Thymic B-cell Research Articles

Treatment Outcomes in Primary Mediastinal Large B-Cell Lymphoma. Experience of the AF Tsyb Medical Radiological Research Center (Obninsk)

AIM. To assess chemotherapy outcomes in patients with primary mediastinal large B-cell lymphoma (PMBCL) treated at the AF Tsyb Medical Radiological Research Center from 2016 to 2023. MATERIALS & METHODS. The analysis focused on the data from 58 patients with the morphologically verified diagnosis of PMBCL. The patients were aged 17–62 years (median 34 years), there were 39 women and 19 men. The median follow-up was 51.2 months (range 0.4–200.9 months). Depending on drug chemotherapy regimens, patients were divided into 3 groups: R-NHL-BFM-90 (n = 9), R-CHOP (n = 17), and R-MACOP-B (n = 32). Most patients (90 %) received mediastinal radiotherapy of total 30–46 Gy. RESULTS. The 5-year overall survival in the therapy groups was 66.7 %, 88.2 %, and 100 %, respectively (p = 0.007), progression-free survival was 66.7 %, 70.6 %, and 96.9 % (p = 0.006), and event-free survival was 66.7 %, 54.7 %, and 90.6 % (p = 0.038). On the whole, the toxicity profile of chemotherapy was quite acceptable. Neither low blood values nor other adverse events essentially affected a complete implementation of chemoradiotherapy program. The intermediate outcomes were based on PET-CT data after 2–4 therapy cycles in 37 (64 %) patients. PET-CT showed that at the stage of drug chemotherapy, complete response (CR) was achieved in 27 (73 %) patients, and partial response (PR) was achieved in 4 (11 %) patients. With respect to the CR and PR criteria, there were 6 (16 %) non-responders. CONCLUSION. PMBCL is one of extranodal lymphomas with thymic B-cells being primary source of tumor growth. PMBCL is characterized by aggressive course and extreme heterogeneity of clinical manifestations. Up to now, the first-line chemotherapy decision making in PMBCL has remained an issue with practical importance. This paper reports immediate and long-term outcomes of the program chemoradiotherapy regimen R-MACOP-B with subsequent consolidation radiotherapy. The results obtained can be termed quite satisfactory and noninferior to the data from national and international sources. Nevertheless, more effective chemoradiotherapy programs for PMBCL continue to be elaborated. In this context, immune checkpoint inhibitors as part of therapy programs seem to hold promise for the treatment of newly diagnosed PMBCL.

Improved T- and B-Cell Neogenesis in Children with Acute Leukemia Given an Alpha-Beta T-Cell Depleted Haplo-HSCT Combined with the Infusion of Donor T-Cells Genetically Modified with Inducible Caspase 9 Suicide Gene (Rivo-cel)

Background αβ T- and B-cell depleted HLA-haploidentical HSCT (αβhaplo-HSCT) is a suitable transplant option promptly available and virtually applicable to any children in need of an allograft. However, the suboptimal recovery of adaptive immunity still represents a limitation of the approach. In order to better deconvolute the reconstitution of adaptive immunity, in this study we measured T-cell receptor and kappa chain-deleting recombination excision circles (TREC and KREC), which represent reliable surrogates of T and B-cell neogenesis, respectively. We also analyzed a cohort of patients who received after the allograft infusion of a titrated number of donor T-cells genetically modified with inducible caspase 9 (iC9) suicide gene (Rivo-cel) as part of a prospective clinical trial (NCT02065869) with the goal of accelerating the recovery of thymus-independent adaptive immunity. Patients and study design We retrospectively analyzed 134 patients (≤ 25 years) with acute lymphoblastic (ALL) or myeloid leukemia (AML) who received a αβ haplo-HSCT between 2014 and 2021; 65 of them received post-transplant infusion of Rivo-cel, at the dose of 1x10 6 cells/kg, after a median time of 26 days (range: 11-87) post-transplant. No patient received post-transplantation pharmacological GVHD prophylaxis (Locatelli et al. Blood 2017). Details on patient and donor characteristics, as well as on graft composition are reported in Table 1. T-cell neogenesis was investigated by quantifying signal joint- (sj-) and beta (b-) TREC while B-cell neogenesis was analyzed by measuring coding-joint (cj-) and sj- KREC. We performed real-time quantitative PCR, as previously described (Arruda et al. 2018), on genomic DNA extracted from PBMC collected at 6 different time points (before and 1, 3, 6, 12 and 18 months after the allograft). At the same time-points peripheral blood of patients was also evaluated by flow-cytometry to phenotypically characterize the pool of leukocytes. Results With a median follow-up of 6 years (range 1-9) the overall (OS) and disease-free survival (DFS) probabilities of the entire cohort were 88,1% and 82%, respectively. The cumulative incidence (CI) of relapse was 15%. CI of grade II-IV acute Graft-versus-Host Didease (GvHD) was 19%, while that of chronic GvHD (cGvHD) was 7%. In the Rivo-cel cohort, sjTREC and bTREC were consistently detectable as early as one month post-HSCT, while started to recover by 3 months after αβhaplo-HSCT alone, and were significantly higher at +3 ( p=0,0006 and p=0,02, respectively) and +6 ( p=0,0003 and p= 0,001) months post-HSCT as compared with αβhaplo-HSCT. sjTREC and bTREC reached pre-transplant values at 6 and 12 months in Rivo-cel and αβhaplo-HSCT cohort, respectively. B-cell neogenesis, assessed by sj and cjKRECs, showed a superimposable recovery kinetics. A higher number of sjKRECs was observed in Rivo-cel cohort at + 1, +3 and +6 months after transplantation as compared with αβhaplo-HSCT ( p=0,007 , p=0,02 and p=0,04for sjKRECs ; p=0,005 , p=0,092 p=0,035forcjKRECs, respectively) . Furthermore, in the Rivo-cel cohort, patients with detectable sj and bTREC values at +3 months after transplant showed a significantly higher overall survival ( p=0,01 p=0,02, respectively). Also in this cohort, aGvHD was confirmed to play a detrimental effect on T-cell neogenesis, at 3 and 6 months after transplant. The same negative effect was documented for chronic GvHD at +6, +12 and +18 months, also affecting B-cell neogenesis at +6 months after transplant. Type of leukemia did not affect T and B-cell neogenesis. Conclusions In patients given αβhaplo-HSCT, T-cell and B-cell neogenesis were shown to be significantly accelerated by the post-transplant infusion of a titrated number of donor T-cells genetically modified with the iC9 suicide gene. Further studies are needed to elucidate the biologic mechanisms responsible for this favorable effect on recovery of adaptive immunity. Our data confirm the detrimental effect of both acute and chronic GvHD in recovery of thymic function and B-cell neogenesis. In this perspective, the possibility to successfully control/abrogate GvHD through the apoptosis of Rivo-cel triggered by the infusion of the dimerizing agent (AP1903) offers also the advantage of, at least partly, preventing the detrimental effect played by this complication on immune recovery.

