MYD88 in the driver's seat of B-cell lymphomagenesis: from molecular mechanisms to clinical implications

Lymphoplasmacytic lymphoma and Waldenström Macroglobulinemia, A Decade After the Discovery of MYD88L265P

There has been remarkable progress over the past 80 years since Jan Waldenstrom first described patients with a hyperviscosity syndrome related to IgM paraprotein in 1944. The definition of Waldenstrom macroglobulinemia (WM) has evolved from a clinical syndrome to a distinct clinicopathologic entity with characteristic morphology, immunophenotype and molecular features. The landmark discovery of MYD88 mutation among most WM cases in 2012 marked the dawning of an era of molecular genomic exploration that led to a paradigm shift in clinical practice. In the current World Health Organization (WHO) classification of hematologic neoplasms, WM is included in the category of lymphoplasmacytic lymphoma (LPL) of which WM represents over 90% of cases. LPL/WM is also better defined, resolving ambiguity in many cases that would have been classified as "low grade B cell lymphoma with plasmacytic differentiation" a decade before. Nevertheless, challenges still face pathologists because criteria for distinguishing LPL/WM from other types of low-grade B cell lymphoma, particularly marginal zone lymphoma (MZL), remain imperfect. In this review, we highlight the current understanding of LPL and WM brought to light by new discoveries, which in turn are increasingly translated to improved diagnosis and personalized therapy. Key concepts in the diagnosis and their clinical implications are emphasized. Controversies and challenges are also discussed.

CaClust: linking genotype to transcriptional heterogeneity of follicular lymphoma using BCR and exomic variants

Tumours exhibit high genotypic and transcriptional heterogeneity. Both affect cancer progression and treatment, but have been predominantly studied separately in follicular lymphoma. To comprehensively investigate the evolution and genotype-to-phenotype maps in follicular lymphoma, we introduce CaClust, a probabilistic graphical model integrating deep whole exome, single-cell RNA and B-cell receptor sequencing data to infer clone genotypes, cell-to-clone mapping, and single-cell genotyping. CaClust outperforms a state-of-the-art model on simulated and patient data. In-depth analyses of single cells from four samples showcase effects of driver mutations, follicular lymphoma evolution, possible therapeutic targets, and single-cell genotyping that agrees with an independent targeted resequencing experiment.

A Rare Case of Richter Transformation to Both Clonally Unrelated and Clonally Related Diffuse Large B-Cell Lymphoma in the Same Patient

Richter transformation (RT) is a rare sequelae of chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). The clonal relationship of the RT to the underlined CLL/SLL is an important prognostic factor as clonally related RT has a worse prognosis than that of clonally unrelated RT. The development of more than one RT in the same patient is exceedingly rare and prior reports have shown cases consisting of RT to diffuse large B-cell lymphoma (DLBCL) and a subsequent or synchronous Hodgkin lymphoma. Here, we present a rare case of RT first to a clonally unrelated DLBCL and subsequently a clonally related DLBCL. Additionally, we retrospectively conducted next-generation sequencing studies of both RT's and found different mutational landscapes, including more clinically aggressive mutations identified in the clonally related RT. To our knowledge, this is the first reported case of clonally related and clonally unrelated RT, both of which are DLBCL, in the same patient.

Good clinical response following Ibrutinib treatment of a rare case of lymphoplasmacytic lymphoma secreting IgA kappa paraprotein: A case report

Lymphoplasmacytic lymphoma (LPL) is a malignant proliferation of small lymphocytes, lymphoplasmocytoid cells and plasmocytes affecting the bone marrow, lymph nodes and spleen. Its incidence is 1/100,000 and represents 8% of all lymphomas. A total of ~5% of patients with LPL may secrete non-IgM of IgG, IgA, kappa or lambda type or be non-secretory. In the present study, a case of a 62-year-old female patient who was diagnosed with non-IgM LPL with kappa light chain monoclonal paraprotein production and normal serum immunoglobulin levels was reported. The MYD88 L265P mutation was detected by molecular genetic analysis using a sample of the bone marrow. The patient underwent initial treatment with a combination of Bendamustine-Rituximab, and later on, Ibrutinib (a Bruton kinase inhibitor) was added to the treatment protocol. The authors' aim was to describe a case of a rare type of LPL studied and cured at the University Hospital 'St. Ivan Rilski', as well as to show the methods used for its diagnosis and their applicability. The difficulty in diagnosing such rare cases of LPL which are associated with marked plasmacytic differentiation and IgA paraprotein secretion resembling plasma cell neoplasia was addressed. From the other side, the characteristic features in favor of LPL diagnosis are the immunophenotype profile of plasmocytes, as well as the presence of MYD88 L265P mutation. Finally, the methods of management and treatment of this type of lymphoma were reported, highlighting the favorable effect of the treatment with Bruton TK inhibitor (Ibrutinib).

