Validation of a Next-Generation Sequencing-Based T-Cell Receptor Gamma Gene Rearrangement Diagnostic Assay: Transitioning from Capillary Electrophoresis to Next-Generation Sequencing.

Assessment of T-cell receptor γ gene (TRG) rearrangements is an importants consideration in the diagnostic workup of lymphoproliferative diseases. Although fragment analysis by PCR and capillary electrophoresis (CE) is the current standard of such assessment in clinical molecular diagnostic laboratories, it does not provide sequence information and is only semi-quantitative. Next-generation sequencing (NGS)-based assays are an attractive alternative to the conventional fragment size-based methods, given that they generate results with specific clonotype sequence information and allow for more accurate quantitation. The present study evaluated various test parameters and performance characteristics of a commercially available NGS-based TRG gene-rearrangement assay by testing 101 clinical samples previously characterized by fragment analysis. The NGS TRG assay showed an overall accuracy of 83% and an analytical specificity of 100%. The concordance rates were 88% to 95% in the Vγ1-8, Vγ10, and Vγ11 gene families, but lower in the Vγ9 gene family. This difference was mostly attributed to the incomplete polyclonal symmetry resulting from the two-tube CE assay versus the one-tube design of the NGS assay. The NGS assay also demonstrated strengths in distinguishing clonotypes of the same fragment size. This clinical validation demonstrated robust performance of the NGS-based TRG assay and identified potential pitfalls associated with CE assay design that are important for understanding the observed discrepancies with the CE-based assay.

Perspective: sensitive detection of residual lymphoproliferative disease by NGS and clonal rearrangements-how low can you go?

Malignant lymphoproliferative disorders collectively constitute a large fraction of the hematological cancers, ranging from indolent to highly aggressive neoplasms. Being a diagnostically important hallmark, clonal gene rearrangements of the immunoglobulins enable the detection of residual disease in the clinical course of patients down to a minute fraction of malignant cells. The introduction of next-generation sequencing (NGS) has provided unprecedented assay specificity, with a sensitivity matching that of polymerase chain reaction-based measurable residual disease (MRD) detection down to the 10-6 level. Although reaching 10-6 to 10-7 is theoretically feasible, employing a sufficient amount of DNA and sequencing coverage is placed in the perspective of the practical challenges when relying on clinical samples in contrast to controlled serial dilutions. As we discuss, the randomness of subsampling must be taken into account to accommodate the sensitivity threshold-in terms of both the required number of cells and sequencing coverage. As a substantial part of the reviewed studies do not state the depth of coverage or even amount of DNA in some cases, we call for increased transparency to enable critical assessment of the MRD assays for clinical implementation and feasibility.

Clinical outcomes of children receiving ABO-incompatible versus ABO-compatible heart transplantation: a multicentre cohort study.

