Primary mediastinal B-cell lymphoma and mediastinal gray zone lymphoma: do they require a unique therapeutic approach?

Autologous stem cell transplantation for primary mediastinal B-cell lymphoma: long-term outcome and role of post-transplant radiotherapy. A report of the European Society for Blood and Marrow Transplantation

The purpose of this retrospective registry study was to investigate the outcome of autoSCT for primary mediastinal B-cell lymphoma (PMBCL) in the rituximab era, including the effects of eventual post-transplant radiotherapy (RT) consolidation. Patients with PMBCL aged between 18 and 70 years who were treated with a first autoSCT between 2000 and 2012 and registered with the EBMT were eligible. Eighty-six patients with confirmed PMBCL and the full data set required for this analysis were evaluable. Sixteen patients underwent autoSCT in remission after first-line therapy (CR/PR1), 44 patients were transplanted with chemosensitive relapsed or primary refractory disease (CR/PR >1), and 24 patients were chemorefractory at the time of autoSCT. With a median follow-up of 5 years, 3-year estimates of relapse incidence, progression-free survival, and overall survival were 6%, 94%, and 100% for CR/PR1; 31%, 64%, and 85% for CR/PR >1; and 52%, 39%, and 41% for REF, respectively. Whilst there was no significant benefit of post-transplant RT in the CR/PR >1 group, RT could completely prevent disease recurrence post d100 in the refractory group. In conclusion, autoSCT with or without consolidating RT is associated with excellent outcome in chemoimmunotherapy-sensitive PMBCL, whereas its benefits seem to be limited in chemoimmunotherapy-refractory disease.

Role of Bruton's tyrosine kinase in B cells and malignancies

Bruton’s tyrosine kinase (BTK) is a non-receptor kinase that plays a crucial role in oncogenic signaling that is critical for proliferation and survival of leukemic cells in many B cell malignancies. BTK was initially shown to be defective in the primary immunodeficiency X-linked agammaglobulinemia (XLA) and is essential both for B cell development and function of mature B cells. Shortly after its discovery, BTK was placed in the signal transduction pathway downstream of the B cell antigen receptor (BCR). More recently, small-molecule inhibitors of this kinase have shown excellent anti-tumor activity, first in animal models and subsequently in clinical studies. In particular, the orally administered irreversible BTK inhibitor ibrutinib is associated with high response rates in patients with relapsed/refractory chronic lymphocytic leukemia (CLL) and mantle-cell lymphoma (MCL), including patients with high-risk genetic lesions. Because ibrutinib is generally well tolerated and shows durable single-agent efficacy, it was rapidly approved for first-line treatment of patients with CLL in 2016. To date, evidence is accumulating for efficacy of ibrutinib in various other B cell malignancies. BTK inhibition has molecular effects beyond its classic role in BCR signaling. These involve B cell-intrinsic signaling pathways central to cellular survival, proliferation or retention in supportive lymphoid niches. Moreover, BTK functions in several myeloid cell populations representing important components of the tumor microenvironment. As a result, there is currently a considerable interest in BTK inhibition as an anti-cancer therapy, not only in B cell malignancies but also in solid tumors. Efficacy of BTK inhibition as a single agent therapy is strong, but resistance may develop, fueling the development of combination therapies that improve clinical responses. In this review, we discuss the role of BTK in B cell differentiation and B cell malignancies and highlight the importance of BTK inhibition in cancer therapy.

Axicabtagene Ciloleucel CAR T-Cell Therapy in Refractory Large B-Cell Lymphoma

BACKGROUND

In a phase 1 trial, axicabtagene ciloleucel (axi-cel), an autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy, showed efficacy in patients with refractory large B-cell lymphoma after the failure of conventional therapy.

METHODS

In this multicenter, phase 2 trial, we enrolled 111 patients with diffuse large B-cell lymphoma, primary mediastinal B-cell lymphoma, or transformed follicular lymphoma who had refractory disease despite undergoing recommended prior therapy. Patients received a target dose of 2×106 anti-CD19 CAR T cells per kilogram of body weight after receiving a conditioning regimen of low-dose cyclophosphamide and fludarabine. The primary end point was the rate of objective response (calculated as the combined rates of complete response and partial response). Secondary end points included overall survival, safety, and biomarker assessments.