The genomic and molecular landscape of splenic marginal zone lymphoma, biological and clinical implications

Splenic marginal zone lymphoma (SMZL) is a rare, predominantly indolent B-cell lymphoma constituting fewer than 2% of lymphoid neoplasms. However, around 30% of patients have a shorter survival despite currently available treatments and the prognosis is especially poor for the 5-15% of cases that transform to a large cell lymphoma. Mounting evidence suggests that the molecular pathogenesis of SMZL is critically shaped by microenvironmental triggering and cell-intrinsic aberrations. Immunogenetic investigations have revealed biases in the immunoglobulin gene repertoire, indicating a role of antigen selection. Furthermore, cytogenetic studies have identified recurrent chromosomal abnormalities such as deletion of the long arm of chromosome 7, though specific disease-associated genes remain elusive. Our knowledge of SMZL's mutational landscape, based on a limited number of cases, has identified recurring mutations in KLF2, NOTCH2, and TP53, as well as genes clustering within vital B-cell differentiation pathways. These mutations can be clustered within patient subgroups with different patterns of chromosomal lesions, immunogenetic features, transcriptional signatures, immune microenvironments, and clinical outcomes. Regarding SMZL epigenetics, initial DNA methylation profiling has unveiled epigenetically distinct patient subgroups, including one characterized by elevated expression of Polycomb repressor complex 2 (PRC2) components. Furthermore, it has also demonstrated that patients with evidence of high historical cell division, inferred from methylation data, exhibit inferior treatment-free survival. This review provides an overview of our current understanding of SMZL's molecular basis and its implications for patient outcomes. Additionally, it addresses existing knowledge gaps, proposes future research directions, and discusses how a comprehensive molecular understanding of the disease will lead to improved management and treatment choices for patients.

Waldenström Macroglobulinemia - A State-of-the-Art Review: Part 1: Epidemiology, Pathogenesis, Clinicopathologic Characteristics, Differential Diagnosis, Risk Stratification, and Clinical Problems

Waldenström macroglobulinemia (WM) is an infrequent variant of lymphoma, classified as a B-cell malignancy identified by the presence of IgM paraprotein, infiltration of clonal, small lymphoplasmacytic B cells in the bone marrow, and the MYD88 L265P mutation, which is observed in over 90% of cases. The direct invasion of the malignant cells into tissues like lymph nodes and spleen, along with the immune response related to IgM, can also lead to various health complications, such as cytopenias, hyperviscosity, peripheral neuropathy, amyloidosis, and Bing-Neel syndrome. Chemoimmunotherapy has historically been considered the preferred treatment for WM, wherein the combination of rituximab and nucleoside analogs, alkylating drugs, or proteasome inhibitors has exhibited notable efficacy in inhibiting tumor growth. Recent studies have provided evidence that Bruton Tyrosine Kinase inhibitors (BTKI), either used independently or in conjunction with other drugs, have been shown to be effective and safe in the treatment of WM. The disease is considered to be non-curable, with a median life expectancy of 10 to 12 years.

