Encyclopedia of CLL Subsets - a Unique Bioinformatics Tool and Database for Analysis of Subsets of Stereotypical B-Cell Receptors in CLL.

BACKGROUND: Chronic lymphocytic leukemia (CLL) is clinically and biologically highly variable disease which is closely related with multiple cellular and molecular markers, including sequence motifs of B-cell receptors. These motifs are highly similar (stereotyped) within one third of CLL patients and create homogeneous groups called stereotyped CLL subsets. The homogeneity is reflected also in clinical and biological characteristics of the disease. To facilitate access to the information about individual subsets, we have created a publicly available web-based tool Encyclopedia of CLL Subsets. MATERIALS AND METHODS: The Encyclopedia of CLL subsets belongs to our bioinformatics platform Antigen Receptor Research Tool (ARResT) developed for analysis, clustering, and annotation of immunoglobulin sequences. To gather primary knowledge about the subsets, we have analyzed a dataset of 7,500 CLL patients published by Agathangelidis et al in 2012 [1]. We have created an overview of major stereotyped subsets and their characteristics. Additional clinical and cytogenomic information about individual subsets has been obtained by machine text processing of available literature from server PubMed and is regularly updated. RESULTS: We have created a unique web-based application Encyclopedia of CLL Subsets available from http: //arrest.tools/subsets for an interactive access to the information about stereotyped CLL subsets. A user can obtain and compare basic information about the major subsets including their clinical and cytogenomic characteristics. These have been manually curated from machine processed results from PubMed database by experts in CLL research. Through the Encyclopedias user interface, user can also directly use our published tool ARResT/AssignSubsets to assign new immunoglobulin sequences to the major subsets. CONCLUSION: The Encyclopedia of CLL Subsets is a publicly available online tool facilitating access to the most recent research knowledge about stereotyped CLL subsets and enabling analysis of own data and interpretation of the results. This gives the Encyclopedia a great potential for its use in clinical routine. This work was supported by Czech Ministry of Health grant No. 34272A. All rights reserved. The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers. Submitted: 1. 3. 2019 Accepted: 4. 3. 2019.

Low-burden TP53 mutations in chronic phase of myeloproliferative neoplasms: association with age, hydroxyurea administration, disease type and JAK2 mutational status.

The multistep process of TP53 mutation expansion during myeloproliferative neoplasm (MPN) transformation into acute myeloid leukemia (AML) has been documented retrospectively. It is currently unknown how common TP53 mutations with low variant allele frequency (VAF) are, whether they are linked to hydroxyurea (HU) cytoreduction, and what disease progression risk they carry. Using ultra-deep next-generation sequencing, we examined 254 MPN patients treated with HU, interferon alpha-2a or anagrelide and 85 untreated patients. We found TP53 mutations in 50 cases (0.2-16.3% VAF), regardless of disease subtype, driver gene status and cytoreduction. Both therapy and TP53 mutations were strongly associated with older age. Over-time analysis showed that the mutations may be undetectable at diagnosis and slowly increase during disease course. Although three patients with TP53 mutations progressed to TP53-mutated or TP53-wild-type AML, we did not observe a significant age-independent impact on overall survival during the follow-up. Further, we showed that complete p53 inactivation alone led to neither blast transformation nor HU resistance. Altogether, we revealed patient's age as the strongest factor affecting low-burden TP53 mutation incidence in MPN and found no significant age-independent association between TP53 mutations and hydroxyurea. Mutations may persist at low levels for years without an immediate risk of progression.

GvL effects in T-prolymphocytic leukemia: evidence from MRD kinetics and TCR repertoire analyses.

Allogeneic stem cell transplantation (alloSCT) is used for treating patients with T-prolymphocytic leukemia (T-PLL). However, direct evidence of GvL activity in T-PLL is lacking. We correlated minimal residual disease (MRD) kinetics with immune interventions and T-cell receptor (TCR) repertoire diversity alterations in patients after alloSCT for T-PLL. Longitudinal quantitative MRD monitoring was performed by clone-specific real-time PCR of TCR rearrangements (n=7), and TCR repertoire diversity assessment by next-generation sequencing (NGS; n=3) Although post-transplant immunomodulation (immunosuppression tapering or donor lymphocyte infusions) resulted in significant reduction (>1 log) of MRD levels in 7 of 10 occasions, durable MRD clearance was observed in only two patients. In all three patients analyzed by TCR-NGS, MRD responses were reproducibly associated with a shift from a clonal, T-PLL-driven profile to a polyclonal signature. Novel clonotypes that could explain a clonal GvL effect did not emerge. In conclusion, TCR-based MRD quantification appears to be a suitable tool for monitoring and guiding treatment interventions in T-PLL. The MRD responses to immune modulation observed here provide first molecular evidence for GvL activity in T-PLL which, however, may be often only transient and reliant on a poly-/oligoclonal rather than a monoclonal T-cell response.