37. Tumorgenetischen Arbeitstagung 2025: 08. bis 10. Mai 2025 in der Messe- und Universitätsstadt Leipzig.

The acquisition of subsequent genetic lesions (clonal evolution, CE) and/or the expansion of existing clones (CEXP) contributes to clonal dynamics (CD) in myelodysplastic syndromes (MDS). Although CD plays an important role in high-risk patients in disease progression and transformation into acute myeloid leukemia (AML), knowledge about CD in lower-risk MDS (LR-MDS) patients is limited due to lack of robust longitudinal data considering the long clinically stable courses of the disease. In this retrospective analysis, we delineate the frequency and the prognostic impact of CD in an unselected real-world cohort of LR-MDS patients. We screened 68 patients with a median follow-up of 40.5 months and a median of 7.5 (range: 2-22) timepoints for CE and CEXP detected by chromosomal banding analysis, fluorescence in situ hybridization (FISH), sequencing, and molecular karyotyping. In 30/68 patients, 47 CE events and a CD rate of 1 event per 4 years were documented. Of note, patients with at least 1 CE event had an increased probability for subsequent treatment. Unexpectedly, CE did not correlate with inferior outcome, which could be reasonably explained by CD detection triggering the subsequent start of a disease-modifying therapy (DMT).