BACKGROUND: ABO-incompatible heart transplantation increases donor availability in young children and is evolving into standard of care in children younger than 2 years. Previous smaller studies suggest similar outcomes to ABO-compatible heart transplantation, but persisting alterations of the immune system in ABO-incompatible recipients might increase the risk of some infections or benefit the graft owing to reduced HLA reactivity. We aimed to assess long-term outcomes in young children after they received ABO-incompatible or ABO-compatible heart transplantation. METHODS: In this multicentre, prospective cohort study, we analysed data from the Pediatric Heart Transplant Society registry to compare children who received ABO-incompatible or ABO-compatible heart transplantation before age 2 years between Jan 1, 1999, and June 30, 2018. Given significantly different clinical demographics between the two groups, we also matched each ABO-incompatible recipient to two ABO-compatible recipients using propensity score matching. We assessed patient and graft survival, coronary allograft vasculopathy, malignancy, acute rejection (any episode resulting in augmentation of immunosuppression), and infections (requiring intravenous antibiotic or antiviral therapy or life-threatening infections treated with oral therapy). FINDINGS: We included 2206 children who received a heart transplant before age 2 years, with 11 332·6 patient-years of cumulative observation time. Children who received an ABO-incompatible transplant (n=364) were younger and a larger proportion had congenital heart disease and ventilator and mechanical circulatory support than the ABO-compatible recipients (n=1842). After matching, only differences in blood group (more O in ABO-incompatible and more AB in ABO-compatible groups) and use of polyclonal induction therapy with anti-thymocyte globulins persisted. The two matched groups had similar post-transplantation graft survival (p=0·74), freedom from coronary allograft vasculopathy (p=0·75), and malignancy (p=0·51). ABO-incompatible recipients showed longer freedom from rejection (p=0·0021) in the overall cohort, but not after matching (p=0·48). Severe infections (p=0·0007), bacterial infections (p=0·0005), and infections with polysaccharide encapsulated bacteria (p=0·0005) that share immunological properties with blood group antigens occurred less frequently after ABO-incompatible heart transplantation. INTERPRETATION: ABO-incompatible heart transplantation for children younger than 2 years is a clinically safe approach, with similar survival and incidences of rejection, coronary allograft vasculopathy, and malignancy to ABO-compatible recipients, despite higher-risk pre-transplant profiles. ABO-incompatible transplantation was associated with less bacterial infection, particularly encapsulated bacteria, suggesting that the acquired immunological changes accompanying ABO tolerance might benefit rather than jeopardise transplanted children. FUNDING: Pediatric Heart Transplant Society.

Distinct decrease in peripheral lymphocytes in EBER-positive cases of MTX-LPD.

OBJECTIVES: To determine the clinical characteristics of methotrexate-associated lymphoproliferative disorder (MTX-LPD). METHODS: In this study, 12 RA patients who developed MTX-LPD were assessed. The peripheral blood lymphocyte (PBL) count at the onset of MTX-LPD was compared to that 6 months before the onset, in Epstein-Barr virus-encoded RNA (EBER)-positive and -negative subgroups. We examined the change in the PBL count after MTX withdrawal. In patients with relapsed LPD, changes in the PBL count before relapse were also examined. RESULTS: Regression of LPD after MTX withdrawal was noted in eight patients. In these patients, the PBL count was decreased at the onset of MTX-LPD compared to 6 months before the onset; the decrease was significantly more prominent in EBER-positive patients. In cases of spontaneous regression of LPD, the PBL count recovered quickly after MTX withdrawal. Four of eight patients showed a recurrence of LPD after they improved following MTX withdrawal. These patients also exhibited a decreased PBL count at recurrence compared to 6 months before recurrence. CONCLUSION: A decrease in the PBL count might be involved in the pathogenesis of MTX-LPD, especially in EBER-positive cases and in patients with LPD relapse after MTX withdrawal following initial improvement.

Clinical aspects in patients with rheumatoid arthritis complicated with lymphoproliferative disorders without regression after methotrexate withdrawal and treatment for arthritis after regression of lymphoproliferative disorders.

OBJECTIVES: To identify predictive factors for lymphoproliferative disorders (LPDs) that persist after methotrexate (MTX) withdrawal (Persistent-LPD) and the optimal treatment for rheumatoid arthritis (RA) after LPD regression. METHODS: Among 3666 patients with RA treated with MTX in our department from 2006 to 2017, 26 cases of LPD that regressed after MTX withdrawal (Regressive-LPD) and 25 cases of Persistent-LPD were compared. Multivariate logistic analysis was performed to identify predictive factors for Persistent-LPD. Retention rates of biological disease-modifying antirheumatic drugs (bDMARDs) were calculated using the Kaplan-Meier Method. RESULTS: In Persistent-LPD, the incidence of diffuse large B-cell lymphoma was higher (76%). The overall 2-year survival rate was 83.9%: 95.8% for Regressive-LPD and 71.0% for Persistent-LPD. The International Prognostic Index (IPI) risk classification was useful for predicting Persistent-LPD. bDMARDs were introduced in 38 RA patients after LPD regression. Unadjusted retention rate of bDMARDs in the 51 LPD patients was significantly lower than that in the 1668 non-LPD RA patients in our bDMARD cohort (controls) (p = 0.029). The 1-year retention rates for bDMARDs were 69% and 64% for tocilizumab and abatacept, respectively vs. 46% for TNF-inhibitor (TNFi). CONCLUSION: Risk assessment using IPI predicted Persistent-LPD. After LPD regression, non-TNFi tended to have higher retention rates.

