Improved biological insight and influence on management in indolent lymphoma. Talk 3: update on nodal and splenic marginal zone lymphoma

Integrated spatial and multimodal single-cell transcriptomics reveal patient-dependent cell heterogeneity in splenic marginal zone lymphoma

Biological hallmarks of splenic marginal zone lymphoma (SMZL) remain poorly described. Herein, we performed in-depth SMZL characterization through multimodal single-cell analyses of paired blood/spleen samples. The 3'-single-cell RNA-sequencing, Cellular Indexing of Transcriptomes and Epitopes by sequencing, and 5'-V(D)J single-cell RNA-sequencing datasets were integrated to characterize SMZL transcriptome profiles, including B-cell receptor and T-cell receptor repertoires. Hyperexpanded B-cell clones in the spleen were at a memory-like stage, whereas recirculating tumor B-cells in blood encompassed multiple differentiation stages, indicating an unexpected desynchronization of the B-cell maturation program in SMZL cells. Spatial transcriptomics showed the enrichment of T-effector and T-follicular helper (TFH) signatures in the nodular subtype of SMZL. This latter also exhibited gene-based cell-cell interactions suggestive of dynamic crosstalk between TFH and cancer cells in transcriptomics, further substantiated by using imaging mass cytometry. Our findings provide a comprehensive high-resolution description of SMZL biological hallmarks and characterize, for the first time in situ, inter- and intra-patient heterogeneity at both transcriptomic and protein levels. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

A genetic profiling guideline to support diagnosis and clinical management of lymphomas

The new lymphoma classifications (International Consensus Classification of Mature Lymphoid Neoplasms, and 5th World Health Organization Classification of Lymphoid Neoplasms) include genetics as an integral part of lymphoma diagnosis, allowing better lymphoma subclassification, patient risk stratification, and prediction of treatment response. Lymphomas are characterized by very few recurrent and disease-specific mutations, and most entities have a heterogenous genetic landscape with a long tail of recurrently mutated genes. Most of these occur at low frequencies, reflecting the clinical heterogeneity of lymphomas. Multiple studies have identified genetic markers that improve diagnostics and prognostication, and next-generation sequencing is becoming an essential tool in the clinical laboratory. This review provides a "next-generation sequencing" guide for lymphomas. It discusses the genetic alterations of the most frequent mature lymphoma entities with diagnostic, prognostic, and predictive potential and proposes targeted sequencing panels to detect mutations and copy-number alterations for B- and NK/T-cell lymphomas.

Florid Lymphoid Hyperplasia or Lymphoma-like Lesion of the Lower Genital Tract: A 35-Year Literature Review in View of the New WHO Classification

Florid lymphoid hyperplasias of the lower female genital tract, also known as pseudolymphoma or lymphoma-like lesions, are benign lesions displaying histologic features which mimic aggressive B-cell lymphomas. Initially described by Young and colleagues in 1985, fewer than 100 cases have been published, making this lesion rather uncommon and subject to misdiagnoses. However, given that this entity has now been included in the World Health Organization's most recent classification, greater clarity would be beneficial for pathologists and physicians. Thus, our report aims to review these entities and provide all available data. We reviewed the available literature according to PRISMA guidelines. We found that lymphoma-like lesions, regardless of their localization, display numerous superficial lymphoid B cells admixed with a polymorphic small lymphocytic and plasmocytic background and, sometimes, superficial ulceration. Large lymphoid cells show prominent nucleoli and mitotic figures. Immunohistochemistry can usually exclude large cell lymphomas, such as high-grade follicular lymphoma and Burkitt lymphoma, when a starry sky pattern is found, as well as Hodgkin Lymphoma; however, the exclusion of diffuse large B-cell lymphoma or marginal zone lymphoma is more difficult. Explorations seeking infectious agents may show Epstein-Barr virus or, rarely, Borrelia burgdorferi involvement. Molecular study occasionally finds a monoclonal B-cell population, but without the subsequent follow-up which would otherwise be worrisome. Despite its somewhat aggressive histologic features, the benignity of this entity must be highlighted to avoid misdiagnosis and complications due to overtreating.