Beklenmedik bir lokalizasyonda ortaya çıkan primer mediastinal büyük B hücreli lenfoma

Primary mediastinal large B-cell lymphoma (PMLBCL) is a mature aggressive large B-cell lymphoma of putative thymic B-cell origin arising in the mediastinum, with distinctive clinical, immunophenotypic, genotypic, and molecular features. Cases that arise outside the mediastinum are very uncommon. A 27-year-old woman presented with mass which had an extramedullary, extradural component at the right T5-6 foramina indenting to the spinal canal, extending craniocaudally from the middle mediastinum to the level of the aortic hiatus. Pathological examination of the mass revealed atypical lymphoid cells with medium-large size, eosinophilic and clear cytoplasm In our case CD23 and MAL expression with morphological findings supported PMLBCL. PMLBCL may be seen with abnormal localization and clinical presentation. Immunohistochemical profile including MAL is helpful to detect these cases.

Patients and Families' Participation in Multidisciplinary Tumor Conferences Improves Patient and Family-Focused Cancer Care: Lessons Learned From a Debate on the Role of Radiation Therapy in Primary Mediastinal Non-Hodgkin Lymphoma.

Incorporation of patients' preferences often leads to improved outcomes when included in the multidisciplinary tumor conference/board (MTC). However, patients' wishes are not included or considered in the MTC decision-making. We need better strategies and approaches for patient-inclusive, shared decision-making. When finding ourselves at a crossroads regarding the next step in a patient's treatment, we saw a unique opportunity for an MTC with the patient and her husband in attendance. The results of a full literature review regarding the role of consolidative radiation therapy (RT) in a patient with primary (thymic) B-cell lymphoma after completion of chemotherapy and fluorodeoxyglucose positron emission tomography-computed tomography (FDG-PET/CT) scan with a Deauville score of 4 were presented in a creative, engaging debate-style forum with visual aids. The patient and her husband were able to follow the discussion and, in the end, a consensus recommendation, heavily focused on the patient's preferences, was offered and adopted, which ultimately resulted in the avoidance of excess treatment and likely improved her long-term quality of life outcome. These collaborative and innovative interactions benefit not only our patients but enrich our lives too as healthcare providers and strengthen us as a cancer care team in terms of understanding diversity in decision-making processes.

Activation-induced cytidine deaminase expression by thymic B cells promotes T-cell tolerance and limits autoimmunity

Elimination of self-reactive Tcells in the thymus is critical to establish T-cell tolerance. A growing body of evidence suggests a role for thymic B cells in the elimination of self-reactive thymocytes. To specifically address the role of thymic B cells in central tolerance, we investigated the phenotype of thymic Bcells in various mouse strains, including non-obese diabetic (NOD) mice, a model of autoimmune diabetes. We noted that isotype switching of NOD thymic B cells is reduced as compared to other, autoimmune-resistant, mouse strains. To determine the impact of B cell isotype switching on thymocyte selection and tolerance, we generated NOD.AID-/- mice. Diabetes incidence was enhanced in these mice. Moreover, we observed reduced clonal deletion and a resulting increase in self-reactive CD4+ Tcells in NOD.AID-/- mice relative to NOD controls. Together, this study reveals that AID expression in thymic Bcells contributes to T-cell tolerance.

Pediatric Aggressive Mature B-Cell Lymphomas, Version 3.2022, NCCN Clinical Practice Guidelines in Oncology.

NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Pediatric Aggressive Mature B-Cell Lymphomas include recommendations for the diagnosis and management of pediatric patients with primary mediastinal large B-cell lymphoma (PMBL) and sporadic variants of Burkitt lymphoma and diffuse large B-cell lymphoma. PMBL is now considered as a distinct entity arising from mature thymic B-cells accounting for 2% of mature B-cell lymphomas in children and adolescents. This discussion section includes the recommendations outlined in the NCCN Guidelines for the diagnosis and management of pediatric patients with PMBL.

