MRD detection in B-cell non-Hodgkin lymphomas using Ig gene rearrangements and chromosomal translocations as targets for real-time quantitative PCR

Circulating Tumor DNA as a Complementary Prognostic Biomarker during CAR-T Therapy in B-Cell Non-Hodgkin Lymphomas

The emergence of CD19-directed chimeric antigen receptor T-cell (CAR-T) therapy has revolutionized the treatment paradigm for R/R B-cell NHLs. However, challenges persist in accurately evaluating treatment response and detecting early relapse, necessitating the exploration of novel biomarkers. Circulating tumor DNA (ctDNA) via liquid biopsy is a non-invasive tool for monitoring therapy efficacy and predicting treatment outcomes in B-NHL following CAR-T therapy. By overcoming the limitations of conventional imaging modalities, ctDNA assessments offer valuable insights into response dynamics, molecular mechanisms of resistance, and early detection of molecular relapse. Integration of ctDNA monitoring into clinical practice holds promise for personalized therapeutic strategies, guiding the development of novel targeted therapies, and enhancing patient outcomes. However, standardization of assay methodologies and consensus on clinical response metrics are imperative to unlock the full potential of ctDNA in the management of B-NHL. Prospective validation of ctDNA in clinical trials is necessary to establish its role as a complementary decision aid.

Minimal Residual Disease Status Predicts Outcome in Patients With Previously Untreated Follicular Lymphoma: A Prospective Analysis of the Phase III GALLIUM Study

PURPOSE

We report an analysis of minimal residual/detectable disease (MRD) as a predictor of outcome in previously untreated patients with follicular lymphoma (FL) from the randomized, multicenter GALLIUM (ClinicalTrials.gov identifier: NCT01332968) trial.

PATIENTS AND METHODS

Patients received induction with obinutuzumab (G) or rituximab (R) plus bendamustine, or cyclophosphamide, doxorubicin, vincristine, prednisone (CHOP) or cyclophosphamide, vincristine, prednisone (CVP) chemotherapy, followed by maintenance with the same antibody in responders. MRD status was assessed at predefined time points (mid-induction [MI], end of induction [EOI], and at 4-6 monthly intervals during maintenance and follow-up). Patients with evaluable biomarker data at diagnosis were included in the survival analysis.

RESULTS

MRD positivity was associated with inferior progression-free survival (PFS) at MI (hazard ratio [HR], 3.03 [95% CI, 2.07 to 4.45]; P < .0001) and EOI (HR, 2.25 [95% CI, 1.53 to 3.32]; P < .0001). MRD response was higher after G- versus R-chemotherapy at MI (94.2% v 88.9%; P = .013) and at EOI (93.1% v 86.7%; P = .0077). Late responders (MI-positive/EOI-negative) had a significantly poorer PFS than early responders (MI-negative/EOI-negative; HR, 3.11 [95% CI, 1.75 to 5.52]; P = .00011). The smallest proportion of MRD positivity was observed in patients receiving bendamustine at MI (4.8% v 16.0% in those receiving CHOP; P < .0001). G appeared to compensate for less effective chemotherapy regimens, with similar MRD response rates observed across the G-chemo groups. During the maintenance period, more patients treated with R than with G were MRD-positive (R-CHOP, 20.7% v G-CHOP, 7.0%; R-CVP, 21.7% v G-CVP, 9.4%). Throughout maintenance, MRD positivity was associated with clinical relapse.

CONCLUSION

MRD status can determine outcome after induction and during maintenance, and MRD negativity is a prerequisite for long-term disease control in FL. The higher MRD responses after G- versus R-based treatment confirm more effective tumor cell clearance.

The Effectiveness of Dual-Staining Immunohistochemistry in the Detection of Mantle Cell Lymphoma in the Bone Marrow

OBJECTIVES

Immunohistochemistry (IHC) is a useful method for mantle cell lymphoma (MCL) detection in the bone marrow (BM). However, recognition of the neoplastic B cells can be challenging, especially when there is low-level disease.

METHODS

We examined BM from 105 patients with MCL. IHC was performed using cyclin D1/CD79a and PAX5/CD5 dual stains, which were compared with single stains that included CD20, CD79a, cyclin D1, and CD5 and with multiparameter flow cytometry (FC).

RESULTS

Based on the FC data, the overall sensitivity of the dual IHC stains was 95.6%. Both dual IHC stains showed better efficacy for detecting MCL cells compared with the aggregated single stains (P = .012). While three cases were positive by FC analysis but negative for dual staining, four cases showed cells positive for cyclin D1/CD79a and PAX5/CD5 dual staining that were not detected by FC. Two of these latter cases were in patients with minimal or focal disease involvement.

CONCLUSIONS

Cyclin D1/CD79a and PAX5/CD5 dual IHC staining is an efficient procedure for the detection of MCL in the marrow and is particularly helpful in low-level or focal involvement by MCL. This approach can be particularly useful when marrow aspirates are inadequate or unavailable.

