effectiveness of rituximab-based chemotherapy in first-line (treatment cohort 1), but failed to demonstrate a benefit in the second-line setting (treatment cohort 2; Table 1). Furthermore, no evidence was found that prior rituximab exposure was associated with the effectiveness of rituximab-based chemotherapy in second-line (treatment cohort 3). Covariates associated with inferior TFS in that particular cohort were age per one-year increase and first-line therapy with a backbone of purine analogues, as compared with a backbone of alkylating agents. Conversely, patients with a longer time to next treatment had better TFS. Summary/Conclusion:In this comprehensive, population-based study, the effectiveness of first-line treatment with rituximab-based chemotherapy was not objectivated in second-line treatment. The lack of effectiveness of rituximab-based chemotherapy in second-line could not be explained by previous rituximab exposure.

Background & Aims. T-cell receptor excision circles (TREC) and к-deleting recombination excision circles (KREC) are extrachromosomal DNA segments generated during V(D)J recombination process that characterize the diversity of the antigen repertoire of T- and B-cells. The aim of our study is to identify the prognostic value of the excision circles in the chronic lymphocytic leukemia (CLL) setting. Methods. The excision circles' levels were assessed by means of real time PCR in 109 patients with high-risk CLL and 16 matched healthy individuals. Results. KREC levels were significantly (p < 0.001) lower in CLL patients vs. the reference group. TREC levels were lower in groups with unmutated status of immunoglobulin heavy chain variable region genes (p < 0.05) and 11q deletions (p < 0.1). Moreover, the KREC levels were higher in NOTCH1 mutation carriers than in noncarriers (p < 0.05). The comparison of treatment outcomes demonstrated a correlation between a high TREC level and achievement of complete remission. The prognostic value of the bio-marker was confirmed by ROC-analysis: AUC_TREC = 0.713 (p = 0.001) Conclusion. Association between excision circles' le' and clinical/laboratory CLL prognostic factors, as well complete remission achievement, makes possible the plementation of the test for early prediction of the treatm outcome.