Selected Articles from This Issue

Ewing sarcoma is characterized by oncogenic gene fusions and elevated lysine-specific demethylase-1 (LSD1) expression. While Theisen and colleagues previously devised a small molecule LSD1 inhibitor that demonstrates therapeutic efficacy against Ewing sarcoma — SP-2509 — treatment with SP-2509 alone potentiates drug resistance. In this study, Tokarsky et al., sought to elucidate molecular mechanisms underlying SP-2509 resistance by using a CRISPR–Cas9 loss-of-function screen in SP-2509–sensitive Ewing sarcoma cell lines. Results from the screen demonstrated that abrogating expression of mitochondrial ribosomal protein L45 (MRPL45) as well as members of electron transport chain complexes III (CIII) and IV (CIV) reduces SP-2509 responsiveness. Accordingly, CIII inhibitors and targeted removal of genes encoding CIII constituents ubiquinone-cytochrome c reductase, Rieske iron-sulfur polypeptide 1 (UQCRFS1) and cytochrome c1 (CYC1) using CRISPR–Cas9 induces SP-2509 resistance in Ewing sarcoma cell lines. Silencing UQCRFS1, CYC1, or MRPL45 expression diminishes transcriptional responses to SP-2509, indicating that mitochondrial function contributes to transcriptional programs underlying SP-2509 cytotoxicity. Overall, this study implicates mitochondrial dysfunction as a mechanism facilitating SP-2509 resistance, providing a target that may augment SP-2509 efficacy.Germline BRCA1/2 mutations increase the risk of multiple cancers that exhibit homologous recombination deficiency (HRD). BRCA1/2 mutations and subsequent HRD are associated with a number of genomic mutational signatures that have been previously described and seem to represent use of backup DNA repair pathways. These signatures, such as HRDetect and others, have been quantified and used to inform prognoses and therapeutic strategies. In this study, Moore and colleagues used current pre-clinical knowledge about polymerase theta-mediated end joining (TMEJ) and the genomic scars most typical of this backup repair pathway to determine if TMEJ signatures have prognostic value in advanced ovarian cancer. The authors found that both a TMEJ deletion signature with 4 or more base pair stretches of microhomology (TMEJ4) and TMEJ-associated templated insertions (TINS) are enriched in tumors with BRCA1/2 mutations. The authors also discovered that patients displaying high HRDetect and TINS signatures survive significantly longer than patients displaying one or neither signature. Taken together, this study highlights the potential utility of TMEJ mutational signatures in advanced ovarian cancer prognosis.Immune checkpoint inhibitors (ICI) are ineffective in pancreatic cancer, rendering combination treatments capable of augmenting ICI imperative. Radiation and inhibition of DNA damage response proteins, such as DNA-dependent protein kinase (DNA-PK), can activate antitumor immunity. However, whether and how DNA-PK inhibition mediates antitumor immunity in typically immunology “cold” cancers, including pancreatic cancer, is unknown. In their study, Wang and colleagues used radiation and DNA-PK inhibitor M3814 in mouse pancreatic cancer models to test whether the combination regimen can enhance antitumor immunity. The authors found that radiation-M3814 treatment induces type I interferon (T1IFN) signaling and slows tumor growth uniquely in mice with intact immune systems. The authors demonstrated that radiation and M3814-mediated T1IFN signaling is dependent on RNA polymerase III (POL III)-retinoic acid-inducible gene I (RIG-I)-mitochondrial anti-viral-signaling protein (MAVS) signaling, presumably through production and recognition of double-stranded RNA. Furthermore, T1IFN signaling induces tumor PD-L1 expression, and radiation-M3814 treatment augments anti-PD-L1 efficacy in vivo. In sum, this study elucidates a novel mechanism by which ICI efficacy may be enhanced in typically immunologically “cold” pancreatic cancers.Increased MYC stabilization is a hallmark of T-cell acute lymphoblastic leukemia (T-ALL), but molecular mechanisms underlying MYC stabilization in T-ALL are incompletely understood. To study effects of two MYC mutations — T58A and S62A — on MYC stabilization and MYC-induced pathophysiology in T-ALL, Daniel and colleagues generated T-cell–specific MycWT, MycT58A, and MycS62A knock-in mouse models in which endogenous wild-type Myc can be maintained or eliminated. The authors observed that MycT58A induces heightened ex vivo T-cell proliferation and thymic mass relative to MycS62A, and that MycT58A causes T-cell lymphomagenesis more rapidly than does MycS62A. Nonetheless, MycS62A does induce clonal T-cell lymphomas that resemble T-ALL and, unlike MycT58A, causes non-transgene driven, incidental thymic B-cell lymphomas with splenomegaly. Differential phenotypes engendered by MycT58A and MycS62A are accompanied by disparate transcriptional programs. MycT58A is associated with altered expression of genes underlying angiogenesis and inflammation, and MycS62A displays changes in expression of genes involved in maintaining genomic stability. Altogether, this study demonstrates that MycT58A and MycS62A induce unique pathophysiology in T-cell lymphomas, which may inform future research and T-ALL disease management strategies.