Undetectable minimal residual disease is an independent prognostic factor in splenic marginal zone lymphoma

The role of minimal residual disease (MRD) in splenic marginal zone lymphoma (SMZL) has not been well studied. We prospectively designed a study to evaluate undetectable MRD (uMRD) by multiparameter flow cytometry as a prognostic factor. Residual disease level of <0·01% was defined as uMRD. A total of 71 newly diagnosed patients with bone marrow involvement were enrolled and all received rituximab-based therapy. The overall response rate (ORR) was 98·5% (70/71), with a complete remission (CR) rate of 54·9% (39/71). There were a total of 295 MRD detections in bone marrow and 77·4% patients (55/71) had uMRD. The 5-year progression-free survival (PFS) [(74·8 ± 6·5)% vs. (31·4 ± 12·6)%, P < 0·001] and 5-year overall survival (OS) [(87·2 ± 5·6)% vs. (68·9 ± 13·4)%, P = 0·035] were significantly higher in uMRD patients than in MRD-positive patients. The 5-year PFS in partial remission (PR) patients with positive MRD was significantly poorer than that of PR patients with uMRD [(21·1 ± 12·9)% vs. (83·3 ± 8·8)%, P = 0·005]. Multivariate prognostic analysis revealed that uMRD was an independent good prognostic factor for PFS (hazard ratio 0·162, 95% confidence interval 0·041-0·635; P = 0·009). All these results highlight uMRD as an independent prognostic factor in patients with SMZL, especially for patients who only achieve PR.

Evaluating ibrutinib for the treatment of relapsed/refractory marginal zone lymphoma

Introduction: Marginal zone lymphoma (MZL) is a heterogeneous disease with a wide range of possible frontline therapies depending on the subtype; there are no shared guidelines for the treatment of relapsed/refractory MZLs. The growing evidence of the importance of the BCR pathway in the pathogenesis of B lymphoproliferative forms has led researchers to consider BTK as a potential therapeutic target in MZL.Area covered: The authors provide the reader with an evaluation of ibrutinib as a treatment option for refractory marginal zone lymphoma. The review includes an overview of the drug's pharmacokinetics and pharmacodynamics, efficacy, and safety. The authors also provide the reader with their expert perspectives on the drug and its place in the treatment of MZL.Expert opinion: The availability of new non-chemotherapeutic agents represents an important opportunity to spare excessive exposure to cytotoxic compounds. Immunomodulators and targeted agents, alone or often in combination with immunotherapy, have been shown to be effective and safe therapies in patients with relapsed/refractory (R/R) MZL. In addition, numerous studies involving new generation targeted agents, alone or in combination, are currently active in both R/R and untreated patient populations, some with encouraging preliminary results.

Superior outcome for splenectomised patients in a population-based study of splenic marginal zone lymphoma in Sweden

Splenic marginal zone lymphoma (SMZL) is a rare low-grade B-cell lymphoma where associations with viral hepatitis and autoimmune and inflammatory diseases (AID) have been indicated. We aimed at assessing the prevalence of viral hepatitis and AID at SMZL diagnosis and outcome by treatment in a Swedish population-based study. A total of 277 SMZL patients registered in the Swedish Lymphoma Register in 2007-2017 were included. A history of viral hepatitis was reported in five (2%) patients and AID prior to SMZL in 72/240 (30%) patients. Treatment was given up front for 207 (75%) patients. Splenectomy with or without systemic treatment was performed in 119 (57%) and was associated with statistically significantly better overall survival [hazard ratio, HR = 0·47 (95% confidence interval, CI: 0·23-0·93), P = 0·03] and progression-free survival (HR = 0·55, 95% CI: 0·35-0·86, P = 0·008) compared to non-splenectomised patients in multivariable analyses. The up-front splenectomised group was younger and generally had a lower Ann Arbor stage, but also more frequently B symptoms and high lactate dehydrogenase than the non-splenectomised group. Viral hepatitis and AID history did not affect SMZL outcome. We report high incidence of AIDs and low incidence of viral hepatitis in this population-based study of SMZL. Splenectomy up front was associated with a favourable outcome.

