Genomic Characterization of HIV-Associated Plasmablastic Lymphoma Identifies Pervasive Mutations in the JAK–STAT Pathway

Plasmablastic lymphoma: 2024 update on diagnosis, risk stratification, and management

DISEASE OVERVIEW

Plasmablastic lymphoma (PBL) is a rare CD20-negative aggressive lymphoma with a poor prognosis under standard treatment options. Though PBL is associated with human immunodeficiency virus infection and other immunosuppressed states, it can also affect immunocompetent individuals.

DIAGNOSIS

The diagnosis requires a high clinical suspicion and pathological confirmation. EBER expression and MYC gene rearrangements are frequently detected. The differential diagnosis includes EBV+ diffuse large B-cell lymphoma, extracavitary primary effusion lymphoma, ALK+ DLBCL, and HHV8+ large B-cell lymphoma, among others.

RISK STRATIFICATION

Age ≥60 years, advanced clinical stage, and high intermediate and high International Prognostic Index scores are associated with worse survival.

MANAGEMENT

Combination chemotherapy regimens, such as EPOCH, are recommended. The addition of bortezomib, lenalidomide, or daratumumab might improve outcomes. Including PBL patients and their participation in prospective clinical trials is warranted.

Update: The molecular spectrum of virus-associated high-grade B-cell non-Hodgkin lymphomas

The vast spectrum of aggressive B-cell non-Hodgkin neoplasms (B-NHL) encompasses several infrequent entities occurring in association with viral infections, posing diagnostic challenges for practitioners. In the emerging era of precision oncology, the molecular characterization of malignancies has acquired paramount significance. The pathophysiological comprehension of specific entities and the identification of targeted therapeutic options have seen rapid development. However, owing to their rarity, not all entities have undergone exhaustive molecular characterization. Considerable heterogeneity exists in the extant body of work, both in terms of employed methodologies and the scale of cases studied. Presently, therapeutic strategies are predominantly derived from observations in diffuse large B-cell lymphoma (DLBCL), the most prevalent subset of aggressive B-NHL. Ongoing investigations into the molecular profiles of these uncommon virus-associated entities are progressively facilitating a clearer distinction from DLBCL, ultimately paving the way towards individualized therapeutic approaches. This review consolidates the current molecular insights into aggressive and virus-associated B-NHL, taking into consideration the recently updated 5th edition of the WHO classification of hematolymphoid tumors (WHO-5HAEM) and the International Consensus Classification (ICC). Additionally, potential therapeutically targetable susceptibilities are highlighted, offering a comprehensive overview of the present scientific landscape in the field.

The influence of immunodeficiency, disease features, and patient characteristics on survival in plasmablastic lymphoma

ABSTRACT

Plasmablastic lymphoma (PBL) is a rare and aggressive non-Hodgkin lymphoma associated with immunodeficiency, characterized by uncertain treatment approaches and an unfavorable prognosis. We conducted a multicenter, international, retrospective cohort study, aiming to characterize the clinical features, risk factors, and outcomes of patients with PBL. Data were collected from 22 institutions across 4 countries regarding patients diagnosed with PBL between 1 January 1999 and 31 December 2020. Survival risk factors were analyzed using both univariate and multivariate regression models. Overall survival (OS) was calculated using Kaplan-Meier statistics. First-line treatment regimens were stratified into standard- and higher-intensity regimens, and based on whether they incorporated a proteasome inhibitor (PI). A total of 281 patients (median age, 55 years) were included. Immunodeficiency of any kind was identified in 144 patients (51%), and 99 patients (35%) had HIV-positive results. The 5-year OS for the entire cohort was 36% (95% confidence interval, 30%-42%). In multivariate analysis, inferior OS was associated with Epstein-Barr virus-negative lymphoma, poor performance status, advanced stage, and bone marrow involvement. In an independent univariate analysis, the international prognostic index was associated with OS outcomes. Neither immunosuppression nor HIV infection, specifically, influenced OS. Among patients treated with curative intent (n = 234), the overall response rate was 72%. Neither the intensity of the treatment regimen nor the inclusion of PIs in first-line therapy was associated with OS. In this large retrospective study of patients with PBL, we identified novel risk factors for survival. PBL remains a challenging disease with poor long-term outcomes.

Clinicopathological and genetic landscape of plasmablastic lymphoma in Taiwan

Plasmablastic lymphoma (PBL) is an aggressive large B-cell lymphoma with a terminal B-cell differentiation phenotype and is frequently associated with immunodeficiency. We aimed to investigate the clinicopathological and immunophenotypic features, genetic alterations, and mutational landscape of PBL in Taiwan. We retrospectively recruited 26 cases. Five (5/18; 28%) patients were HIV-positive and 21 (81%) presented extranodally. There were two morphological groups: one with purely monomorphic large cells (85%) and the other comprising large cells admixed with plasmacytic cells (15%). Phenotypically, the tumors expressed MYC (8/10; 80%), CD138 (20/26; 77%), and MUM1 (20/20; 100%), but not CD20 (n = 26; 0%). Fourteen (54%) cases were positive for EBV by in situ hybridization; the EBV-positive cases were more frequently HIV infected (p = 0.036), with extranodal presentation (p = 0.012) and CD79a expression (p = 0.012), but less frequent light chain restriction (p = 0.029). Using fluorescence in situ hybridization, we identified 13q14 deletion, MYC rearrangement, and CCND1 rearrangement in 74%, 30%, and 5% cases, respectively, without any cases having rearranged BCL6 or IGH::FGFR3 fusion. In the 15 cases with adequate tissue for whole exome sequencing, the most frequent recurrent mutations were STAT3 (40%), NRAS (27%), and KRAS (20%). In conclusion, most PBL cases in Taiwan were HIV-unrelated. Around half of the cases were positive for EBV, with distinct clinicopathological features. Deletion of chromosome 13q14 was frequent. The PBL cases in Taiwan showed recurrent mutations involving JAK-STAT, RAS-MAPK, epigenetic regulation, and NOTCH signaling pathways, findings similar to that from the West.

Plasmablastic Lymphoma. A State-of-the-Art Review: Part 1-Epidemiology, Pathogenesis, Clinicopathologic Characteristics, Differential Diagnosis, Prognostic Factors, and Special Populations

This two-part review aims to present a current and comprehensive understanding of the diagnosis and management of plasmablastic lymphoma. The first section, as presented in this paper, reviews epidemiology, etiology, clinicopathological characteristics, differential diagnosis, prognostic variables, and the impact of plasmablastic lymphoma on specific populations. Plasmablastic lymphoma (PBL) is a rare and aggressive form of lymphoma. Previous and modern studies have demonstrated a significant association between the human immunodeficiency virus (HIV) and the development of the disease. The limited occurrence of PBL contributes to a need for a more comprehensive understanding of the molecular mechanisms involved in its etiology. Consequently, the diagnostic procedure for PBL poses a significant difficulty. Among the group of CD20-negative large B-cell lymphomas, PBL can be correctly diagnosed by identifying its exact clinical characteristics, anatomical location, and morphological characteristics. PBL cells do not express CD20 or PAX5 but possess plasmacytic differentiation markers such as CD38, CD138, MUM1/IRF4, Blimp1, and XBP1. PBL must be distinguished from other B-cell malignancies that lack the CD20 marker, including primary effusion lymphoma, anaplastic lymphoma kinase-positive large B-cell lymphoma, and large B-cell lymphoma (LBCL). This condition is frequently associated with infections caused by the Epstein-Barr virus and genetic alterations involving the MYC gene. Despite advances in our comprehension of this disease, the prognosis remains dismal, resulting in a low overall survival rate, although recent reports suggest an apparent tendency towards substantial improvement.