RESULTS

Among the 111 patients who were enrolled, axi-cel was successfully manufactured for 110 (99%) and administered to 101 (91%). The objective response rate was 82%, and the complete response rate was 54%.With a median follow-up of 15.4 months, 42% of the patients continued to have a response, with 40% continuing to have a complete response. The overall rate of survival at 18 months was 52%. The most common adverse events of grade 3 or higher during treatment were neutropenia (in 78% of the patients), anemia (in 43%), and thrombocytopenia (in 38%). Grade 3 or higher cytokine release syndrome and neurologic events occurred in 13% and 28% of the patients, respectively. Three of the patients died during treatment. Higher CAR T-cell levels in blood were associated with response.

CONCLUSIONS

In this multicenter study, patients with refractory large B-cell lymphoma who received CAR T-cell therapy with axi-cel had high levels of durable response, with a safety profile that included myelosuppression, the cytokine release syndrome, and neurologic events. (Funded by Kite Pharma and the Leukemia and Lymphoma Society Therapy Acceleration Program; ZUMA-1 ClinicalTrials.gov number, NCT02348216 .).

Clinicopathologic consensus study of gray zone lymphoma with features intermediate between DLBCL and classical HL

Gray zone lymphoma (GZL) is described as sharing features with classical Hodgkin lymphoma (cHL) and diffuse large B-cell lymphoma (DLBCL). However, there remains complexity in establishing diagnosis, delineating prognosis, and determining optimum therapy. Sixty-eight cases diagnosed as GZL across 15 North American academic centers were evaluated by central pathology review to achieve consensus. Of these, only 26 (38%) were confirmed as GZL. Morphology was critical to GZL consensus diagnosis (eg, tumor cell richness); immunohistochemistry showed universal B-cell derivation, frequent CD30 expression, and rare Epstein-Barr virus (EBV) positivity (CD20⁺, 83%; PAX5⁺, 100%; BCL6⁺, 20%; MUM1⁺, 100%; CD30⁺, 92%; EBV⁺, 4%). Forty-two cases were reclassified: nodular sclerosis (NS) cHL, n = 27 (including n = 10 NS grade 2); lymphocyte predominant HL, n = 4; DLBCL, n = 4; EBV⁺ DLBCL, n = 3; primary mediastinal large BCL n = 2; lymphocyte-rich cHL and BCL-not otherwise specified, n = 1 each. GZL consensus-confirmed vs reclassified cases, respectively, more often had mediastinal disease (69% vs 41%; P = .038) and less likely more than 1 extranodal site (0% vs 25%; P = .019). With a 44-month median follow-up, 3-year progression-free survival (PFS) and overall survival for patients with confirmed GZL were 39% and 95%, respectively, vs 58% and 85%, respectively, for reclassified cases (P = .19 and P = .15, respectively). Interestingly, NS grade 2 reclassified patients had similar PFS as GZL consensus-confirmed cases. For prognostication of GZL cases, hypoalbuminemia was a negative factor (3-year PFS, 12% vs 64%; P = .01), whereas frontline cyclophosphamide, doxorubicin, vincristine, and prednisone ± rituximab (CHOP±R) was associated with improved 3-year PFS (70% vs 20%; P = .03); both factors remained significant on multivariate analysis. Altogether, accurate diagnosis of GZL remains challenging, and improved therapeutic strategies are needed.

Advances in Diagnosis and Management of Diffuse Large B-cell Lymphoma

The management of diffuse large B-cell lymphoma (DLBCL) has been gradually evolving since the discovery of its 2 major forms, the germinal center B-like (GCB) and activated B-cell (ABC) types. Although the reference standard for the identification of these cell types is considered gene expression profiling (GEP), currently the only method commercially available is immunohistochemistry (IHC). The application of various IHC-based algorithms and their correlation with GEP and clinical outcome are discussed. Because of the adverse prognostic implications of the non-GCB type and its potential effects on treatment selection, the recently revised World Health Organization classification has included these biologic cell types. The management of double hit lymphomas, which almost exclusively fall under the GCB category, is discussed, together with the double expresser phenotype, which is usually grouped under the non-GCB type. The role of lenalidomide and ibrutinib in the management of the non-GCB type is examined. We also discuss the front-line management of primary mediastinal large cell lymphoma using the EPOCH (etoposide, prednisolone, Oncovin [vincristine], cyclophosphamide, hydroxydaunorubicin [doxorubicin]) regimen and examine new salvage data on immune checkpoint inhibitors for this clinical subtype. The prognosis, clinical features, and management of de novo CD5+ DLBCL are discussed, and newer and promising developments in the management of primary central nervous system lymphomas are presented in detail. The most popular salvage regimens and the application of high-dose chemotherapy with stem cell transplantation are assessed in detail. Finally, data on new treatment tactics such as CART (chimeric antigen receptor T-cell) cells and promising new drugs, including blinatumomab and venetoclax, are presented.

