Low-burden TP53 mutations represent frequent genetic events in CLL with an increased risk for treatment initiation

TP53 aberrations predict chemoresistance and represent a contraindication for the use of standard chemoimmunotherapy in chronic lymphocytic leukaemia (CLL). Recent next-generation sequencing (NGS)-based studies have identified frequent low-burden TP53 mutations with variant allele frequencies below 10%, but the clinical impact of these low-burden TP53 mutations is still a matter of debate. In this study, we aimed to scrutinise the subclonal architecture and clinical impact of TP53 mutations using a sensitive, NGS-based mutation analysis in a 'real-world' cohort of 901 patients with CLL. In total, 225 TP53 mutations were identified in 17.5% (158/901) of the patients; 48% of these alterations represented high-burden mutations, while 52% were low-burden TP53 mutations. Low-burden mutations as sole alterations were identified in 39% (62/158) of all mutated cases with 82% (51/62) of these being represented by a single low-burden TP53 mutation. Patients harbouring low-burden TP53 mutations had significantly lower time to first treatment compared to patients with wild-type TP53. Our study has expanded the knowledge on the frequency, clonal architecture, and clinical impact of low-burden TP53 mutations. By demonstrating that patients with sole low-burden TP53 variants represent more than one-third of patients with TP53 mutations and have an increased risk for treatment initiation, our findings strengthen the need to redefine the threshold of TP53 variant reporting to below 10% in the routine diagnostic setting.

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.

[Novelties and experience with tyrosine kinase inhibitor therapy in chronic myeloid leukemia]

The introduction of tyrosine kinase inhibitor (TKI) treatment has resulted in dramatically improved survival in chronic myeloid leukemia (CML). With the new generation of TKIs the majority of patients reach optimal molecular response. Due to the improving survival and the need for lifelong treatment, the safety profile of the various TKIs and the comorbidities of patients have to be considered. More than half of our CML patients had comorbidities that could have influenced the choice of therapy. Because of the high prevalence of cardiovascular comorbidities, cardiovascular risk assessment plays an important role in the care of CML patients. The aim of this article is to summarize the current national and international guidelines of the treatment in CML and to show the importance of comorbidities and cardiovascular risk assessment in our CML patients.

[Treatment options and limitations in the management of myelofibrosis]

Primary myelofibrosis has the worst outcome among classical chronic myeloproliferative neoplasms. The past decade has brought numerous discoveries elucidating the role of proliferative mutations in disease pathogenesis. Mutations of the genes JAK2, MPL and CALR are present in about 90 percent of all primary myelofibrosis cases. The prognosis of myelofibrosis is considered heterogeneous, the expected survival of patients may range from one year to more than a decade based on several prognostic factors. Estimated survival can be assessed based on clinical prognostic scores. The aim of treatment is to reduce mortality and to alleviate the main aspects of disease-associated morbidity, e.g. anemia, splenomegalia and systemic symptoms. The effect of conventionally used cytoreductive agent hydroxyurea is usually transient. Use of allogeneic hematopoietic stem cell transplantation is limited by significant procedure-associated mortality. JAK2 tyrosine kinase inhibitors are the first treatment modality with evidence of improved overall survival, however, even these molecularly targeted therapies have failed to bring complete and permanent remission for the majority of myelofibrosis patients. Further improvement in overall survival for myelofibrosis can be expected from better understanding of the underlying molecular pathology and novel molecular therapeutic targets.

[Novelties in the diagnostics and therapy of hairy cell leukemia]

Differential diagnosis of hairy cell leukemia (HCL) and related disorders (hairy cell leukemia variant and splenic marginal zone lymphoma) is of utmost importance since the treatment and prognosis of these lymphomas differ. Since 2011 diagnosis of hairy cell leukemia has been easier because of discovery of the disease defining somatic mutation BRAF V600E mutation, which has been also known as driver mutation in malignant melanoma. The presence of this mutation enabled targeted molecular therapy in HCL as well. As first line therapy purine nucleoside analogues are the gold standard, but refractory/relapsed patient are candidates for targeted BRAF-inhibitor therapy. This manuscript serves as guidance in making diagnosis and standard treatment of HCL, and summarizes newest data about molecular therapy, including our single center experience collected from 75 patients.