CT imaging with [89Zr]DFO*-7065 showed reduced binding to normal bone marrow and immune cells in humanized immune system mice compared to [89Zr]DFO*-anti-CD33. For therapy, we developed [225Ac]Macropa-PEG4-7065 using an optimized chelator-linker combination. Treatment with [225Ac]Macropa-PEG4-7065 in Nomo-1 and PDX AML disseminated models delayed tumor growth and improved overall survival compared to controls, including [225Ac]DOTA-anti-CD33, a clinical stage-radioimmunotherapy under evaluation in AML. Relapsed tumors demonstrated persistent aITGB2 expression, supporting continued development of fractionated dosing schemes, and proteomics analysis indicated activation of TCA cycle and carbon metabolism pathways, consistent with therapy-induced stress responses. These findings highlight [89Zr]DFO*-7065 and [225Ac]Macropa-7065 as a promising aITGB2-targeted theranostic pair with potential for imaging and treatment in future clinical translation.

This study demonstrates promising preclinical efficacy of aITGB2-targeted radiotheranostics for selective imaging and therapy in AML.