How immunologic and genetic biomarkers impact Hodgkin lymphoma classification, diagnosis, and management: a huge potential that yet needs to be exploited

"Ne è passata di acqua sotto i ponti." It has been a long time since the diagnosis of Hodgkin lymphoma (HL) was exclusively based on the detection of typical Reed-Sternberg cells and the recognition of the characteristic morpho-histological background, as well as on the pathologist's skill. The discovery of immunologic, molecular genetic and virologic biomarkers has provided an objective contribution to the diagnosis and a scientific basis for a modern classification of HL. Recent updates have clarified the nature of the so-called nodular lymphocyte predominant HL and its link to the T-cell/histiocyte-rich large B-cell lymphomas as well as its relationship with the lymphocyte-rich subset of classical HL (CHL). Molecular virology studies assessed a role for the Epstein-Barr virus in the pathogenesis of a fraction of CHL of the general population, and virtually in all cases of CHL occurring in people infected by HIV. Finally, immunologic and genetic findings corroborated the existence of grey zone lymphomas at the edges of CHL. Overall, these advances provided additional and useful information to address the treatment of patients affected by HL.

Axicabtagene ciloleucel, a first-in-class CAR T cell therapy for aggressive NHL

The development of clinically functional chimeric antigen receptor (CAR) T cell therapy is the culmination of multiple advances over the last three decades. Axicabtagene ciloleucel (formerly KTE-C19) is an anti-CD19 CAR T cell therapy in development for patients with refractory diffuse large B cell lymphoma (DLBCL), including transformed follicular lymphoma (TFL) and primary mediastinal B cell lymphoma (PMBCL). Axicabtagene ciloleucel is manufactured from patients' own peripheral blood mononuclear cells (PBMC) during which T cells are engineered to express a CAR that redirects them to recognize CD19-expressing cells. Clinical trials have demonstrated the feasibility of manufacturing axicabtagene ciloleucel in a centralized facility for use in multicenter clinical trials and have demonstrated potent antitumor activity in patients with refractory DLBCL. Main acute toxicities are cytokine release syndrome and neurologic events. Axicabtagene ciloleucel holds promise for the treatment of patients with CD19-positive malignancies, including refractory DLBCL.

Gray Zone Lymphoma: Current Diagnosis and Treatment Options

The morphology of gray zone lymphoma (GZL) is variable with tumor cells spanning the spectrum of diffuse large B-cell lymphoma (DLBCL) and classical Hodgkin lymphoma. The immunophenotype is frequently discordant. Clinically, the initial case descriptions of GZL were primarily with mediastinal presentation; however, a nonmediastinal (systemic) clinical subtype is now recognized. Patients with GZL have high relapse rates. Recommended treatment of GZL is with a DLBCL-directed regimen with consideration for consolidative radiotherapy for bulk disease. Continued biologic examination of this entity is needed and there should be exploration toward integration of novel targeted therapeutic agents into the treatment paradigm of GZL.

XPO1 in B cell hematological malignancies: from recurrent somatic mutations to targeted therapy

Many recent publications highlight the large role of the pivotal eukaryotic nuclear export protein exportin-1 (XPO1) in the oncogenesis of several malignancies, and there is emerging evidence that XPO1 inhibition is a key target against cancer. The clinical validation of the pharmacological inhibition of XPO1 was recently achieved with the development of the selective inhibitor of nuclear export compounds, displaying an interesting anti-tumor activity in patients with massive pre-treated hematological malignancies. Recent reports have shown molecular alterations in the gene encoding XPO1 and showed a mutation hotspot (E571K) in the following two hematological malignancies with similar phenotypes and natural histories: primary mediastinal diffuse large B cell lymphoma and classical Hodgkin's lymphoma. Emerging evidence suggests that the mutant XPO1 E571K plays a role in carcinogenesis, and this variant is quantifiable in tumor and plasma cell-free DNA of patients using highly sensitive molecular biology techniques, such as digital PCR and next-generation sequencing. Therefore, it was proposed that the XPO1 E571K variant may serve as a minimal residual disease tool in this setting. To clarify and summarize the recent findings on the role of XPO1 in B cell hematological malignancies, we conducted a literature search to present the major publications establishing the landscape of XPO1 molecular alterations, their impact on the XPO1 protein, their interest as biomarkers, and investigations into the development of new XPO1-targeted therapies in B cell hematological malignancies.

