Primary mediastinal B-cell lymphoma: biology and evolving therapeutic strategies

Outcome of Primary Mediastinal Large B Cell Lymphoma Treated with RCHOP

Purpose

Primary mediastinal large B-cell Lymphoma (PMLBCL) is a rare aggressive lymphoma with unique clinical, pathological, and molecular features. The optimal frontline therapy is subject of ongoing debate. Our study aims to evaluate the outcomes of PMLBCL treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (RCHOP) at King Hussein Cancer Center.

Patients and Methods

Adult patients >18 years of age with PMLBCL treated with RCHOP from January 2011 to July 2020 were identified. All demographics, disease and treatment related variables were retrospectively collected. Correlations of clinical and laboratory variables with progression-free survival (PFS) and overall survival (OS) were determined by univariate and multivariate analyses using backward stepwise Cox regression models. The PFS and OS were plotted using Kaplan‒Meier curves.

Results

49 patients were included with a median age of 29 years. 14 (28.6%) had stage III or IV, 31 (63.3%) had mediastinal bulky disease. International prognostic index (IPI) was 0-1 in 35 (71.4%). Radiotherapy was given to 32 (65.3%) patients. End of treatment (EOT) response was complete (CR) in 32 (65.3%), partial response (PR) in 8 (16.3%) and progressive disease (PD) in 9 (18.4%). Patients who achieved CR at EOT, compared favorably with those who did not in regard to 4-year OS (92.5% vs 26.9%, p=<0.001). Overall objective response to salvage chemotherapies was 26.7%. At a median follow-up of 46 months, 4-year PFS and OS were 60% and 71% respectively. In multivariate analysis, IPI > one correlated with the EOT response (p=0.009), PFS (p=0.004) and OS (p= 0.019).

Conclusion

In PMLBCL, RCHOP chemotherapy backbone in the frontline therapy is suboptimal but can be used in patients with low IPI. Adapting more intensive chemoimmunotherapy regimens may be considered for patients with high IPI. Salvage chemotherapy has limited activity in patients with relapsed or refractory disease.

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.

STR Profiling Reveals Tumor Genome Instability in Primary Mediastinal B-Cell Lymphoma

Primary mediastinal B-cell lymphoma (PMBCL) is the only non-Hodgkin’s lymphoma variant responding to immune checkpoint inhibitor (ICI) therapy, approximately in half of the cases; however, no molecular markers predicting a response to ICI therapy in PMBCL have been described so far. In this study, we assessed the incidence of the loss of heterozygosity (LOH), elevated microsatellite alteration at selected tetranucleotides (EMAST), and microsatellite instability (MSI) in the tumor genomes of 72 patients with PMBCL undergoing high-dose chemotherapy treatment at the National Research Center for Hematology (Moscow, Russia). Tumor DNA was isolated from biopsy samples taken at diagnosis. Control DNA was isolated from the blood of patients in complete remission or from buccal epithelium. STR-profiles for LOH and EMAST were assessed by PCR with COrDIS Plus multiplex kit (Gordiz Ltd., Moscow, Russia). LOH was detected in 37 of 72 patients (51.4%). EMAST was found in 40 patients (55.5%); 24 had a combination of EMAST with LOH. MSI-high was not found, while MSI-low was detected only in one patient. The association of certain genetic lesions with the clinical outcome in patients receiving treatment according to the standard clinical protocol R-Da-EPOCH-21 has been estimated (58 patients out of 72) and no associations with the worst overall or event-free survival were found.

Prognostic significance of clinical characteristics and 18Fluorodeoxyglucose-positron emission tomography/computed tomography quantitative parameters in patients with primary mediastinal B-cell lymphoma

Objective

Primary mediastinal B-cell lymphoma (PMBCL) lacks standard treatment regimens. This study aimed to identify the disease’s clinical features and prognostic factors.

Methods

This retrospective study included 56 patients with PMBCL. Patient demographic details and clinicopathological characteristics were summarized, and their effects on progression-free survival (PFS) and overall survival (OS) were analyzed.

Results

The median patient age was 29 years (range, 14–56). Twenty-two patients received DA-EPOCH-R (dose-adjusted etoposide, vincristine, and doxorubicin for 96 hours with bolus doses of cyclophosphamide and oral prednisone, as well as rituximab), and 34 patients received R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone). Clinical/laboratory parameters, overall response rates, and 5-year PFS and OS rates did not differ between the treatment groups. Kaplan–Meier analysis indicated that late-stage disease and a higher International Prognostic Index (IPI) were associated with shorter PFS and OS. Furthermore, patients with B symptoms and first-line treatment non-responders exhibited worse OS. ¹⁸Fluorodeoxyglucose-positron emission tomography/computed tomography quantitative parameters, such as higher metabolic tumor volume (MTV) and total lesion glycolysis (TLG), were corrected with shorter PFS.