Current and future best practice in imaging, staging, and response assessment for Non-Hodgkin's lymphomas: the Specialist Integrated Haematological Malignancy Imaging Reporting (SIHMIR) paradigm shift

Non-Hodgkin's lymphoma (NHL) encompasses over 40 different haematological malignancies, including low and high-grade neoplasms, such as follicular lymphoma (FL) and diffuse large B-cell lymphoma (DLBCL) respectively. A key clinical issue in the context of NHL is delayed and inaccurate diagnosis, which contributes adversely to patient morbidity and mortality. This article will address relevant imaging aspects, with particular reference to advancements in NHL imaging, including computed tomography (CT), integrated positron-emission tomography (PET)-CT, and magnetic resonance imaging (MRI). We provide multiparametric (anato-functional) imaging display items, including histological correlation. We will also introduce our original concept of "Specialist Integrated Haematological Malignancy Imaging Reporting" (SIHMIR), a paradigm shift in lymphoma radiology.

Molecular response after obinutuzumab plus high-dose cytarabine induction for transplant-eligible patients with untreated mantle cell lymphoma (LyMa-101): a phase 2 trial of the LYSA group

BACKGROUND

Obinutuzumab monotherapy has shown promising efficacy in mantle cell lymphoma. We aimed to investigate the activity of obinutuzumab plus DHAP (dexamethasone, high-dose cytarabine, and cisplatin), measured by minimal residual disease quantitative (q)PCR status in the bone marrow after four cycles.

METHODS

LyMa-101 was a prospective, open-label, single-arm, phase 2 trial. Participants were enrolled from 28 hospitals in France. Newly diagnosed patients with mantle cell lymphoma (aged 18 to <66 years) who were eligible for autologous stem-cell transplantation received four cycles of obinutuzumab plus DHAP (obinutuzumab 1000 mg/m² intravenously on days 1, 8, and 15 at cycle 1 and day 1 at cycles 2, 3, and 4; dexamethasone 40 mg intravenously on days 1-4, cytarabine 2 g/m² intravenously every 12 h on day 1, and according to local investigator, cisplatin 100 mg/m² by continuous infusion over 24 h on day 1 or carboplatin area under the curve 5 or oxaliplatin 130 mg/m²) every 21 days before transplantation, and 3 years of obinutuzumab (1000 mg/m² every 2 months) maintenance followed by minimal residual disease-based obinutuzumab on-demand maintenance. The primary outcome was minimal residual disease negativity in the bone marrow after four cycles of obinutuzumab plus DHAP at the end of induction, measured in the efficacy set (all minimal residual disease-informative [bone marrow or peripheral blood] patients who received at least one dose of obinutuzumab). Obinutuzumab plus DHAP was considered effective if bone marrow minimal residual disease negativity was 70% or more by intention to treat. The trial is closed to recruitment and registered with ClinicalTrials.gov, NCT02896582.

FINDINGS

86 patients were enrolled between Nov 29, 2016, and May 2, 2018. 81 patients completed induction, 73 underwent autologous stem-cell transplantation, and 69 started maintenance therapy. 55 (75%) of 73 patients in the efficacy set reached minimal residual disease negativity in bone marrow at end of induction. According to the protocol definition, 18 (25%) of 73 patients in the efficacy set were minimal residual disease-positive: 12 patients who were minimal residual disease-positive in the bone marrow, plus two patients who progressed during induction, and four patients who did not have minimal residual disease assessment. The most common grade 3-4 treatment-emergent adverse events were anaemia (grade 3, 26 [31%] of 85 patients; grade 4, three [4%] of 85 patients) and neutropenia (grade 3, 13 [15%] of 85 patients; grade 4, 32 [38%] of 85 patients). 58 serious adverse events occurred during the induction phase. There were no treatment-related deaths.

INTERPRETATION

Obinutuzumab plus DHAP is a well tolerated regimen and has good activity for inducing minimal residual disease negativity in the bone marrow of transplant-eligible patients with mantle cell lymphoma. Obinutuzumab plus DHAP has potential activity as induction chemotherapy, with bone marrow minimal residual disease negativity potentially predicting long-term disease control.

FUNDING

Roche SAS.

Immunoglobulin kappa deleting element rearrangements are candidate targets for minimal residual disease evaluation in mantle cell lymphoma

Minimal residual disease (MRD) assessment is of high clinical relevance in patients with mantle cell lymphoma (MCL). In mature B-cell malignancies, the presence of somatic hypermutations (SHM) in Variable-Diversity-Joining Heavy chain (VDJH) rearrangements leads to frequent mismatches between primers, probes, and the target, thus impairing tumor cells quantification. Alternative targets, such as immunoglobulin kappa-deleting-element (IGK-Kde) rearrangements, might be suitable for MRD detection. We aimed at evaluating the applicability of IGK-Kde rearrangements for MRD quantification in MCL patients by real-time quantitative polymerase chain reaction (RQ-PCR)/digital-droplet-PCR (ddPCR). IGK screening was performed on bone marrow samples from two cohorts: the first from Turin (22 patients enrolled in the FIL-MCL0208 trial, NCT02354313) and the second from Rome (15 patients). IGK-Kde rearrangements were found in 76% (28/37) of cases, representing the sole molecular marker in 73% (8/11) of IGH-BCL1/IGH negative cases. MRD RQ-PCR monitoring was possible in 57% (16/28) of cases, showing a 100% concordance with the conventional targets. However, the frequent background amplification affected the sensitivity of the assay, that was lower in MCL compared to acute lymphoblastic leukemia and in line with multiple myeloma published results. ddPCR had a good concordance with RQ-PCR and it might help to identify false positive/negative results. From a clinical perspective, we suggest that IGK-Kde can be a candidate target for MRD monitoring and deserves a validation of its predictive value in prospective MCL series.

