Splenic Marginal Zone Lymphoma Research Articles

Favorable Outcomes of Splenic Marginal Zone Lymphoma in an International Study of 934 Patients with Long Follow-up

Introduction: Splenic marginal zone lymphoma (SMZL) is a rare, indolent disease. There is no universally accepted standard therapy and long-term outcome data are limited. Rituximab monotherapy is increasingly used over splenectomy in the first-line setting despite a paucity of comparative studies. In the absence of randomized trials, large-scale international real-world data studies are critical to evaluate outcomes of different treatment interventions and to understand the natural history of SMZL in the rituximab-era. Methods: Adult patients with SMZL diagnosed between Jan 1 st 2000 and Dec 31 st 2018 were identified using regional/nationwide population-based registries or hospital registries in Europe, the UK, North America, and Australia. Medical records and pathology reports from eligible patients were reviewed locally by clinicians with specialty experience in hemato-oncology. SMZL cases were required to meet the diagnostic criteria by Matutes et al. Detailed data on clinico-pathological features, comorbidities, treatments (including treatment intention), treatment responses and survival outcomes were entered in a central study database. Overall survival (OS) was defined as time from diagnosis until death from any cause or censoring at last follow-up unless stated otherwise. Event-free survival (EFS) was defined as the time from diagnosis until histological transformation, initiation of new chemotherapy or death from any cause. Survival probabilities were estimated using the Kaplan-Meier estimator. Cumulative risk of transformation was estimated with death as a competing risk. Primary endpoints were 10-year OS and 5-year EFS respectivly. Results: A total of 934 patients from 25 sites were included. Median age at diagnosis was 68 years (IQR 60-76) and 54% were female. Bone marrow involvement was present in 96% (564/590) of those assessed, anemia (Hb <12g/dL for women or <13g/dL for men) in 58%, LDH >UNL in 46%, lymphocytosis (>5 x10 9/L) in 34%, and B-symptoms in 34%. Treatment data were available for 97% of patients. Median follow-up was 9.1 years (range 0-23). Watch and wait was the initial strategy in 28% and 88% of patients received at least one line of treatment during follow-up with the most common being splenectomy (45%), immuno-chemotherapy (19%) or rituximab monotherapy (8%). Fifteen percent received “other” treatments (i.e., combinations of listed therapies and/or radiation). The overall response rate to first-line treatment was 88% (95%CI: 85-90%) with 61% (95%CI: 57-64%) achieving CR. Second line (2L) therapy was needed in 34% during follow-up, 3L in 20% and 4L+ in 9%. The 5-year EFS and OS for all patients were 61% (95%CI: 57-65%) and 77% (95%CI: 74-80%) respectively. The 10-year OS and lymphoma-specific mortality (with non-SMZL deaths as competing risk) estimates were 60% (95%CI: 57-64%) and 11% (95%CI: 9-14%) respectively. The 5-year OS after 2L and 3L were 61% (95%CI: 55-68%) and 51% (95%CI: 42-61%) respectively (figure 1). The 10-year cumulative risk of histological transformation was 17% (95%CI: 13-21%), with 5-year post-transformation OS of 42% (32-54%). At the time of transformation, 60% were chemo-naive and 52% had never been treated for SMZL. The 5-year OS for chemo-naive patients with transformation was 54% (95%CI: 41-71%) versus 24% (95% CI: 13-44%) for transformations after (immuno)chemotherapy (p = 0.01). When comparing patients intended for treatment in first line with splenectomy (n=312) versus rituximab (n=70), patients treated with splenectomy more frequently presented with extra-hilar lymphadenopathy (35% vs 18%), splenomegaly (92% vs 87%) and anemia (64% vs 48%). OS was similar for the two groups (Figure 2, p = 0.53). The 5-year EFS were 63% (95%CI: 57-68%) and 64% (95%CI: 54-77%), respectively (p = 0.31). Conclusions: To date, this is the largest real-world study of SMZL with detailed treatment and outcome data. The study shows that histological transformation was not uncommon with 10-year risk of 17%. However, outcomes for the entire cohort were excellent irrespective of initial treatment and both OS and EFS were similar after first line rituximab versus splenectomy. Long-term survival remained relatively high even following multiple lines of therapy.

DNA Methylation-Based Classification of Hairy Cell Leukemia and Splenic B Cell Lymphoma