Next-Generation Sequencing Technology to Identify Minimal Residual Disease in Lymphoid Malignancies.

Next-generation sequencing (NGS) of immunoglobulin (IG) and T cell receptor (TR) rearrangements represents a modern alternative to classical RQ-PCR-based minimal residual disease (MRD) detection. The same primer sets and conditions can be used for all patients, which is undoubtedly one of the most important benefits of NGS, not only reducing the labor required to perform the analysis but also enabling the assay to comply with the upcoming EU IVD regulation. So far, only one standardized academic protocol for this task has been published, developed, and validated within the EuroClonality-NGS working group. In this chapter we describe the materials and methods for amplicon library preparation for sequencing on Illumina MiSeq, and the bioinformatic pipeline for this protocol.

Diagnostic performance of the ClearLLab 10C B cell tube.

INTRODUCTION: Pre-analytical and analytical errors can threaten the reliability of flow cytometry (FC) results. A potential solution to some of these is the use of dry, pre-mixed antibodies, such as the ClearLLab 10C system. The purpose of the present study was to compare the diagnostic performance of the ClearLLab 10C B cell tube with that of our standard laboratory practice. METHODS: We compared the diagnoses made with the ClearLLab 10C B cell tube (experimental strategy) with those made with standard laboratory practice (standard strategy). Samples were selected aiming for representation of the full spectrum of B cell disorders, with an emphasis on mature B cell malignancies, as well as healthy controls. RESULTS: We included 116 samples (34 normal controls, 4 acute lymphoblastic leukemias, 54 mature lymphoproliferative disorders in peripheral blood and bone marrow, 3 myelomas, 6 bone marrow samples with involvement by lymphoma and 1 with elevated hematogone count, 14 lymph node samples, 1 cerebrospinal fluid, and 1 pleural effusion). There were two diagnostic errors (1.7%). The agreement between the two strategies in the percentage of CD19 cells and fluorescence intensity of CD5, CD19, CD20, CD200, and CD10 was very good. CONCLUSIONS: In this study, the ClearLLab 10C B cell tube performed similarly to our standard laboratory practice to diagnose and classify mature B cell malignancies.

Rapid identification and characterization of infected cells in blood during chronic active Epstein-Barr virus infection.

Epstein-Barr virus (EBV) preferentially infects epithelial cells and B lymphocytes and sometimes T and NK lymphocytes. Persistence of EBV-infected cells results in severe lymphoproliferative disorders (LPDs). Diagnosis of EBV-driven T or NK cell LPD and chronic active EBV diseases (CAEBV) is difficult, often requiring biopsies. Herein, we report a flow-FISH cytometry assay that detects cells expressing EBV-encoded small RNAs (EBERs), allowing rapid identification of EBV-infected cells among PBMCs. EBV-infected B, T, and/or NK cells were detectable in various LPD conditions. Diagnosis of CAEBV in 22 patients of Caucasian and African origins was established. All exhibited circulating EBV-infected T and/or NK cells, highlighting that CAEBV is not restricted to native American and Asian populations. Proportions of EBV-infected cells correlated with blood EBV loads. We showed that EBV-infected T cells had an effector memory activated phenotype, whereas EBV-infected B cells expressed plasma cell differentiation markers. Thus, this method achieves accurate and unambiguous diagnoses of different forms of EBV-driven LPD and represents a powerful tool to study their pathophysiological mechanisms.