Minimal Residual Disease in Mantle Cell Lymphoma: Methods and Clinical Significance

Several biological and clinical features have been recognized in mantle cell lymphoma (MCL). In recent years, the minimal residual disease (MRD) has been extensively investigated and is now considered as one of the strongest clinical predictors in this lymphoma. This article reviews methods used for the assessment of MRD in MCL and discusses their strengths and weaknesses. In addition, it examines the MRD contribution to the biology knowledge of MCL and the development of effective strategies for its management, including the possibility of personalized treatment based on MRD response.

Droplet Digital PCR Quantification of Mantle Cell Lymphoma Follow-up Samples From Four Prospective Trials of the European MCL Network

Minimal residual disease (MRD) has been increasingly investigated in mantle cell lymphoma (MCL), including for individual therapeutic stratification and pre-emptive treatment in clinical trials. Although patient/allele specific real-time quantitative polymerase chain reaction (qPCR) of IGH or BCL1-IGH clonal markers is the gold-standard method, its reliance on a standard curve for relative quantification limits quantification of low-level positivity within the 1E-4 to 1E-5 range; over half of positive MRD samples after treatment fall below the quantitative range (BQR) of the standard curve. Droplet digital PCR (ddPCR), in contrast, allows absolute quantification, including for samples with no baseline determination of tumor infiltration by multicolor flow cytometry (MFC), avoiding the need for a reference standard curve. Using updated, optimized, ddPCR criteria we compared it with qPCR in 416 MRD samples (and with MFC in 63), with over-representation (61%) of BQR results by qPCR, from a total of 166 patients from four prospective MCL clinical trials. ddPCR, qPCR and MFC gave comparable results in MRD samples with at least 0.01% (1E-4) positivity. ddPCR was preferable to qPCR since it provided more robust quantification at positivity between 1E-4 and 1E-5. Amongst 240 BQR samples with duplicate or triplicate analysis, 39% were positive by ddPCR, 49% negative and only 12% remained positive below quantifiable ddPCR limits. The prognostic relevance of ddPCR is currently under assessment in the context of prospective trials within the European MCL Network.

The application of antigen receptor gene rearrangement of BIOMED-2 in the pathologic diagnosis of 348 cases with non-Hodgkin lymphoma in a single institution in Southwest of China

OBJECTIVE

To explore the clinical value of immunoglobulin (Ig) and T cell receptor (TCR) gene rearrangement in the diagnosis of non-Hodgkin lymphoma.

METHODS

Using the standardized BIOMED-2 multiplex PCR strategy to detect IgH, IgK and TCR in 272 cases of mature B-cell lymphoma, 55 cases of mature T-cell lymphoma, 21 cases of extranodal NK/ T-cell lymphoma, nasal type, and 20 cases of lymphoid tissue reactive hyperplasia.

RESULTS

Among all mature B-cell lymphomas, the sensitivity of Ig gene rearrangement was 91.18% (248/272), IgH and IgK gene rearrangement was 76.47% (208/272) and 75.00% (204/272), respectively, meanwhile the sensitivity of TCRγ rearrangement was 3.68% (10/272). In the 55 cases of mature T-cell lymphoma, the sensitivity of the detection of TCRγ was 76.36% (44/55), at the same time the sensitivity of Ig gene rearrangement was 14.55% (8/55), IgH and IgK gene rearrangement was 7.27% (4/55) and 12.73% (7/55), respectively. In 21 cases of extranodal NK/T cell lymphoma, nasal type, and 20 cases of reactive lymphoid hyperplasia, no gene rearrangement was found in the samples of IgH, IgK and TCR. The sensitivity of gene rearrangement in Ig/TCR in B and T-cell lymphoma was significantly different from that in the control group (P < 0.05).

CONCLUSION

The Ig/TCR gene rearrangement of BIOMED-2 multiplex PCR strategy has important auxiliary value in the diagnosis of B/T-cell non-Hodgkin lymphoma respectively, however, a few B-cell lymphomas may company TCR gene rearrangement as well as a few T-cell lymphomas may accompany Ig gene rearrangement, it must be comprehensively judged with the combination of morphology, immunohistochemistry and clinical features.

MRD response in relapsed/refractory FL after obinutuzumab plus bendamustine or bendamustine alone in the GADOLIN trial

We report assessment of minimal residual disease (MRD) status and its association with outcome in rituximab-refractory follicular lymphoma (FL) in the randomized GADOLIN trial (NCT01059630). Patients received obinutuzumab (G) plus bendamustine (Benda) induction followed by G maintenance, or Benda induction alone. Patients with a clonal marker (t[14;18] translocation and/or immunoglobulin heavy or light chain rearrangement) detected at study screening were assessed for MRD at mid-induction (MI), end of induction (EOI), and every 6–24 months post-EOI/discontinuation by real-time quantitative PCR. At MI, 41/52 (79%) patients receiving G-Benda were MRD-negative vs. 17/36 (47%) patients receiving Benda alone (p = 0.0029). At EOI, 54/63 (86%) patients receiving G-Benda were MRD-negative vs. 30/55 (55%) receiving Benda alone (p = 0.0002). MRD-negative patients at EOI had improved progression-free survival (HR, 0.33, 95% CI, 0.19–0.56, p < 0.0001) and overall survival (HR, 0.39, 95% CI, 0.19–0.78, p = 0.008) vs. MRD-positive patients, and maintained their MRD-negative status for longer if they received G maintenance than if they did not. These results suggest that the addition of G to Benda-based treatment during induction can significantly contribute to the speed and depth of response, and G maintenance in MRD-negative patients potentially delays lymphoma regrowth.