Nomogram for predicting survival of patients with diffuse large B-cell lymphoma

The international prognostic index (IPI) system has been widely used to predict prognosis in diffuse large B-cell lymphoma (DLBCL). However, this system categorizes DLBCL patients into four risk groups, and cannot optimize individualized prognosis. In addition, other clinicopathological factors, such as molecular aberrations, are not incorporated into the system. To partly overcome these weak points, we developed nomograms to predict individual patient survival. We also incorporated MYD88L265P and CD79BY196 mutations into the nomograms since these mutations are associated with a worse prognosis and their signaling pathways have been highlighted as a therapeutic target. We analyzed 302 DLBCL cases for which multivariate analysis by Cox proportional hazard regression was performed. Nomograms for progression-free survival (PFS) and overall survival (OS) were constructed and assessed by a concordance index (C-index). The nomograms were also evaluated using an open external dataset (n = 187). The MYD88L265P and/or CD79BY196 (MYD88/CD79B) mutation was detected in 62/302 patients. The nomograms incorporating IPI factors exhibited a C-index of 0.738 for PFS and a C-index of 0.765 for OS. The nomograms incorporating IPI factors and the MYD88/CD79B mutation showed a C-index of 0.745 for PFS and a C-index of 0.769 for OS. The nomograms we created were evaluated using an external dataset and were well validated. The present nomograms incorporating IPI factors and the MYD88/CD79B mutation have sufficient discrimination ability, and may effectively predict prognosis in DLBCL patients. The prognostic models we have presented here may help clinicians personalize prognostic assessments and clinical decisions.

Marginal zone lymphomas: a consensus practice statement from the Australasian Lymphoma Alliance

Marginal zone lymphomas (MZLs) are a rare, indolent group of non-Hodgkin lymphomas with different diagnostic, genetic and clinical features and therapeutic implications. The most common is extranodal MZL of mucosa-associated lymphoid tissue, followed by splenic MZL and nodal MZL. Patients with MZL generally have good outcomes with long survival rates but frequently have a relapsing/remitting course requiring several lines of therapy. The heterogeneous presentation and relapsing course present the clinician with several diagnostic and therapeutic challenges. This position statement presents evidence-based recommendations in the setting of Australia and New Zealand.

Detection of circulating tumor DNA in plasma of patients with primary CNS lymphoma by digital droplet PCR

BACKGROUND

Primary central nervous system lymphoma (PCNSL) are rare mature B-cell lymphoproliferative diseases characterized by a high incidence of MYD88 L265P and CD79B Y196 hotspot mutations. Diagnosis of PCNSL can be challenging. The aim of the study was to analyze the detection rate of the MYD88 L265P and CD79B Y196 mutation in cell free DNA (cfDNA) in plasma of patients with PCNSL.

METHODS

We analyzed by digital droplet PCR (ddPCR) to determine presence of the MYD88 L265P and CD79B Y196 hotspot mutations in cfDNA isolated from plasma of 24 PCNSL patients with active disease. Corresponding tumor samples were available for 14 cases. Based on the false positive rate observed in 8 healthy control samples, a stringent cut-off for the MYD88 L265P and CD79B Y196 mutation were set at 0.3% and 0.5%, respectively.

RESULTS

MYD88 L265P and CD79B Y196 mutations were detected in 9/14 (64%) and 2/13 (15%) tumor biopsies, respectively. In cfDNA samples, the MYD88 L265P mutation was detected in 3/24 (12.5%), while the CD79B Y196 mutation was not detected in any of the 23 tested cfDNA samples. Overall, MYD88 L265P and/or CD79B Y196 were detected in cfDNA in 3/24 cases (12.5%). The detection rate of the combined analysis did not improve the single detection rate for either MYD88 L265P or CD79B Y196.

CONCLUSION

The low detection rate of MYD88 L265P and CD79B Y196 mutations in cfDNA in the plasma of PCNSL patients argues against its use in routine diagnostics. However, detection of MYD88 L265P by ddPCR in cfDNA in the plasma could be considered in challenging cases.

A Rare Case of Non-IgM Lymphoplasmacytic Lymphoma with Unusual Lack of Immunoglobulin Light Chain Production