Unraveling the molecular landscape: a comparative analysis of PI3K and MAPK signaling pathways in plasmablastic lymphoma and diffuse large B-cell lymphoma with therapeutic implications

Plasmablastic lymphoma (PBL) is a rare and aggressive subtype of non-Hodgkin lymphoma that shares features with diffuse large B-cell lymphoma (DLBCL). While significant progress has been made in treating DLBCL, the prognosis for PBL remains poor, highlighting the need to identify new therapeutic targets. Using RNA expression analysis, we compared the expression of genes involved in the phosphatidylinositol-3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) signaling pathways between PBL and DLBCL. We used critical PI3K (n = 201) and MAPK (n = 57) signaling probe sets to achieve this objective. Our results demonstrate unique molecular mechanisms underlying PBL pathogenesis compared to DLBCL, particularly within the PI3K and MAPK signaling pathways. We found that elevated STAT3 expression in PBL correlates with hyperactive MAPK and PI3K pathways, unlike DLBCL. Additionally, the hyperactivation of the PI3K signaling axis in PBL is unrelated to B-cell receptor or phosphatase and tensin homolog activity, indicating a distinct mechanism compared to DLBCL. Furthermore, we observed unique activation patterns in MAPK pathways between PBL and DLBCL, with PBL exhibiting high expression of the neurotrophic tyrosine kinase receptor (NTKR) family, specifically NTRK1 and NTRK2 genes, which have therapeutic potential. We also found that neither human immunodeficiency virus nor Epstein-Barr virus infection influences gene expression profiles linked to PI3K and MAPK signaling in PBL. These findings could lead to adapting targeted therapies developed for DLBCL to address the specific needs of PBL patients better and contribute to developing novel, targeted therapeutic strategies to improve patient outcomes.

The importance of SOCS1 - 1478 CA/del polymorphism and expression in breast cancer: a case-control study in the north of Iran

PURPOSE

This project aimed to evaluate the relationship between the suppressor of cytokine signaling-1 (SOCS1) - 1478 CA > del genetic variation and breast cancer susceptibility. Moreover, we investigated the SOCS1 mRNA expression level in cancerous tissues.

METHODS

A total of 100 patients with breast cancer and 120 healthy individuals were selected. Genomic DNA was extracted from blood. SOCS1 genotyping and relative gene expression were performed using ARMS-PCR (Amplification-Refractory Mutation System-Polymerase Chain Reaction) and real-time PCR, respectively.

RESULTS

In breast cancer patients, the prevalence of genotype frequencies of SOCS1 (- 1478 CA > del) CA/CA, CA/del, and del/del was 52, 31, and 17%, respectively. Among controls, the distribution of CA/CA, CA/del, and del/del was 63, 15, and 22%, respectively. The chi-square test reported that a significant difference was observed in the genotypic distribution of SOCS1 (- 1478 CA > del) polymorphism between cases and controls (χ2 = 8.08, P = 0.01). In addition, the presence of the CA/del genotype was associated with an elevated risk of breast cancer (in the codominant model: OR 2.51; 95% CI 1.27-4.96, P = 0.007 and in the over dominant model: OR 2.54; 95% CI 1.32-4.90, P = 0.005). However, there was no significant difference in allelic distributions between the groups (P > 0.05). There was no significant difference in the breast cancer risk associated with the dominant and recessive genetic models when the reference was CA/CA and CA/CA + CA/del genotype, respectively (P = 0.09 and P = 0.38). Moreover, the expression of SOCS1 decreased in cancerous tissues as compared to the adjacent non-cancerous tissues (P < 0.0001).

CONCLUSION

In conclusion, a functional SOCS1 promoter polymorphism (- 1478 CA > del) may affect breast cancer susceptibility.

Plasmablastic Lymphoma: Past, Present, and Future

Plasmablastic Lymphoma is a rare large B-cell lymphoma with unique immunohistochemical and morphological features. It was most commonly associated with HIV infection; however, it's now seen in other immunosuppressed states like autoimmune conditions, post-transplant settings, and even in elderly immunocompetent individuals. Although rare, it is an aggressive lymphoma with unfavorable outcomes. The aim of this manuscript is to have an in-depth review of the current knowledge of epidemiology, pathophysiology, prognostic markers, and treatment approaches currently in use and in clinical trials for this challenging disease.

Identification of Potential Therapeutic Targets for Plasmablastic Lymphoma Through Gene Expression Analysis: Insights into RAS and Wnt Signaling Pathways

Plasmablastic lymphoma (PBL) is a rare and aggressive B-cell lymphoma with overlapping characteristics with diffuse large B-cell lymphoma (DLBCL) and multiple myeloma. Hyperactive Wnt signaling derails homeostasis and promotes oncogenesis and chemoresistance in DLBCL and multiple myeloma. Evidence suggests active cross-talk between the Wnt and RAS pathways impacting metastasis in solid cancers in which combined targeted therapies show effective results. Recent genomic studies in PBL demonstrated a high frequency of mutations linked with the RAS signaling pathway. However, the role of RAS and Wnt signaling pathway molecule expression in PBL remained unknown. We examined the expression of Wnt and RAS pathway-related genes in a well-curated cohort of PBL. Because activated B cells are considered immediate precursors of plasmablasts in B cell development, we compared this data with activated B-cell type DLBCL (ABC-DLBCL) patients, employing NanoString transcriptome analysis (770 genes). Hierarchical clustering revealed distinctive differential gene expression between PBL and ABC-DLBCL. Gene set enrichment analysis labeled the RAS signaling pathway as the most enriched (37 genes) in PBL, including upregulating critical genes, such as NRAS, RAF1, SHC1, and SOS1. Wnt pathway genes were also enriched (n = 22) by gene set enrichment analysis. Molecules linked with Wnt signaling activation, such as ligands or targets (FZD3, FZD7, c-MYC, WNT5A, WNT5B, and WNT10B), were elevated in PBL. Our data also showed that, unlike ABC-DLBCL, the deranged Wnt signaling activity in PBL was not linked with hyperactive nuclear factor κB and B-cell receptor signaling. In divergence, Wnt signaling inhibitors (CXXC4, SFRP2, and DKK1) also showed overexpression in PBL. The high expression of RAS signaling molecules reported may indicate linkage with gain-in-function RAS mutations. In addition, high expression of Wnt and RAS signaling molecules may pave pathways to explore benefiting from combined targeted therapies, as reported in solid cancer, to improve prognosis in PBL patients.