Minimal residual disease (MRD) in non‐Hodgkin lymphomas: Interlaboratory reproducibility on marrow samples with very low levels of disease within the FIL (Fondazione Italiana Linfomi) MRD Network

In 2009, the four laboratories of the Fondazione Italiana Linfomi (FIL) minimal residual disease (MRD) Network started a collaborative effort to harmonize and standardize their methodologies at the national level, performing quality control (QC) rounds for follicular lymphoma (FL) and mantle cell lymphoma (MCL) MRD assessment. In 16 QC rounds between 2010 and 2017, the four laboratories received 208 bone marrow (BM) samples (126 FL; 82 MCL); 187 were analyzed, according to the EuroMRD Consortium guidelines, by both nested (NEST) polymerase chain reaction (PCR) and real-time quantitative (RQ) PCR for BCL2/IGH MBR or IGHV rearrangements. Here, we aimed at analyzing the samples that challenged the interlaboratory reproducibility and data interpretation. Overall, 156/187 BM samples (83%) were concordantly classified as NEST+/RQ+ or NEST-/RQ- by all the four laboratories. The remaining 31 samples (17%) resulted alternatively positive and negative in the interlaboratory evaluations, independently of the method and the type of rearrangement, and were defined "borderline" (brd) samples: 12 proved NEST brd/RQ brd, 7 NEST-/RQ brd, 10 NEST brd/RQ positive not quantifiable (PNQ), and 2 NEST brd/RQ-. Results did not change even increasing the number of replicates/sample. In 6/31 brd samples, droplet digital PCR (ddPCR) was tested and showed no interlaboratory discordance. Despite the high interlaboratory reproducibility in the MRD analysis obtained and maintained by the QC round strategy, samples with the lowest MRD levels can still represent a challenge: 17% (31/187) of our samples showed discordant results in interlaboratory assessments, with 6.4% (12/187) remained brd even applying the two methods. Thus, although representing a minority, brd samples are still problematic, especially when a clinically oriented interpretation of MRD results is required. Alternative, novel methods such as ddPCR and next-generation sequencing have the potential to overcome the current limitations.

Minimal Residual Disease Quantification in Chronic Lymphocytic Leukemia: Clinical Significance and Flow Cytometric Methods

The very sensitive quantification of leukemia cells that persist in chronic lymphocytic leukemia patients after successful therapy is steadily gaining interest with clinical scientists. Minimal residual disease (MRD) has demonstrated prognostic significance in the context of different treatment modalities leading to its approval as an intermediate endpoint for licensure in randomized trials by the European Medicine Agency. Data supporting the clinical impact of MRD as well as a highly standardized and broadly available method for MRD assessments by flow cytometry are described herein. Examples of gating strategies are provided with comprehensive explanations to allow the reader the application of the technology to blood and bone samples with high and very low level MRD, respectively. This chapter has a particular focus on samples acquired shortly after anti-CD20 treatment. The standardization developed by the EuroFlow consortium is additionally described as technical basis for reproducible and standardized flow cytometric MRD assessments.

Rituximab With Involved Field Irradiation for Early-stage Nodal Follicular Lymphoma: Results of the MIR Study

The MabThera and Involved field Radiotherapy study investigated efficacy and safety of involved field (IF) radiotherapy in combination with the anti-CD20 antibody Rituximab for early-stage follicular lymphoma (FL) in a prospective, single-arm multicenter phase 2 design. Eighty-five stage I–II FL patients received 8 cycles of Rituximab (375 mg/m²) and IF irradiation (30/40 Gy). The primary endpoint was progression-free survival (PFS) 2 years from treatment start. Secondary endpoints were overall survival (OS), complete response rates, toxicity, quality of life, and minimal residual disease (MRD) response with protocol defined visits up to month 30. For the primary endpoint, PFS at 2 years was 85% for the intention-to-treat set. Long-term data were captured in selected sites and evaluated as post hoc analysis in the per protocol (PP) set: PFS and OS were 78% and 96% at 5 years with a median follow-up of 66 or 78 months, respectively. There were 17/76 recurrences in the PP set, of which 14 were outside the radiation volume only. MRD analyses revealed a clonal marker in 36% of patients at diagnosis. All but 1 marker positive patients experienced a molecular treatment response. There were 13 serious adverse events (4 related to the therapy) during the first 30 months. IF radiotherapy combined with Rituximab is well tolerated and highly efficient with low rates of recurrence in the first years in early-stage FL. The efficacy is comparable with more aggressive therapy approaches without compromising the quality of life and maintains for an extended follow-up of more than 5 years.

