Page 125 - Haematologica Vol. 110 - January 2025

ARTICLE - Chronic Myeloid Leukemia
Single-cell proteo-transcriptomic profiling reveals altered characteristics of stem and progenitor cells in patients receiving cytoreductive hydroxyurea in early-phase chronic myeloid leukemia
Hana Komic,1,2* Malin S. Nilsson,1,3* Lovisa Wennström,4 Tagore Sanketh Bandaru,2 Pekka Jaako,5 Kristoffer Hellstrand,1,6 Fredrik B. Thorén1,2# and Anna Martner1,3#
1TIMM Laboratory at Sahlgrenska Center for Cancer Research, University of Gothenburg; 2Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg; 3Department of Microbiology and Immunology, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg; 4Department of Hematology, Sahlgrenska University Hospital; 5Sahlgrenska Center for Cancer Research, Department of Microbiology and Immunology, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg and 6Department of Infectious Diseases, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
*HK and MSN contributed equally as first authors. #FBT and AM contributed equally as senior authors.
Abstract
Hydroxyurea (HU) is frequently used in the early phase of chronic myeloid leukemia (CML) to achieve cytoreduction prior to tyrosine kinase inhibitor therapy. However, its impact on CML stem and progenitor cells (SPC) remains largely unknown. This study utilized targeted proteo-transcriptomic expression data on 596 genes and 51 surface proteins in 60,000 CD14-CD34+ cells from chronic phase CML patients to determine effects of short-term HU treatment (4-19 days) on CML SPC. Periph- eral blood and bone marrow samples were obtained from 17 CML patients eligible for short-term HU treatment (3 patients before and after HU, 7 patients before HU and 7 patients after HU) and subjected to single-cell CITE-sequencing and/or flow cytometry analysis. The analysis revealed enhanced frequencies of hemoglobin-expressing (HBA1, HBA2, HBB) erythroid pro- genitor cells in blood and bone marrow following HU treatment. In addition, there was an accumulation of cell subsets with S/G2/M phase-related gene and protein expression, likely representing cells arrested in, or progressing slowly through, the cell cycle. The increased frequency of cells in S/G2/M phase after HU was observed already among the most immature leukemic stem cells (LSC), and patients with a large fraction of LSC in the S/G2/M phase showed poor responsiveness to tyrosine kinase inhibitor treatment. We conclude that short-term HU treatment entails differentiation of erythroid progen- itor cells and alters the characteristics of LSC in CML. The results imply that studies of LSC and progenitor populations in CML should take effects of initial HU therapy into account.
Introduction
Chronic myeloid leukemia (CML) is a clonal myeloprolifera- tive neoplasm characterized by a balanced t(9;22) translo- cation leading to formation of the Philadelphia chromosome and the BCR::ABL1 fusion oncogene.1,2 BCR::ABL1 conveys constitutive tyrosine kinase activity that translates into expansion and accumulation of malignant cells of different maturation stages in blood and bone marrow.2 Imatinib as
well as second and third-generation tyrosine kinase inhibi- tors (TKI) competitively block BCR::ABL1 kinase activity and have drastically improved survival in CML.3,4
Prior to the introduction of TKI therapy, CML patients re- ceived treatment with the chemotherapeutics hydroxyurea (HU) and busulfan, the cytokine interferon-a or alloge- neic stem cell transplants.5,6 While these treatments are no longer first-line options, many CML patients receive a short-term course of HU to reduce hyperleukocytosis
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Correspondence: A. Martner anna.martner@gu.se
Received: Accepted: Early view:
January 15, 2024. August 6, 2024. August 15, 2024.
https://doi.org/10.3324/haematol.2024.285071
©2025 Ferrata Storti Foundation Published under a CC BY-NC license