Conclusions

This study revealed that stage IV disease, higher IPI, and B symptoms were poor prognostic factors in patients with PMBCL. Significantly, higher MTV and TLG portended worse PFS.

How I Diagnose Primary Mediastinal (Thymic) Large B-Cell Lymphoma

OBJECTIVES

Primary mediastinal (thymic) large B-cell lymphoma (PMBL) is an uncommon large B-cell neoplasm recognized by the World Health Organization as a distinct entity on the basis of its unique clinical features, histogenesis, phenotype, and pathogenetic mechanisms. The diagnosis of PMBL can be challenging because of features that may overlap with other (Hodgkin and non-Hodgkin) lymphoma types. This review describes our approach to the diagnosis of PMBL.

METHODS

Two cases are presented to illustrate how we diagnose PMBL and separate PMBL from related histologic and biological mimickers, such as Hodgkin lymphoma and gray zone lymphoma.

RESULTS

A diagnosis of PMBL requires correlation of morphology and immunophenotype with clinical and staging data. Gene expression analysis is not typically performed in clinical labs but has expanded our understanding of the functional pathways underlying this disease and helped identify biomarkers that can be translated to diagnostic practice and possibly to future therapeutic options.

CONCLUSIONS

PMBL and closely related entities can pose diagnostic challenges. It is important to understand the borders between PMBL and other closely related lymphoma types so that patients receive successful primary treatment with curative intent.

Mediastinal Lymphoproliferative Disorders

Lymphoproliferative disorders comprise 50% to 60% of all mediastinal malignancies in both children and adults. Primary mediastinal involvement is rare (∼5%), whereas secondary mediastinal involvement by systemic disease is more common (10% to 25%). Primary mediastinal disease is defined as involvement by a lymphoproliferative disorder of mediastinal lymph nodes, the thymus, and/or extranodal mediastinal organs without evidence of systemic disease at presentation. In this review, the clinical, radiologic, histopathologic, immunohistochemical, and genetic features of some of the most characteristic mediastinal lymphoproliferative disorders are presented. The entities discussed here include: classic Hodgkin lymphoma with emphasis on nodular sclerosis and mixed cellularity types, and non-Hodgkin lymphomas, including primary mediastinal (thymic) large B-cell lymphoma, mediastinal gray zone lymphoma, mediastinal diffuse large B-cell lymphoma, thymic marginal zone lymphoma, mediastinal plasmacytoma, T-lymphoblastic lymphoma, and anaplastic large cell lymphoma. Although not a malignant process, hyaline vascular Castleman disease is also discussed here as this disorder commonly involves the mediastinum. Despite multiple advances in hematopathology in recent decades, the day-to-day diagnosis of these lesions still requires a morphologic approach and a proper selection of immunohistochemical markers. For this reason, it is crucial for general pathologists to be familiar with these entities and their particular clinicoradiologic presentation.

Pembrolizumab in the treatment of refractory primary mediastinal large B-cell lymphoma: safety and efficacy

Introduction: Primary mediastinal large B-cell lymphoma (PMBL) is a rare subtype of lymphoma, clinically and biologically distinct from diffuse large B-cell lymphoma (DLBCL) that shows overlapping features with classical Hodgkin lymphoma (cHL). If first-line strategies lead to 80-85% of curability, relapse occurs early with a chemo-refractory disease and a poor outcome. The presence of 9p24.1 rearrangement, conducting to the overexpression of the immune checkpoint molecules PDL1 and 2, has paved the way for immune checkpoint blockers development in these entities. Pembrolizumab, an anti PD-1 checkpoint antibody, was initially approved in solid cancer and later on in the lymphoma field in cHL.Areas covered: We summarize the biology and clinical need in PMBL, leading to the rationale for checkpoint inhibitors development, as well as pembrolizumab clinical studies in this entity. To do so, we performed a PubMed search using the terms: 'PMBCL,' 'lymphoma,' 'Immune checkpoint,' and 'Pembrolizumab.'Expert opinion: Pembrolizumab showed tolerable safety profile and efficacy data in patients with PMBL who have relapsed after, or are ineligible for autologous stem cell transplant (ASCT). Some combination strategies have shown promising preliminary results, while others are currently being conducted.