FMOD expression in whole blood aids in distinguishing between chronic lymphocytic leukemia and other leukemic lymphoproliferative disorders. A pilot study.

BACKGROUND: Within the hematopoietic compartment, fibromodulin (FMOD) is almost exclusively expressed in chronic lymphocytic leukemia (CLL) lymphocytes. We set out to determine whether FMOD could be of help in diagnosing borderline lymphoproliferative disorders (LPD). METHODS: We established 3 flow cytometry-defined groups (CLL [n = 65], borderline LPD [n = 28], broadly defined as those with CLLflow score between 35 and -20 or discordant CD43 and CLLflow, and non-CLL LPD [n = 40]). FMOD expression levels were determined by standard RT-PCR in whole-blood samples. Patients were included regardless of lymphocyte count but with tumor burden ≥40%. RESULTS: FMOD expression levels distinguished between CLL (median 98.5, interquartile range [IQR] 37.8-195.1) and non-CLL LPD (median 0.012, IQR 0.003-0.033) with a sensitivity and specificity of 1. Most borderline LPDs were CD5/CD23/CD200-positive with no loss of B-cell antigens and negative or partial expression of CD43. 16/22 patients with available cytogenetic analysis showed trisomy 12. In 25/28 (89%) of these patients, FMOD expression levels fell between CLL and non-CLL (median 3.58, IQR 1.06-6.21). DISCUSSION: This study could suggest that borderline LPDs may constitute a distinct group laying in the biological spectrum of chronic leukemic LPDs. Future studies will have to confirm these results with other biological data. Quantification of FMOD can potentially be of help in the diagnosis of phenotypically complex LPDs.

The clinical impact of absolute lymphocyte count in peripheral blood among patients with methotrexate - associated lymphoproliferative disorders.

Regressive lymphoproliferative disorders (R-LPD) after methotrexate (MTX) withdrawal are one of the specific features of methotrexate - associated lymphoproliferative disorders (MTX-LPD). Although the impact of the absolute lymphocyte count (ALC) on the pathogenesis of R-LPD has been recently emphasized, understanding relapse/regrowth events (RRE) and differences among LPD subtypes is necessary. In this study, we confirmed ALC recovery in the regressive group (R-G; R-LPD without RRE) and relapse/regrowth group (R/R-G; R-LPD with RRE). The increase in ALC lasted at least 2 years in R-G, whereas it decreased within 3 years in R/R-G, supporting the better overall survival (OS) in R-G, as previously reported. In addition, our study suggested that an ALC of 1000/µL at the time of development of LPD is a significant predictor for treatment-free survival (TFS). Furthermore, an ALC of 1000/µL at 6 months after MTX withdrawal was found to be a significant indicator of TFS and OS for R-G and R/R-G. The ALC decreased gradually before LPD development in R/R-G, whereas it decreased 6 months before LPD development in R-G, confirming the important role of ALC in the pathogenesis of MTX-LPD such as regressive events and RRE. In addition to ALC, other predictive factors, such as serum C-reactive protein and soluble interleukin-2 receptors, may be helpful in the management of MTX-LPD, including the decision making for an additional chemotherapy for regressive LPD after MTX withdrawal.

Alteration of Cell Surface Markers CD38 and CD138 in Lymphoproliferative Disorders in the Ocular Adnexa.

