Raveendran, A. | bioRxiv Science

bioRxiv2025

Effective imaging and treatment of Acute Myeloid Leukemia with radiotheranostics targeting the activated conformation of integrin-Beta2

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-{beta}2 (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. One Sentence SummaryThis study demonstrates promising preclinical efficacy of aITGB2-targeted radiotheranostics for selective imaging and therapy in AML.

cancer biology↗

bioRxiv2022

PKM2-mediated epigenetic reprogramming regulates hypoxic expression of PFKFB3 to promote breast cancer progression

The hypoxic milieu is a critical modulator of aerobic glycolysis, yet the regulatory mechanisms existing between the key glycolytic enzymes in hypoxic cancer cells are largely unexplored. In particular, M2 isoform of pyruvate kinase (PKM2) - the ratelimiting enzyme of glycolysis, is well-known to confer adaptive advantages under hypoxia. Herein, we report a non-canonical role of PKM2 in functioning as a co-activator of HIF-1 to govern the transcription of 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3). Nuclear PKM2 enhances HIF-1 and p300 occupancy at PFKFB3 hypoxia responsive elements (HREs) resulting in its upregulation. Consequently, absence of nuclear PKM2 fails to recruit HIF-1 which activates an opportunistic occupancy of HIF-2 at PFKFB3 HREs. Enhanced binding of HDAC3 also occurs in the absence of PKM2 which prevents HIF-2 from efficiently inducing PFKFB3 to hamper proliferation of hypoxic breast cancer cells. In addition, clinical relevance of the study has been investigated by demonstrating that Shikonin blocks nuclear translocation of PKM2 to suppress PFKFB3 expression. Furthermore, MCF7 cells-derived xenograft tumors in mice exhibited substantial tumor growth inhibition when treated with shikonin, highlighting the vitality of targeting PKM2. Taken in concert, this work provides novel insights into contributions of PKM2 in modulating hypoxic transcriptome and a previously unreported molecular axis exhibited by the hypoxic breast cancer cells for ensuring the maintenance of PFKFB3 expression essential for achieving high glycolytic flux. Statement of significanceNuclear PKM2 orchestrates the binding of histone modifiers to epigenetically alter PFKFB3 promoter and affects the binding of HIF-2. Notably, targeting this axis attenuates proliferation of hypoxic breast cancer cells.

cancer biology↗