Clinicopathological and molecular features of indolent natural killer-cell lymphoproliferative disorder of the gastrointestinal tract

AIMS

Indolent natural killer (NK) cell lymphoproliferative disorder of the gastrointestinal (GI) tract (iNKLPD) is a rare, recently recognised neoplasm. Most of the reported tumours are confined to the GI tract, while a small subset of the tumours harbour JAK3 mutations. We collected four cases of iNKLPD with the goal of adding additional information to the current knowledge of this disease regarding the clinicopathological, immunohistochemical and molecular features.

METHODS AND RESULTS

Similar features including medium- to large-sized lymphoid cells with variable amounts of pale or slightly eosinophilic cytoplasm, and no evidence of EBER, TCR rearrangement were found in four cases. JAK3 K563_C565del mutation was found in one of three cases that were subjected to targeted next-generation sequencing. Unique findings of our study include one iNKLPD encountered for the first time in nasopharynx, where lesions could be inadvertently diagnosed as extranodal NK/T cell lymphoma, and one iNKLPD located in the gallbladder extended deeply into muscular and adventitial layers. Exceptional CD8-positive expression was observed in one iNKLPD. In addition, positive staining of phospho-STAT5, phospho-STAT3 and phospho-p38 were found in our cases. None of the four patients received therapy for lymphoma, but all had a benign clinical outcome during a follow-up time of 20-99 months.

CONCLUSIONS

We present four iNKLPDs with clinical, immunohistochemical and molecular features similar to the reported cases, as well as some unusual characters, which expand our knowledge on this disease, and further support the neoplastic nature of iNKLPDs.

Genomic landscape of virus-associated cancers

It has been estimated that 15%-20% of human cancers are attributable to infections, mostly by carcinogenic viruses. The incidence varies worldwide, with a majority affecting developing countries. Here, we present a comparative analysis of virus-positive and virus-negative tumors in nine cancers linked to five viruses. We find that virus-positive tumors occur more frequently in males and show geographical disparities in incidence. Genomic analysis of 1,658 tumors reveals virus-positive tumors exhibit distinct mutation signatures and driver gene mutations and possess a lower somatic mutation burden compared to virus-negative tumors of the same cancer type. For example, compared to the respective virus-negative counterparts, virus-positive cases across different cancer histologies had less often mutations of TP53 and deletions of 9p21.3/ CDKN2 A- CDKN1A ; Epstein-Barr virus-positive (EBV+) gastric cancer had more frequent mutations of EIF4A1 and ARID1A and less marked mismatch repair deficiency signatures; and EBV-positive cHL had fewer somatic genetic lesions of JAK-STAT, NF-κB, PI3K-AKT and HLA-I genes and a less pronounced activity of the aberrant somatic hypermutation signature. In cHL, we also identify germline homozygosity in HLA class I as a potential risk factor for the development of EBV-positive Hodgkin lymphoma. Finally, an analysis of clinical trials of PD-(L)1 inhibitors in four virus-associated cancers suggested an association of viral infection with higher response rate in patients receiving such treatments, which was particularly evident in gastric cancer and head and neck squamous cell carcinoma. These results illustrate the epidemiological, genetic, prognostic, and therapeutic trends across virus-associated malignancies.

MIR-29A-3P, MIR-29C-3P, MIR-146B-5P AND MIR-150-5P, Their Target Genes and lncrnas in HIV Infection: A Bioinformatic Study

INTRODUCTION

Increasing evidence suggests that microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) have emerged as attractive targets in viral infections, including Human immunodeficiency virus (HIV).

OBJECTIVE

To deepen the understanding of the molecular mechanisms that lead to HIV and provide potential targets for the future development of molecular therapies for its treatment.

METHODS

Four miRNAs were selected as candidates based on a previous systematic review. A combination of bioinformatic analyses was performed to identify their target genes, lncRNAs and biological processes that regulate them.

RESULTS

In the constructed miRNA-mRNA network, 193 gene targets are identified. These miRNAs potentially control genes from several important processes, including signal transduction and cancer. LncRNA-XIST, lncRNA-NEAT1 and lncRNA-HCG18 interact with all four miRNAs.

CONCLUSION

This preliminary result forms the basis for improving reliability in future studies to fully understand the role these molecules and their interactions play in HIV.

Primary refractory plasmablastic lymphoma: A precision oncology approach

Introduction

Hematologic malignancies are currently underrepresented in multidisciplinary molecular-tumor-boards (MTB). This study assesses the potential of precision-oncology in primary-refractory plasmablastic-lymphoma (prPBL), a highly lethal blood cancer.

Methods

We evaluated clinicopathological and molecular-genetic data of 14 clinically annotated prPBL-patients from initial diagnosis. For this proof-of-concept study, we employed our certified institutional MTB-pipeline (University-Cancer-Center-Schleswig-Holstein, UCCSH) to annotate a comprehensive dataset within the scope of a virtual MTB-setting, ultimately recommending molecularly stratified therapies. Evidence-levels for MTB-recommendations were defined in accordance with the NCT/DKTK and ESCAT criteria.

Results

Median age in the cohort was 76.5 years (range 56-91), 78.6% of patients were male, 50% were HIV-positive and clinical outcome was dismal. Comprehensive genomic/transcriptomic analysis revealed potential recommendations of a molecularly stratified treatment option with evidence-levels according to NCT/DKTK of at least m2B/ESCAT of at least IIIA were detected for all 14 prPBL-cases. In addition, immunohistochemical-assessment (CD19/CD30/CD38/CD79B) revealed targeted treatment-recommendations in all 14 cases. Genetic alterations were classified by treatment-baskets proposed by Horak et al. Hereby, we identified tyrosine-kinases (TK; n=4), PI3K-MTOR-AKT-pathway (PAM; n=3), cell-cycle-alterations (CC; n=2), RAF-MEK-ERK-cascade (RME; n=2), immune-evasion (IE; n=2), B-cell-targets (BCT; n=25) and others (OTH; n=4) for targeted treatment-recommendations. The minimum requirement for consideration of a drug within the scope of the study was FDA-fast-track development.

Discussion

The presented proof-of-concept study demonstrates the clinical potential of precision-oncology, even in prPBL-patients. Due to the aggressive course of the disease, there is an urgent medical-need for personalized treatment approaches, and this population should be considered for MTB inclusion at the earliest time.

Plasmablastic lymphoma: from genetics to treatment

Plasmablastic lymphoma (PBL) represents a rare distinct lymphoma entity with plasmablastic morphology and plasmacytic immunophenotype that is characterized by an aggressive clinical course. Standard chemotherapeutic regimens often remain insufficient to cure affected patients. Recently, comprehensive molecular analyses of large cohorts of primary PBL samples have revealed the mutational landscape as well as the pattern of copy number alterations of this rare lymphoma subtype. Identification of recurrent aberrations affecting the JAK-STAT, RAS-RAF, NOTCH, IRF4, and MYC signaling pathways drive the molecular pathogenesis of PBL and hold great potential for novel targeted therapeutic approaches.

