• Ákos Nagy, Bence Bátai, Laura Kiss, Stefánia Gróf, Péter Attila Király, Ádám Jóna, Judit Demeter, Hermina Sánta, Árpád Bátai, Piroska Pettendi, Tamás Szendrei, Márk Plander, Gábor Körösmezey, Hussain Alizadeh, Béla Kajtár, Gábor Méhes, László Krenács, Botond Timár, Judit Csomor, Erika Tóth, Tamás Schneider, Gábor Mikala, András Matolcsy, Donát Alpár, András Masszi, and Csaba Bödör.
• HCEMM-SE Molecular Oncohematology Research Group, Department of Pathology and Experimental Cancer Research, Semmelweis University, Budapest, Hungary.
• J. Intern. Med. 2023 Sep 1; 294 (3): 295313295-313.

BackgroundRecent genomic studies revealed enhancer of zeste homolog 2 (EZH2) gain-of-function mutations, representing novel therapeutic targets in follicular lymphoma (FL) in around one quarter of patients. However, these analyses relied on single-site tissue biopsies and did not investigate the spatial heterogeneity and temporal dynamics of these alterations.ObjectivesWe aimed to perform a systematic analysis of EZH2 mutations using paired tissue (tumor biopsies [TB]) and liquid biopsies (LB) collected prior to treatment within the framework of a nationwide multicentric study.MethodsPretreatment LB and TB samples were collected from 123 patients. Among these, 114 had paired TB and LB, with 39 patients characterized with paired diagnostic and relapse samples available. The EZH2 mutation status and allele burden were assessed using an in-house-designed, highly sensitive multiplex droplet digital PCR assay.ResultsEZH2 mutation frequency was found to be 41.5% in the entire cohort. In patients with paired TB and LB samples, EZH2 mutations were identified in 37.8% of the patients with mutations exclusively found in 5.3% and 7.9% of TB and LB samples, respectively. EZH2 mutation status switch was documented in 35.9% of the patients with paired diagnostic and relapse samples. We also found that EZH2 wild-type clones may infiltrate the bone marrow more frequently compared to the EZH2 mutant ones.ConclusionThe in-depth spatio-temporal analysis identified EZH2 mutations in a considerably higher proportion of patients than previously reported. This expands the subset of FL patients who most likely would benefit from EZH2 inhibitor therapy.© 2023 The Authors. Journal of Internal Medicine published by John Wiley & Sons Ltd on behalf of Association for Publication of The Journal of Internal Medicine.

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