Genomic and Transcriptional Characterization of Primary Mediastinal Large B Cell Lymphoma

Introduction: Primary mediastinal large B-cell lymphoma (PMBL) is a rare non-Hodgkin lymphoma subtype that occurs predominantly in young adults, with an overall favorable prognosis. The cell of origin is presumed to be thymic medullary B-cells and the gene expression profile of PMBL is similar to classic Hodgkin lymphoma. Recent studies have begun unravelling the genomic alterations underlying PMBL. Frequent, recurrent mutations (e.g. B2M, TNFAIP3, SOCS1, STAT6, GNA13) have been reported, but most of the studies have analyzed a small number of cases. To gain further insights into disease biology, we recruited 63 cases of PMBL as part of the Atlas of Blood Cancer Genomes (ABC-G) initiative, a consortium consisting of 25 institutions.Methods: Formalin-fixed paraffin-embedded (FFPE) biopsies and clinical data were collected. All cases were subjected to centralized review by an experienced panel of hematopathologists to ensure accurate diagnosis. Whole-exome DNA and RNA sequencing was performed using the Illumina platform and the DNA and RNA reads aligned to the GRCh38 genome and transcriptome respectively. Exonic variants were filtered using a set of paired normal samples and population-based databases to identify putative driver mutations, which were then aggregated at the gene level. Mutational analysis was performed on 56 samples that passed quality filtering and expression analysis on 45 samples. RNAseq data was normalized using DESeq2.Results: The cohort included samples from 16 males and 24 females, with a median age of 33 years (range 16 - 72) at the time of diagnosis. The majority of patients were treated with R-CHOP (47%) or R-EPOCH (43%), with 93% of patients surviving through the end of follow-up (median follow-up: 60.1 months). Besides the known recurrent mutations involving the JAK-STAT (STAT6 -21%, SOCS1 - 26%), NFKB (TNFAIP3 - 27%, NFKB1A - 7%), immune escape (B2M - 20%, LTB - 11%, IRF8 - 9%, IRF4 -9%), and chromatin modification (ZNF217 - 16%, CREBBP - 11%, KMT2D -11%) pathways , we discovered recurrent somatic variants in novel candidate driver genes in this disease, including NOTCH4 (7%), DICER1 (11%), MCL1 (7%), amongst others. EZH2, EP300, and XPO1 mutations were not detected. CIITA mutations and fusions were observed in 14% and 11% of cases, respectively, with novel partner genes (IGHA2, IGHG1, CDC6) detected in 67% of the fusion positive cases. Copy number alterations included gains at 2p16.1 (REL - 20%) and 9p24.2 (JAK2/PDL1/PDL2 - 24%), as well as loci not previously implicated in PMBL, 8q24.3 and 9q34.3 (each in 20%). Of note, CIITA alterations and 9p24 gains were virtually mutually exclusive, highlighting diverse mechanisms of immune escape in this entity. The transcriptomes of cases harboring CIITA alterations demonstrated differential enrichment of genes involved in protein glycosylation. The PMBLs in our series showed significant enrichment of the reported PMBL genetic classifier score, compared to nodal diffuse large B cell lymphoma (DLBCL) (p=0.0003). Finally, the gene expression profile of thymic B cells was more similar to that of PMBL than nodal DLBCL (p=0.0144).Conclusions: Our study, representing one of the largest comprehensive genomic and transcriptomic analyses of PMBL, expands the mutational landscape of PMBL, provides evidence for biologically distinct disease subsets and suggests an origin of PMBLs from thymic B-cells. DisclosuresHsi: AbbVie: Research Funding; Eli Lilly: Research Funding; Cytomx: Honoraria; Seattle Genetics: Honoraria. McKinney: BTG: Consultancy; Celgene: Consultancy, Research Funding; Epizyme: Consultancy; Genetech: Consultancy, Honoraria, Research Funding; Incyte: Research Funding; Kite/Gilead: Honoraria, Speakers Bureau; Molecular Templates: Consultancy, Research Funding; Nordic Nanovector: Research Funding; Novartis: Research Funding; Pharmacyclics: Consultancy; Verastem: Consultancy; Beigene: Research Funding; ADC Therapeutics: Consultancy, Speakers Bureau. Jaye: Stemline Therapeutics: Honoraria. Cohen: Genentech, Takeda, BMS/Celgene, BioInvent, LAM, Astra Zeneca, Novartis, Loxo/Lilly: Research Funding; Janssen, Adaptive, Aptitude Health, BeiGene, Cellectar, Adicet, Loxo/Lilly, AStra ZenecaKite/Gilead: Consultancy. Behdad: Lilly: Speakers Bureau; Roche/Foundation Medicine: Speakers Bureau; Thermo Fisher: Speakers Bureau. Dave: Data Driven Bioscience: Current equity holder in publicly-traded company.

TAK-981, a First-in-Class SUMO-Activating Enzyme Inhibitor, Combined with Rituximab in Adult Patients (Pts) with CD20-Positive Relapsed/Refractory (R/R) Non-Hodgkin Lymphoma (NHL): Phase 1 Data

TAK-981, a First-in-Class SUMO-Activating Enzyme Inhibitor, Combined with Rituximab in Adult Patients (Pts) with CD20-Positive Relapsed/Refractory (R/R) Non-Hodgkin Lymphoma (NHL): Phase 1 Data

