Szymczyk A, et al. - In this investigation, researchers sought to study the possible role of microRNAs as markers predicting the outcome of chemotherapy based on purine nucleoside analogs (PNA) – fludarabine and cladribine in chronic lymphocytic leukemia (CLL) patients. In patients with high miR-34a expression, a significantly higher rate of apoptosis induced by PNA compared to those with low expression was detected. Interestingly, in standard cytogenetic patients such differences have been detected. These outcomes can prove an important role for miR-34a expression as an apoptosis predictor, even in cases where there are no other risk factors such as cytogenetic abnormalities. An evaluation of the expression of microRNAs appears to be useful as an indicator of PNA sensitivity and can help predict the outcome of PNA-based therapy.