Treatment of Primary Mediastinal B-Cell Lymphoma With R-CEOP (Rituximab, Cyclophosphamide, Etoposide, Vincristine, and Prednisone)

Primary mediastinal B-cell lymphoma (PMBCL) is a rare subtype of non-Hodgkin's lymphoma. It typically has an aggressive behavior with potential clinical emergencies including cardiac tamponade, thrombosis of major neck vessels, airway obstruction, and tumor lysis syndrome. In this case report, a 38-year-old Caucasian male presented with shortness of breath, a two-month history of 40-pound weight loss, and a left-sided chest wall mass. CT imaging showed a mediastinal mass, measuring 13 × 14.6 × 8.6 cm³, with invasion and partial occlusion of the brachiocephalic veins and upper superior vena cava causing superior vena cava syndrome, and encasement of multiple coronary artery segments. CT-guided biopsy showed high-grade B-cell lymphoma. Cytology biomarkers were positive for CD20, CD45, and PAX5. A trans-thoracic echocardiogram (TTE) was obtained prior to chemotherapy initiation to establish a baseline for cardiac function, which showed an ejection fraction (EF) of 45-50%, right ventricle volume overload and dilation, and pulmonary hypertension. R-CEOP (rituximab, cyclophosphamide, etoposide, vincristine, and prednisone) chemotherapy regimen was initiated and a follow-up echocardiogram after three cycles, revealed a significant improvement in EF; the patient subsequently received three additional cycles of R-EPOCH. Current regimens in the United States utilize dose-adjusted R-EPOCH and R-CHOP, but they must be used cautiously in patients with compromised cardiac function, due to the cardiotoxic side effects of the chemotherapy agent, doxorubicin. This case illustrates that anthracycline-free regimens should be considered in patients with reduced cardiac function, with this case showing the utilization of an anthracycline-free regimen (R-CEOP) for the first three cycles, followed by a transition to R-EPOCH.

How I treat lymphoma in pregnancy

Lymphomas afflict all age groups of people, with certain types demonstrating a female predilection in adolescents and young adults. A proportion of lymphomas that are diagnosed in this population demographic occur in the setting of pregnancy. Most of these behave aggressively at presentation and require immediate or urgent therapy. Treatment must consider both maternal and fetal health, and management approaches are therefore influenced by gestational age at diagnosis and treatment and timing of delivery. Although there is a paucity of literature on how to treat these patients, limited retrospective reports demonstrate generally good outcomes and highlight the necessity of an experienced multidisciplinary team approach to management.

Distinct molecular profile of IRF4-rearranged large B-cell lymphoma

Pediatric large B-cell lymphomas (LBCLs) share morphological and phenotypic features with adult types but have better prognosis. The higher frequency of some subtypes such as LBCL with IRF4 rearrangement (LBCL-IRF4) in children suggests that some age-related biological differences may exist. To characterize the genetic and molecular heterogeneity of these tumors, we studied 31 diffuse LBCLs (DLBCLs), not otherwise specified (NOS); 20 LBCL-IRF4 cases; and 12 cases of high-grade B-cell lymphoma (HGBCL), NOS in patients ≤25 years using an integrated approach, including targeted gene sequencing, copy-number arrays, and gene expression profiling. Each subgroup displayed different molecular profiles. LBCL-IRF4 had frequent mutations in IRF4 and NF-κB pathway genes (CARD11, CD79B, and MYD88), losses of 17p13 and gains of chromosome 7, 11q12.3-q25, whereas DLBCL, NOS was predominantly of germinal center B-cell (GCB) subtype and carried gene mutations similar to the adult counterpart (eg, SOCS1 and KMT2D), gains of 2p16/REL, and losses of 19p13/CD70. A subset of HGBCL, NOS displayed recurrent alterations of Burkitt lymphoma-related genes such as MYC, ID3, and DDX3X and homozygous deletions of 9p21/CDKN2A, whereas other cases were genetically closer to GCB DLBCL. Factors related to unfavorable outcome were age >18 years; activated B-cell (ABC) DLBCL profile, HGBCL, NOS, high genetic complexity, 1q21-q44 gains, 2p16/REL gains/amplifications, 19p13/CD70 homozygous deletions, and TP53 and MYC mutations. In conclusion, these findings further unravel the molecular heterogeneity of pediatric and young adult LBCL, improve the classification of this group of tumors, and provide new parameters for risk stratification.