The Landscape of Nucleic-Acid-Based Aptamers for Treatment of Hematologic Malignancies: Challenges and Future Directions

Hematologic malignancies, including leukemia, lymphoma, myeloproliferative disorder and plasma cell neoplasia, are genetically heterogeneous and characterized by an uncontrolled proliferation of their corresponding cell lineages in the bone marrow, peripheral blood, tissues or plasma. Although there are many types of therapeutic drugs (e.g., TKIs, chemotherapy drugs) available for treatment of different malignancies, the relapse, drug resistance and severe side effects due to the lack of selectivity seriously limit their clinical application. Currently, although antibody–drug conjugates have been well established as able to target and deliver highly potent chemotherapy agents into cancer cells for the reduction of damage to healthy cells and have achieved success in leukemia treatment, they still also have shortcomings such as high cost, high immunogenicity and low stability. Aptamers are ssDNA or RNA oligonucleotides that can also precisely deliver therapeutic agents into cancer cells through specifically recognizing the membrane protein on cancer cells, which is similar to the capabilities of monoclonal antibodies. Aptamers exhibit higher binding affinity, lower immunogenicity and higher thermal stability than antibodies. Therefore, in this review we comprehensively describe recent advances in the development of aptamer–drug conjugates (ApDCs) with cytotoxic payload through chemical linkers or direct incorporation, as well as further introduce the latest promising aptamers-based therapeutic strategies such as aptamer–T cell therapy and aptamer–PROTAC, clarifying their bright application, development direction and challenges in the treatment of hematologic malignancies.

Clinicopathologic and Molecular Characterization of Epstein-Barr Virus-positive Plasmacytoma

Epstein-Barr virus (EBV)-positive plasmacytoma is a rare plasma cell neoplasm. It remains unclear whether EBV-positive plasmacytoma represents a distinct entity or a variant of plasmacytoma. It shares morphologic features with plasmablastic lymphoma (PBL) and may cause diagnostic uncertainty. To better understand EBV-positive plasmacytoma and explore diagnostic criteria, this study describes 19 cases of EBV-positive plasmacytoma, compared with 27 cases of EBV-negative plasmacytoma and 48 cases of EBV-positive PBL. We reviewed the clinicopathologic findings and performed immunohistochemistry, in situ hybridization for EBV, fluorescence in situ hybridization for MYC , and next-generation sequencing. We found that 63.2% of patients with EBV-positive plasmacytoma were immunocompromised. Anaplastic features were observed in 7/19 cases. MYC rearrangement was found in 25.0% of them, and extra copies of MYC in 81.3%. EBV-positive and EBV-negative plasmacytomas possessed similar clinicopathologic features, except more frequent cytologic atypia, bone involvement and MYC aberrations in the former group. The survival rate of patients with EBV-positive plasmacytoma was comparable to that of patients with EBV-negative plasmacytoma. In comparison to PBL, EBV-positive plasmacytoma is less commonly associated with a "starry-sky" appearance, necrosis, absence of light chain expression, and a high Ki67 index (>75%). The most recurrently mutated genes/signaling pathways in EBV-positive plasmacytoma are epigenetic regulators, MAPK pathway, and DNA damage response, while the most frequently reported mutations in PBL are not observed. Collectively, EBV-positive plasmacytoma should be regarded as a biological variant of plasmacytoma. Thorough morphologic examination remains the cornerstone for distinguishing EBV-positive plasmacytoma and PBL, and molecular studies can be a valuable complementary tool.

Plasmablastic lymphoma: An update

Plasmablastic lymphoma (PBL) is a highly aggressive B cell non-Hodgkin lymphoma frequently associated with immunosuppression, particularly human immunodeficiency virus (HIV) infection. Although PBL is rare globally, South Africa has a high burden of HIV infection leading to a higher incidence of PBL in the region. Laboratory features in PBL may overlap with plasmablastic myeloma and other large B cell lymphomas with plasmablastic or immunoblastic morphology leading to diagnostic dilemmas. There are, however, pertinent distinguishing laboratory features in PBL such as a plasma cell immunophenotype with MYC overexpression, expression of Epstein-Barr virus-encoded small RNAs and lack of anaplastic lymphoma kinase (ALK) expression. This review aims to provide a summary of current knowledge in PBL, focusing on the epidemiology, pathophysiology, laboratory diagnosis and clinical management.

HIV-related lymphomas

PURPOSE OF REVIEW

To summarize the recent evidence on the pathology, current standard of care and recent advances in the treatment of HIV-related lymphomas.

RECENT FINDINGS

Lymphomas remain a major cause of morbidity and mortality in people living with HIV, even in the era of combination antiretroviral therapy (cART). However, treatment outcomes for these malignancies have improved in recent decades, due to full-dose chemotherapy, effective cART and supportive care. Recent advances include the identification of novel driving signaling pathways as promising molecular targets to improve lymphoma outcomes.

SUMMARY

Patients with HIV-related lymphomas who receive effective cART should be treated like the general population.

Towards precision medicine in lymphoid malignancies

Careful histopathologic examination remains the cornerstone in the diagnosis of the clinically and biologically heterogeneous group of lymphoid malignancies. However, recent advances in genomic and epigenomic characterization using high-throughput technologies have significantly improved our understanding of these tumors. Although no single genomic alteration is completely specific for a lymphoma entity, some alterations are highly recurrent in certain entities and thus can provide complementary diagnostic information when integrated in the hematopathological diagnostic workup. Moreover, other alterations may provide important information regarding the clinical course, that is, prognostic or risk-stratifying markers, or response to treatment, that is, predictive markers, which may allow tailoring of the patient's treatment based on (epi)genetic characteristics. In this review, we will focus on clinically relevant diagnostic, prognostic, and predictive biomarkers identified in more common types of B-cell malignancies, and discuss how diagnostic assays designed for comprehensive molecular profiling may pave the way for the implementation of precision diagnostics/medicine approaches. We will also discuss future directions in this rapidly evolving field, including the application of single-cell sequencing and other omics technologies, to decipher clonal dynamics and evolution in lymphoid malignancies.

Plasmablastic myeloma in Taiwan frequently presents with extramedullary and extranodal mass mimicking plasmablastic lymphoma

