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1686 Metabolic Adaptation to Tyrosine Kinase Inhibition in Chronic Myelogenous Leukemia Stem Cells

Program: Oral and Poster Abstracts
Session: 631. Myeloproliferative Syndromes and Chronic Myeloid Leukemia: Basic and Translational: Poster I
Hematology Disease Topics & Pathways:
Research, Translational Research
Saturday, December 10, 2022, 5:30 PM-7:30 PM

Shaowei Qiu, MD1,2*, Vipul Sheth1*, Chengcheng Yan, MD1*, Juan Liu3*, Balu K. Chacko4*, Hui Li, BS1*, David Crossman5*, Seth D. Fortmann6,7*, Sajesan Aryal, BS1, Maria B. Grant6*, Robert S. Welner, PhD1*, Andrew J. Paterson, PhD1*, Adam R. Wende4*, Victor M Darley-Usmar, PhD4*, Rui Lu, PhD8, Jason W. Locasale3* and Ravi Bhatia, MD9

1Division of Hematology/Oncology, University of Alabama At Birmingham, Birmingham, AL
2State Key Laboratory of Experimental Hematology, National Clinical Research Center for Blood Diseases, Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin, China
3Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC
4Department of Pathology, Mitochondrial Medicine Laboratory, University of Alabama at Birmingham, Birmingham, AL
5Genomics Core Facility, University of Alabama at Birmingham, Birmingham, AL
6Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL
7Medical Scientist Training Program (MSTP), School of Medicine, University of Alabama at Birmingham, Birmingham, AL
8Division of Hematology and Oncology, Department of Medicine, University of Alabama At Birmingham, Birmingham, AL
9Division of Hematology and Oncology, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL

Objectives: BCR-ABL tyrosine kinase inhibitors (TKI) are highly effective in treatment of chronic myelogenous leukemia (CML) but fail to eliminate leukemia stem cells, which persist as a source of disease recurrence. Previous studies have suggested that primitive CML cells rely on upregulated oxidative metabolism for survival. However, there is limited knowledge about the effects of TKI treatment on CML stem cell metabolism and the role of metabolic adaptations in stem cell persistence after TKI treatment. Here we evaluated the metabolic response to TKI treatment in CML stem and progenitor cells using a representative SCL-tTA/BCR-ABL mouse model of CML.

Methods: CML mice were treated with the TKI Nilotinib or vehicle for 2 days, to evaluate initial effects of treatment, and for 2 weeks, to evaluate response to continued treatment. Bioenergetics, metabolite profiling, and stable isotope metabolic labeling was performed on BM c-Kit+ progenitor cells obtained from vehicle and TKI treated mice. The effects of TKI treatment on metabolism-related gene expression in CML hematopoietic stem cells (HSC) was studied using single cell RNA-Seq (scRNA) analysis of BM Lin- c-Kit+ Sca-1+ (LSK) cells from CML mice treated with vehicle or TKI for 2 days or 2 weeks.

Results: Extracellular flux analysis revealed that TKI treatment initially inhibited oxygen consumption rate (OCR), representing mitochondrial respiration, and extracellular acidification rate (ECAR), representing glycolysis, in CML progenitor cells, but that these were restored with continued TKI treatment. Metabolite profiling using high-resolution mass spectrometry (HRMS) identified significant initial reduction in glycolytic, glutaminolytic and tricarboxylic acid cycle (TCA) intermediates after 2 days of TKI treatment. However, metabolite levels were restored to levels similar to controls with continued TKI treatment. Steady-state metabolic labeling with [U-13C6]-glucose or [U-13C5]-Glutamine showed reduced glycolytic flux, glutaminolysis and TCA intermediates after treatment with TKI for 2 days, but restoration of glycolytic activity and increased glucose-mediated lactate generation, and increased glutaminolytic and TCA cycle activity with continued treatment. The above studies indicate initial inhibition of energy metabolism in CML progenitors with TKI treatment, but metabolic adaptation to continued TKI exposure. scRNA analysis of CML HSC populations showed that TKI exposure led to selective enrichment of primitive HSC subsets characterized by reduced OXPHOS, glycolysis, nucleotide metabolism, and MYC gene signatures. Treatment with TKI for 2 days further reduced metabolic gene signatures, but continued treatment led to restoration of MYC and OXPHOS gene signature expression coupled with enrichment of HSC and quiescence signatures in persistent HSC. TKI-treated stem cells showed increased levels of Hif1a protein and enhanced activity of HIF-1, a key transcriptional regulator of energy metabolism. Treatment of CML mice with a HIF-1 inhibitor, Echinomycin, in combination with TKI treatment, resulted in significant depletion of CML stem cells compared to TKI alone. The combination of HIF-1 inhibitor with TKI treatment also depleted human CML stem cells in xenografted mice.

Conclusions: Our results demonstrate metabolic adaptation in CML and progenitor stem cells following TKI treatment, and identify HIF-1 activation as a targetable mechanism to enhance elimination of CML stem cell that persist after TKI treatment.

Disclosures: No relevant conflicts of interest to declare.

*signifies non-member of ASH