Improved classification of rare lymphoid neoplasms would be aided by a deeper understanding of their underlying molecular features and is important for diagnosis, prognosis and therapy. Tumor entities classified within the WHO category of splenic B cell lymphomas and leukemias often exhibit heterogenous, transecting features, and include hairy cell leukemia (HCL), splenic diffuse red pulp lymphoma (SDRPL), splenic marginal zone lymphoma (SMZL), and the newly described WHO entity, splenic B cell lymphoma/leukemia with prominent nucleoli (SBLPN); the latter including patients formerly classified as HCL-variant (HCL-V). Genome-wide epigenetic information provides a tumor cell fingerprint combining cell-of-origin and tumor-specific events. Here we used DNA methylation to perform an unbiased molecular subclassification and to explore novel biological aspects of these patients. Samples from patients with a pathological diagnosis of HCL, HCL-V, SDRPL and SMZL (made prior to the 5 th WHO revision and ICC classifications) were obtained from 19 institutions across 9 countries, totaling 367 patients. Cells were FACS-purified where necessary and DNA was analyzed by 450/850K Illumina DNA methylation arrays. Genetic mutations were assessed by whole-exome or targeted sequencing, IGHV-D-J sequences by Sanger sequencing, and copy number alterations (CNAs) by Illumina arrays. The 1000 most variable CpG methylation sites were used for k-means clustering. Recursive feature elimination/random forest algorithms were used to develop a classifier for DNA methylation-based subgroups with 98% accuracy. Unsupervised clustering of 197 patients diagnosed with HCL, HCL-V or SDRPL revealed 5 distinct DNA methylation (M) subgroups ( Figure 1). Subgroup assignment was stable throughout longitudinal sampling (including pre/post-treatment) and consistent between splenic, bone marrow and PBMC derived cells. A subgroup with universally clonal BRAF-V600E mutations and majority diagnosed as HCL was termed the M-HCL subgroup ( Table 1). Four other groups termed M-SBLPN1-4 contained all HCL-V and SDRPL diagnosed samples and were devoid of BRAF-V600E mutations. M-SBLPN1 comprised MAP2K1 mutations (91%) and was enriched for CREBBP, ARIDIA and TERT-promoter mutations. These patients displayed an HCL-like immunophenotype (64.3% CD25+) with 1/3 diagnosed as HCL. M-SBLPN2 exhibited the highest prevalence of TP53 mutations and concomitant genomic instability. Patients in M-SBLPN1,2 were enriched in unmutated IGHV4-34 rearrangements. M-SBLPN3,4 subgroups displayed an immunophenotype more dissimilar to HCL, mutated IGHV genes, and enrichment of IGLL5, SYK and BIRC3 mutations. M-SBLPN4 contained the most SDRPL samples, suggesting it may represent the SDRPL entity retained by the WHO. We next uncovered that 29/170 SMZL patients displayed DNA methylation patterns mapping to M-SBLPN2-4. These patients were phenotypically and molecularly similar to SBLPN (70% displaying villous morphology and depleted in IGHV1-2*04, NOTCH2, KLF2 mutations), likely representing SMZL patients suggested for reassignment to SBLPN in the updated WHO classification. To elucidate molecular pathways governing the biology of M-SBLPN subgroups, transcription factor motif enrichment analysis in hypomethylated genomic regions revealed selective activation of AP-1 in M-HCL along with ETS in M-SBLPN1,2. Both transcription factors are downstream of MAPK signaling, consistent with activating BRAF and MAP2K1 mutations in these subgroups. However, we observed strong ETS enrichment in the absence of MAP2K1 in M-SBLPN along with mutual exclusivity of MAP2K1 and TP53 mutations, suggesting TP53 mutations are driving ETS activation. Although lymphoid neoplasms rarely exhibit TERT promoter mutations, 83% of M-SBLPN1 patients showed the c.-124C>T mutation commonly observed in other cancers producing an ETS binding site and ectopic TERT activation. ETS activation and gain of an ETS site by mutation implies oncogenesis involves aberrant TERT activation in this subgroup. In summary, we have developed a DNA methylation-based classifier that resolves 4 SBLPN subgroups with distinct molecular features, and reclassifies a subset of SMZL and HCL patients, adding further information to the updated WHO/ICC entities. We reveal distinct biological pathways operating in M-SBLPN subgroups that may aid targeted therapy approaches.

Epidemiology and Survival of Patients with Marginal Zone Lymphoma Treated at the National Cancer Institute of Peru. a Retrospective Analysis of 187 Cases

Background Marginal zone lymphoma (MZL) represents a heterogeneous subgroup, classified as extranodal, splenic and nodal lymphoma. Extranodal cases, also termed mucosa-associated lymphoid tissue (MALT), account for 70% of MZLs. Splenic marginal zone B-cell lymphoma (SMZL) accounts for <2% of all NHL. There is no data about marginal zone lymphoma in Latin American patients. Methods We evaluated retrospectively all patients diagnosed with marginal zone lymphoma at the National Cancer Institute from 2010 to 2019. Baseline characteristics, treatments and survival were retrieved from medical records. Kaplan Meier method was used to analyze the overall survival. The estimate of the survival curves was performed by the Kaplan-Meier method, and the differences were computed by the log-rank test. The Cox proportional hazard models were used to identify predictors of survival of MZL. A level of p <0.05 was considered for a statistical significance. Results During the study period 2010-2019, 4437 patients with B-cell non-Hodgkin lymphoma were evaluated at the INEN, 187 of them were marginal zone lymphomas, representing 4.2% of all cases. The most frequent marginal zone lymphoma was MALT, followed by nodal and splenic lymphoma with 89.8%, 5.3% and 4.8% of cases, respectively. The median age for the entire cohort was 59 years (range 17-89). The median age for the MALT, nodal and splenic MZL cohort were 58.5 years (range 17-89), 75 years (range 52-88), 68 years (range 43-87), respectively. 37.4% were male for the entire cohort, and 37%, 40%, 44% for the MALT, nodal and splenic MZL group. Elevated LDH was seen in 13% of the entire cohort and in 11% and 24% of the MALT and splenic MZL group. Transformed lymphoma was reported in 6.4% of the entire cohort, but in the 20% of nodal MZL and no one case of the splenic MZL. More data you can see in the table 1. The most frequent primary site locations for MALT lymphoma were gastric, ocular adnexal, parotid gland, cutaneous, intestinal and CNS with 36%, 30%, 7%, 5%, 5% and 5%, respectively. The median overall survival was 114 months (IQR 76-133) for the entire cohort and 133 months, 59 and 59 months for the MALT, nodal MZL, and splenic MZL, respectively (p=0.0011), see the figure 1. The 5-year OS was 81.4% (95% CI, 71.6-88.1) for the entire cohort and 85.7% (95% CI, 76.5-91.5) for the MALT lymphoma group. No one patients were alive at 5 years in both nodal and splenic lymphoma groups. Conclusion Marginal zone lymphoma is a relatively rare type of B-cell lymphoma. The most frequent type is MALT lymphoma, followed by nodal MZL. The median age for the entire group was 59 years, however patients with nodal MZL were older with a median age of 75 years. Transformed lymphoma was present in 6% of the entire cohort and in the 20% of the nodal MZL. Gastric, ocular adnexal and parotid gland were the most common primary site of MALT lymphoma. MALT lymphoma had long survival, but nodal and splenic MZL had shorter survival with no one surviving 5 years from diagnosis.

