Abstract 7469: Inflammation plays an important role in the progression of chronic myeloid leukemia

Abstract The development of Tyrosine Kinase Inhibitors (TKIs) resulted in a significant increase in the life expectancy of patients with chronic myeloid leukemia (CML). Nevertheless, TKIs still fail in a significant proportion of therapy-naïve patients, or their effectiveness is hampered by secondary resistance. It is therefore urgent to explore the underlying mechanisms in order to develop new therapeutic approaches to cure CML instead of controlling the disease with a lifelong TKI therapy. Using the ScltTA/TRE-BCR: : ABL1 mouse model for chronic phase CML we show that BCR: : ABL1 leads to the elevation of pro-inflammatory cytokines, known to be important in disease initiation and progression. This is supported by our data from CML patients, where we also observe higher levels of pro-inflammatory cytokines in the serum compared to healthy individuals. Furthermore, we demonstrate that BCR: : ABL1 drives the expansion of bone marrow derived mast cells (BMMCs) and sensitizes them for FcεRI triggered degranulation. Interestingly, these BMMCs show differences in their lipid metabolism. Hence, sphingomyelin and lysophosphatidylcholine, both known to be involved in inflammation and cancer progression, are upregulated in BCR: : ABL1-positive mast cells compared to their negative counterparts. By crossing in the Cpa3Cre mediated model for mast cell deficiency, we demonstrate for the first time that the lack of mast cells prevents the BCR: : ABL1 induced upregulation of pro-inflammatory cytokines and also the development of splenomegaly. In addition, we were able to show that splenomegaly in CML patients is associated with high bone marrow mast cell counts and that an upregulation of pro-inflammatory cytokines in patient serum samples correlated with tryptase levels. In summary, our study identifies mast cells and their inflammatory cytokines as important factors in disease progression and suggests considering them as additional targets in CML therapy. Citation Format: Melanie Langhammer, Julia Schöpf, Timo Jaquet, Katharina Horn, Moritz Angel, Daniel Mohl, Simon Lagies, Corinna Spohr, Daniel Christen, Franziska Maria Uhl, Tiago Maié, Henrike Jacobi, Thorsten B. Feyerabend, Julia Huber, Marcus Panning, Cassian Sitaru, Ivan Costa, Robert Zeiser, Konrad Aumann, Heiko Becker, Till Braunschweig, Steffen Koschmieder, Bernd Kammerer, Khalid Shoumariyeh, Michael Huber, Mirle Schemionek-Reinders, Tilman Brummer, Sebastian Halbach. Inflammation plays an important role in the progression of chronic myeloid leukemia abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 7469.