Supplementary Material for: IRF4 gene expression on the trail of molecular response: looking at chronic myeloid leukemia from another perspective

Introduction Interferon regulatory factor 4 (IRF4) is a transcriptional factor with a key role in the modulation of inflammation and immune surveillance. The IRF4 gene is downregulated in Philadelphia-negative myeloproliferative neoplasms, and its expression is associated with prognosis and response to treatment. Methods We evaluated the IRF4 expression kinetics during tyrosine kinase inhibitor (TKI) treatment in a cohort of 116 chronic myeloid leukemia (CML) patients to elucidate its role in the disease course. Results A relationship between the IRF4 expression and the disease burden was observed at various disease stages. A correlation analysis between the International Scale (IS) and IRF4 values confirmed this close association. A significant increase is detected after 3 months of TKI treatment. Patients achieving early molecular response (EMR) had higher IRF4 values at both diagnosis and after 3 months of therapy as compared to those failing the EMR target. Patients achieving treatment-free remission (TFR) did not show IRF4 fluctuations during monitoring, while a decreased IRF4 expression emerged at the time of molecular relapse. Conclusion Our data seem to confirm the relevance of IRF4 in the pathogenesis of CML, suggesting a pivotal role at the disease onset and a predictive value during the CML course.