BRACHIAL PLEXOPATHY AND CARDIAC TAMPONADE: AN UNCOMMON PRESENTATION OF DIFFUSE LARGE B-CELL MEDIASTINAL LYMPHOMA

TOPIC: Disorders of the Mediastinum TYPE: Medical Student/Resident Case Reports INTRODUCTION: Primary mediastinal large B-cell lymphoma (PMLBCL) is a unique type of B-cell lymphoma probably arising from a putative thymic medulla B-cell. PMLBCL comprises seven percent of diffuse large B cell lymphomas (2.4 percent of all non-Hodgkin lymphomas). There is a female predominance and a median age at diagnosis in the third to fourth decade. In some cases, the presentation can be an oncological emergency with locally invasive anterior mediastinal mass arising from thymus causing external pressure on the heart and the surrounding structures. PMLBCL presenting as brachial plexopathy with cardiac tamponade is an uncommon presentation. CASE PRESENTATION: 37-year-old female, who presented to the ED with a 3-week history of left- sided neck pain and progressive swelling with associated 2 weeks history of numbness in the left wrist, tingling sensation in her 4th and 5th finger with weakness on the same side. She endorsed exertional dyspnea and palpitation that worsened over the last 4 days prior to presentation.On examination she was noted to have left sided neck mass about 6 x 8cm, firm, nontender, non-mobile with extension below the clavicle. Tachycardic with Muffled heart sounds and grade 3/6 Systolic Ejection Murmur at right upper sternal border. Flexion deformity with reduced sensation of the left 4th and 5th finger. Chest X-ray shows cardiomegaly with widened mediastinum. Computed Tomography scan was suggestive of anterior mediastinal mass. Echocardiogram done showed large pericardial effusion with Echocardiographic findings consistent with tamponade physiology.She underwent pericardiocentesis with 700 cc of serosanguinous fluid drained and subsequently had CT guided biopsy of the anterior mediastinal mass. Biopsy report showed high grade B-cell lymphoma with Immunostain showing lymphoma cells positive for CD20, BCL6 and negative for BCL2, CD5. She was diagnosed to be High grade stage IIB, commenced on chemotherapy and completed 6 cycles of DA-EPOCH-R.Left hand weakness and neuropathy resolved following chemotherapy. Repeat CT chest and Echocardiogram showed near resolution of the anterior mediastinal mass and pericardial effusion respectively. DISCUSSION: The majority of patients with primary diffuse large B-cell mediastinal lymphoma are symptomaticat the time of diagnosis. Patients present with a locally invasive anterior mediastinal massoriginating in the thymus, with frequent airway compromise and superior vena cava (SVC)syndrome. Symptoms related to the compression or invasion of local structures (i.e., cough, dyspnea, dysphagia, hoarseness) are common, systemic B-symptoms occurs in about 47% ofpatients, brachial plexopathy is an uncommon presentation. CONCLUSIONS: PMBL is a tumor of young adults who present with a rapidly proliferating tumor. At diagnosis, the tumor is usually limited to the mediastinum, therefore high index of suspicion is required in making the diagnosis. REFERENCE #1: A clinical evaluation of the International Lymphoma Study Group classification of non-Hodgkin's lymphoma. The Non-Hodgkin's Lymphoma Classification Project. Blood. 1997 Jun1;89(11):3909-18. PMID: 9166827 REFERENCE #2: Armitage JO, Weisenburger DD. New approach to classifying non-Hodgkin's lymphomas:clinical features of the major histologic subtypes. Non-Hodgkin's Lymphoma ClassificationProject. J Clin Oncol. 1998 Aug;16(8):2780-95. doi: 10.1200/JCO.1998.16.8.2780. PMID:9704731. REFERENCE #3: van Besien K, Kelta M, Bahaguna P. Primary mediastinal B-cell lymphoma: a review ofpathology and management. J Clin Oncol. 2001 Mar 15;19(6):1855-64. doi:10.1200/JCO.2001.19.6.1855. PMID: 11251018. DISCLOSURES: No relevant relationships by Regine Afable, source=Web Response No relevant relationships by Ibrahim Omore, source=Web Response No relevant relationships by Farbod Raiszadeh, source=Web Response

Correlation of Immunohistochemistry, FISH and Clinical Outcomes in Primary Mediastinal (Thymic) Large B-Cell Lymphoma

IntroductionPrimary Mediastinal (thymic) B-cell lymphoma (PMBCL) is a distinct B-cell lymphoma which accounts for 2-4% of Non-Hodgkin's lymphoma. PMBCL is unique as although B-cell markers are readily expressed, morphologically and on gene expression profiling, PMBCL resembles classical Hodgkin's lymphoma. The poor prognostic impact of BCL2/BCL6 and MYC immunohistochemistry and FISH have been well published in Diffuse large B-cell lymphoma patients from other sites, however less is known about their significance in PMBCL. We retrospectively analysed 36 patients with PMBCL and correlated immunohistochemistry and FISH with clinical outcome.MethodsPatient selectionWe performed a search for all PMBCL cases in our pathology database from 2008-2016. 36 cases who had sufficient tissue and fulfilled the clinicopathological criteria were included.Histologic and Immunohistochemical MethodsImmunohistochemical studies were performed using formalin-fixed, paraffin-embedded tissue sections. Antibodies against CD3, CD20, CD79A, CD10, BCL6, MUM1, BCL2, C-MYC , Ki-67 and PDL1 were used for immunohistochemical studies. These studies were performed using an automated immunostainer (Benchmark XT) and a streptavidin-biotin peroxidase detection system. Tissue specimens were reviewed for percent tumour positivity and nuclear intensity. The cutoff scores for positive antibody staining were: 30% for CD10, 30% for BCL6, 60% for MUM1, 40% for CMYC and 70% for BCL2. PDL1 was graded positive if 3+/2+ (complete membranous staining in at least 10-30% of cells) and negative if 1+/0.In-situ hybridizationFor detection of Epstein-Barr virus encoded RNA (EBER), in situ hybridization was performed on formalin-fixed, paraffin-embedded tissue sections using the Ventana ready-to-use kit as prescribed by the manufacturer.Molecular fluorescence in situ hybridization (FISH) studiesFor detection of MYC/BCL2/BCL6 gene rearrangements, the Vysis LSI Dual Color, Break Apart Rearrangement Probes performed on formalin-fixed, paraffin-embedded tissue using the Vysis paraffin pre-treatment kit II system.ResultsOut of the 36 cases, 15 (42%) were of the germinal center phenotype while 21 (58%) were non germinal center phenotype by the Hans criteria. MYC was expressed in 26 cases (72%). 44% of cases were double expressors. In addition, there was also increased BCL6 (N=35, 97%), Ki67>60% (N=31, 86%), MUM1 (N=25, 69%) and PDL1 expression (N=24, 66%) noted. EBERISH was not present in any of the cases in this series. Table 1 summarizes the IHC findings. Of the 36 cases, only 1 case had unsatisfactory BCL2 FISH analysis. Out of 35 evaluable cases, there was 1 positive MYC FISH and 2 positive BCL6 FISH. There were no cases with positive BCL2 FISH.We compared our results with published results from DLBCL cases1,2 and found higher proportion of MYC/BCL6 positivity and Ki67% by IHC. BCL2 IHC expression was similar. FISH positivity for myc/bcl2/bcl6 translocations was lower in PMBCL compared to DLBCL. By Han's criteria, there was no significant difference in GC and non-GC, however a higher proportion of double expressors was noted. PDL1 expression was also higher than those published in DLBCL, similar to PDL1 expression in Hodgkin's lymphoma3. Table 2 summarizes the comparison between our data and results from other studies.In our cohort of 36 patients, the median age was 29 years (range 15-61) with 19 female patients. The majority had early stage (n= 24 ,66.7%) and bulky disease (n=24, 66.7%). All 36 patients were treated with immunochemotherapy (R-CHOP n=11, R-EPOCH n=21). With a median follow up of 41 months, PFS and OS was 95% and 81% respectively. There was no correlation between IHC/FISH markers, clinical prognostic markers (bulk, stage, age, IPI) with outcomes on univariate and multivariate analysis.ConclusionOur results validate that PMBCL is a unique lymphoma which has similarities with DLBCL yet bears resemblance to Hodgkin's lymphoma on IHC. The usual prognostic markers for DLBCL have not correlated with clinical outcome in statistical analysis suggesting that due to the uniqueness of this lymphoma, novel markers should be explored to improve prognostic accuracy and thus improve patient outcomes.