Composite Lymphoma: Opposite Ends of Spectrum Meet

An 18-year-old African-American female presented with an episode of syncope. Initial investigations revealed large lung mass with invasion into right atrium along with lesions in kidneys and liver. Patient also developed superior vena cava syndrome due to lung mass. Biopsy of lung mass revealed diagnosis of composite lymphoma with involvement by primary mediastinal B-cell lymphoma (PMBCL) and classical Hodgkin lymphoma. Patient was started on dose-adjusted etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin and rituximab (EPOCH-R) with complete response to treatment. This case represents an extremely rare type of aggressive lymphoma and can guide clinicians in managing such cases since there are no standard guidelines for treatment. To the best of our knowledge, this is the first reported case of composite lymphoma of PMBCL and classical Hodgkin lymphoma successfully treated with dose-adjusted EPOCH-R regimen.

Mature aggressive B-cell lymphoma across age groups - molecular advances and therapeutic implications

INTRODUCTION

Mature B-cell lymphoma represents the most common type of Non-Hodgkin lymphoma, and different subtypes prevail at different patient ages. Areas covered: We review recent data on differences and commonalities in mature B-cell lymphoma occurring in adult and pediatric patients, with a special emphasis on molecular advances and therapeutic implications. To this end, we will discuss knowledge on diffuse large B-cell lymphoma and Burkitt lymphoma/leukemia, which are the most frequent subtypes in adult and pediatric patients, respectively, and on primary mediastinal B-cell lymphoma, which is a subtype of mature B-cell lymphoma occurring mainly in adolescents and young adults with a female predominance. Expert commentary: Molecular profiling has revealed molecular alterations that can be used to further classify the subtypes of mature B-cell lymphoma. These new subgroups frequently respond differentially to targeted therapeutic strategies. Future clinical trials utilizing new drugs will address this issue by combining clinical data and response assessment with a molecular workup of the corresponding lymphomas.

Frequent NFKBIE deletions are associated with poor outcome in primary mediastinal B-cell lymphoma

We recently reported a truncating deletion in the NFKBIE gene, which encodes IκBε, a negative feedback regulator of NF-κB, in clinically aggressive chronic lymphocytic leukemia (CLL). Because preliminary data indicate enrichment of NFKBIE aberrations in other lymphoid malignancies, we screened a large patient cohort (n = 1460) diagnosed with different lymphoid neoplasms. While NFKBIE deletions were infrequent in follicular lymphoma, splenic marginal zone lymphoma, and T-cell acute lymphoblastic leukemia (<2%), slightly higher frequencies were seen in diffuse large B-cell lymphoma, mantle cell lymphoma, and primary central nervous system lymphoma (3% to 4%). In contrast, a remarkably high frequency of NFKBIE aberrations (46/203 cases [22.7%]) was observed in primary mediastinal B-cell lymphoma (PMBL) and Hodgkin lymphoma (3/11 cases [27.3%]). NFKBIE-deleted PMBL patients were more often therapy refractory (P = .022) and displayed inferior outcome compared with wild-type patients (5-year survival, 59% vs 78%; P = .034); however, they appeared to benefit from radiotherapy (P =022) and rituximab-containing regimens (P = .074). NFKBIE aberrations remained an independent factor in multivariate analysis (P = .003) and when restricting the analysis to immunochemotherapy-treated patients (P = .008). Whole-exome sequencing and gene expression profiling verified the importance of NF-κB deregulation in PMBL. In summary, we identify NFKBIE aberrations as a common genetic event across B-cell malignancies and highlight NFKBIE deletions as a novel poor-prognostic marker in PMBL.

PD-1-PD-L1 immune-checkpoint blockade in B-cell lymphomas

Cancer cells can escape T-cell-mediated cellular cytotoxicity by exploiting the inhibitory programmed cell-death protein 1 (PD-1)/programmed cell death 1 ligand 1 (PD-L1) immune checkpoint. Indeed, therapeutic antibodies that block the PD-1-PD-L1 axis induce durable clinical responses against a growing list of solid tumours. B-cell lymphomas also leverage this checkpoint to escape immune recognition, although the outcomes of PD-1-PD-L1 blockade, and the correlations between PD-L1 expression and treatment responses, are less-well elucidated in these diseases than in solid cancers. Nevertheless, in patients with Hodgkin lymphoma, amplification of the gene encoding PD-L1 is commonly associated with increased expression of this protein on Reed-Sternberg cells. Correspondingly, PD-1 blockade with nivolumab has been demonstrated to result in response rates as high as 87% in unselected patients with relapsed and/or refractory Hodgkin lymphoma, leading to the FDA approval of nivolumab for this indication in May 2016. The PD-1/PD-L1 axis is probably also important for immune evasion of B-cell lymphomas with a viral aetiology, including those associated with human immunodeficiency virus (HIV) and Epstein-Barr virus (EBV). This Review is focused on the role of PD-1-PD-L1 blockade in unleashing host antitumour immune responses against various B-cell lymphomas, and summarizes the clinical studies of this approach performed to date.