Plasmablastic myeloma (PBM) is a blastic morphologic variant of plasma cell myeloma with less favorable prognosis than those with non-blastic morphology. PBM is rare, without clear-cut definition and detailed clinicopathologic features in the literature. PBM may mimic plasmablastic lymphoma (PBL) as they share nearly identical morphology and immunophenotype. Using the criteria of ≥ 30% plasmablasts in tissue sections, we retrospectively recruited PBM cases and analyzed their clinical, imaging, and pathologic findings, with emphasis on extramedullary involvement. We performed immunohistochemistry, in situ hybridization for Epstein-Barr virus (EBER), and fluorescence in situ hybridization (FISH) for lymphoma- and myeloma-associated genetic alterations. Of the 25 recruited cases, 15 (60%) had extramedullary involvement, which occurred as initial presentation in nine cases. The most common extramedullary sites were soft tissue and/or skin (10/15, 67%), followed by pleural effusion, the lungs, and lymph nodes. Immunohistochemically, tumor cells expressed MYC (74%; 17/23), CD56 (56%; 14/25), and cyclin D1 (16%; 4/25), while CD117 was all negative (n = 25). Of the 20 cases stained with p53, four (20%) cases were diffusely positive, and the remaining 16 cases showed a heterogeneous pattern. EBER was negative in all 24 cases examined. Of the 13 cases examined with FISH, the genetic aberrations identified included del(13q14)(92%; 12/13), gain of chromosome 1q (90%; 9/10), loss of chromosome 1p (60%; 6/10), IGH-FGFR3 reciprocal translocation (23%; 3/13), rearranged MYC (15%; 2/13), and rearranged CCND1 (8%; 1/13), while there were no cases with TP53 deletion (n = 10) or rearrangement of BCL2 (n = 13) or BCL6 (n = 13). The prognosis was dismal regardless of the presence or absence of extramedullary involvement. In conclusion, PBM in Taiwan frequently presented as extramedullary and extranodal lesions, particularly in soft tissue and/or skin, mimicking PBL. FISH for targeted genetic alterations such as del(13q14), gain of chromosome 1q, loss of chromosome 1p, and IGH-FGFR3 might be helpful for the differential diagnoses. Larger studies are warranted to investigate the genetic alterations between PBM and PBL.

A Comprehensive Clinicopathologic and Molecular Study of 19 Primary Effusion Lymphomas in HIV-infected Patients

Primary effusion lymphoma (PEL) is associated with human herpesvirus 8 and frequently with Epstein-Barr virus (EBV). We report here a single-center series of 19 human immunodeficiency virus-associated PELs, including 14 EBV+ and 5 EBV- PELs. The objectives were to describe the clinicopathologic features of PELs, with a focus on programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) expression, to search for genetic alterations by targeted deep sequencing analysis, and to compare the features between EBV+ and EBV- cases. All the patients were male, and the median age at diagnosis was 47 years old (interquartile range: 40 to 56 y). Reflecting the terminal B-cell differentiation, immunophenotypic profiles showed low expression levels of B-cell markers, including CD19 (0/19), CD20 (1/19), CD79a (0/19), PAX5 (1/19), BOB1 (3/19), and OCT2 (4/19), contrasting with a common expression of CD38 (10/19), CD138 (7/19), and IRF4/MUM1 (18/19). We observed a frequent aberrant expression of T-cell markers, especially CD3 (10/19), and less frequently CD2 (2/19), CD4 (3/19), CD5 (1/19), and CD8 (0/19). Only 2 cases were PD-L1 positive on tumor cells and none PD-1 positive. With respect to immune cells, 3 samples tested positive for PD-L1 and 5 for PD-1. Our 36-gene lymphopanel revealed 7 distinct variants in 5/10 PELs, with either a single or 2 mutations per sample: B2M (n=2), CD58 (n=1), EP300 (n=1), TNFAIP3 (n=1), ARID1A (n=1), and TP53 (n=1). Finally, we did not observe any major clinical, pathologic, or immunohistochemical differences between EBV+ and EBV- PELs and the outcome was similar (2-y overall survival probability of 61.9% [95% confidence interval, 31.2-82.1] vs. 60.0% [95% confidence interval, 12.6-88.2], respectively, P=0.62).

KRAS and RAS-MAPK Pathway Deregulation in Mature B Cell Lymphoproliferative Disorders

KRAS mutations account for the most frequent mutations in human cancers, and are generally correlated with disease aggressiveness, poor prognosis, and poor response to therapies. KRAS is required for adult hematopoiesis and plays a key role in B cell development and mature B cell proliferation and survival, proved to be critical for B cell receptor-induced ERK pathway activation. In mature B cell neoplasms, commonly seen in adults, KRAS and RAS-MAPK pathway aberrations occur in a relevant fraction of patients, reaching high recurrence in some specific subtypes like multiple myeloma and hairy cell leukemia. As inhibitors targeting the RAS-MAPK pathway are being developed and improved, it is of outmost importance to precisely identify all subgroups of patients that could potentially benefit from their use. Herein, we review the role of KRAS and RAS-MAPK signaling in malignant hematopoiesis, focusing on mature B cell lymphoproliferative disorders. We discuss KRAS and RAS-MAPK pathway aberrations describing type, incidence, mutual exclusion with other genetic abnormalities, and association with prognosis. We review the current therapeutic strategies applied in mature B cell neoplasms to counteract RAS-MAPK signaling in pre-clinical and clinical studies, including most promising combination therapies. We finally present an overview of genetically engineered mouse models bearing KRAS and RAS-MAPK pathway aberrations in the hematopoietic compartment, which are valuable tools in the understanding of cancer biology and etiology.

Oral versus extra-oral plasmablastic lymphoma: A comparative analysis of 101 cases

AIMS

Originally described exclusively orally in HIV-infected patients, plasmablastic lymphoma (PBL) is increasingly described extra orally and in non-HIV-infected persons. The study comparatively analysed the clinico-pathologic features of oral PBLs (n = 55) to previously published extra-oral PBLs (n = 45 + 1) diagnosed over a seven-year period at the same institution in an HIV prevalent setting in South Africa in order to clarify any distinction between oral and extra-oral PBLs.

METHODS AND RESULTS

Tumours were assessed histologically and immunohistochemically with CD45 (LCA), CD3, CD20, CD79a, PAX5, CD138, MUM1, BLIMP1, VS38c, Ki-67, BCL6 and CD10 using standard protocols. Age ranged from 22 to 76 years (oral) and 9 and 59 years (extra-oral). Most PBL patients were HIV positive [oral (84%); extra-oral (65%)]. Male:female ratio was 2.7:1 for oral and 1.4:1 for extra-oral PBLs. Favoured oral and extra-oral sites were the maxilla and anus. PBLs displayed an indistinguishable immunohistochemical profile with unusually high CD45 expression (oral: 98%, extra-oral: 84%). EBV assessed by chromogenic in situ hybridisation (ISH) showed positivity in all oral PBLs and 95% extra-oral PBLs. MYC rearrangements (fluorescence ISH MYC break-apart probe) were similar in all the PBLs.

CONCLUSIONS

Extra-oral PBL is identical to its oral counterpart in gender and age distribution, HIV status, morphological appearances, immunophenotypic profile and EBV association. PBL should be regarded as the same tumour irrespective of oral or extra-oral site of origin.

Genome Instability in Multiple Myeloma: Facts and Factors

Multiple myeloma (MM) is a malignant neoplasm of terminally differentiated immunoglobulin-producing B lymphocytes called plasma cells. MM is the second most common hematologic malignancy, and it poses a heavy economic and social burden because it remains incurable and confers a profound disability to patients. Despite current progress in MM treatment, the disease invariably recurs, even after the transplantation of autologous hematopoietic stem cells (ASCT). Biological processes leading to a pathological myeloma clone and the mechanisms of further evolution of the disease are far from complete understanding. Genetically, MM is a complex disease that demonstrates a high level of heterogeneity. Myeloma genomes carry numerous genetic changes, including structural genome variations and chromosomal gains and losses, and these changes occur in combinations with point mutations affecting various cellular pathways, including genome maintenance. MM genome instability in its extreme is manifested in mutation kataegis and complex genomic rearrangements: chromothripsis, templated insertions, and chromoplexy. Chemotherapeutic agents used to treat MM add another level of complexity because many of them exacerbate genome instability. Genome abnormalities are driver events and deciphering their mechanisms will help understand the causes of MM and play a pivotal role in developing new therapies.

