A 3′ tRNA‐derived fragment produced by tRNALeuAAG and tRNALeuTAG is associated with poor prognosis in B‐cell chronic lymphocytic leukemia, independently of classical prognostic factors.

Objective: 3′ tRNA‐derived fragments (3′ tRFs) are important epigenetic regulators in normal and pathological conditions. In this study, we aimed to explore the potential value of a 3′ tRF as a prognostic and/or screening biomarker for B‐cell chronic lymphocytic leukemia (B‐CLL). Methods: Publicly available next‐generation sequencing data from 20 B‐CLL cases were analyzed, followed by prediction of targets of the most abundantly and ubiquitously expressed 3′ tRFs, leading to selection of tRF‐LeuAAG/TAG. PBMCs were isolated from blood samples of 91 B‐CLL patients and 43 non‐leukemic donors, followed by total RNA extraction, in‐vitro polyadenylation, and first‐strand cDNA synthesis. Next, a real‐time quantitative PCR (qPCR) assay was developed for the accurate quantification of tRF‐LeuAAG/TAG and applied in all samples, prior to biostatistical analysis. Results: High tRF‐LeuAAG/TAG levels are associated with inferior overall survival (OS) of B‐CLL patients. The unfavorable significance of tRF‐LeuAAG/TAG was independent of established prognostic factors in B‐CLL. Stratified Kaplan‐Meier OS analysis uncovered the unfavorable prognostic role of high tRF‐LeuAAG/TAG levels for patients in Binet A or Rai I stage, negative CD38 expression, mutated, or unmutated IGHV genomic locus. Conclusion: Our approach revealed the independent prognostic value of a particular 3′ tRF, derived from tRNALeuAAG and tRNALeuTAG (tRF‐LeuAAG/TAG) in B‐CLL. [ABSTRACT FROM AUTHOR]