Mediastinal gray zone lymphoma: clinico-pathological characteristics and outcomes of 99 patients from the Lymphoma Study Association

Mediastinal gray zone lymphoma, B-cell lymphomas with intermediate features between classical Hodgkin lymphoma and primary mediastinal B-cell lymphoma, have not been well described in the literature. We report the clinical characteristics and outcomes of a large retrospective series of 99 cases centrally reviewed by a panel of hematopathologists, with a consensus established for the diagnosis. Cases were defined as classical Hodgkin lymphoma-like morphology (64.6%) with primary mediastinal B-cell lymphoma immunophenotype, primary mediastinal B-cell lymphoma-like morphology (30.3%) with classical Hodgkin lymphoma or composite (5.1%) (synchronous occurrence of classical Hodgkin lymphoma and primary mediastinal B-cell lymphoma). The median age was 32 years (13-83 years); 55% were women. Thirteen of 81 evaluable cases (16%) were Epstein-Barr virus-positive. Twenty-eight percent of patients presented primary refractory disease (progression under first-line treatment or relapse within one year). The 3-year event-free and overall survival rates were 63% and 80%, respectively. Patients treated with a standard regimen (RCHOP/ABVD) had worse event-free survival (P=0.003) and overall survival (P=0.02) than those treated with a dose-intensive chemotherapy (high-dose RCHOP/escalated BEACOPP). Rituximab added to chemotherapy was not associated with better event-free survival (P=0.55) or overall survival (P=0.88). Radiotherapy for patients in complete remission had no impact on event-free survival. In multivariate prognostic analysis, ECOG-PS and anemia were the strongest factors associated with a shorter event-free survival and overall survival, respectively. In conclusion, this report describes the largest series of mediastinal gray zone lymphoma. Our data suggest that a dose-intensive treatment might improve the outcome of this rare and aggressive disease.

Mediastinal Gray Zone Lymphoma with Features Intermediate between Classical Hodgkin Lymphoma and Primary Mediastinal B-Cell Lymphoma

BACKGROUND

Mediastinal gray zone lymphoma (MGZL) shares clinical characteristics with primary mediastinal B-cell lymphoma (PMBCL) and nodular sclerosing Hodgkin lymphoma (NSHL). However, MGZL is extremely rare, and an appropriate treatment for it has not yet been established.

METHODS

We retrospectively analyzed 8 patients who were treated with systemic chemotherapy for MGZL between 2007 and 2014.

RESULTS

The patients with MGZL were predominantly young and male (median age 26 years), and 62.5% of patients had bulky disease. The overall response rate (ORR) and complete remission (CR) rate were both 75% (6/8) for all treated patients The median overall survival (OS) and progression-free survival (PFS) was 40.7 and 3.9 months, respectively. Most responders (4/6, 66.7%) were treated with R-CHOP (rituximab + cyclophosphamide, hydroxydaunorubicin, Oncovin and prednisolone) as the frontline therapy. The CR rate of patients who received R-CHOP and those who did not was 100% (4/4) and 50% (2/4), respectively. Particularly striking was the finding that the median PFS of patients who received R-CHOP frontline chemotherapy was 11.4 months, which was superior to the median PFS of patients who did not receive R-CHOP.

CONCLUSIONS

Of the 8 patients with MGZL who were treated with systemic chemotherapy, superior treatment responses were observed in patients who received R-CHOP as the frontline therapy.

Recurrent mutations of the exportin 1 gene (XPO1) and their impact on selective inhibitor of nuclear export compounds sensitivity in primary mediastinal B-cell lymphoma