Hairy Cell Leukemia with Severe Leukocytosis

Introduction Hairy cell leukemia (HCL) is a rare indolent mature B-cells neoplasm that typically manifests with pancytopenia and splenomegaly. Nevertheless, significant splenomegaly, high hairy cells count in the blood, elevated β 2 microglobulin, and increased LDH can predict resistance to purine analogs. The absence of BRAF V600E mutation in HCL is rare and is associated with poorer outcomes. Case Presentation A 68-year-old female patient presented with symptomatic massive splenomegaly, leukocytosis (89,000 /microliter), monocytopenia, and thrombocytopenia. β 2microgobulin level was 4.4 mcg/L. Lactate dehydrogenase was 521 U/L. Peripheral blood and bone marrow examinations revealed typical hairy cells morphology, and the cells were positive for CD19, CD20, CD103, CD25, CD11c, CD200 (dim), and surface-Kappa. CD38 was negative. BRAF V600E result was wild-type. IGHV was mutated (IGHV3-49). She received first-line therapy with a 5-day course of Cladribine (0.15 mg/kg/day) with initial resolution of leukocytosis, normalization of platelets, and a 50% reduction in spleen size. This was followed by consolidation with an 8-weekly course of Rituximab (375 mg/m 2). Soon after the 2 nd dose of Rituximab, leukocytosis recurred, and she was initiated on second-line therapy with Bendamustine (90 mg/m 2 on days 1 and 2) along with Rituximab (BR). She has not achieved any durable response following two cycles of BR. Unfortunately, she suffered a septic shock requiring admission to our intensive care unit. Upon routine mental status evaluation, brain MRI revealed innumerable supratentorial and infratentorial bilateral acute/subacute and old microhemorrhages (Figure 1). This prompted further evaluation of unexplained recurrent episodes of pulmonary hemorrhages while on mechanical ventilation that were found to be secondary to pulmonary end-arterial cavitating lesions suggestive of hairy cells infiltration (Figure 2 arrowheads). As she was clinically unstable, we attempted to control leukocytosis with corticosteroids, leukapheresis aggressively and started the patient on Ibrutinib, but she succumbed to her disease. Discussion Recently, the 5 th edition of the World Health Organization classification of hematolymphoid tumors highlighted the splenic B-cell lymphoma and leukemia family that encompasses hairy cell leukemia (HCL), splenic B-cell lymphoma/leukemia with prominent nucleoli (SBLPN), formerly known as hairy-cell leukemia variant, splenic diffuse red pulp small B-cell lymphoma (SDRPL) and splenic marginal zone lymphoma (SMZL). HCL is typically an indolent mature B-cell neoplasm with characteristic pathologic features that preferentially insinuate the bone marrow and the spleen causing impaired hematopoiesis and splenomegaly. Unlike other disorders within this group, HCL commonly harbors BRAF V600E somatic mutation in almost all cases. Rarely, patients with HCL can have extramedullary involvement by the malignant cells. Leukocytosis in HCL appears to increase the risk of developing extramedullary lesions that can present unique clinical challenges necessitating early and effective therapy. According to the literature, brain lesions in HCL were described in three other cases, and leukocytosis was a common denominator. Our patient with significant leukocytosis had brainand pulmonary lesions, and the latter was the cause of her demise due tounusually aggressive and refractory disease. Therefore, we hypothesize that leukocytosis in HCL can be “the tip of the iceberg”. The higher the leukocytosis, the higher the burden of extramedullary disease, as in our case, who had simultaneous lesions in the brain and lungs. Patients with HCL and leukocytosis may warrant initial diagnostic evaluation to ensure the absence of potentially sinister lesions, which can inform subsequent monitoring and management plans. Additionally, more novel therapies could be considered sooner in the treatment course to control the disease and these lesions. Finally, our patient did not harbor BRAF V600E mutation, which likely resulted in further worse outcomes and limited the usage of targeted therapies like BRAF inhibitors.

Transformation to diffuse large B-cell lymphoma and its impact on survival in patients with marginal zone lymphoma: A population-based study.