New Molecular Technologies for Minimal Residual Disease Evaluation in B-Cell Lymphoid Malignancies

The clearance of malignant clonal cells significantly correlates with clinical outcomes in many hematologic malignancies. Accurate and high throughput tools for minimal residual disease (MRD) detection are needed to overcome some drawbacks of standard molecular techniques; such novel tools have allowed for higher sensitivity analyses and more precise stratification of patients, based on molecular response to therapy. In this review, we depict the recently introduced digital PCR and next-generation sequencing technologies, describing their current application for MRD monitoring in lymphoproliferative disorders. Moreover, we illustrate the feasibility of these new technologies to test less invasive and more patient-friendly tissues sources, such as "liquid biopsy".

SOX11 expression as a MRD molecular marker for MCL in comparison with t(11;14) and IGH rearrangement

The main cause of death in mantle cell lymphoma (MCL) patients is relapse due to undetermined minimal residual disease (MRD) and therefore monitoring MRD is crucial for making the best treatment decisions. The gold standard method for MRD analysis is the quantitative polymerase chain reaction. The most commonly used molecular markers for measuring MRD in MCL are: t(11;14)(q13;p32) translocation or CCND1 expression and IGH rearrangement. Such markers can, however, be found in other B cell non-Hodgkin lymphomas. Recent studies demonstrate that SOX11 expression is highly specific for MCL and could be used as a marker for measuring MRD. Moreover, evidence shows that SOX11 level could be predictive for overall survival (OS) and progression-free survival (PFS). We have measured MRD level in follow-up samples from 27 patients diagnosed with MCL using the molecular markers: t(11;14), IGH rearrangement and SOX11 expression. We compared all markers by their sensitivity, utility and quantitative range. We also examined the predictive value of SOX11 expression for OS and PFS. SOX11 expression was found to have better specificity, quantitative range and utility than the t(11;14). The predictive value of SOX11 expression was confirmed. At diagnosis, patients with high SOX11 expression had shorter PFS than patients with low SOX11 expression (p = 0.04*); differences between OS being statistically insignificant. To our best knowledge this is a first study comparing SOX11 with t(11;14) and IGH rearrangement as markers of MRD level. Moreover, in this study we confirmed that SOX11 is useful in cases when other molecular markers cannot be used.

Droplet Digital PCR for Minimal Residual Disease Detection in Mature Lymphoproliferative Disorders

Minimal residual disease (MRD) detection has a powerful prognostic relevance for response evaluation and prediction of relapse in hematological malignancies. Real-time quantitative PCR (qPCR) has become the settled and standardized method for MRD assessment in lymphoid disorders. However, qPCR is a relative quantification approach, since it requires a reference standard curve. Droplet digital^TM PCR (ddPCR^TM) allows a reliable absolute tumor burden quantification withdrawing the need for preparing, for each experiment, a tumor-specific standard curve. We have recently shown that ddPCR has a good concordance with qPCR and could be a feasible and reliable tool for MRD monitoring in mature lymphoproliferative disorders. In this chapter we describe the experimental workflow, from the detection of the clonal molecular marker to the MRD monitoring by ddPCR, in patients affected by multiple myeloma, mantle cell lymphoma and follicular lymphoma. However, standardization programs among different laboratories are needed in order to ensure the reliability and reproducibility of ddPCR-based MRD results.

Cyclin D1 mRNA as a molecular marker for minimal residual disease monitoring in patients with mantle cell lymphoma

Chromosomal translocation t(11;14)(q13;q32) is a characteristic molecular marker of mantle cell lymphoma (MCL) and leads to the fusion of the immunoglobulin heavy chain enhancer-promoter with the cyclin D1 gene. Both aberrant cyclin D1 expression and underlying chromosomal aberration may be used as molecular targets for monitoring minimal residual disease (MRD). The present study aims to assess the usefulness of quantitative cyclin D1 gene expression compared to the standardised but more technologically demanding DNA-based method for immunoglobulin heavy chain (IGH) or t(11;14) clone-specific gene rearrangement quantification in a cohort of bone marrow (BM) and peripheral blood (PB) samples from patients with MCL. We simultaneously evaluated DNA-MRD and cyclin D1 expression levels in 234 samples from 57 patients. We observed that both in DNA-MRD positive and negative BM/PB pairs from the same time points the expression levels of cyclin D1 are lower in PB than in BM (median 19×, BM/PB range 0.41-352). The correlation of cyclin D1 transcript levels with DNA-MRD or with flow cytometry was good only in samples with a very high infiltration. In DNA-MRD-negative BM samples, we observed a significant heterogeneity of cyclin D1 expression (in the range of more than three orders of magnitude). This is in contrast to previous reports demonstrating the usefulness of cyclin D1 for MRD monitoring that did not use DNA-based method as a reference. In PB, the specificity of cyclin D1 expression was better due to a lower physiological background. In conclusion, we show that cyclin D1 is unsuitable for MRD monitoring in BM.

Ficoll-hypaque separation vs whole blood lysis: Comparison of efficiency and impact on minimal residual disease analysis

INTRODUCTION

The high-throughput era remarkably changed molecular laboratory practice. Actually, the increasing number of processed samples requires to reduce the risk of operator biases, by automating or simplifying as much as possible both the analytical and the pre-analytical phases. Minimal residual disease (MRD) studies in hematology often require a simultaneous processing of many bone marrow and peripheral blood samples from patients enrolled in prospective, multicenter, clinical trials, monitored at several planned time points.