Gene Expression Profiling of Mediastinal Gray Zone Lymphoma and Its Relationship to Primary Mediastinal B-cell Lymphoma and Classical Hodgkin Lymphoma

Mediastinal gray zone lymphoma (MGZL) has immunopathologic features between classical Hodgkin lymphoma (cHL) and primary mediastinal thymic B-cell lymphoma (PMBL), leading to uncertainty regarding its biological relationship to these entities. We performed gene expression profiling from patients with MGZL (20), cHL (18), and PMBL (17) and show MGZL clusters between cHL and PMBL. Expression signatures reveal germinal B-cell and IFN regulatory factor 4 (IRF4) signatures were relatively low in MGZL and cHL compared with PMBL, indicating downregulation of the B-cell program in MGZL, a hallmark of cHL. T-cell and macrophage signatures were higher in MGZL and cHL compared with PMBL, consistent with infiltrating immune cells, which are found in cHL. The NFκB signature was higher in MGZL than PMBL, and like cHL, MGZL and PMBL express NFκB inducing kinase (NIK), indicating noncanonical signaling. These findings indicate that while MGZL has distinctive clustering, it is biologically closer to cHL.

Role of ancillary techniques in diagnosis of challenging common hematological malignancies

Background: Usually, hematolymphoid malignancies present as generalized lymphadenopathy, splenomegaly, and cytopenias. However, sometimes, this may not be the scenario, and that is where the challenge arises. These unusual scenarios are present either in extranodal lymphoma or extramedullary acute leukemia, especially occurring at unusual sites and these often lays down a diagnostic dilemma. Aims: This study aims to evaluate the utility of extensive workup with amalgamation of radiological imaging, immunohistochemical panel, and flow-cytometry to diagnose these unusual hematolymphoid malignancies. Materials and Methods: This is a retrospective observational study of results obtained from a series of nine patients with various unusual manifestations of extranodal lymphoma or acute leukemia at tertiary center of Northern India since the past 18 months. Results: All nine cases which showed variable and unusual clinical presentations were studied involving all available ancillary techniques in the form of immunohistochemistry (IHC), flow cytometry (FCM). These cases because of their unusual presentation in the form of recurrent pericardial/peritoneal effusion, abdominopelvic masses, chronic cervicitis, and subacute intestinal obstruction mimicked various neoplastic and nonneoplastic lesions. IHC and/or FCM evaluating CD34, MPO, CD117 along with Tdt and B/T-cell markers played a vital role for a definitive diagnosis of aleukemic myeloid sarcoma primarily involving intestine, T-cell lymphoblastic lymphoma (LBL) in ovary, diffuse large B-cell lymphoma in ovary, cervix, and intestine with peritoneal carcinomatosis. Two cases of mediastinal masses revealed primary thymic B-cell lymphoma and T-cell LBL, respectively. Conclusion: Cases have highlighted the unusual clinical presentation of hematolymphoid malignancies and elicit the importance of providing a definitive opinion, which is mandatory to give appropriate effective and timely management for the best outcome.

OR29 Establishment of an assay to assess the thymic function recovery and B-cell neogenesis for allogenic haematopoetic stem cell transplant recipients

OR29 Establishment of an assay to assess the thymic function recovery and B-cell neogenesis for allogenic haematopoetic stem cell transplant recipients

Thymic B cell development is controlled by the B potential of progenitors via both hematopoietic-intrinsic and thymic microenvironment-intrinsic regulatory mechanisms.