Some patients with marginal zone lymphoma (MZL) experience histological transformation to diffuse large B-cell lymphoma (DLBCL). Because of the paucity of long-term data on transformation, we conducted a population-based study to estimate the risk of transformation and its impact on survival in MZL. Using the Surveillance, Epidemiology and End Results database, we identified 23 221 patients with histology-proven MZL between 2000 and 2018. Competing risk method, Kaplan-Meier and Cox proportional hazards regression were performed to analyze time-to-event outcomes. Based on 420 events of transformation, the 10-year cumulative incidence rate of transformation is 2.23% (95% CI: 2.00%-2.46%) in MZL, 1.5% (95% CI: 1.3%-1.8%), 2.7% (95% CI: 2.3%-3.2%) and 5.8% (95% CI: 4.6%-7.1%) in extranodal, nodal and splenic MZL (EMZL, NMZL and SMZL), respectively. Patients with SMZL (subdistribution hazard ratio [SHR], 2.96; 95% CI: 2.21-3.96) or NMZL (SHR, 1.49; 95% CI: 1.17-1.90) have a higher risk of transformation than those with EMZL. For each MZL subtype, patients with transformation had a significantly shorter overall survival. Patients with transformation >18 months since MZL diagnosis had longer OS than those who presented within 18 months (5-year rate, 87.4% [95% CI: 83.7%-91.2%] vs 47.9% [95% CI: 38.8%-59.0%]; P < .001). Compared to patients with matched de novo DLBCL, those whose DLBCL was transformed from MZL had a shorter OS (5-year rate, 56.6% [95% CI: 51.9%-61.8%] vs 46.1% [95% CI: 40.9%-51.9%]; P < .001). We concluded that patients with SMZL had the highest risk of transformation. Regardless of MZL subtype, transformation resulted in significantly increased mortality.

S2403 Abdominal Pain Due to Acquired Angioedema Associated With Splenic Marginal Zone Lymphoma

S2403 Abdominal Pain Due to Acquired Angioedema Associated With Splenic Marginal Zone Lymphoma

IBCL-270 Signatures of Immune Exhaustion and Suppression in the Tumor Microenvironment of Splenic Marginal Zone Lymphoma Correlate With Inferior Clinical Outcomes

IBCL-270 Signatures of Immune Exhaustion and Suppression in the Tumor Microenvironment of Splenic Marginal Zone Lymphoma Correlate With Inferior Clinical Outcomes

POSTER: IBCL-270 Signatures of Immune Exhaustion and Suppression in the Tumor Microenvironment of Splenic Marginal Zone Lymphoma Correlate With Inferior Clinical Outcomes

POSTER: IBCL-270 Signatures of Immune Exhaustion and Suppression in the Tumor Microenvironment of Splenic Marginal Zone Lymphoma Correlate With Inferior Clinical Outcomes

BCL3 rearrangements in B-cell lymphoid neoplasms occur in two breakpoint clusters associated with different diseases.

The t(14;19)(q32;q13) often juxtaposes BCL3 with immunoglobulin heavy chain (IGH) resulting in overexpression of the gene. In contrast to other oncogenic translocations, BCL3 rearrangement (BCL3-R) has been associated with a broad spectrum of lymphoid neoplasms. Here we report an integrative whole-genome sequence, transcriptomic, and DNA methylation analysis of 13 lymphoid neoplasms with BCL3-R. The resolution of the breakpoints at single base-pair revealed that they occur in two clusters at 5' (n=9) and 3' (n=4) regions of BCL3 associated with two different biological and clinical entities. Both breakpoints were mediated by aberrant class switch recombination of the IGH locus. However, the 5' breakpoints (upstream) juxtaposed BCL3 next to an IGH enhancer leading to overexpression of the gene whereas the 3' breakpoints (downstream) positioned BCL3 outside the influence of the IGH and were not associated with its expression. Upstream BCL3-R tumors had unmutated IGHV, trisomy 12, and mutated genes frequently seen in chronic lymphocytic leukemia (CLL) but had an atypical CLL morphology, immunophenotype, DNA methylome, and expression profile that differ from conventional CLL. In contrast, downstream BCL3-R neoplasms were atypical splenic or nodal marginal zone lymphomas (MZL) with mutated IGHV, complex karyotypes and mutated genes typical of MZL. Two of the latter four tumors transformed to a large B-cell lymphoma. We designed a novel fluorescence in situ hybridization assay that recognizes the two different breakpoints and validated these findings in 17 independent tumors. Overall, upstream or downstream breakpoints of BCL3-R are mainly associated with two subtypes of lymphoid neoplasms with different (epi)genomic, expression, and clinicopathological features resembling atypical CLL and MZL, respectively.

Time Trend Analysis of Splenectomy for Splenic Marginal Zone Lymphoma: Declining Surgery, Promising Survival.

The purpose of current study was to examine the incidence, characteristics, treatment, and survival of splenic marginal zone lymphoma (SMZL). Using SEER-18 database, patients diagnosed with SMZL between 2000 and 2018 were included. Effect of splenectomy on survival was evaluated after balancing the confounding factors by propensity score matching. Rates of splenectomy and 1-year relative survival were calculated for each year. A logistic regression model identified factors related to splenectomy, and a Cox regression model assessed factors linked to overall survival (OS). A total of 2790 patients with SMZL were analyzed. The majority were older than 60 years, female, and white. The age-adjusted incidence of SMZL was 0.17/100,000 person-years, with higher incidence in males. Incidence increased by 0.68%/year and peaked at 80-84 years for both genders. The SMZL-specific survival rates at 3 and 5 years were 89.6% and 85.3%, respectively. Meanwhile, the relative survival rates for the same periods were 88.6% and 85.9%, respectively. Splenectomy patients were more likely to be younger, male, and diagnosed with early-stage disease. Despite the decreasing utilization rate of splenectomy from 59.4% in 2000 to 16.2% in 2018, the 1-year relative survival rate remained relatively stable with minor fluctuations over time. Whether or not the patient underwent splenectomy was not found to be a significant prognostic indicator for OS. Our study demonstrated a decreasing use of splenectomy but a relatively stable survival in patients with SMZL, highlighting the urgency to better understand the role of splenectomy and its associated outcomes.

