Next-generation sequencing of immunoglobulin gene rearrangements for clonality assessment: a technical feasibility study by EuroClonality-NGS.

One of the hallmarks of B lymphoid malignancies is a B cell clone characterized by a unique footprint of clonal immunoglobulin (IG) gene rearrangements that serves as a diagnostic marker for clonality assessment. The EuroClonality/BIOMED-2 assay is currently the gold standard for analyzing IG heavy chain (IGH) and κ light chain (IGK) gene rearrangements of suspected B cell lymphomas. Here, the EuroClonality-NGS Working Group presents a multicentre technical feasibility study of a novel approach involving next-generation sequencing (NGS) of IGH and IGK loci rearrangements that is highly suitable for detecting IG gene rearrangements in frozen and formalin-fixed paraffin-embedded tissue specimens. By employing gene-specific primers for IGH and IGK amplifying smaller amplicon sizes in combination with deep sequencing technology, this NGS-based IG clonality analysis showed robust performance, even in DNA samples of suboptimal DNA integrity, and a high clinical sensitivity for the detection of clonal rearrangements. Bioinformatics analyses of the high-throughput sequencing data with ARResT/Interrogate, a platform developed within the EuroClonality-NGS Working Group, allowed accurate identification of clonotypes in both polyclonal cell populations and monoclonal lymphoproliferative disorders. This multicentre feasibility study is an important step towards implementation of NGS-based clonality assessment in clinical practice, which will eventually improve lymphoma diagnostics.

Results of the European survey on the assessment of deep molecular response in chronic phase CML patients during tyrosine kinase inhibitor therapy (EUREKA registry).

PURPOSE: The advent of tyrosine kinase inhibitor (TKI) therapies has revolutionized the treatment of chronic myeloid leukemia (CML). The European LeukemiaNet (ELN) recommends quantification of BCR-ABL1 transcripts by real-time quantitative PCR every 3 months during TKI treatment. Since a proportion of patients in deep molecular response (DMR: MR4, MR4.5, MR5) maintain remission after treatment stop, assessment of DMR is crucial. However, systematically collected molecular data, monitored with sensitive standardized assays, are not available outside clinical trials. METHODS: Data were collected on the standardized assessment of molecular response in the context of real-life practice. BCR-ABL1 transcript levels after > 2 years of TKI therapy were evaluated for DMR by local laboratories as well as standardized EUTOS laboratories. Since standardized molecular monitoring is a prerequisite for treatment discontinuation, central surveillance of the performance of the participating laboratories was carried out. RESULTS: Between 2014 and 2017, 3377 peripheral blood samples from 1117 CML patients were shipped to 11 standardized reference laboratories in six European countries. BCR-ABL1 transcript types were b3a2 (41.63%), b2a2 (29.99%), b2a2/b3a2 (3.58%) and atypical (0.54%). For 23.72% of the patients, the initial transcript type had not been reported. Response levels (EUTOS laboratory) were: no MMR, n = 197 (6.51%); MMR, n = 496 (16.40%); MR4, n = 685 (22.64%); MR4.5, n = 937 (30.98%); MR5, n = 710 (23.47%). With a Cohen's kappa coefficient of 0.708, a substantial agreement between EUTOS-certified and local laboratories was shown. CONCLUSIONS: Multicenter DMR assessment is feasible in the context of real-life clinical practice in Europe. Information on the BCR-ABL1 transcript type at diagnosis is crucial to accurately monitor patients' molecular response during or after TKI therapy.

Favorable radiation field decrease in gastric marginal zone lymphoma : Experience of the German Study Group on Gastrointestinal Lymphoma (DSGL).

PURPOSE: Long-term impact of stage-adapted field reduction in a large cohort of gastric marginal zone lymphoma (gMZL) patients treated conservatively with curative radiation therapy (RT). PATIENTS AND METHODS: Prospective analysis of paper records of 290 patients with stage IE-IIE gMZL, treated in 78 radiotherapeutic institutions in Germany from 1992-2013. Stage-adapted radiation fields decreased from extended field (EF) to involved field (IF) over the course of three consecutive prospective trials of the German Study Group on Gastrointestinal Lymphoma (DSGL). Treatment results were compared between the three cohorts. RESULTS: Overall collective with median age of 60 years, slight male predominance (m:f = 1.1:1) and ratio of disease stage I:stage II = 2.1:1. Median follow-up 6.4 years in total: 13.0 years in the first gastrointestinal study (GIT 1992), 8.2 years in the second (GIT 1996) and 4.7 years in the third study (DSGL 01/2003). Stage-adapted radiation field decrease together with further technological development led to reduced relative frequencies of acute/chronic adverse effects and until now was accompanied by lower disease recurrence. The third study design with smallest field size (IF in stage I, locoregional EF in stage II) achieved the best survival outcome at the 5­year follow-up (overall survival 92.7%, event-free survival 89.5% and lymphoma-specific survival 100.0%). Disease relapse observed in 10 patients. Cumulative incidence of disease-specific death was 1.7% of the followed patients. Primary disease stage associated with lymphoma-specific survival. CONCLUSION: Stage-adapted reduction towards IF in gMZL resulted in favorable adverse effects, local control and survival rates. These results support further decreases in modern RT of gMZL.

Quantitative assessment of molecular remission after high-dose therapy with autologous stem cell transplantation predicts long-term remission in mantle cell lymphoma.

To evaluate the prognostic impact of minimal residual disease (MRD), quantitative real-time polymerase chain reaction (RQ-PCR) of clonal IGH rearrangements was performed in 29 patients with mantle cell lymphoma (MCL) treated with high-dose radiochemotherapy and autologous stem cell transplantation (ASCT). Fourteen of 27 patients evaluable for MRD after ASCT achieved complete clinical and molecular remission, whereas 13 patients had detectable MRD within the first year after ASCT. Molecular remission after ASCT was strongly predictive for improved outcome, with a median progression-free survival (PFS) of 92 months in the MRD-negative group compared with 21 months in the MRD-positive group (P < .001). Median overall survival (OS) was 44 months in the MRD-positive group and has not been reached in the MRD-negative group (P < .003). In multivariate analysis, molecular remission and bulky disease were independent prognostic factors for PFS (P = .001 and P = .021, respectively). While cyclophosphamide, doxorubicin, vincristine, prednisolone (CHOP)-like cytoreduction had only modest influence, ara-C-containing mobilization and myeloablative radiochemotherapy significantly reduced MRD. Quantitative MRD measured in the stem cell products of 27 patients was not predictive for molecular remission. We conclude that sequential quantitative monitoring of residual disease after ASCT is a powerful indicator for treatment outcome in MCL and defines subgroups of patients with a significantly different prognosis.