METHODS

In this study, we demonstrate that red blood cell lysis (RBL) pre-analytical procedure can replace the time-consuming Ficoll stratification as cell recovering step. Here, we show a MRD comparison study using both total white blood cells and mononuclear cells recovered by the 2 procedures from 46 follicular lymphoma (FL), 15 multiple myeloma (MM), and 11 mantle cell lymphoma (MCL) patients enrolled in prospective clinical trials.

RESULTS

The experiments were performed in the 4 laboratories of the Fondazione Italiana Linfomi (FIL) MRD Network and showed superimposable results, in terms of good correlation (R = 0.87) of the MRD data obtained by recovering blood cells by the 2 approaches.

CONCLUSION

Based on these results, the FIL MRD Network suggests to optimize the pre-analytical phases introducing RBL approach for cell recovery in the clinical trials including MRD analysis.

Minimal residual disease in non-Hodgkin lymphoma - current applications and future directions

Non-Hodgkin Lymphomas (NHLs) are a heterogeneous group of tumours with distinct treatment paradigms, but in all cases the goal of treatment is to maximize quality and duration of remission while minimizing therapy-related toxicity. Identification of persistent disease or relapse is most often the trigger to intensify or re-initiate anti-neoplastic therapy, respectively. In the current era of NHL treatment, this determination is mostly based on imaging and clinical evaluations, tools with imperfect sensitivity and specificity. The availability of minimal residual disease (MRD) monitoring could transform treatment paradigms by allowing intensification of treatment in at-risk patients or early intervention for impending relapse. Novel methods based on polymerase chain reaction and next-generation sequencing are now being studied in NHL with promising results. This review outlines the current status of the field in the use of MRD techniques for diffuse large B-cell lymphoma, mantle cell lymphoma and follicular lymphoma. Specifically, we address their demonstrated and potential clinical utility in risk stratification, monitoring of remission status, and guiding interim and post-treatment escalation. Future applications of these techniques could identify novel markers of MRD, improve initial treatment selection, guide treatment escalation or de-escalation, and allow for real-time monitoring of patterns of clonal evolution, which together could redefine NHL treatment paradigms.

The value of detecting immunoglobulin gene rearrangements in the diagnosis of B-cell lymphoma

Objective

To discuss the clinical value of immunoglobulin gene rearrangements in the diagnosis of B-cell lymphoma.

Methods

A total of 209 cases of B-cell lymphomas and 35 cases of reactive lymphoid hyperplasia were selected for DNA extraction and PCR amplification using the BIOMED-2 primer system. Gel electrophoresis of heteroduplexes was used to analyze immunoglobulin gene rearrangements.

Results

A total of 209 cases of B-cell lymphoma, including 69 extranodal marginal zone B-cell lymphomas of mucosa-associated lymphoid tissue, 63 diffuse large B-cell lymphomas, 39 follicular lymphomas, 15 small lymphocytic lymphomas, 6 plasmacytomas, 6 mantle cell lymphomas, 7 nodal marginal zone B-cell lymphomas, and 4 lymphoplasmacytoid lymphomas, were examined. Immunoglobulin gene rearrangements were found in all 209 cases, with 93 IGHA, 122 IGHB, 98 IGHC, 167 IGK, 100 IGL, 167 IGHA/B/C, 204 IGH/IGK, 209 IGH/IGK/IGL, 129 IGH+IGK, 81 IGH+IGL, 83 IGK+IGL and 68 IGH+IGK+IGL gene rearrangements. Immunoglobulin gene rearrangements were not found in the 35 cases of reactive lymphoid hyperplasia. IGH and IGK gene rearrangements were mainly found in mantle cell lymphomas, small lymphocytic lymphomas, extranodal marginal zone B-cell lymphomas of mucosa-associated lymphoid tissue and diffuse large B-cell lymphomas. The IGH gene rearrangement was mainly found in lymphoplasmacytoid lymphomas and follicular lymphomas. IGK and IGL gene rearrangements were mainly found in plasmocytoma, and the IGK gene rearrangement was mainly found in nodal marginal zone B-cell lymphomas.

Conclusions

The BIOMED-2 standardized immunoglobulin gene rearrangement detection system is an important tool in B-cell lymphoma diagnosis. Analysis of IGH, IGK and IGL gene rearrangements is valuable in confirming the classification of B-cell NHL.

The Combination of Rituximab and Bendamustine as First-Line Treatment Is Highly Effective in the Eradicating Minimal Residual Disease in Follicular Lymphoma: An Italian Retrospective Study