BACKGROUND Non-IgM lymphoplasmacytic lymphoma (LPL) is a rare subtype of LPL, constituting less than 5% of the cases, and is often associated with IgG, IgA, or light chain paraproteins and is rarely a non-secretor. Non-IgM LPL remains poorly studied, and the differential diagnosis from other small B-cell lymphomas with plasmacytic differentiation and plasma cell neoplasm is challenging. CASE REPORT A 67-year-old woman presented with weight loss, persistent anemia, and borderline leukopenia. Serum protein electrophoresis and immunofixation demonstrated a faint IgG and kappa band against a dense polyclonal background. Bone marrow biopsy revealed hypercellular marrow with involvement by abnormal B cells with undetectable surface and cytoplasmic immunoglobulin light chains. Interestingly, these B cells showed no expression of light chains or production of IgG and IgM; however, they showed production of intracytoplasmic IgA. The concomitant neoplastic plasma cells also displayed no definitive light chain expression. Both IgH and IgK gene rearrangements were positive for clonal process. Molecular studies showed positive MYD88 L265P mutation and CXCR4 mutation (c.1013C>G). The overall findings confirmed marrow involvement by non-IgM LPL. The patient received 6 cycles of rituximab and bendamustine treatment, and no residual marrow involvement was found on the follow-up bone marrow biopsy. CONCLUSIONS We report a non-IgM LPL case featuring no light chain production and no heavy chain secretion, which we believe is the first reported case of this kind in the literature.

Molecular complexity of diffuse large B-cell lymphoma: a molecular perspective and therapeutic implications

Diffuse large B-cell lymphoma (DLBCL) stands as a formidable challenge in the landscape of non-Hodgkin's lymphomas. This review illuminates the remarkable strides made in comprehending DLBCL's molecular intricacies and devising targeted treatments. DLBCL, the most prevalent non-Hodgkin's lymphoma, has seen transformative progress in its characterization. Genetic investigations, led by high-throughput sequencing, have unveiled recurrent mutations in genes such as MYC, BCL2, and BCL6, casting light on the underlying genetic chaos propelling DLBCL's aggressiveness. A pivotal facet of this understanding centers on cell signaling pathways. Dysregulation of B-cell receptor (BCR) signaling, NF-κB, PI3K/Akt/mTOR, JAK/STAT, Wnt/β-Catenin, and Toll-like receptor pathways plays a critical role in DLBCL pathogenesis, offering potential therapeutic targets. DLBCL's complex tumor microenvironment (TME) cannot be overlooked. The dynamic interplay among tumor cells, immune cells, stromal components, and the extracellular matrix profoundly influences DLBCL's course and response to therapies. Epigenetic modifications, including DNA methylation and histone changes, add another layer of intricacy. Aberrant epigenetic regulation plays a significant role in lymphomagenesis, offering prospects for epigenetic-based therapies. Promisingly, these molecular insights have spurred the development of personalized treatments. Targeted therapies and immunotherapies, guided by genomic profiling and molecular classification, are emerging as game-changers in DLBCL management. In conclusion, this review underscores the remarkable strides in understanding DLBCL's molecular underpinnings, spanning genetics, cell signaling, the tumor microenvironment, and epigenetics. These advances pave the way for more effective, personalized treatments, renewing hope for DLBCL patients.

B-Cell Receptor Signaling and Beyond: The Role of Igα (CD79a)/Igβ (CD79b) in Normal and Malignant B Cells

B-cell receptor (BCR) is a B cell hallmark surface complex regulating multiple cellular processes in normal as well as malignant B cells. Igα (CD79a)/Igβ (CD79b) are essential components of BCR that are indispensable for its functionality, signal initiation, and signal transduction. CD79a/CD79b-mediated BCR signaling is required for the survival of normal as well as malignant B cells via a wide signaling network. Recent studies identified the great complexity of this signaling network and revealed the emerging role of CD79a/CD79b in signal integration. In this review, we have focused on functional features of CD79a/CD79b, summarized signaling consequences of CD79a/CD79b post-translational modifications, and highlighted specifics of CD79a/CD79b interactions within BCR and related signaling cascades. We have reviewed the complex role of CD79a/CD79b in multiple aspects of normal B cell biology and how is the normal BCR signaling affected by lymphoid neoplasms associated CD79A/CD79B mutations. We have also summarized important unresolved questions and highlighted issues that remain to be explored for better understanding of CD79a/CD79b-mediated signal transduction and the eventual identification of additional therapeutically targetable BCR signaling vulnerabilities.

Molecular characteristics in Chinese with chronic lymphocytic leukemia by next-generation sequencing: A single-center retrospective analysis

INTRODUCTION

Although the prevalence of Asian chronic lymphocytic leukemia (CLL) patients is not as high as that of Caucasians, there are more atypical CLLs in Asia whose genetic characteristics and their clinical significance are distinct and remain unclear.