Clinical and Therapeutic Implications of Epstein-Barr Virus in HIV-Related Lymphomas

The incidence of lymphomas is increased in people living with HIV (PLWH). Aggressive B-cell non-Hodgkin lymphomas (NHLs) are the most common and are considered an AIDS-defining cancer (ADC). Although Hodgkin lymphoma (HL) is not considered an ADC, its incidence is also increased in PLWH. Among all HIV-related lymphomas (HRL), the prevalence of Epstein-Barr virus (EBV) is high. It has been shown that EBV is involved in different lymphomagenic mechanisms mediated by some of its proteins, contributing to the development of different lymphoma subtypes. Additionally, cooperation between both HIV and EBV can lead to the proliferation of aberrant B-cells, thereby being an additional lymphomagenic mechanism in EBV-associated HRL. Despite the close relationship between EBV and HRL, the impact of EBV on clinical aspects has not been extensively studied. These lymphomas are treated with the same therapeutic regimens as the general population in combination with cART. Nevertheless, new therapeutic strategies targeting EBV are promising for these lymphomas. In this article, the different types of HRL are extensively reviewed, focusing on the influence of EBV on the epidemiology, pathogenesis, clinical presentation, and pathological characteristics of each lymphoma subtype. Moreover, novel therapies targeting EBV and future strategies to treat HRL harboring EBV are discussed.

Integrative genomic and transcriptomic analysis in plasmablastic lymphoma identifies disruption of key regulatory pathways

WES coupled with RNA-sequencing of a large PBL cohort reveals genetic drivers of oncogenesis in RTK-RAS, NF-kB, and JAK/STAT signaling.

The mutational landscape and SCNV data emphasize the distinctness of EBV⁺/EBV^– PBL from both DLBCL and multiple myeloma.

Plasmablastic lymphoma (PBL) represents a clinically heterogeneous subtype of aggressive B-cell non-Hodgkin lymphoma. Targeted-sequencing studies and a single-center whole-exome sequencing (WES) study in HIV-positive patients recently revealed several genes associated with PBL pathogenesis; however, the global mutational landscape and transcriptional profile of PBL remain elusive. To inform on disease-associated mutational drivers, mutational patterns, and perturbed pathways in HIV-positive and HIV-negative PBL, we performed WES and transcriptome sequencing (RNA-sequencing) of 33 PBL tumors. Integrative analysis of somatic mutations and gene expression profiles was performed to acquire insights into the divergent genotype–phenotype correlation in Epstein-Barr virus–positive (EBV⁺) and EBV^– PBL. We describe a significant accumulation of mutations in the JAK signal transducer and transcription activator (OSMR, STAT3, PIM1, and SOCS1), as well as receptor tyrosine-kinase RAS (ERBB3, NRAS, PDGFRB, and NTRK) pathways. We provide further evidence of frequent perturbances of NF-κB signaling (NFKB2 and BTK). Induced pathways, identified by RNA-sequencing, closely resemble the mutational profile regarding alterations accentuated in interleukin-6/JAK/STAT signaling, NF-κB activity, and MYC signaling. Moreover, class I major histocompatibility complex–mediated antigen processing and cell cycle regulation were significantly affected by EBV status. An almost exclusive upregulation of phosphatidylinositol 3-kinase/AKT/mTOR signaling in EBV⁺ PBL and a significantly induced expression of NTRK3 in concert with recurrent oncogenic mutations in EBV^– PBL hint at a specific therapeutically targetable mechanism in PBL subgroups. Our characterization of a mutational and transcriptomic landscape in PBL, distinct from that of diffuse large B-cell lymphoma and multiple myeloma, substantiates the pathobiological independence of PBL in the spectrum of B-cell malignancies and thereby refines the taxonomy for aggressive lymphomas.

Janus Kinase Signaling: Oncogenic Criminal of Lymphoid Cancers

Simple Summary

Janus kinases (JAKs) are transmembrane receptors that pass signals from extracellular ligands to downstream. Increasing evidence has suggested that JAK family aberrations promote lymphoid cancer pathogenesis and progression through mediating gene expression via the JAK/STAT pathway or noncanonical JAK signaling. We are here to review how canonical JAK/STAT and noncanonical JAK signalings are represented and deregulated in lymphoid malignancies and how to target JAK for therapeutic purposes.

Abstract

The Janus kinase (JAK) family are known to respond to extracellular cytokine stimuli and to phosphorylate and activate signal transducers and activators of transcription (STAT), thereby modulating gene expression profiles. Recent studies have highlighted JAK abnormality in inducing over-activation of the JAK/STAT pathway, and that the cytoplasmic JAK tyrosine kinases may also have a nuclear role. A couple of anti-JAK therapeutics have been developed, which effectively harness lymphoid cancer cells. Here we discuss mutations and fusions leading to JAK deregulations, how upstream nodes drive JAK expression, how classical JAK/STAT pathways are represented in lymphoid malignancies and the noncanonical and nuclear role of JAKs. We also summarize JAK inhibition therapeutics applied alone or synergized with other drugs in treating lymphoid malignancies.

Plasmablastic lymphomas show restricted EBV latency profile and MYC gene aberrations

The pathogenesis of plasmablastic lymphoma (PBL) involves the Epstein-Barr virus (EBV), human immunodeficiency virus (HIV), and MYC gene aberrations. We aimed to determine the EBV latent infection pattern and frequency of MYC gene aberrations in PBLs. Immunohistochemistry was performed using antibodies for EBNA1, EBNA2, and LMP1 while fluorescence in situ hybridization was performed using a MYC probe. The patient cohort comprised 49 adult cases (44 were HIV-positive and three were HIV-negative). Forty-one cases were EBV-positive with 11 EBNA1-positive cases, all cases EBNA2-negative, and four LMP1-positive cases. Latency 0 was determined in 29 cases, latency I in eight cases, and latency II in four cases. The MYC gene was rearranged in eight cases, showed copy number alterations in 11 cases and, no rearrangement in 11 cases. This is the largest cohort of PBLs from South Africa to show a predominantly restricted EBV latency pattern with MYC gene aberrations as a common finding.

Lymphoproliferative Neoplasms With Plasmablastic Morphology: An Overview and Diagnostic Approach

CONTEXT.—

Plasmablastic morphology can be seen in several uncommon lymphoproliferative neoplasms. Sometimes it is difficult to distinguish these neoplasms from each other.

OBJECTIVE.—

To review the current understanding of major lymphoproliferative neoplasms with plasmablastic morphology; summarize the clinical, morphologic, immunophenotypic, cytogenetic, and molecular characteristics of each disease entity; and highlight a practical approach for differential diagnosis.

DATA SOURCES.—

Peer-reviewed medical literature and the authors' personal experience.