Unraveling the genetics of transformed splenic marginal zone lymphoma.

The genetic mechanisms associated with splenic marginal zone lymphoma (SMZL) transformation are not well defined. We studied 41 patients with SMZL that eventually underwent large B-cell lymphoma transformation. Tumor material was obtained either only at diagnosis (9 patients), at diagnosis and transformation (18 patients), and only at transformation (14 patients). Samples were categorized in 2 groups: (1) at diagnosis (SMZL, n= 27 samples), and (2) at transformation (SMZL-T, n= 32 samples). Using copy number arrays and a next-generation sequencing custom panel, we identified that the main genomic alterations in SMZL-T involved TNFAIP3, KMT2D, TP53, ARID1A, KLF2, 1q gains, and losses of 9p21.3 (CDKN2A/B) and 7q31-q32. Compared with SMZL, SMZL-T had higher genomic complexity, and higher incidence of TNFAIP3 and TP53 alterations, 9p21.3 (CDKN2A/B) losses, and 6p gains. SMZL and SMZL-T clones arose by divergent evolution from a common altered precursor cell that acquired different genetic alterations in virtually all evaluable cases (92%, 12 of 13 cases). Using whole-genome sequencing of diagnostic and transformation samples in 1 patient, we observed that the SMZL-T sample carried more genomic aberrations than the diagnostic sample, identified a translocation t(14;19)(q32;q13) present in both samples, and detected a focal B2M deletion due to chromothripsis acquired at transformation. Survival analysis showed that KLF2 mutations, complex karyotype, and International Prognostic Index score at transformation were predictive of a shorter survival from transformation (P= .001; P= .042; and P= .007; respectively). In summary, SMZL-T are characterized by higher genomic complexity than SMZL, and characteristic genomic alterations that could represent key players in the transformation event.

REALMA: Subset of patients with Marginal Zone Lymphomas from the French nationwide REALYSA real‐world prospective cohort.

Background: Marginal Zone Lymphomas (MZL) are a heterogeneous group of lymphomas that include three subtypes: extranodal MZL (EMZL), splenic MZL (SMZL) and nodal MZL (NMZL). Since most of the knowledge comes from clinical trials (with stringent inclusion criteria and limited representativeness), there is a crucial need for real-world evidence in MZL. In 2018 the French REALYSA (Real world dAta in LYmphoma in Adults) study was initiated as a nationwide multicentric prospective cohort of patients newly diagnosed with lymphoma. By Dec 31, 2021, a total of 207 patients with MZL were included in the study. Methods: Patients were recruited in 35 French hematology centers and received routine care. Data were collected from medical records and questionnaires. A first abstraction was performed on Jan 1, 2023, to parse out the available data regarding MZL patients with >1 year of follow-up. Each case was reviewed by medical and pathological experts, and treatments were classified on an intent-to-treat basis. Results: Of the 207 patients with MZL included up to Dec 31, 2021, 111 (53%) presented with EMZL, 47 (23%) with SMZL and 49 (24%) with NMZL. At baseline, median age was of 67 years old (IQR 60,75), 53% of patients were females, 5.5% of patients had a PS of 2–4, 70% were stage III-IV, 19% presented with B-symptoms, 20% had a bulky mass >7 cm and 5.8% had a compressive syndrome. Only 7% of patients reported an auto-immune disease. Diagnosis of MZL was mostly evoked by general practitioners (48%) but patients were finally treated by hematologists (98%). Only 9 patients were referred to an onco-geriatrician. Regarding the initial workup, while at least one imagery was offered in 97% of patients, 18FDG-PET/CT (EMZL 78%, SMZL 62%, NMZL 78%) was performed more frequently than CT-scan at baseline (EMZL 73%, SMZL 62%, NMZL 71%), although 47% patients underwent both procedures. Among the 207 patients, 58 (28%) were not treated. Only 10 patients exclusively received local therapy (radiotherapy n = 6, surgery n = 2, antibiotics n = 2). Regarding systemic therapies, rituximab-chlorambucil was mainly offered in patients with EMZL (40%), while rituximab-monotherapy was preferred in SMZL (60%). For patients with NMZL, physicians mainly offered RCHOP (33%) and rituximab-bendamustine (27%). Only 7 patients with EMZL received the combination of ibrutinib and rituximab. At end of 1st line, 93% of patients had responded to therapy and 75% were in complete response. Among patients assessed with 18FDG-PET/CT, a metabolic complete response was observed in 52/58 (90%) of cases. Conclusion: This is the first analysis describing real-world data of patients with MZL in France. Our cohort features high-quality data both on epidemiological and clinical outcomes. When the total number of patients will increase and data will mature, this dataset will provide insightful information regarding both endpoints and treatment evaluations. Keyword: Indolent non-Hodgkin lymphoma Conflicts of interests pertinent to the abstract. C. Bommier Research funding: Inserm/AvieSan/ITMO Cancer, LYSA/ELI (Bertrand Coiffier Prize), Philippe Foundation, Institut Servier

17th International Conference on Malignant Lymphoma, Palazzo dei Congressi, Lugano, Switzerland, 13 - 17 June, 2023.

