Parallel testing of liquid biopsy (ctDNA) and tissue biopsy samples reveals a higher frequency of EZH2 mutations in follicular lymphoma

BACKGROUND

Recent 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.

OBJECTIVES

We 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.

METHODS

Pretreatment 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.

RESULTS

EZH2 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.

CONCLUSION

The 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.

[TP53 mutation analysis in chronic lymphocytic leukaemia]

INTRODUCTION

In recent years much progress has been made in the therapy of chronic lymphocytic leukaemia, as the new innovative medicine proved to be effective in managing patients carrying TP53 abnormalities. To identify all these patients, it is essential to screen for both forms of TP53 defects, including both 17p deletions and TP53 mutations.

AIM

The aim of this study was to determine the frequency of TP53 mutations and their association with 17p deletions in a large Hungarian cohort of 196 patients suffering from chronic lymphocytic leukaemia.

METHOD

We performed mutation analysis of TP53 (exons 3-10) using Sanger sequencing.

RESULTS

TP53 mutations were present in 15.8% of patients, half of which were associated with 17p deletion. By analysing both forms, TP53 defect was identified in 25.4% of the patients.

CONCLUSIONS

Our study demonstrates that by performing a TP53 mutation analysis, an additional 10% of high-risk patients can be detected. Orv. Hetil., 2017, 158(6), 220-228.

[Clinical and genetic background of familial myelodysplasia and acute myeloid leukemia]

Myelodysplastic syndrome and acute myeloid leukaemia are mainly sporadic diseases, however, rare familial cases exist. These disorders are considered rare, but are likely to be more common than currently appreciated, and are characterized by the autosomal dominant mutations of hematopoietic transcription factors. These syndromes have typical phenotypic features and are associated with an increased risk for developing overt malignancy. Currently, four recognized syndromes could be separated: familial acute myeloid leukemia with mutated CEBPA, familial myelodysplastic syndrome/acute myeloid leukemia with mutated GATA2, familial platelet disorder with propensity to myeloid malignancy with RUNX1 mutations, and telomere biology disorders due to mutations of TERC or TERT. Furthermore, there are new, emerging syndromes associated with germline mutations in novel genes including ANKRD26, ETV6, SRP72 or DDX41. This review will discuss the current understanding of the genetic basis and clinical presentation of familial leukemia and myelodysplasia.