METHODS

A retrospective analysis of 85 CLL samples in our center was conducted from 2019 to 2022. We used next-generation sequencing with a 172 gene panel to explore the multi-gene mutational data and the mutational status of immunoglobulin heavy variable (IGHV) gene.

RESULTS

MYD88 (20.0%) was the most frequently mutated gene, much higher than in Europe, followed in order by TP53 (18.8%), NOTCH1 (14.1%), IGLL5 (11.8%), and DNMT3A (8.2%). In addition, the incidence of ATM and SF3B1 mutations was relatively lower in our centre compared to Europe. Mutated (M)-IGHV patients were more likely to have a cooccurrence of MYD88 mutation, while complex karyotype and DNMT3A mutation were more common in the unmutated (U)-IGHV group. MYD88 mutated CLL was characterized by prevalence in young males in high-risk staging, with isolated 13q deletion and concomitant mutation of IGLL5. CLL patients with MYD88 and TP53 mutation showed an unfavorable prognosis.

CONCLUSION

These results would be valuable in helping to understand the characteristics and significance of cytogenetic genetics in Chinese patients with CLL.

Prognostic impact of MYD88 and TP53 mutations in diffuse large B Cell lymphoma

Diffuse large B cell lymphoma (DLBCL) is the most common subtype of lymphoma. It is a highly heterogeneous lymphoid neoplasm, with variations in gene expression profiles and genetic alterations. MYD88 and TP53 genes are common to be expressed and mutated in DLBCL patients with controversy regarding their role in prognosis and survival. This study aims to determine the predictive and prognostic role of MYD88 and TP53 gene mutation in DLBCL. A prospective cohort study was conducted on 50 patients who were diagnosed with DLBCL and 30 healthy individuals to assess the sensitivity and specificity of MYD88 and TP53 genetic mutations. MYD88 and TP53 gene mutations were more sensitive, specific, and accurate in predicting overall mortality and disease progression in comparison with the international prognostic index. Mutant MYD88 and TP53 showed their prognostic importance for worse objective response rates and survival outcomes. Both mutant MYD88 and TP53 were associated with worse ORR. There was a significant statistical difference for both MYD88 and TP53 with regard to 2-year PFS and 2-year OS rate. Hence, both mutant MYD88 and TP53 can be used in predicting disease progression and overall mortality.

MYD88L265P augments proximal B-cell receptor signaling in large B-cell lymphomas via an interaction with DOCK8

Diffuse large B-cell lymphoma (DLBCL) is a clinically and genetically heterogeneous disease with at least 5 recognized molecular subtypes. Cluster 5 (C5)/MCD tumors frequently exhibit concurrent alterations in the toll-like receptor (TLR) and B-cell receptor (BCR) pathway members, MYD88L265P and CD79B, and have a less favorable prognosis. In healthy B cells, the synergy between TLR and BCR signaling pathways integrates innate and adaptive immune responses and augments downstream NF-κB activation. In addition, physiologic TLR9 pathway engagement via MYD88, protein tyrosine kinase 2 (PYK2), and dedicator of cytokinesis 8 (DOCK8) increases proximal BCR signaling in healthy murine B cells. Although C5/MCD DLBCLs are selectively sensitive to Bruton tyrosine kinase (BTK) inhibition in in vitro studies and certain clinical trials, the role of mutated MYD88 in proximal BCR signaling remains undefined. Using engineered DLBCL cell line models, we found that concurrent MYD88L265P and CD79B alterations significantly increased the magnitude and duration of proximal BCR signaling, at the level of spleen tyrosine kinase and BTK, and augmented PYK2-dependent DOCK8 phosphorylation. MYD88L265P DLBCLs have significantly increased colocalization of DOCK8 with both MYD88 and the proximal BCR-associated Src kinase, LYN, in comparison with MYD88WT DLBCLs, implicating DOCK8 in MYD88L265P/proximal BCR cross talk. Additionally, DOCK8 depletion selectively decreased proximal BCR signaling, cellular proliferation, and viability of DLBCLs with endogenous MYD88L265P/CD79BY196F alterations and increased the efficacy of BTK blockade in these lymphomas. Therefore, MYD88L265P/DOCK8-enhanced proximal BCR signaling is a likely mechanism for the increased sensitivity of C5/MCD DLBCLs to BTK blockade.