BackgroundHematopoietic stem cells (HSCs) derived from birth through adult possess differing differentiation potential for T or B cell fate in the thymus; neonatal bone marrow (BM) cells also have a higher potential for B cell production in BM compared to adult HSCs. We hypothesized that this hematopoietic-intrinsic B potential might also regulate B cell development in the thymus during ontogeny.MethodsFoxn1lacZ mutant mice are a model in which down regulation of a thymic epithelial cell (TEC) specific transcription factor beginning one week postnatal causes a dramatic reduction of thymocytes production. In this study, we found that while T cells were decreased, the frequency of thymic B cells was greatly increased in these mutants in the perinatal period. We used this model to characterize the mechanisms in the thymus controlling B cell development.ResultsFoxn1lacZ mutants, T cell committed intrathymic progenitors (DN1a,b) were progressively reduced beginning one week after birth, while thymic B cells peaked at 3–4 weeks with pre-B-II progenitor phenotype, and originated in the thymus. Heterochronic chimeras showed that the capacity for thymic B cell production was due to a combination of higher B potential of neonatal HSCs, combined with a thymic microenvironment deficiency including reduction of DL4 and increase of IL-7 that promoted B cell fate.ConclusionOur findings indicate that the capacity and time course for thymic B-cell production are primarily controlled by the hematopoietic-intrinsic potential for B cells themselves during ontogeny, but that signals from TECs microenvironment also influence the frequency and differentiation potential of B cell development in the thymus.

Immune rebound associates with a favorable clinical response to autologous HSCT in systemic sclerosis patients

AbstractTo evaluate the immunological mechanisms associated with clinical outcomes after autologous hematopoietic stem cell transplantation (AHSCT), focusing on regulatory T- (Treg) and B- (Breg) cell immune reconstitution, 31 systemic sclerosis (SSc) patients underwent simultaneous clinical and immunological evaluations over 36-month posttransplantation follow-up. Patients were retrospectively grouped into responders (n = 25) and nonresponders (n = 6), according to clinical response after AHSCT. Thymic function and B-cell neogenesis were respectively assessed by quantification of DNA excision circles generated during T- and B-cell receptor rearrangements. At the 1-year post-AHSCT evaluation of the total set of transplanted SSc patients, thymic rebound led to renewal of the immune system, with higher T-cell receptor (TCR) diversity, positive correlation between recent thymic emigrant and Treg counts, and higher expression of CTLA-4 and GITR on Tregs, when compared with pretransplant levels. In parallel, increased bone marrow output of newly generated naive B-cells, starting at 6 months after AHSCT, renovated the B-cell populations in peripheral blood. At 6 and 12 months after AHSCT, Bregs increased and produced higher interleukin-10 levels than before transplant. When the nonresponder patients were evaluated separately, Treg and Breg counts did not increase after AHSCT, and high TCR repertoire overlap between pre- and posttransplant periods indicated maintenance of underlying disease mechanisms. These data suggest that clinical improvement of SSc patients is related to increased counts of newly generated Tregs and Bregs after AHSCT as a result of coordinated thymic and bone marrow rebound.

A rare case of primary B cell lymphoma of the thymus

The thymus is a primary lymphoid organ which establishes and maintains the pool of effector T-cells throughout life; however, it is one of the sites for antigen-independent B-cell maturation. Primary thymic B-cell lymphoma is a rare entity, unremarkable clinically but amenable to chemotherapy. We report a 34-year-old male who presented with nonspecific right-sided chest pain, backache, and shortness of breath for 4 months. Computed tomography scan of the thorax revealed a mass in the superior mediastinum, extending to anterior mediastinum with the right pleural effusion. The suggested diagnosis was thymoma. A median sternotomy was done to resect the thymus. The definitive histologic study revealed a primary thymic B-cell lymphoma positive for CD45/leukocyte common antigen and CD20 and negative for CK and CD30. Thymic lymphoma may be considered among the diagnostic options of a mediastinal mass.