CONCLUSIONS.—

Plasmablastic lymphoma; plasmablastic myeloma; primary effusion lymphoma; human herpesvirus 8-positive diffuse large B-cell lymphoma, not otherwise specified; and anaplastic lymphoma kinase (ALK)-positive large B-cell lymphoma are major lymphoproliferative neoplasms with plasmablastic morphology. These neoplasms share many common morphologic and immunophenotypic characteristics. Definitive diagnosis requires a thorough understanding of disease phenotype and diagnostic criteria of each category. Recognition of expression pattern of Epstein-Barr virus-encoded small RNA, human herpesvirus 8, and ALK in these neoplasms is critical for diagnosis in cases with typical presentation. Additional ancillary studies and clinical findings may help in difficult cases.

Hematological cancers in individuals infected by HIV

HIV infection increases cancer risk and is linked to cancers associated to infectious agents classified as carcinogenic to humans by the International Agency for Research on Cancer. Lymphomas represent one of the most frequent malignancies among individuals infected by HIV. Diffuse large B-cell lymphoma remains a leading cancer after the introduction of combined antiretroviral therapy (cART). The incidence of other lymphomas including Burkitt lymphoma, primary effusion lymphomas, and plasmablastic lymphoma of the oral cavity remain stable, while the incidence of Hodgkin lymphoma and Kaposi sarcoma-associated herpesvirus (KSHV)-associated Multicentric Castleman Disease has increased. The heterogeneity of lymphomas in individuals infected by HIV likely depends on the complexity of involved pathogenetic mechanisms, i.e. HIV-induced immunosuppression, genetic abnormalities, cytokine dysregulation, co-infection with the gamma-herpesviruses, Epstein Barr virus and KSHV, and the dysregulation of the immune responses controlling these viruses. In the modern cART era, standard treatments for HIV-associated lymphoma including stem cell transplantation in relapsed/refractory disease, mirrors that of the general population. The combination of cART and anti neoplastic treatments has resulted in remarkable prolongation of long-term survival. However, oncolytic and immunotherapic strategies, and therapies targeting specific viral oncogenes will need to be developed primarily.

Molecular and functional profiling identifies therapeutically targetable vulnerabilities in plasmablastic lymphoma

Plasmablastic lymphoma (PBL) represents a rare and aggressive lymphoma subtype frequently associated with immunosuppression. Clinically, patients with PBL are characterized by poor outcome. The current understanding of the molecular pathogenesis is limited. A hallmark of PBL represents its plasmacytic differentiation with loss of B-cell markers and, in 60% of cases, its association with Epstein-Barr virus (EBV). Roughly 50% of PBLs harbor a MYC translocation. Here, we provide a comprehensive integrated genomic analysis using whole exome sequencing (WES) and genome-wide copy number determination in a large cohort of 96 primary PBL samples. We identify alterations activating the RAS-RAF, JAK-STAT, and NOTCH pathways as well as frequent high-level amplifications in MCL1 and IRF4. The functional impact of these alterations is assessed using an unbiased shRNA screen in a PBL model. These analyses identify the IRF4 and JAK-STAT pathways as promising molecular targets to improve outcome of PBL patients.

Plasmablastic lymphoma (PBL) is an aggressive lymphoma subtype characterized by poor prognosis but the molecular knowledge of the disease is limited. Here, the authors perform whole exome sequencing and copy number determination of primary samples highlighting IRF4 and JAK-STAT pathways as therapeutic targets for PBL.

EBV-positive HIV-associated diffuse large B cell lymphomas are characterized by JAK/STAT (STAT3) pathway mutations and unique clinicopathologic features

Even in the era of highly active combination antiretroviral therapy (cART), patients with HIV have a disproportionate risk of developing aggressive lymphomas that are frequently Epstein-Barr virus (EBV)-related. Here, we investigate HIV-associated diffuse large B-cell lymphoma (HIV-DLBCL) and compare EBV-positive and EBV-negative cases. HIV-DLBCL were identified from two academic medical centres and characterised by immunohistochemistry, EBV status, fluorescence in situ hybridisation, cell of origin determination by gene expression profiling, and targeted deep sequencing using a custom mutation panel of 334 genes. We also applied the Lymphgen tool to determine the genetic subtype of each case. Thirty HIV-DLBCL were identified, with a median patient age of 46 years and male predominance (5:1). Thirteen cases (48%) were EBV-positive and 14 (52%) EBV-negative. Nine of the 16 tested cases (56%) had MYC rearrangement, three (19%) had BCL6 (two of which were double hit MYC/BCL6) and none had BCL2 rearrangements. Using the Lymphgen tool, half of the cases (15) were classified as other. All HIV-DLBCL showed mutational abnormalities, the most frequent being TP53 (37%), MYC (30%), STAT3 (27%), HIST1H1E (23%), EP300 (20%), TET2 (20%), SOCS1 (17%) and SGK1 (17%). EBV-negative cases were mostly of germinal centre B-cell (GCB) origin (62%), showed more frequent mutations per case (a median of 13·5/case) and significant enrichment of TP53 (57% vs. 15%; P = 0·046), SGK1 (36% vs. 0%; P = 0·04), EP300 (43% vs. 0%; P = 0·02) and histone-modifying gene (e.g. HIST1H1E, HIST1H1D, 79% vs. 31%; P = 0·02) mutations. EBV-positive cases were mostly of non-GCB origin (70%), with fewer mutations per case (median 8/case; P = 0·007), and these tumours were enriched for STAT3 mutations (P = 0·10). EBV-positive cases had a higher frequency of MYC mutations but the difference was not significant (36% vs. 15%; P = 0·38). EBV-association was more frequent in HIV-DLBCLs, arising in patients with lower CD4 counts at diagnosis (median 46·5 vs. 101, P = 0·018). In the era of cART, approximately half of HIV-DLBCL are EBV-related. HIV-DLBCL are enriched for MYC rearrangements, MYC mutations and generally lack BCL2 rearrangements, regardless of EBV status. Among HIV-DLBCL, tumours that are EBV-negative and EBV-positive appear to have important differences, the latter arising in context of lower CD4 count, showing frequent non-GCB origin, lower mutation burden and recurrent STAT3 mutations.

MAP-kinase and JAK-STAT pathways dysregulation in plasmablastic lymphoma

Plasmablastic lymphoma (PBL) is an aggressive B-cell lymphoma with an immunoblastic/large cell morphology and plasmacytic differentiation. The differential diagnosis with Burkitt lymphoma (BL), plasma cell myeloma (PCM) and some variants of diffuse large B-cell lymphoma (DLBCL) may be challenging due to the overlapping morphological, genetic and immunophenotypic features. Furthermore, the genomic landscape in PBL is not well known. To characterize the genetic and molecular heterogeneity of these tumors, we investigated thirty-four PBL using an integrated approach, including fluorescence in situ hybridization, targeted sequencing of 94 B-cell lymphoma related genes, and copy-number arrays. PBL were characterized by high genetic complexity including MYC translocations (87%), gains of 1q21.1-q44, trisomy 7, 8q23.2-q24.21, 11p13-p11.2, 11q14.2-q25, 12p and 19p13.3-p13.13, losses of 1p33, 1p31.1-p22.3, 13q and 17p13.3-p11.2, and recurrent mutations of STAT3 (37%), NRAS and TP53 (33%), MYC and EP300 (19%) and CARD11, SOCS1 and TET2 (11%). Pathway enrichment analysis suggested a cooperative action between MYC alterations and MAPK (49%) and JAK-STAT (40%) signaling pathways. Of note, EBVnegative PBL cases had higher mutational and copy-number load and more frequent TP53, CARD11 and MYC mutations, whereas EBV-positive PBL tended to have more mutations affecting the JAK-STAT pathway. In conclusion, these findings further unravel the distinctive molecular heterogeneity of PBL identifying novel molecular targets and the different genetic profile of these tumors related to EBV infection.