Primary mediastinal B-cell lymphoma (PMBL) is an entity of B-cell lymphoma distinct from the other molecular subtypes of diffuse large B-cell lymphoma (DLBCL). We investigated the prevalence, specificity, and clinical relevance of mutations of XPO1, which encodes a member of the karyopherin-β nuclear transporters, in a large cohort of PMBL. PMBL cases defined histologically or by gene expression profiling (GEP) were sequenced and the XPO1 mutational status was correlated to genetic and clinical characteristics. The XPO1 mutational status was also assessed in DLBCL, Hodgkin lymphoma (HL) and mediastinal gray-zone lymphoma (MGZL).The biological impact of the mutation on Selective Inhibitor of Nuclear Export (SINE) compounds (KPT-185/330) sensitivity was investigated in vitro. XPO1 mutations were present in 28/117 (24%) PMBL cases and in 5/19 (26%) HL cases but absent/rare in MGZL (0/20) or DLBCL (3/197). A higher prevalence (50%) of the recurrent codon 571 variant (p.E571K) was observed in GEP-defined PMBL and was associated with shorter PFS. Age, International Prognostic Index and bulky mass were similar in XPO1 mutant and wild-type cases. KPT-185 induced a dose-dependent decrease in cell proliferation and increased cell-death in PMBL cell lines harboring wild type or XPO1 E571K mutant alleles. Experiments in transfected U2OS cells further confirmed that the XPO1 E571K mutation does not have a drastic impact on KPT-330 binding. To conclude the XPO1 E571K mutation represents a genetic hallmark of the PMBL subtype and serves as a new relevant PMBL biomarker. SINE compounds appear active for both mutated and wild-type protein. Am. J. Hematol. 91:923-930, 2016. © 2016 Wiley Periodicals, Inc.

[Primary mediastinal large B-cell lymphoma in women: about five cases]

Primary mediastinal large B-cell lymphoma (PMBL) is a lymphoma occurring in the anterior mediastinum starting from the cells B of the thymique medullary zone. This is a rare entity characterized by epidemiological, clinical and evolutionary peculiarities as well as by pathological and immunohistochemical peculiarities. We report a case series of 5 patients with diagnosed PMBL hospitalized in Pulmonology Department of Ibn Sina Hospital between January 2012 and May 2016. The average age was 34 years, the median of consultation time was 2 months. Reported symptoms were dyspnea, chest pain, dry cough; two patients suffered from superior vena cava syndrome. LDH level was high in 4 patients. Thoracic imaging showed an anterior mediastinal tissue processing in 5 patients. Histological diagnosis was based on ultrasound-guided transparietal puncture biopsy in 5 patients. The contribution of immunohistochemistry was decisive in all cases. Patients were sent to the National Institute of Oncology for therapeutic management. PMBL prognosis is reserved, it most commonly occurs in young women, which increases the need of aggressive therapy to improve survival rate.

Improved survival with combined modality therapy in the modern era for primary mediastinal B-cell lymphoma

Primary mediastinal B-cell lymphoma (PMBCL) is an uncommon lymphoma for which existing data is limited. We utilized the National Cancer Database (NCDB) to evaluate PMBCL and the impact of radiotherapy (RT) on outcomes in the years following FDA approval of rituximab. We queried the NCDB for patients with PMBCL diagnosed from 2006 to 2011 and treated with multiagent chemotherapy. Kaplan-Meier overall survival (OS) estimates, univariate (UVA), and multivariate (MVA) Cox proportional hazards regression analyses were performed. Propensity score matched analysis (PSMA) was performed to account for indication bias and mitigate heterogeneity between treatment groups. 465 patients were identified with a median follow-up of 36 months. Median age was 36 years; 43% received RT. 5-year OS for the entire cohort was 87%, and for the no-RT and RT groups, 83% versus 93%, respectively. On UVA, OS was improved with RT (HR 0.34, P = 0.002). On MVA, RT remained significantly associated with improved OS (HR 0.44, P = 0.028) while Medicaid insurance status and increasing stage remained significantly associated with OS decrement. PSMA confirmed the OS benefit associated with RT. This analysis is the largest PMBCL dataset to date and demonstrates a significant survival benefit associated with RT in patients receiving multiagent chemotherapy in the rituximab era. More than half of patients treated in the United States during this time period did not receive RT. In the absence of phase III data to support omission, combined modality therapy with its associated survival benefit should be the benchmark against which other therapies are compared.

Primary Mediastinal Large B-Cell Lymphoma With Translocations Involving BCL6 and MYC (Double-Hit Lymphoma)

OBJECTIVES

Primary mediastinal large B-cell lymphomas (PMLBCLs) are aggressive lymphomas with characteristic clinical, morphologic, and immunophenotypic features. "Double-hit" (DH) lymphomas are B-cell neoplasms characterized by a translocation involving MYC and either BCL2 or BCL6 In the indexed literature, there are no reported cases of PMLBCL associated with DH or triple-hit events.

METHODS

Herein, we present a case of a 15-year-old girl with PMLBCL who had typical clinical, morphologic, and immunophenotypic features.