New developments in non-Hodgkin lymphoid malignancies

The revised fourth edition of the World Health Organization (WHO) Classification of Tumours of Haematopoietic and Lymphoid Tissues (2017) reflects significant advances in understanding the biology, genetic basis and behaviour of haematopoietic neoplasms. This review focuses on some of the major changes in B-cell and T-cell non-Hodgkin lymphomas in the 2017 WHO and includes more recent updates. The 2017 WHO saw a shift towards conservatism in the classification of precursor lesions of small B-cell lymphomas such as monoclonal B-cell lymphocytosis, in situ follicular and in situ mantle cell neoplasms. With more widespread use of next generation sequencing (NGS), special entities within follicular lymphoma and mantle cell lymphoma were recognised with recurrent genetic aberrations and unique clinicopathological features. The diagnostic workup of lymphoplasmacytic lymphoma and hairy cell leukaemia has been refined with the discovery of MYD88 L265P and BRAF V600E mutations, respectively, in these entities. Recommendations in the immunohistochemical evaluation of diffuse large B-cell lymphoma include determining cell of origin and expression of MYC and BCL2, so called 'double-expressor' phenotype. EBV-positive large B-cell lymphoma of the elderly has been renamed to recognise its occurrence amongst a wider age group. EBV-positive mucocutaneous ulcer is a newly recognised entity with indolent clinical behaviour that occurs in the setting of immunosuppression. Two lymphomas with recurrent genetic aberrations are newly included provisional entities: Burkitt-like lymphoma with 11q aberration and large B-cell lymphoma with IRF4 rearrangement. Aggressive B-cell lymphomas with MYC, BCL2 and/or BCL6 rearrangements, so called 'double-hit/triple-hit' lymphomas are now a distinct entity. Much progress has been made in understanding intestinal T-cell lymphomas. Enteropathy-associated T-cell lymphoma, type II, is now known to not be associated with coeliac disease and is hence renamed monomorphic epitheliotropic T-cell lymphoma. An indolent clonal T-cell lymphoproliferative disorder of the GI tract is a newly included provisional entity. Angioimmunoblastic T-cell lymphoma and nodal T-cell lymphomas with T-follicular helper phenotype are included in a single broad category, emphasising their shared genetic and phenotypic features. Anaplastic large cell lymphoma, ALK- is upgraded to a definitive entity with subsets carrying recurrent rearrangements in DUSP22 or TP63. Breast implant-associated anaplastic large cell lymphoma is a new provisional entity with indolent behaviour. Finally, cutaneous T-cell proliferations include a new provisional entity, primary cutaneous acral CD8-positive T-cell lymphoma, and reclassification of primary small/medium CD4-positive T-cell lymphoma as lymphoproliferative disorder.

Identification of a Splenic Marginal Zone Lymphoma Signature: Preliminary Findings With Diagnostic Potential

Splenic marginal zone lymphoma (SMZL) is a rare, indolent non-Hodgkin's lymphoma that affects 0. 13 per 100,000 persons annually. Overall survival of SMZL is estimated to reach 8-11 years in most cases, but up to 30% of SMZL cases develop aggressive presentations resulting in greatly diminished time of survival. SMZL presents with a very heterogeneous molecular profile, making diagnosis problematic, and accurate prognosis even less likely. The study herein has identified a potential diagnostic gene expression signature with highly specific predictive utility, coined the SMZL-specific Gene Expression Signature (SSGES). Additionally, five of the most impactful markers identified within the SSGES were selected for a five-protein panel, for further evaluation among control and SMZL patient samples. These markers included EME2, ERCC5, SETBP1, USP24, and ZBTB32. When compared with control spleen and other B-cell lymphoma subtypes, significantly higher expression was noticed in SMZL samples when stained for EME2 and USP24. Additionally, ERCC5, SETBP1, USP24, and ZBTB32 staining displayed indications of prognostic value for SMZL patients. Delineation of the SSGES offers a unique SMZL signature that could provide diagnostic utility for a malignancy that has historically been difficult to identify, and the five-marker protein panel provides additional support for such findings. These results should be further investigated and validated in subsequent molecular investigations of SMZL so it may be potentially incorporated into standard oncology practice for improving the understanding and outlook for SMZL patients.