MYC status in HIV-associated plasmablastic lymphoma: dual-colour CISH, FISH and immunohistochemistry

AIMS

We utilised chromogenic and fluorescence in-situ hybridisation (CISH and FISH) to evaluate MYC gene copy numbers and rearrangements within HIV-associated plasmablastic lymphomas (PBLs). Thereafter, clinicopathological features were explored retrospectively.

METHODS AND RESULTS

Sixty-seven (n = 67) patients were included and the HIV seropositive status was confirmed in 98% (63 of 64) with a median viral load of 55 587 (IQR 273 582) copies/ml and median CD4 count of 170 (IQR 249) cells/µl. The mean age was 41 ± 10.1 years and females comprised 54%. PBL was documented predominantly at extra-oronasal topographic regions. Starry-sky (SS) appearance was evident in 33% in association with monomorphic morphology (P-value 0.02). c-MYC protein was expressed in 81% and latent EBV infection was detected in 90%. EBER ISH-positive status and MYC rearrangement occurred in 67% of HIV PBL. MYC aberrations included MYC rearrangement (70%), low-level increase in MYC gene copy numbers (43%), concurrent MYC rearrangement and increased MYC gene copy numbers (49%) as well as low-level chromosome 8 polysomy (6%). MYC aberrations in HIV PBLs were significantly associated with SS appearance (P -0.01), monomorphic morphology (P - 0.03), c-MYC protein expression ≥40% (P - 0.03) and mortality (P - 0.03). There was advanced stage (Ann Arbor III/IV) at presentation (77%) and the median overall survival for HIV PBL was 75 days (95% CI 14-136).

CONCLUSION

Majority of the HIV-associated PBL tumours harbour MYC aberrations. Due to the persistently inferior survival outcome of HIV-associated PBL in the era of antiviral treatment, targeted and/or intensified therapy of oncogenic MYC may need to be explored in future.

SOCS, SPRED, and NR4a: Negative regulators of cytokine signaling and transcription in immune tolerance

Cytokines are important intercellular communication tools for immunity. Most cytokines utilize the JAK-STAT and Ras-ERK pathways to promote gene transcription and proliferation; however, this signaling is tightly regulated. The suppressor of cytokine signaling (SOCS) family and SPRED family are a representative negative regulators of the JAK-STAT pathway and the Ras-ERK pathway, respectively. The SOCS family regulates the differentiation and function of CD4⁺ T cells, CD8⁺ T cells, and regulatory T cells, and is involved in immune tolerance, anergy, and exhaustion. SPRED family proteins have been shown to inactivate Ras by recruiting the Ras-GTPase neurofibromatosis type 1 (NF1) protein. Human genetic analysis has shown that SOCS family members are strongly associated with autoimmune diseases, allergies, and tumorigenesis, and SPRED1 is involved in NF1-like syndromes and tumors. We also identified the NR4a family of nuclear receptors as a key transcription factor for immune tolerance that suppresses cytokine expression and induces various immuno-regulatory molecules including SOCS1.

Recent advances upper gastrointestinal lymphomas: molecular updates and diagnostic implications

Approximately one-third of extranodal non-Hodgkin lymphomas involve the gastrointestinal (GI) tract, with the vast majority being diagnosed in the stomach, duodenum, or proximal small intestine. A few entities, especially diffuse large B-cell lymphoma and extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue, represent the majority of cases. In addition, there are diseases specific to or characteristic of the GI tract, and any type of systemic lymphoma can present in or disseminate to these organs. The recent advances in the genetic and molecular characterisation of lymphoid neoplasms have translated into notable changes in the classification of primary GI T-cell neoplasms and the recommended diagnostic approach to aggressive B-cell tumours. In many instances, diagnoses rely on morphology and immunophenotype, but there is an increasing need to incorporate molecular genetic markers. Moreover, it is also important to take into consideration the endoscopic and clinical presentations. This review gives an update on the most recent developments in the pathology and molecular pathology of upper GI lymphoproliferative diseases.

Phenogenomic heterogeneity of post-transplant plasmablastic lymphomas

Plasmablastic lymphoma (PBL) is a rare and clinically aggressive neoplasm that typically occurs in immunocompromised individuals, including those infected with human immunodeficiency virus (HIV) and solid organ allograft recipients. Most prior studies have focused on delineating the clinico-pathological features and genetic attributes of HIVrelated PBL, in which MYC deregulation, Epstein-Barr virus (EBV) infection and, more recently, mutations in JAK/STAT, MAP kinase, and NOTCH pathway genes have been implicated in disease pathogenesis. The phenotypic spectrum of post-transplant (PT)-PBL is not well characterized and data on underlying genetic alterations are limited. This led us to perform comprehensive histopathological and immunophenotypic evaluation and targeted sequencing of 18 samples from 11 patients (8 males, 3 females; age range, 12-76 years) with PT-PBL; eight de novo and three preceded by other types of post-transplant lymphoproliferative disorders. Post-transplant PBL displayed morphological and immunophenotypic heterogeneity and some features overlapped those of plasmablastic myeloma. Six (55%) cases were EBV positive and five (45%) showed MYC rearrangement by fluorescence in situ hybridization. Recurrent mutations in epigenetic regulators (KMT2/MLL family, TET2) and DNA damage repair and response (TP53, mismatch repair genes, FANCA, ATRX), MAP kinase (KRAS, NRAS, HRAS, BRAF), JAK/STAT (STAT3, STAT6, SOCS1), NOTCH (NOTCH1, NOTCH3, SPEN), and immune surveillance (FAS, CD58) pathway genes were observed, with the mutational profiles of EBV⁺ and EBV^– cases exhibiting both similarities and differences. Clinical outcomes also varied, with survival ranging from 0-15.9 years after diagnosis. Besides uncovering the biological heterogeneity of PT-PBL, our study highlights similarities and distinctions between PT-PBL and PBL occurring in other settings and reveals potentially targetable oncogenic pathways in subsets of the disease.

The Genomic Landscape of HIV-Associated Plasmablastic Lymphoma

A combined whole-exome and targeted sequencing study of 110 cases of human immunodeficiency virus-associated plasmablastic lymphomas revealed a distinct landscape of genetic lesions for this lymphoma entity, including a particular role of mutations in STAT3 and other members of the JAK-STAT signaling pathway, and of the RAS family in its pathogenesis. See related article by Liu et al., p. 112.