The development of some lymphomas has been associated with infections caused by bacterial species discovered in the 1980s, for example, Helicobacter pylori and Borrelia burgdorferi s.l. The first cases of human infection with a bacterial species that was first described in 2004, the tick-borne bacterium Neoehrlichia mikurensis were published in 2010. Patients with malignant B cell lymphomas emerged as a risk group for severe cases of infection, presenting with fever of unknown cause and venous thromboembolism. The infection is missed by routine microbiologic diagnostic procedures such as blood culture and can only be detected by PCR. Vascular endothelium is a likely target of N. mikurensis infection. Asymptomatic carriage of the infection for months to years appears to occur. We hypothesized that N. mikurensis causes latent infections that can reactivate when B cell defenses are compromised. It was whilst conducting a study of patients with malignant B cell lymphomas scheduled to receive treatment with rituximab that we discovered several patients who had the infection already before the start of treatment. This led us to hypothesize that persistent latent infections with N. mikurensis might contribute to the development of certain cases of malignant B cell lymphoma. Splenic engagement, restricted repertoires of the Immunoglobulin heavy chain variable (IGHV) regions, and mutations of the IGHV regions from the germline configuration featured among these cases of lymphoma, which encompassed chronic lymphocytic leukemia, splenic marginal zone lymphoma, mantle cell lymphoma and non-classified indolent splenic lymphoma. Remarkably, three out of five patients could cease lymphoma therapy after eradication of the infection. Our aim is to confirm and expand these findings of a possible causality between N. mikurensis infection and the development of malignant B cell lymphomas. To this end, we are starting a prospective study of the prevalence of N. mikurensis infection in newly diagnosed patients with malignant B cell lymphomas, and the response of such lymphomas to eradication of the infection. We will also attempt to identify a genetic signature of N. mikurensis infection by studying IGHV gene usage, the mutations induced by somatic hypermutations, as well as the physicochemical properties of the complementarity-determining region 3 (CDR3), the most hypervariable part of the B cell receptor of infected patients. This will help establish if it is mainly post-germinal center B cells that undergo malignant B cell transformation in cases of N. mikurensis-associated lymphoma. The research was funded by: the Swedish Research Council, the Swedish Cancer Society, the Swedish state under the agreement between the Swedish government and the county councils, the ALF-agreement, and the Cancer and Allergy Foundation. Keywords: indolent non-Hodgkin lymphoma, tumor biology and heterogeneity, chronic lymphocytic leukemia (CLL) No conflicts of interests pertinent to the abstract.

Marginal zone lymphomas.

The three main types of marginal zone lymphoma (MZL), recognized by the current lymphoma classifications are the extranodal MZL of mucosa-associated lymphoid tissue, the splenic MZL, and the nodal MZL. They share some karyotype lesions (trisomies of chromosomes 3 and 18, deletions at 6q23), and alterations of the nuclear factor kappa B (NFkB) pathway are also common in all of them. However, they differ in the presence of recurrent translocations, mutations affecting the Notch signaling pathway (NOTCH2 and less commonly NOTCH1), the transcription factors Kruppel-like factor 2 (KLF2) or the receptor-type protein tyrosine phosphatase delta (PTPRD). This review summarizes the most recent and significant advances in our understanding of the epidemiology, genetics, and biology of MZLs and outlines the current principles of the standard management of MZL at different anatomic sites.

17th International Conference on Malignant Lymphoma, Palazzo dei Congressi, Lugano, Switzerland, 13 - 17 June, 2023.

