Program DHC-Virtual
20 - 21 January 2021
Abstracts Lymphoid session 3
Abstract
Early detection of Chronic Lymphocytic Leukemia up to 18 years before diagnosis
21 January
08:30 08:42
M. Kolijn
Paper

UTILIZATION OF NEXT GENERATION SEQUENCING TECHNOLOGY FOR EARLY DETECTION OF CHRONIC LYMPHOCYTIC LEUKEMIA UP TO 18 YEARS BEFORE DIAGNOSIS

 

P. Martijn Kolijn (1), Fatemeh Saberi Hosnijeh (2), Florentin Späth (3), Peter Nilsson (4), Olle Melander (4), Roel C. Vermeulen (2), Anton W. Langerak (1)
(1) Erasmus MC, Department of Immunology, Rotterdam, (2) Institute for Risk Assessment Sciences, Division of Environmental Epidemiology and Veterinary Public Health, Utrecht, (3) Umeå University, Department of Radiation Sciences, Umeå, (4) Lund University, Department of Clinical Sciences, Malmö
No potential conflicts of interest
Introduction

Chronic lymphocytic leukemia (CLL) is preceded by an asymptomatic stage known as monoclonal B-cell lymphocytosis (MBL). Previous studies have shown that an MBL clone can be detected up to 77 months before diagnosis, with CLL-like MBL progressing to CLL requiring treatment  at a rate of 1.1% per year. However, it remains unclear how long before CLL diagnosis skewing in the immunoglobulin gene (IG) repertoire becomes detectable and what features of MBL arise during the early stages of development.  Insights in the characteristics of the early MBL stages would be useful to uncover the initial underlying biological processes that lead to lymphocytosis. 

 

Methods

Peripheral blood was drawn from healthy volunteers as a part of the European Prospective Investigation into Cancer and Nutrition (EPIC). For our study we selected 58 individuals who were later diagnosed with CLL  along with 58 matched controls. One buffy coat sample was available from each participant. Date of CLL diagnosis ranged from 3 months to 21 years after sampling. Genomic DNA was isolated from buffy coats of the 116 participants and the IGH gene repertoire was sequenced using a leader-based IGH assay on the Illumina Miseq platform. Lymphocyte counts at time of sampling were available for half of the participants. The IGH repertoire was characterized using the ARResT/Interrogate immunoprofiler.

Results

Significant skewing in the IGH repertoire could be detected in 39 out of 58 participants (68% ) as far as 18 years prior to CLL diagnosis, while lymphocyte counts only identified CLL patients up to 7 years before diagnosis. Even though the degree of skewing of the repertoire was variable,  with  dominant  clonotypes  ranging  from  2%  to  95%  of  the  total IGH reads  per  sample,  the dominant clonotype was strongly elevated over the polyclonal background in each of these cases. The degree of skewing of the IGH repertoire increased strongly with the shorter time to diagnosis. Surprisingly, we identified the majority of unmutated dominant clonotypes between 8 to 18 years before CLL diagnosis. Three dominant clonotypes, matching stereotypic CLL clonotypes (CLL#2, CLL#8 and CLL#16), were identified between 16-13 years before CLL diagnosis in separate individuals.

 

 

Conclusion

We performed NGS-based analysis of the IGH gene repertoire of CLL patients between 3 months to 21 years before diagnosis. Significant skewing in the IGH repertoire could be detected up to 18 years prior to CLL diagnosis while lymphocyte counts only identified CLL patients up to 7 years before diagnosis. We are currently working to obtain repeated samples, clinical data and material taken at CLL diagnosis to verify that the clonotypes identified years before diagnosis remain present and stable until diagnosis.

 

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