BACKGROUND/AIM: CD38 is a cell surface marker commonly present in plasma cells and activated T cells, while CD138 is a representative plasma cell marker. The aim of this study was to describe the expression of cell surface markers including CD38 and CD138, in the tumors of patients with IgG4-related ophthalmic disease (IgG4-ROD) and extranodal marginal zone B-cell lymphoma (EMZL) of the ocular adnexa. MATERIALS AND METHODS: Twenty-four consecutive patients of whom 12 had IgG4-ROD and 12 EMZL were enrolled in this study. Medical records were reviewed for flow cytometry (FCM) results on conventional T-cell markers, B-cell markers, CD38 and CD138. RESULTS: Positive rates of T-cell markers, CD38 and CD138 were significantly higher in IgG4-ROD than in EMZL (p<0.01 and p<0.05, respectively). CONCLUSION: Our FCM results on CD38 and CD138 showed that the lymphocyte populations were different between IgG4-ROD and EMZL, which may reflect the different pathophysiology of the two diseases.

A homozygote novel L451W mutation in CECR1 gene causes deficiency of adenosine deaminase 2 in a pediatric patient representing with chronic lymphoproliferation and cytopenia.

Deficiency of Adenosine Deaminase 2 (DADA2) is a monogenic autoinflammatory disorder characterized by livedo reticularis, skin ulcers, subcutaneous rash, aphthous ulcers, and leukocytoclastic vasculitis, neurological signs such as early onset stroke and polyneuropathy. A minority of DADA2 patients suffer from severe cytopenia and lymphoproliferation. Herein, we report an adolescent patient, followed up as having a hematological disorder for many years, eventually diagnosed as having DADA2. In view of the presence of elevated acute phase reactants, hepatosplenomegaly, low IgM level, lymphopenia, anemia, and neutropenia, and a subtle neurological involvement we considered DADA2 diagnosis. The diagnosis was confirmed by identification of a novel L451W mutation in CECR1 gene. The patient has been successfully treated with etanercept, monthly intravenous immunoglobulin replacement, and low-dose methylprednisolone. In conclusion, although the absence of skin and neurological findings, low IgM levels, and persistent lymphopenia should lead the physicians to consider DADA2 in patients with particularly complicated hematological abnormalities.

Lymphocyte subset at time of Epstein-Barr viremia post-allogeneic hematopoietic stem cell transplantation in children may predict development of post-transplant lymphoproliferative disease: CD8:CD20 ratio as a sensitive predictor.

EBV-associated PTLD following allogeneic HSCT is a serious complication associated with significant mortality. In this retrospective study, we evaluated whether lymphocyte subset numbers and CD8:CD20 ratio at time of EBV viremia in children undergoing allogeneic HSCT could predict development of PTLD. Absolute lymphocyte count, lymphocyte subsets, and CD8:CD20 ratio at the time of EBV viremia were analyzed. Patients who were treated preemptively with rituximab for high blood EBV viral load were excluded. Out of 266 patients transplanted during the study period, 26 patients were included in the analysis. Patients were divided into two cohorts; cohort 1 included patients with EBV-associated PTLD (n = 5; four with proven, one with probable PTLD). Cohort 2 included patients with EBV viremia without PTLD (n = 21). Lymphocyte recovery was slower in the PTLD group. CD8:CD20 ratio was significantly lower in the PTLD group (median 0.15) compared to the non-PTLD group (median 2.4, P = .012). Using the ROC curve and 1 as the cutoff value, CD8:CD20 ratios were analyzed. In the PTLD group, 4/5 patients (80%) had a ratio <1 whereas in the non-PTLD group, all 21 patients had a ratio >1. Sensitivity and specificity were 80% and 100%, respectively. Negative and PPVs were 95% and 100%, respectively. Profoundly low T-cell count and CD8:CD20 ratio may be used to predict development of PTLD in the context of EBV viremia in children post-allogeneic HSCT. Further studies are needed to validate this finding.

Viral DNA Loads in Various Blood Components of Patients With Epstein-Barr Virus-Positive T-Cell/Natural Killer Cell Lymphoproliferative Diseases.