Paralog-specific signaling by IRAK1/4 maintains MyD88-independent functions in MDS/AML

Dysregulation of innate immune signaling is a hallmark of hematologic malignancies. Recent therapeutic efforts to subvert aberrant innate immune signaling in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) have focused on the kinase IRAK4. IRAK4 inhibitors have achieved promising, though moderate, responses in preclinical studies and clinical trials for MDS and AML. The reasons underlying the limited responses to IRAK4 inhibitors remain unknown. In this study, we reveal that inhibiting IRAK4 in leukemic cells elicits functional complementation and compensation by its paralog, IRAK1. Using genetic approaches, we demonstrate that cotargeting IRAK1 and IRAK4 is required to suppress leukemic stem/progenitor cell (LSPC) function and induce differentiation in cell lines and patient-derived cells. Although IRAK1 and IRAK4 are presumed to function primarily downstream of the proximal adapter MyD88, we found that complementary and compensatory IRAK1 and IRAK4 dependencies in MDS/AML occur via noncanonical MyD88-independent pathways. Genomic and proteomic analyses revealed that IRAK1 and IRAK4 preserve the undifferentiated state of MDS/AML LSPCs by coordinating a network of pathways, including ones that converge on the polycomb repressive complex 2 complex and JAK-STAT signaling. To translate these findings, we implemented a structure-based design of a potent and selective dual IRAK1 and IRAK4 inhibitor KME-2780. MDS/AML cell lines and patient-derived samples showed significant suppression of LSPCs in xenograft and in vitro studies when treated with KME-2780 as compared with selective IRAK4 inhibitors. Our results provide a mechanistic basis and rationale for cotargeting IRAK1 and IRAK4 for the treatment of cancers, including MDS/AML.

New hopes in relapsed refractory primary central nervous system lymphoma

PURPOSE OF REVIEW

Patients with relapsed/refractory primary central nervous system lymphoma (rrPCNSL) have poor prognosis, with a median survival after relapse of 6.8 months. In this review, we discuss the evolving landscape and the possible future directions related to this important unmet clinical need.

RECENT FINDINGS

The modern two-phase approach for newly diagnosed PCNSL based on an induction using high-dose methotrexate (HD-MTX) combinations and a subsequent consolidation, has significantly improved the outcome in this setting. However, this strategy is able to cure more or less 50% of patients. rrPCNSL patients have a very poor prognosis with a reported 5-year overall survival of 18%. Late relapses (after third year) and use of high-dose chemotherapy and autologous stem cell transplantation (HDT-ASCT) represent important factors associated with a better outcome in this setting. On the basis of the growing acquisition of knowledge on the molecular characteristics of PCNSL, the use of non-chemotherapeutic drugs such as bruton tyrosine kinase inhibitors (BTK-is), immunomodulatory drugs (IMiDs) and immune checkpoint blockers (ICBs) is increasing in the last years along with the introduction of novel approaches (CAR-T cells and blood--brain barrier disruption). However, despite high responses in some cases, durations are often short, translating in outcome results still unsatisfactory.

SUMMARY

Treatment of rrPCNSL patients is challenging. As no standard of care exist in this setting, it is of paramount importance to acquire new knowledge related to this condition and start multidisciplinary collaboration in order to improve pts outcome.

Complete Remission of a Diffuse Large B-Cell Lymphoma in a Young Patient, with Severe Tuberous Sclerosis, Treated with Metronomic Chemotherapy and Ibrutinib: A Case Report

Tuberous sclerosis (TS) is a rare autosomal dominant genetic multisystem disease caused by mutations in either the TSC1 or TSC2 gene and results in the growth of non-cancerous masses in several organs. Diffuse large B-cell lymphoma (DLBCL) is the predominant non-Hodgkin lymphoma in adolescents and young adults. Metronomic chemotherapy (mCHEMO) can be defined as the frequent, regular administration of drug doses able to maintain a low, but active, range of concentrations of chemotherapeutic drugs during prolonged periods of time. We present the case of a young woman with severe TS who developed DLBCL. She was treated consecutively with the mCHEMO schedule R-DEVEC (prednisone, vinorelbine, etoposide, cyclophosphamide, plus rituximab) and then ibrutinib, achieving an impressive long-lasting complete remission. In conclusion, alternative treatments could be necessary when comorbidities are present in patients, and mCHEMO can be a potential successful therapeutic approach in frail subjects.