Prognostic factors, therapeutic approaches, and distinct immunobiologic features in patients with primary mediastinal large B-cell lymphoma on long-term follow-up

Primary mediastinal large B-cell lymphoma (PMBCL) is a rare and distinct subtype of diffuse large B-cell lymphoma (DLBCL) without prognostic factors or a single standard of treatment clearly defined. In this study we performed retrospective analysis for clinical outcomes of 166 patients with PMBCL. In overall PMBCL, higher International Prognostic Index, stage, Ki-67 proliferation index, and positron emission tomography (PET) maximum standardized uptake values (SUVmax) at diagnosis were significantly associated with poorer survival, whereas MUM1 expression and higher peripheral blood lymphocyte/monocyte ratios were significantly associated with better survival. Patients who received R-HCVAD or R-EPOCH had better clinical outcome than did those who received the standard treatment R-CHOP. Treatment response and end-of-treatment PET SUVmax had remarkable correlations with survival outcome. In patients with refractory or relapsed PMBCL, stem cell transplant significantly improved overall survival. PMBCL had distinct gene expression signatures compared with overall DLBCL–NOS but not with DLBCL with PD-L1/PD-L2 amplification. PMBCL also showed higher PD-L2 expression in B-cells, lower PD-1 expression in T-cells, and higher CTLA-4 expression in T-cells and distinct miRNA signatures compared with DLBCL-NOS. The prognostic factors, effectiveness of treatment, transcriptional and epigenetic signatures, and immunologic features revealed by this study enrich our understanding of PMBCL biology and support future treatment strategy.

PET-Derived Quantitative Metrics for Response and Prognosis in Lymphoma

Lymphoma is a potentially curable disease; however, the clinical challenge lies in further improvement of outcomes. PET with fludeoxyglucose is an effective imaging tool. PET-derived quantitative metrics have raised significant interest to be used as a prognostic factor to complement clinical parameters for treatment decisions. The most optimized use of these quantitative PET metrics, however, will be possible with the standardization of imaging procedures. In this article, we review the technical and methodological considerations related to PET-derived quantitative metrics, and the relevant published data to emphasize the potential value of these metrics in patient prognosis and treatment response in lymphoma.

Primary Mediastinal Nodal and Extranodal Non-Hodgkin Lymphomas: Current Concepts, Historical Evolution, and Useful Diagnostic Approach: Part 1

Primary mediastinal non-Hodgkin lymphomas (PM-NHLs) represent ~5% of all NHLs and comprise lymphomas of B-cell and T-cell origin. PM-NHLs are defined as involvement of mediastinal lymph nodes, thymus, and/or mediastinal organs (heart, lung, pleura, pericardium) by NHL without evidence of systemic disease at presentation. The clinical scenario is variable and depends on the lymphoma subtype. The radiologic presentation is also variable ranging from a mediastinal mass with or without superior vena cava syndrome, a pleural or a cardiac mass associated with an effusion, or as an effusion only. The diagnosis of PM-NHLs can only be established by microscopic evaluation, and therefore, general pathologists should be aware of these tumors and familiar with their diagnostic approach. The most common anterior mediastinal NHLs (90% to 95%) are primary mediastinal large B-cell lymphoma and T lymphoblastic lymphoma. Thymic marginal zone lymphoma and mediastinal gray zone lymphoma are very rare. The remainder PM-NHLs involving middle or posterior mediastinum include diffuse large B-cell lymphoma (DLBCL) and rare cases of T-cell lymphoma, including anaplastic large cell lymphoma and breast implant-associated anaplastic large cell lymphoma extending to the anterior mediastinum. Primary pleural and cardiac NHLs are mostly DLBCLs. Other rare subtypes of PM-NHLs include DLBCL associated with chronic inflammation/pyothorax-associated lymphoma, fibrin-associated DLBCL (both EBV), and pleural and/or pericardial primary effusion lymphoma (HHV-8/EBV). We review the historical aspects, epidemiology, clinico-radiologic features, histopathology, immunohistochemistry, differential diagnosis, and relevant cytogenetic and molecular features of PM (thymic) LBCL, PM "nonthymic" DLBCL, BCL, unclassifiable, with features intermediate between DLBCL and classic Hodgkin lymphoma (mediastinal gray zone lymphoma), DLBCL associated with chronic inflammation (pyothorax-associated lymphoma), fibrin-associated DLBCL, and primary effusion lymphoma. This review represents the first part of 2 manuscripts covering PM-NHLs.

Front-Line Treatment of High Grade B Cell Non-Hodgkin Lymphoma

PURPOSE OF REVIEW

Rituximab-based chemoimmunotherapy has resulted in a marked improvement in the survival of diffuse large B cell lymphoma (DLBCL). We reflect upon the history front-line (1L) therapy and highlight advances in management.