Marginal Zone Lymphoma: State-of-the-Art Treatment

OPINION STATEMENT

Despite being the second most common indolent non-Hodgkin's lymphoma (iNHL), marginal zone lymphoma (MZL) remains largely understudied, and given its underlying disease heterogeneity, it is challenging to define a single treatment approach for these patients. For localized disease, local therapy is recommended such as triple therapy for H. pylori in gastric extranodal MZL, splenectomy for splenic MZL, and radiotherapy for nodal MZL. For disseminated disease with low tumor burden, a watch and wait or single-agent rituximab can be used. However, for symptomatic disease, a similar approach to follicular lymphoma (FL) can be used with chemoimmunotherapy approaches such as bendamustine and rituximab. High FDG uptake is not common in MZL and is not diagnostic by itself of transformation to high-grade lymphoma but informs the choice of the site to be biopsied. Transformation into a large B cell lymphoma is treated with R-CHOP-like regimens. Patients with relapsing disease after at least one CD20-based therapy have several recently approved chemotherapy-free options including B cell receptor inhibitors such ibrutinib (approved specifically in MZL) and immunomodulatory agents such as lenalidomide and rituximab (FDA approved in MZL and FL). Phosphoinositide 3-kinase (PI3K) inhibitors have shown excellent activity in iNHL, specifically in MZL, with breakthrough designation status for copanlisib and umbralisib, allowing off label use of this class of agents in clinical practice. With the availability of prospective clinical trials using chemo-free approaches, specifically those targeting abnormal signaling pathways activated in MZL tumors and its microenvironment, treating physicians are encouraged to enroll patients on these clinical trials in order to better understand the underlying biology, mechanisms of response, and resistance to current therapies and help design future rationale combination strategies.

IGHV mutational status of nodal marginal zone lymphoma by NGS reveals distinct pathogenic pathways with different prognostic implications

The precise B cell of origin and molecular pathogenesis of nodal marginal zone lymphoma (NMZL) remain poorly defined. To date, due to the rarity of NMZL, the vast majority of already-published studies have been conducted on a limited number of samples and the technical approach to analyze the immunoglobulin genes was of amplifying rearranged variable region genes with the classical direct sequencing of the PCR products followed by cloning. Here, we studied the B cell Ig heavy-chain repertoires by next-generation sequencing (NGS) in 30 NMZL cases. Most of the cases were mutated (20/28; 71.5%) with homologies to the respective germ line genes ranging from 85 to 97, 83%, whereas 8/28 (28.5%) were unmutated. In addition, our results show that NMZL cases have a biased usage of specific immunoglobulin heavy-chain variable (IGHV) region genes. Moreover, we documented intraclonal diversity in all (100%) of the mutated cases and ongoing somatic hypermutations (SHM) have been confirmed by hundreds of reads. We analyzed the mutational pattern to detect and quantify antigen selection pressure and we found a positive selection in 4 cases, whereas in the remaining cases there was an unspecific stimulation. Finally, the disease-specific survival and the progression-free survival were significantly different between cases with mutated and unmutated IGHV genes, pointing out mutational status as a possible new biomarker in NMZL.

Actualités dans les lymphomes à petites cellules non folliculaires

Non-follicular small cell lymphomas include several entities whose clinical and pathological descriptions have been refined in the last 20 years. MALT lymphoma, developed at the expense of lymphoid tissue associated with the mucosa, is usually localized to a given organ, but can also disseminate. Some patients with MALT lymphoma can be treated by eradicating the associated infectious agent, whereas local treatment should be preferred for other cases ; disseminated forms and relapsed patients are eligible for anti-CD20 antibodies associated with cytotoxic agents. Patients with mantle cell lymphoma have benefited from many advances, including the use of cytarabine and bendamustine, anti-CD20 antibodies, intensive treatments (autograft) and recently targeted therapy (ibrutinib, inhibitor or the Bruton tyrosine kinase). Patients with splenic nodal marginal zone lymphomas should be evaluated for different options, of which immunochemotherapy remains important. For all these entities, the implementation of treatments may be delayed by several years for certain groups of patients. Although considered as incurable, the prognosis of these pathologies has improved significantly and the majority of patients will be able to live for many years with often treatment-free intervals.