Prognosis of a Chinese patient with chronic lymphocytic leukemia who acquired a TP53 mutation following treatment with a BTK inhibitor

Chronic lymphocytic leukemia (CLL) is a common type of adult leukemia that occurs in Western countries, and its incidence has gradually increased in China in recent years. The characteristics of CLL are highly heterogeneous. Despite promising response rates achieved with targeted therapy, new targets still need to be expanded due to the heterogeneous of disease. Bruton's tyrosine kinase inhibitor (BTKi) has been used in the treatment of TP53 mutation. In this report, we present a case with myeloid differentiation primary response 88 (MYD88) mutation who developed a TP53 mutation after application of BTKi. Here, the patient was CLL unmutated (U-CLL) with MYD88 (L265P) mutation before initial treatment. After traditional treatment, the effect was not good, and BTKi was used for treatment, then TP53 mutation appeared. It is well known that immunoglobulin heavy chain unmutated (IGHV-U) and TP53 mutation in CLL indicate poor prognosis. The case suggests that whenever TP53 mutation occurs, BTKi is the best choice. This result is considered to be related to signal pathways. We aim to add to the collective knowledge by highlighting this rare cases of CLL with MYD88 (L265P) mutation in an Asian patient.

Oral IRAK-4 Inhibitor CA-4948 Is Blood-Brain Barrier Penetrant and Has Single-Agent Activity against CNS Lymphoma and Melanoma Brain Metastases

PURPOSE

An ongoing challenge in cancer is the management of primary and metastatic brain malignancies. This is partly due to restrictions of the blood-brain barrier and their unique microenvironment. These challenges are most evident in cancers such as lymphoma and melanoma, which are typically responsive to treatment in systemic locations but resistant when established in the brain. We propose interleukin-1 receptor-associated kinase-4 (IRAK-4) as a potential target across these diseases and describe the activity and mechanism of oral IRAK-4 inhibitor CA-4948.

EXPERIMENTAL DESIGN

Human primary central nervous system lymphoma (PCNSL) and melanoma brain metastases (MBM) samples were analyzed for expression of IRAK-4 and downstream transcription pathways. We next determined the central nervous system (CNS) applicability of CA-4948 in naïve and tumor-bearing mice using models of PCNSL and MBM. The mechanistic effect on tumors and the tumor microenvironment was then analyzed.

RESULTS

Human PCNSL and MBM have high expression of IRAK-4, IRAK-1, and nuclear factor kappa B (NF-κB). This increase in inflammation results in reflexive inhibitory signaling. Similar profiles are observed in immunocompetent murine models. Treatment of tumor-bearing animals with CA-4948 results in the downregulation of mitogen-activated protein kinase (MAPK) signaling in addition to decreased NF-κB. These intracellular changes are associated with a survival advantage.

CONCLUSIONS

IRAK-4 is an attractive target in PCNSL and MBM. The inhibition of IRAK-4 with CA-4948 downregulates the expression of important transcription factors involved in tumor growth and proliferation. CA-4948 is currently being investigated in clinical trials for relapsed and refractory lymphoma and warrants further translation into PCNSL and MBM.

Prevalence and prognostic value of MYD88 and CD79B mutations in ocular adnexal large B-cell lymphoma: a reclassification of ocular adnexal large B-cell lymphoma

AIMS

To (1) reclassify ocular adnexal large B-cell lymphomas (OA-LBCLs) per 2016 WHO lymphoma classification and (2) determine the prevalence of MYD88 and CD79B mutations and their association with clinical parameters among OA-LBCLs.