To evaluate diagnostic values for Epstein-Barr virus (EBV) DNA loads in different blood components of patients with EBV-positive T-cell/natural killer cell lymphoproliferative diseases, EBV DNA loads were compared among disease categories in each blood component from 59 patients. Plasma viral loads were significantly higher in "active" disease in chronic active EBV infection. EBV DNA was not detected in the plasma from 7 patients in whom EBV DNA was detected in peripheral blood mononuclear cells and whole blood. Diagnostic cutoff values for whole blood EBV DNA loads of patients with chronic active EBV infection compared with those of infectious mononucleosis was 104.2 (15 800) IU/mL.

Risk factors and clinical outcomes of Epstein-Barr virus DNAemia and post-transplant lymphoproliferative disorders after haploidentical and matched-sibling PBSCT in patients with hematologic malignancies.

In allogeneic hematopoietic stem cell transplantation recipients, reactivation of Epstein-Barr virus (EBV) can cause post-transplantation lymphoproliferative disorder (PTLD), which may rapidly progress to multiorgan failure and even death. Development of EBV PTLD correlates very closely with use of anti-thymocyte globulin (ATG) and type of transplant. To assess the incidences and clinical features of EBV DNAemia and PTLD in the setting of stem cell transplantation using unmanipulated G-CSF-primed allogeneic peripheral blood stem cells as graft, we performed a retrospective analysis of stem cell transplantation from HLA-matched sibling donors (MSD-SCT, n = 90) or HLA-haploidentical related donors (HID-SCT, n = 110) in patients with hematological malignancies. All of HID-SCT recipients and 27.8% of MSD-SCT recipients received an ATG-containing conditioning regimen. One-year cumulative incidence of EBV DNAemia was 44.1%, ranging from 4.8% in MSD-SCT recipients not using ATG to 20.0% in MSD-SCT recipients using ATG, and 73.7% in HID-SCT recipients. Risk factors for EBV reactivation included use of ATG (p = 0.008), male donor (p = 0.034), and cytomegalovirus DNAemia (p < 0.001). One-year incidence of EBV PTLD was 11.9%, ranging from 1.8% in recipients of MSD-SCT not using ATG to 4.4% in recipients of MSD-SCT using ATG, and 23.5% in recipients of HID-SCT. Risk factors for PTLD after HID-SCT included in fludarabine-containing conditioning regimen (p = 0.010), cytomegalovirus DNAemia (p = 0.036), and patient's age < 40-yr (p = 0.032). Two-year non-relapse mortality was higher for patients with EBV DNAemia than those without EBV DNAemia (35.8% vs. 15.3%, p = 0.002). One-year relapse-free survival and overall survival among patients with PTLD were 40.2% and 44.9%, respectively, as opposed to 63.4% and 68.4% among patients without PTLD (both p < 0.05). In multivariate analyses, EBV DNAemia predicted a lower risk of relapse (p = 0.025), while PTLD was a marginally significant predictor of relapse (p = 0.092). This study identified patients at risk of EBV reactivation and PTLD after unmanipulated allogeneic peripheral blood stem cell transplantation.

Establishing Absolute Lymphocyte Count Thresholds for Further Review of Peripheral Blood Lymphocytosis to Judiciously Screen for Monoclonal B-Cell Populations in Older Adults.

OBJECTIVES: Lymphocytosis may represent either a lymphoproliferative disorder (LPD) or a reactive process. The absolute lymphocyte count (ALC) threshold for further evaluation of lymphocytosis is not well established. METHODS: We prospectively performed flow cytometry on blood samples from patients 50 years or older with ALCs of 4.0 × 109 cells/L or greater without a history of an LPD. RESULTS: Monoclonal B-cell populations were found in 34 (19.1%) of 178 cases, with incidence increasing with age. In patients younger than 75 years, no monoclonal B-cell population was identified in patients with ALCs less than 4.4 × 109 cells/L, while such clones were found below and above this threshold in patients 75 years and older. CONCLUSIONS: These findings support a threshold for smear review and flow cytometry no lower than 4.4 × 109 cells/L in patients younger than 75 years and a threshold as low as 4.0 × 109 cells/L in patients 75 years and older.