Introduction: MZL is a heterogeneous disease comprising 3 subtypes, extra-nodal MZL of mucosa-associated lymphoid tissue, nodal MZL, and splenic MZL. Treatment of R/R MZL is similar to other indolent B-cell non-Hodgkin lymphoma (B-NHL) subtypes (e.g., follicular lymphoma [FL]), comprising rituximab-based immunochemotherapy regimens that achieve an objective response rate (ORR) of ∼45%–80%. Options after progression on rituximab-based regimens include the BTK inhibitor ibrutinib, which demonstrated an ORR of 46%, but a compete response (CR) rate of only 3%, in its pivotal trial in R/R MZL. Overall, limited options are available after progression on current therapies, and a need remains for more effective treatments for R/R MZL. Odronextamab is a bispecific antibody that binds CD20-expressing B-NHL cells and CD3 on T cells. In the Phase 1 ELM-1 study, odronextamab monotherapy showed antitumor activity and a manageable safety profile in a range of R/R B-NHL subtypes, including MZL (n = 6; ORR 67%) (Bannerji et al. Lancet Haematol, 2022). In the Phase 2 ELM-2 study, odronextamab elicited an ORR of 82% and CR rate of 75% in patients with heavily pretreated R/R FL (Kim, et al. ASH, 2022). These positive data in an indolent B-NHL subtype support evaluation of odronextamab in R/R MZL. Methods: ELM-2 (NCT03888105) is an open-label study of odronextamab in patients with R/R B-NHL comprising 5 disease-specific cohorts: FL, diffuse large B-cell lymphoma, mantle cell lymphoma, MZL, and other B-NHLs. Each cohort will be evaluated separately, and patients recruited from sites across North America, Europe, and Asia-Pacific regions. The MZL cohort is planned to include 78 patients, who will receive IV odronextamab monotherapy until disease progression or other protocol-defined reason for treatment discontinuation. Odronextamab is administered according to a step-up regimen during the first 21-day cycle (C), consisting of 0.7 mg split over C1 Day (D) 1 (0.2 mg) and C1D2 (0.5 mg), 4 mg split over C1D8 and C1D9, and 20 mg split over C1D15 and C1D16. The full 80 mg dose is given QW during C2 to C4, then 160 mg Q2W from C5 onwards. If a patient achieves a CR and has a durable response for ≥9 months after initial determination of the CR, then dosing interval will be decreased from Q2W to Q4W. Patients eligible for the MZL cohort will be ≥18 years of age; relapsed/refractory to ≥2 prior lines of systemic therapy; ECOG performance status ≤1; and have adequate bone marrow and hepatic functions. Patients with prior allogeneic stem cell transplant or CAR T treatment will be excluded. Primary endpoint is ORR (Lugano classification; assessed by independent central review). Key secondary endpoints include ORR (investigator evaluation); CR rate; progression-free survival; overall survival; duration of response; safety; pharmacokinetics; and patient-reported quality of life outcomes. As of January 2023, 19 patients with MZL had enrolled. Encore Abstract—previously submitted to ASCO 2023 and EHA 2023 The research was funded by: Regeneron Pharmaceuticals, Inc. Keywords: indolent non-Hodgkin lymphoma, immunotherapy, ongoing trials Conflicts of interests pertinent to the abstract. T. M. Kim Consultant or advisory role Boryung, AstraZeneca/MedImmune, Takeda, Novartis, Janssen, Hanmi, and Regeneron Pharmaceuticals, Inc Honoraria: Takeda, Janssen, Regeneron Pharmaceuticals, Inc, Samsung Bioepis, and AstraZeneca Research funding: Celgene, Boryung, Boehringer-Ingelheim, BMS, Bayer, AstraZeneca/MedImmune, Takeda, Roche/Genentech, Novartis, Janssen, Hanmi, Genmab, Merck Serono, Merck Sharp & Dohme, Regeneron Pharmaceuticals, Inc, and Sanofi M. Taszner Consultant or advisory role Roche and Takeda Honoraria: Roche, Takeda, Novartis, and Servier Educational grants: Roche A. Chaudhry Employment or leadership position: Regeneron Pharmaceuticals, Inc Stock ownership: Regeneron Pharmaceuticals, Inc M. Ufkin Employment or leadership position: Regeneron Pharmaceuticals, Inc Stock ownership: Regeneron Pharmaceuticals, Inc A. Uppala Employment or leadership position: Regeneron Pharmaceuticals, Inc Stock ownership: Regeneron Pharmaceuticals, Inc A. Sabir Employment or leadership position: Regeneron Pharmaceuticals, Inc Stock ownership: Regeneron Pharmaceuticals, Inc H. Mohamed Employment or leadership position: Regeneron Pharmaceuticals, Inc Stock ownership: Regeneron Pharmaceuticals, Inc S. Ambati Employment or leadership position: Regeneron Pharmaceuticals, Inc Stock ownership: Regeneron Pharmaceuticals, Inc E. Bachy Consultant or advisory role Roche, Gilead, ADC Therapeutics, Takeda, Novartis, and Incyte Honoraria: Kite, Gilead, Novartis, Roche, Incyte, Miltenyi Biotech, Takeda, and Sanofi Research funding: Amgen and BMS

Splenic marginal zone lymphoma in Sweden 2000-2020: Increasing rituximab use and better survival in the elderly.

The treatment of splenic marginal zone lymphoma is debated: splenectomy (the old standard-of-care) is better than chemotherapy but maybe not better than rituximab-containing treatment. We examined all 358 patients diagnosed with splenic marginal zone lymphoma in Sweden 2000-2020. The median overall survival was 11.0 years. The median age was 73 years; 61% were women. Age was the only independently prognostic clinical characteristic. Eighty-six patients were started on wait-and-watch, 90 rituximab monotherapy, 47 rituximab-chemotherapy, 88 splenectomy, 37 chemotherapy, and 10 both systemic therapy and splenectomy. Overall survival was inferior in patients treated with chemotherapy, but equal in patients treated with rituximab, rituximab-chemotherapy and splenectomy. Patients treated with both systemic therapy and splenectomy showed good outcome, suggesting that surgery can be safely reserved for nonresponders. After adjustment for age, survival did not differ between patients started on wait-and-watch and those treated with splenectomy or rituximab-containing therapy. Over time, rituximab use and survival increased in patients ≥73 years. This is, to our knowledge, the largest population-based study of splenic marginal zone lymphoma patients treated with upfront rituximab. We conclude that wait-and-watch remains the most reasonable option in asymptomatic splenic marginal zone lymphoma patients. Symptomatic patients should be offered single-agent rituximab in first line.