RECENT FINDINGS

Since the introduction of R-CHOP, the majority of randomized studies in the front-line treatment of DLBCL have failed to show a benefit. Such studies have involved treatment intensification, adding novel agents to the R-CHOP backbone and targeting such novel agents to biologically defined subgroups. R-CHOP therefore remains standard-of-care for most but new insights into the molecular biology of these diseases, and the development of active targeted molecules offers promise for the future. Accumulating evidence in the very elderly suggests dose attenuation does not compromise survival. Intensification in primary mediastinal B cell lymphoma may avoid the need for radiotherapy, but must be balanced against the risks. PET-CT- and ctDNA-based response assessment may now enable response adapted therapy and early prognostication, improving patient selection and potentially outcomes. Novel technologies and therapies in combination with novel molecular diagnostics will likely become the standard-of-care approach for the personalized therapy of DLBCL but need to be proven in well-designed and conducted randomized trials.

Mediastinal Lymphoma Presenting in Cardiogenic Shock with Superior Vena Cava Syndrome in a Primigravida at Full Term: Salvage Resection after Prolonged Extracorporeal Life Support

Primary mediastinal large B-cell lymphoma (PMBCL) is a rare type of non-Hodgkin lymphoma that typically has a good response rate to first line chemotherapy regimens. There have been reports of successful chemotherapy, but with a residual mass from fibrosis. Here, we report the case of a 19-year-old primigravida presenting with cardiogenic shock and superior vena cava (SVC) syndrome at full term who was found to have a PMBCL. Following delivery via urgent cesarean section, she was put on veno-arterial extra corporeal membrane oxygenation (VA-ECMO) and once hemodynamically stable was started on chemotherapy. In view of limited change in tumor size on consecutive CT scans and questionable response to chemotherapy, there were multidisciplinary meetings wherein withdrawing support was discussed and put forward to the family. At that point, surgical debulking was offered on compassionate grounds to be able to wean her off the VA-ECMO. This case report highlights the role of salvage resection when there are no other options.

Stage I non-Hodgkin lymphoma: no plateau in disease-specific survival ?

Stage I non-Hodgkin lymphoma (NHL) is rare; prognostic impact of different histologic subtypes and treatment modality is still unclear. We used the Surveillance, Epidemiology and End Results (SEER) database to evaluate survival outcomes among adult patients (age ≥ 18 years, N = 58,230) diagnosed with stage I NHL of various histologic subtypes between 1998 and 2014. Five-year disease-specific survival of patients with stage I diffuse large B cell lymphoma (DLBCL), follicular lymphoma (FL), marginal zone lymphoma (MZL), small lymphocytic lymphoma (SLL), Burkitt lymphoma (BL), mantle cell lymphoma (MCL), and peripheral T cell lymphoma (PTCL) was 82%, 92%, 95%, 89%, 78%, 77%, and 77%, respectively. The median disease-specific survival was not reached in all histologic subtypes analyzed; however, there does not appear to be a plateau in disease-specific survival of patients with stage I NHL irrespective of subtypes. Although lymphoma was the most common cause of death (40.7%), death from other cancer (17.4%) and cardiovascular disease (13.6%) were also frequent. Chemotherapy appeared favorably associated with OS in patients with DLBCL, BL, and MCL while patients with FL, MZL, SLL, and PTCL who require chemotherapy for initial treatment showed shorter OS. Patients with stage I NHL have favorable disease-specific survival; however, no plateau was seen regardless of histologic subtypes thus suggesting that patients may need attention and follow-up even in aggressive lymphomas after 5 years of remission.

Small cell lung cancer mimicking lymphoma in CT and 68Ga-DOTA-NOC PET/CT: A case report

RATIONALE

Small cell lung cancer accounts for 15-20% of all lung cancers and is the most common pulmonary neuroendocrine neoplasm. Most small cell lung cancers arise from lobar or main bronchi, the most common manifestations of small cell lung cancer is a large mass centrally located within the lung parenchyma or a mediastinal mass involving the hilus. Small cell lung cancer is easily ignored by clinicians without lung parenchyma and hilus involvement. Here, we report a case of small cell lung cancer, which was misdiagnosed as the lymphoma in contrast enhanced CT and Ga-DOTA-NOC PET/CT imagings.

PATIENT CONCERNS

A 49-year-old male with chief complaint of discontinuous cough for 1 month.

DIAGNOSES

Small cell lung cancer.

INTERVENTIONS

Radiotherapy and chemotherapy were given thereafter.

OUTCOMES

The case had multiple enlarged lymph nodes due to tumor progression.

LESSONS

Small cell lung cancer is a malignant and progressive disease, and easy to be ignored in clinical. The case of small cell lung cancer without parenchyma and hilus involvement has never been reported before. Here, we report it and hope it provides a differential diagnosis for clinicians in the following similar cases.