R-Bendamustine is an effective treatment for follicular lymphoma (FL). Previous large trials demonstrated the prognostic role of the molecular minimal residual disease (MRD) during the most frequently adopted chemotherapeutic regimens, but there are not yet conclusive data about the effect of combination of rituximab (R) and bendamustine in terms of MRD clearance. Thus, the aim of this retrospective study was to assess if and in what extent the combination of rituximab and bendamustine would exert a significant reduction of the molecular disease in 48 previously untreated FL patients. The molecular marker at baseline was found in the 62.5% of cases; no significant differences were observed between patients with or without the molecular marker in respect of the main clinical features. Moreover, the quantization of the baseline molecular tumor burden showed a great variability: the median value was 1.4 × 10-2 copies, ranging from 3 × 10-5 to 4 × 104. The initial molecular tumor burden did not correlate with clinical features and did not impact on the subsequent quality of response. After treatment, 93% of cases became MRD-negative; the median reduction of the BCL2/JH load was 4 logs. The 2-years PFS was 85%; it was significantly longer for patients in complete than for those in partial response (91 vs. 57%; p = 0.002), and for cases with lower FLIPI-2 score (88 vs. 60%; p = 0.004). On the contrary, PFS did not differ between patients with or without the molecular marker at baseline; a molecular tumor burden 15 times higher was observed in the relapsed subgroup in comparison to the relapse-free one, but this difference did not change the PFS length. The 2-years OS was 93.6%; the only variable that significantly impacted on it was the FLIPI-2 score; the presence of the molecular marker at baseline or its behavior after treatment did not impact on survival. This study, even if retrospective and conducted on a small series of patients, would represent a proof of concept that R-bendamustine is able to so efficaciously eradicate MRD that it could be able to by-pass the prognostic significance of MRD already demonstrated for other chemotherapeutic regimens in FL.

Clinicogenetic risk models predict early progression of follicular lymphoma after first-line immunochemotherapy

Follicular lymphoma (FL) is a clinically and molecularly heterogeneous disease. Posttreatment surrogate end points, such as progression of disease within 24 months (POD24) are promising predictors for overall survival (OS) but are of limited clinical value, primarily because they cannot guide up-front treatment decisions. We used the clinical and molecular data from 2 independent cohorts of symptomatic patients in need of first-line immunochemotherapy (151 patients from a German Low-Grade Lymphoma Study Group [GLSG] trial and 107 patients from a population-based registry of the British Columbia Cancer Agency [BCCA]) to validate the predictive utility of POD24, and to evaluate the ability of pretreatment risk models to predict early treatment failure. POD24 occurred in 17% and 23% of evaluable GLSG and BCCA patients, with 5-year OS rates of 41% (vs 91% for those without POD24, P < .0001) and 26% (vs 86%, P < .0001), respectively. The m7-FL International Prognostic Index (m7-FLIPI), a prospective clinicogenetic risk model for failure-free survival, had the highest accuracy to predict POD24 (76% and 77%, respectively) with an odds ratio of 5.82 in GLSG (P = .00031) and 4.76 in BCCA patients (P = .0052). A clinicogenetic risk model specifically designed to predict POD24, the POD24-PI, had the highest sensitivity to predict POD24, but at the expense of a lower specificity. In conclusion, the m7-FLIPI prospectively identifies the smallest subgroup of patients (28% and 22%, respectively) at highest risk of early failure of first-line immunochemotherapy and death, including patients not fulfilling the POD24 criteria, and should be evaluated in prospective trials of precision medicine approaches in FL.

Detection of minimal residual disease in mantle cell lymphoma-establishment of novel eight-color flow cytometry approach

BACKGROUND

Minimal residual disease (MRD) detection is an essential tool for therapy response assessment in a considerable number of hematooncologic disorders, including mantle cell lymphoma (MCL). Flow cytometry (FCM) ranks among the most effective approaches, which allows rapid sample processing and compete successfully with highly sensitive molecular methods like polymerase chain reaction. Because FCM is ordinarily applied to detect MRD in B-lineage diseases like chronic lymphocytic leukemia, a similar method could be used in MCL. We decided to test our novel eight-color FCM approach in MCL MRD detection.

METHODS

Using an eight-color FCM protocol designed by us, the expression of 24 selected surface antigens in a cohort of 30 patients with newly diagnosed leukemic MCL and 20 normal controls were compared to establish markers that can reliably distinguish normal B-lymphocytes from the MCL population. The sensitivity of the designed protocol was tested using serial dilution studies.

RESULTS

Although MCL presents high immunophenotypic variability, the combination of CD20/23/5/19/200/62L/3/45 seems to be very favorable in flow cytometric MRD measurement.

CONCLUSIONS

Our eight-color FCM protocol could easily detect MRD in MCL patients, and reaches a sensitivity of up to 2 × 10(-4) .

Pathology of B-cell lymphomas: diagnosis and biomarker discovery

The diagnosis of B-cell non-Hodgkin lymphomas has changed significantly over the past few decades as new immunophenotypic markers, molecular subtype classification schemes, and novel biomarkers have emerged. Meanwhile, there has been an increasing emphasis on individualizing treatment approaches in accordance with a biologic heterogeneity that has been uncovered within many of the individual B-cell lymphoma entities. The application of high-throughput genomic sequencing to B-cell lymphomas has yielded large amounts of valuable information. The data encompass discoveries essential to an understanding of pathogenesis, clonal or tumoral evolution, and identification of biomarkers that may be useful for prognostic or therapeutic considerations. The following review discusses several of the more common, primarily tissuebased B-cell lymphomas, with a focus on pathologic classification and certain phenotypic characteristics or genetic lesions that apply to refinement of diagnosis and therapy.