Bone Marrow Involvement in Primary Mediastinal B-Cell Large-Cell Lymphoma

Abstract Introduction: Primary Mediastinal Large B-cell Lymphoma (PMBCL) is one of the primary extranodal lymphomas and originating from the thymic medulla B-cells. PMBCL is localized in the anterior and upper mediastinum, often with compression of the superior vena cava and with tumor infiltration of the pericardium, lungs, pleura. Sometimes there is impairment of the kidneys, adrenals, liver and central nervous system. Usually the bone marrow is not including. According to the WHO Classification 2008, if bone marrow is infiltrated by large B-cell lymphoma with mediastinal tumor mass, differential diagnosis between diffuse large B-cell lymphoma (DLBCL) andPMBCLshould be performed. Evaluation of the expression level of the genes JAK2, PDL1, PDL2, MAL, TRAF1 by polymerase chain reaction allows to different PMBCL and DLBCL. Diagnosis the PMBCL is established if detection of hyperexpression two or more genes. We did not find any publications with description of PMBCL with bone marrow involvement. We present here 2 clinical cases. Materials and methods: 154 patients with PMBCL treated in our center were examined. 16 (10,4%) of them had an extra-mediastinal localization. 2 patients (1,3%) were diagnosed with PMBCL with bone marrow involvement. Results: Case 1 A 42 years old female was hospitalized for vital indications with respiratory failure and syndrome of compression of the superior vena cava. In the mediastinum a tumor was 138x116.5 mm, involving the upper and middle lobes of the right lung. Tumor infiltrated the soft tissues of anterior wall of the chest, pericardium. The biopsy of the mediastinal tumor revealed the fragments of fibrous fat tissue with a dense infiltrate of medium size and large cells with oval nuclei, with one large or smalls nucleoli, a moderately pronounced light cytoplasm (Fig.1). Tumor cells expressed the CD20, PAX5, co-expressed CD23, CD30-, IgM-, Ki-67 80%. LDH level in blood was 578 E/l (208-378 E/l). International Prognosis Index (IPI) - 4. Peripheral blood was normal. Histology of the bone marrow showed diffuse interstitial infiltration by lymphoid cells of medium and large size with several small distinct nucleoli, mainly with the morphology of centroblasts, increased mitotic activity (Fig. 2). Tumor cells of bone marrow were CD20 +. Hyperexpression of JAK2, PDL1, TRAF1 genes in the bone marrow was revealed by PCR method. So the PMBCL was diagnosed. The patient received 6 courses of R-DA-EPOCH-21. At the end of treatment tumor lesions were still positive by PET/CT (Deauville score 5). The patient received the second line therapy, with HSCT. PET/CT was positive again (Deauville score 5). Hyperexpression of JAK2, PDL1, TRAF1 genes persisted in the bone marrow. The patient is alive now at 18 month from start of treatment. According to the CT there is no signs tumor progression. Case 2 B 69 years old female complained of weakness, profuse sweating, pain in the left scapular, temperature 38,0 C, weight loss by 11% of body weight, for the last 3 months. In the left hemithorax tumor mass of 135x67 mm, embracing the first rib with a pathological fracture. Tumor cells expressed CD20, PAX5, CD79α, TNFAI2, co-expressed CD23 and CD30, Ki-67 - 80%. LDH level in blood 994 E/l. IPI - 4. Peripheral blood was normal. Histological study of the bone marrow revealed a focal-interstitial lymphoid infiltration with small and medium sized cells with oval and irregularly shaped nuclei. Hyperexpression of the genes JAK2, MAL, TRAF1 was revealed in the bone marrow. The patient received 6 courses of R-DA-EPOCH-21. After the end of treatment FDG-PET/CT was positive (Deauville score 5). The patient received the second line therapy. After the treatment disease progression was established. Hyperexpression of JAK2, MAL, TRAF1 genes persisted in the bone marrow. The patient is alive now at 18 month from start of treatment, but with PMBCL. Conclusion: Both cases demonstrated resistant to R-DA-EPOCH lymphoma, though the frequency of complete remissions in patients with PMBCL is almost 90%. New approadies should be developed in such cases. Each year, with the accumulation of research data it became evident that within each well-defined nosological form there are borderline cases or those in which our understanding is insufficient to explain a particular phenomenon. The detection of bone marrow involvement in patients with PMBCL makes one think about the criteria for diagnosing the disease. Download : Download high-res image (228KB) Download : Download full-size image Disclosures No relevant conflicts of interest to declare.

Abstract 2652: Favorable outcome of primary mediastinal large B-cell lymphoma treated by Dose Adjusted EPOCH-Rituximab regimen

Abstract Background Primary Mediastinal Large B-Cell Lymphoma (PMLBCL) is a unique type of B-cell lymphoma probably arising from a putative thymic medulla B-cell. One to 2% of NHL, 7% of all diffuse large B-cell lymphomas (DLBCL), occurring more often in young females. Often presents with superior vena cava syndrome and airway compromise. Treatment is with chemotherapy combined with Rituximab, followed by involved field radiation therapy to mediastinum. PMLBCL has better outcome than others DLBCL. We aimed to develop a more dose-dense/intense regimens that improves the rate of cure with an attempt to avoid mediastinal radiation. Patients and methods A prospective study was conducted in our department from January to December 2015, in 6 patients with untreated primary mediastinal B-cell lymphoma. An infusional dose-adjusted etoposide, doxorubicin, and cyclophosphamide with vincristine, prednisone, and rituximab (DA-EPOCH-R) has been administred according to the protocol Day 1 : Rituximab 375 mg/m2 IV Day 1-4 : Etoposide 50 mg/m2 IV, Doxorubicin 10 mg/m2 AND Vincristine 0.4 mg/m2 Day 5 : Cyclophosphamide 750 mg/m2 Days 1-5 : Prednisone 60 mg/m2 PO BID. Administer G-CSF 5 mcg/kg SQ on day 6 until ANC exceeds nadir Cycles were repeated every 3 weeks for a toal of 6 cycles Results The median age of the patients was 32 years, the male to female ratio : 2:4. Systemic symptoms mainly fever and weight loss, were present in all cases; increased LDH levels were also observed in 50% of cases. Majority of the patients (83%) presented with stage I/II disease, bulky mass with a median tumor diameter 15 cm. Most had features of local extension like pleuro-pericardial effusion. Absence of infradiaphragmatic lymph nodes and no bone marrow involvement at presentation. All patients required biopsy from the mediastinal mass by image guided core biopsy. The patients were treated by RDA-EPOCH, they received 4 to 6 courses, without involved field radiotherapy (only one patient underwent radiotherapy for residual mass). No late morbidity or cardiac toxic effects were found in any patients. After 24 months of follow-up, one patient still received treatment and was not evaluable. 5 patients achieved complete remission and were disease-free at the last visit. Conclusion PMBCL is a specific lymphoma entity seen in the young with good survival. It has a distinct clinical behavior and prognosis, and therefore require a different therapeutic approach. The R/DA-EPOCH regimen need to be confirmed in further prospective study for a large cohort. Note: This abstract was not presented at the meeting. Citation Format: Fatiha Grifi, Soraya Bougherira. Favorable outcome of primary mediastinal large B-cell lymphoma treated by Dose Adjusted EPOCH-Rituximab regimen [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2652. doi:10.1158/1538-7445.AM2017-2652

IV. Masses in the mediastinum: primary mediastinal lymphoma and intermediate types.

IV. Masses in the mediastinum: primary mediastinal lymphoma and intermediate types.