Diede van Bladel1, Michiel van den Brand1, Jos Rijntjes1, Arjen Brinkman1,2, Tomas Reigl3, Nikos Darzentas3,4, Corine Hess5, Konnie Hebeda1, Han van Krieken1, Patricia Groenen1, Blanca Scheijen1
1 Department of Pathology, Radboud University Medical Center, Nijmegen, the Netherlands, 2 Department of Molecular Biology, Radboud Institute for Molecular Life Sciences, Radboud University, Nijmegen, the Netherlands, 3 CEITEC-Central European Institute of Technology, Masaryk University, Brno, Czech Republic, 4 Department of Hematology, University Hospital Schleswig-Holstein, Kiel, Germany, 5 Department of Hematology, Radboud University Medical Center, Nijmegen, the Netherlands
Hodgkin lymphoma (HL) is often a disease at relatively young age, and several risk factors have been described. HL is associated with a high cure rate, but relapse may occur in 10%–15% with early stage HL and 15%–30% with advanced HL. However, case reports and small series have shown that some of these relapses appear to be second primary HL. Assessment of clonal relationship between primary diagnosis and recurrent HL after treatment will distinguish true relapse from second primary lymphoma. Clonality detection in HL using conventional clonality assays has been severely hampered by the low frequency of clonal Hodgkin and Reed-Sternberg (HRS) cells and limited DNA quality obtained from formalin-fixed paraffin-embedded (FFPE) material. Together with the EuroClonality-NGS consortium, we have developed a novel approach to detect immunoglobulin (IG) heavy chain (IGH) and light chain (IGK) gene rearrangements by next-generation sequencing (NGS) that is highly suitable for detecting IG rearrangements in FFPE tissue specimens. By employing IGH-VJ, IGH-DJ and IGKV/intron-J/DE gene-specific primers and smaller amplicon sizes in combination with Ion Torrent PGM, we show that NGS-based IG clonality analysis can now be performed, even in samples of suboptimal DNA quality. Bioinformatic analyses with the interactive web-based immunoprofiler ARResT/Interrogate allows run/sample quality control and accurate identification of clonotypes. We have collected 70 paired primary and relapse samples, of which 38 cases showed a second lesion within three years, and 32 cases after three years. Results of our NGS-based clonality comparison will be presented. This study is an important step towards implementation of NGS-based clonality assessment in clinical practice for HL, which will improve lymphoma diagnostics and may alter therapeutic management of second primary HL.