Common consensus LNA probe for quantitative PCR assays in cancer: vehicles for minimal residual disease detection in t(11;14) and t(14;18) positive malignant lymphomas

The use of locked nucleic acid (LNA) probes and primers potentially improves sensitivity and specificity of quantitative PCR (qPCR) assays. One area of application is that of minimal residual cancer where PCR techniques have proved to be highly relevant tools in patient follow-up. We present here sensitive and specific consensus qPCR assays for quantification of the malignant lymphoma translocations, t(11;14) and t(14;18), by taking advantage of the thermodynamic properties of LNA. The assays were applied to genomic DNA from patients diagnosed with mantle cell lymphoma (MCL) and follicular lymphoma (FL), respectively. Two consensus forward primers targeting the BCL1 and BCL2 genes were designed together with a common consensus reverse primer and hydrolysis probe, the latter consisting exclusively of LNA, both targeting the J segments of the immunoglobulin heavy chain (IgH) gene. The quantitative range of both assays was 1×10(0) to 5×10(-5), and the sensitivity was 10(-5), without the need for patient-specific primers. Peripheral blood (PB) and bone marrow (BM) samples from 36 patients diagnosed with MCL and nine patients diagnosed with FL were analysed using this novel qPCR approach. The level of minimal residual disease (MRD) using t(11;14) and t(14;18) as genetic targets reflected the clinical status of the patients: low levels of MRD at clinical remission, and increasing levels at disease progression. The present assays could prove as useful tools in lymphoma therapy.

How we manage follicular lymphoma

Major changes have taken place within the last few years in the management of follicular lymphoma (FL) leading to substantial improvement in prognosis and overall survival. For some patients with limited disease stages I and II, radiotherapy may be associated with durable responses; however, it is unclear whether patients are cured and new approaches such as the combination of irradiation with rituximab or even single-agent rituximab need to be explored. Whereas watch and wait is the current standard for stage III and IV disease with low tumour burden, better indices are warranted to potentially select patients for whom early intervention is preferred. For advanced stages with a high tumour burden, immunochemotherapy followed by 2 years of rituximab maintenance is widely accepted as standard therapy, although re-treatment at recurrence may be an alternative option. Highly attractive new therapeutic options have recently arisen from new antibodies, and from new agents targeting oncogenic pathways such as B-cell receptor signalling pathways or inhibition of bcl 2. Furthermore, immunomodulatory drugs may add to the therapeutic armamentarium and may lead to 'chemotherapy-free' therapies in the near future. Hence, the management of FLs has become a moving target and the hope is justified that the long-term perspectives of patients suffering from the disease will be further improved in the near future.

Next-generation sequencing and real-time quantitative PCR for minimal residual disease detection in B-cell disorders

In this study, we compared immunoglobulin heavy-chain-gene-based minimal residual disease (MRD) detection by real-time quantitative PCR (RQ-PCR) and next-generation sequencing (NGS) to assess whether NGS could overcome some limitations of RQ-PCR and further increase sensitivity, specificity, accuracy and reproducibility. In total, 378 samples from 55 patients with acute lymphoblastic leukemia (ALL), mantle cell lymphoma (MCL) or multiple myeloma (MM) were investigated for clonotype identification, clonotype identity and comparability of MRD results. Forty-five clonotypes were identified by RQ-PCR and 49 by NGS. Clonotypes identified by both tools were identical or >97% homologous in 96% of cases. Both tools were able to routinely reach a sensitivity level of 1 × E-05. A good correlation of MRD results was observed (R=0.791, P<0.001), with excellent concordance in 79.6% of cases. Few discordant cases were observed across all disease subtypes. NGS showed at least the same level of sensitivity as allele-specific oligonucleotides-PCR, without the need for patient-specific reagents. We conclude that NGS is an effective tool for MRD monitoring in ALL, MCL and MM. Prospective comparative analysis of unselected cases is required to validate the clinical impact of NGS-based MRD assessment.

Next-generation sequencing and real-time quantitative PCR for minimal residual disease detection in B-cell disorders

In this study, we compared immunoglobulin heavy-chain-gene-based minimal residual disease (MRD) detection by real-time quantitative PCR (RQ-PCR) and next-generation sequencing (NGS) to assess whether NGS could overcome some limitations of RQ-PCR and further increase sensitivity, specificity, accuracy and reproducibility. In total, 378 samples from 55 patients with acute lymphoblastic leukemia (ALL), mantle cell lymphoma (MCL) or multiple myeloma (MM) were investigated for clonotype identification, clonotype identity and comparability of MRD results. Forty-five clonotypes were identified by RQ-PCR and 49 by NGS. Clonotypes identified by both tools were identical or >97% homologous in 96% of cases. Both tools were able to routinely reach a sensitivity level of 1 × E-05. A good correlation of MRD results was observed (R=0.791, P<0.001), with excellent concordance in 79.6% of cases. Few discordant cases were observed across all disease subtypes. NGS showed at least the same level of sensitivity as allele-specific oligonucleotides-PCR, without the need for patient-specific reagents. We conclude that NGS is an effective tool for MRD monitoring in ALL, MCL and MM. Prospective comparative analysis of unselected cases is required to validate the clinical impact of NGS-based MRD assessment.

Persistence of minimal residual disease in bone marrow predicts outcome in follicular lymphomas treated with a rituximab-intensive program

PCR negativity is a strong outcome predictor after rituximab-intensive immunochemotherapy at multiple posttreatment times. PCR is predictive even when maintenance is delivered, and accumulation of PCR-negative results further reduces the likelihood of relapse.