Prognostic value of clonal evolution identified by sequential FISH in untreated chronic lymphocytic leukaemia

Aim: The aim of the current study was to evaluate the potential clinical impact of clonal evolution detected by fluorescence in situ hybridization (FISH) in untreated chronic lymphocytic leukaemia (CLL) patients managed with a watch-and-wait strategy. Methods: We performed both overall survival (OS) and time to first treatment (TTFT) analysis. For the first one, we exploited a real-life cohort of 123 consecutive CLL patients followed at our institution, for which at least a second FISH evaluation during watch and wait was available. For TTFT analysis, we considered only patients treated after the second FISH sample (n = 69). Results: Considering the original cohort, patients who acquired a FISH abnormality displayed a worse outcome with a median OS of 91.9 months compared to 147.3 months for patients who did not acquire any FISH abnormalities (P = 0.007). Unmutated immunoglobulin heavy chain gene (IGHV) genes were associated with a higher probability of acquiring a FISH abnormality (P = 0.04). Turning to TTFT analysis, patients who gained at least one FISH abnormality (n = 7, 10%) were characterised by an earlier treatment requirement with a median TTFT of 1.1 months, compared to 2.7 months in patients who did not acquire any FISH abnormalities (n = 62, 90%) (P = 0.025). Conclusions: The dynamic acquisition of karyotypic abnormalities by FISH predicts poor outcomes and early treatment requirement in CLL patients. Our results suggest that FISH analysis could be integrated with other clinical and biological features to obtain dynamic scores that are able to predict outcomes at different phases of disease history.