Indolent B-cell splenic lymphomas have T cells with an exhausted phenotype

Abstract T cell dysregulation has been observed in many tumors, but has not been well-characterized in rare B-cell splenic lymphomas. We began defining the T cell populations in the tumor microenvironments of four human indolent B cell splenic lymphomas: splenic marginal zone lymphoma (SMZL), hairy cell leukemia (HCL), hairy cell leukemia variant (HCLv), and splenic diffuse red pulp small B-cell lymphoma (SDRPL). After Institutional Research Subjects Review Board approval, we studied de-identified cryopreserved bulk splenic tumor suspension cell isolates from fresh (less than 4 h) splenectomy tissue and matched intact formalin-fixed paraffin embedded (FFPE) tissue sections from 17 splenic lymphoma patients and 4 trauma patients (controls). Initial immunohistochemical staining analysis of FFPE tissue sections suggests that the distribution of intratumoral T cells is markedly different among B cell splenic lymphomas. In HCL, residual T cell zones appear retained, albeit diminished, while HCLv and SDRPL have markedly reduced T cells throughout with non-distinct zonation, and SMZL has prominent peritumoral collections of T cells at the interface of the neoplastic white pulp. High-parameter (32-color) fluorescence spectral flow cytometry (Cytek Aurora) analysis suggests that splenic lymphomas exhibit CD4+ and CD8+ T cells with higher proportions of transitional memory, regulatory, and exhausted phenotypes than controls. T cell activation may be enhanced in HCLv. HCLv and SMZL may have decreased naïve T cells. Finally, splenic lymphomas had higher proportions of T cells with an exhausted phenotype compared to trauma samples. In summary, our data suggests T cells are dysregulated in B-cell splenic lymphomas. American Association of Immunologists, Hairy Cell Leukemia Foundation / Sass Foundation for Medical Research, and generous donations by Elizabeth Aaron.

Characterization of immune exhaustion and suppression in the tumor microenvironment of splenic marginal zone lymphoma.

The role of the tumor microenvironment (TME) and intratumoral T cells in splenic marginal zone lymphoma (sMZL) is largely unknown. In the present study, we evaluated 36 sMZL spleen specimens by single cell analysis to gain a better understanding of the TME in sMZL. Using mass cytometry (CyTOF), we observed that the TME in sMZL is distinct from that of control non-malignant reactive spleen (rSP). We found that the number of TFH cells varied greatly in sMZL, ICOS+ TFH cells were more abundant in sMZL than rSP, and TFH cells positively correlated with increased numbers of memory B cells. Treg cell analysis revealed that TIGIT+ Treg cells are enriched in sMZL and correlate with suppression of TH17 and TH22 cells. Intratumoral CD8+ T cells were comprised of subsets of short-lived, exhausted and late-stage differentiated cells, thereby functionally impaired. We observed that T-cell exhaustion was present in sMZL and TIM-3 expression on PD-1low cells identified cells with severe immune dysfunction. Gene expression profiling by CITE-seq analysis validated this finding. Taken together, our data suggest that the TME as a whole, and T-cell population specifically, are heterogenous in sMZL and immune exhaustion is one of the major factors impairing T-cell function.

Transformations of marginal zone lymphomas and lymphoplasmacytic lymphomas: Report from the 2021 SH/EAHP Workshop.

To summarize the conclusions of the 2021 Society for Hematopathology/European Association for Haematopathology workshop regarding transformations of marginal zone lymphoma (MZL) and lymphoplasmacytic lymphoma (LPL). Nineteen cases were submitted to this portion of the workshop. Additional studies were performed in cases with sufficient material. Cases included splenic MZL (n = 4), splenic diffuse red pulp small B-cell lymphoma (n = 2), nodal MZL (n = 4), extranodal MZL (n = 1), and LPL (n = 8). The most common transformation was to diffuse large B-cell lymphoma (DLBCL), but others included classic Hodgkin lymphoma, high-grade B-cell lymphomas with MYC and BCL6 rearrangements, plasmablastic lymphoma, and plasma cell leukemia. Two splenic MZLs with transformation to DLBCL contained t(14;19)(q32;q13.3) IGH::BCL3 rearrangements in both samples. Paired sequencing studies in 5 MZLs with transformation to clonally related DLBCL identified a variety of mutations and gene fusions at the time of transformation, including CARD11, IGH::MYC, NOTCH2, P2RY8, TBLX1X1, and IGH::CD274. Marginal zone lymphoma and LPL may undergo a variety of transformation events, most commonly to DLBCL, which is usually, although not always, directly clonally related to the underlying low-grade lymphoma. Multiparameter analysis including broad-based sequencing studies can assist in the diagnosis and classification of these uncommon cases.

Transformation and survival in marginal zone lymphoma: a Finnish nationwide population-based study

Marginal zone lymphoma (MZL) is an indolent B-cell malignancy with heterogeneous anatomical and clinical presentation. While MZLs are generally associated with long survival, some patients experience histological transformation to aggressive large B-cell lymphoma. Population-based long-term data on the transformation of MZL is limited. We conducted a nationwide population-based study to estimate the risk of transformation and relative survival in patients diagnosed with MZL in Finland from 1995–2018. We identified a total of 1454 patients with MZL from the Finnish Cancer Registry (FCR). The cumulative incidence of transformation was 4.7% (95% CI, 3.6−6.2) at 10 years. The highest incidence of transformation was observed in the patients with splenic MZL (14.0%; 95% CI, 8.6−22.7). The transformation was associated with a substantially increased risk of death (HR, 5.18; 95% CI, 3.58–7.50). Ten-year relative survival was 79% (95% CI, 73‒83%). Transformation, nodal MZL subtype, and older age at diagnosis were associated with increased excess mortality, whereas patients diagnosed at a later calendar period had a lower excess risk of death. We conclude that transformation resulted in a substantially increased mortality irrespective of MZL subtype compared with the patients without transformation. Our results also suggest a reduction in excess mortality in recent years.