RESULTS

Fluorescent in situ hybridization studies showed rearrangements involving MYC and BCL6 We also excluded the possibility of a reciprocal t(3;8) (3q27;8q24) BCL6/MYC translocation.

CONCLUSIONS

This case expands the current spectrum of lymphomas subtypes in which DH can be found and supports the rationale for cytogenetic testing for DH abnormalities in all cases of aggressive large B-cell lymphomas regardless of subtype.

Novel drug targets for personalized precision medicine in relapsed/refractory diffuse large B-cell lymphoma: a comprehensive review

Diffuse large B-cell lymphoma (DLBCL) is a clinically heterogeneous lymphoid malignancy and the most common subtype of non-Hodgkin's lymphoma in adults, with one of the highest mortality rates in most developed areas of the world. More than half of DLBLC patients can be cured with standard R-CHOP regimens, however approximately 30 to 40 % of patients will develop relapsed/refractory disease that remains a major cause of morbidity and mortality due to the limited therapeutic options.Recent advances in gene expression profiling have led to the identification of at least three distinct molecular subtypes of DLBCL: a germinal center B cell-like subtype, an activated B cell-like subtype, and a primary mediastinal B-cell lymphoma subtype. Moreover, recent findings have not only increased our understanding of the molecular basis of chemotherapy resistance but have also helped identify molecular subsets of DLBCL and rational targets for drug interventions that may allow for subtype/subset-specific molecularly targeted precision medicine and personalized combinations to both prevent and treat relapsed/refractory DLBCL. Novel agents such as lenalidomide, ibrutinib, bortezomib, CC-122, epratuzumab or pidilizumab used as single-agent or in combination with (rituximab-based) chemotherapy have already demonstrated promising activity in patients with relapsed/refractory DLBCL. Several novel potential drug targets have been recently identified such as the BET bromodomain protein (BRD)-4, phosphoribosyl-pyrophosphate synthetase (PRPS)-2, macrodomain-containing mono-ADP-ribosyltransferase (ARTD)-9 (also known as PARP9), deltex-3-like E3 ubiquitin ligase (DTX3L) (also known as BBAP), NF-kappaB inducing kinase (NIK) and transforming growth factor beta receptor (TGFβR).This review highlights the new insights into the molecular basis of relapsed/refractory DLBCL and summarizes the most promising drug targets and experimental treatments for relapsed/refractory DLBCL, including the use of novel agents such as lenalidomide, ibrutinib, bortezomib, pidilizumab, epratuzumab, brentuximab-vedotin or CAR T cells, dual inhibitors, as well as mechanism-based combinatorial experimental therapies. We also provide a comprehensive and updated list of current drugs, drug targets and preclinical and clinical experimental studies in DLBCL. A special focus is given on STAT1, ARTD9, DTX3L and ARTD8 (also known as PARP14) as novel potential drug targets in distinct molecular subsets of DLBCL.

Using the pathology report in initial treatment decisions for diffuse large B-cell lymphoma: time for a precision medicine approach

Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of non Hodgkin lymphoma in the Western world, and is potentially curable with standard R-CHOP chemoimmunotherapy. Historically, clinical risk assessments provided prognostic information, but did not define treatment approach. We are now in an era where the heterogeneity of DLBCL is defined genetically and molecularly, and rational subset-specific therapeutic targets are guiding clinical trials. Primary mediastinal DLBCL is a unique clinicopathologic entity, and alternatives to R-CHOP may confer superior outcome. Rearrangement of the myc oncogene occurs in ∼10% of patients with DLBCL, and confers a very poor prognosis with standard R-CHOP, particularly when there is concomitant rearrangement of bcl-2, a condition referred to as “double-hit” DLBCL. A larger subset of DLBCL demonstrates overexpression of both myc and bcl-2 by immunohistochemistry. Cell of origin, determined by gene expression analysis, immunohistochemistry algorithms, or a novel Lymph2Cx platform, provides prognostic information, and guides therapeutic decisions in both relapsed and de novo disease. This article will define specific subsets of DLBCL and provide subtype-specific treatment options, including novel approaches under investigation. Understanding these key features of the pathology report, and limitations of these assays defining subsets of DLBCL, allows for an evolving precision medicine approach to this disease.

Genomic Landscape of Primary Mediastinal B-Cell Lymphoma Cell Lines

Primary mediastinal B-Cell lymphoma (PMBL) is a recently defined entity comprising ~2–10% non-Hodgkin lymphomas (NHL). Unlike most NHL subtypes, PMBL lacks recurrent gene rearrangements to serve as biomarkers or betray target genes. While druggable, late chemotherapeutic complications warrant the search for new targets and models. Well characterized tumor cell lines provide unlimited material to serve as preclinical resources for verifiable analyses directed at the discovery of new biomarkers and pathological targets using high throughput microarray technologies. The same cells may then be used to seek intelligent therapies directed at clinically validated targets. Four cell lines have emerged as potential PMBL models: FARAGE, KARPAS-1106P, MEDB-1 and U-2940. Transcriptionally, PMBL cell lines cluster near c(lassical)-HL and B-NHL examples showing they are related but separate entities. Here we document genomic alterations therein, by cytogenetics and high density oligonucleotide/SNP microarrays and parse their impact by integrated global expression profiling. PMBL cell lines were distinguished by moderate chromosome rearrangement levels undercutting cHL, while lacking oncogene translocations seen in B-NHL. In total 61 deletions were shared by two or more cell lines, together with 12 amplifications (≥4x) and 72 homozygous regions. Integrated genomic and transcriptional profiling showed deletions to be the most important class of chromosome rearrangement. Lesions were mapped to several loci associated with PMBL, e.g. 2p15 (REL/COMMD1), 9p24 (JAK2, CD274), 16p13 (SOCS1, LITAF, CIITA); plus new or tenuously associated loci: 2p16 (MSH6), 6q23 (TNFAIP3), 9p22 (CDKN2A/B), 20p12 (PTPN1). Discrete homozygous regions sometimes substituted focal deletions accompanied by gene silencing implying a role for epigenetic or mutational inactivation. Genomic amplifications increasing gene expression or gene-activating rearrangements were respectively rare or absent. Our findings highlight biallelic deletions as a major class of chromosomal lesion in PMBL cell lines, while endorsing the latter as preclinical models for hunting and testing new biomarkers and actionable targets.

Clinical impact of molecular features in diffuse large B-cell lymphoma and follicular lymphoma

Our understanding of the pathogenesis and heterogeneity of diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL) has been dramatically enhanced by recent attempts to profile molecular features of these lymphomas. In this article, we discuss ways in which testing for molecular features may impact DLBCL and FL management if clinical trials are designed to incorporate such tests. Specifically, we discuss how distinguishing lymphomas on the basis of cell-of-origin subtypes or the presence of other molecular features is prognostically and therapeutically significant. Conversely, we discuss how the molecular similarities of DLBCL and FL have provided insight into the potential of both DLBCL and FL cases to respond to agents targeting alterations they have in common. Through these examples, we demonstrate how the translation of our understanding of cancer biology into improvements in patient outcomes depends on analyzing the molecular correlates of treatment outcomes in clinical trials and in routinely treated patients.

Primary mediastinal large B-cell lymphoma

The management of primary mediastinal large B-cell lymphoma (PMBCL) requires a balance between optimizing chances of cure and reducing risk of long-term toxicities. The combination of rituximab to cyclophosphamide, doxorubicin, vincristine and prednisone (RCHOP) followed by mediastinal radiation results in a plateau in progression-free survival after first few years of follow-up. In rituximab era, a negative positron emission tomography (PET) scan performed after the completion of immunochemotherapy has a high predictive value for durable remission. Consequently, end-of-therapy PET may be utilizable to avoid radiation without compromising survival. Additionally, intensified chemotherapy alone has shown excellent survival. PMBCL is frequently associated with amplification of programmed death ligand (PDL) 1/2 and constitutive activation of JAK-STAT and NFKB pathways; these may serve as promising therapeutic targets. Clinical trials that integrate novel therapies into upfront immunochemotherapy and utilize end-of-therapy PET scan to guide mediastinal radiation have potential to further enhance survival and prevent long-term toxicities.

Summary and future directions

Our understanding of disease biology and treatment paradigms in diffuse large B-cell lymphoma (DLBCL) is now sufficiently mature that we are poised to enter a new phase of hematological oncology. To achieve the goal of precision medicine and begin to logically deploy the vast array of currently available, novel targeted therapies we must develop a roadmap for clinical research. We urgently need robust biomarkers to inform the results of current and planned randomized, controlled phase III clinical trials. These biomarkers should capitalize on our current understanding of the genetic landscape of DLBCL and will help to define those patients destined to fail R-CHOP. But more importantly, they will inform the molecular correlates of treatment failure for planned clinical trials testing novel agents and combinations. If successful, we can move the field past the vast array of prognostic markers and develop predictive biomarkers that direct future therapy.