METHODS

This study is a retrospective analysis of all OA-LBCLs diagnosed in Denmark between 1980 and 2018. Medical records and tissue samples were retrieved. Thirty-four OA-LBCLs were included. Fluorescence in situ hybridisation and Epstein-Barr-encoded RNA in situ hybridisation were used for the reclassification. Mutational status was established by allele-specific PCR and confirmed by Sanger sequencing. Primary endpoints were overall survival, disease-specific survival (DSS) and progression-free survival (PFS).

RESULTS

Two LBCL subtypes were identified: diffuse large B-cell lymphoma (DLBCL) (27 of 32; 84%) and high-grade B-cell lymphoma (HGBL) with MYC and BCL2 and/or BCL6 rearrangements (5 of 32; 16%). cMYC/BCL2 double-expressor DLBCLs had a poorer DSS than non-double-expressor DLBCLs (5-year DSS, 25% vs 78%) (HR 0.23; 95% CI 0.06 to 0.85; p=0.014). MYD88 mutations were present in 10 (29%) of 34 lymphomas and carried a poorer PFS than wild-type cases (5-year PFS, 0% vs 43%) (HR 0.78; 95% CI 0.61 to 0.98; p=0.039). CD79B mutations were present in 3 (9%) of 34 cases.

CONCLUSION

OA-LBCL consists mainly of two subtypes: DLBCL and HGBL with MYC and BCL2 and/or BCL6 rearrangements. MYD88 mutations are important drivers of OA-LBCL. MYD88 mutations, as well as cMYC/BCL2 double-expressor DLBCL, appear to be associated with a poor prognosis. Implementing MYD88 mutational analysis in routine diagnostics may improve OA-LBCL prognostication.

Transcriptome Analysis of Diffuse Large B-Cell Lymphoma Cells Inducibly Expressing MyD88 L265P Mutation Identifies Upregulated CD44, LGALS3, NFKBIZ, and BATF as Downstream Targets of Oncogenic NF-κB Signaling

During innate immune responses, myeloid differentiation primary response 88 (MyD88) functions as a critical signaling adaptor protein integrating stimuli from toll-like receptors (TLR) and the interleukin-1 receptor (IL-1R) family and translates them into specific cellular outcomes. In B cells, somatic mutations in MyD88 trigger oncogenic NF-κB signaling independent of receptor stimulation, which leads to the development of B-cell malignancies. However, the exact molecular mechanisms and downstream signaling targets remain unresolved. We established an inducible system to introduce MyD88 to lymphoma cell lines and performed transcriptomic analysis (RNA-seq) to identify genes differentially expressed by MyD88 bearing the L265P oncogenic mutation. We show that MyD88L265P activates NF-κB signaling and upregulates genes that might contribute to lymphomagenesis, including CD44, LGALS3 (coding Galectin-3), NFKBIZ (coding IkBƺ), and BATF. Moreover, we demonstrate that CD44 can serve as a marker of the activated B-cell (ABC) subtype of diffuse large B-cell lymphoma (DLBCL) and that CD44 expression is correlated with overall survival in DLBCL patients. Our results shed new light on the downstream outcomes of MyD88L265P oncogenic signaling that might be involved in cellular transformation and provide novel therapeutical targets.

Plasma Cell Leukemia with Successful Upfront Venetoclax in Combination with Allogeneic Transplantation

BACKGROUND Plasma cell leukemia (PCL) is an aggressive form of plasma cell neoplasm. We report the first case of primary PCL successfully treated with upfront novel agents consisting of Venetoclax and daratumumab in combination with intensive chemotherapy and allogeneic transplantation. CASE REPORT A 59-year-old woman presented with epistaxis, gum bleeding, and blurred vision. On examination, she appeared pale, with multiple petechiae and hepatomegaly. Fundoscopy revealed retinal hemorrhages. Laboratory investigations revealed bicytopenia and leukocytosis, with mild coagulopathy and hypofibrinogenemia. Elevated globulin and calcium levels were also observed. Serum protein electrophoresis demonstrated IgG lambda paraproteinemia, with a serum-free light chain kappa-to-lambda ratio of 0.074. A skeletal survey revealed the presence of lytic lesions. Bone marrow investigations confirmed the presence of lambda-light-chain-restricted clonal plasma cells. FISH detected t(11;14) and 17p13.1 deletion. Therefore, a final diagnosis of primary PCL was made. The patient received 1 cycle of bortezomib, cyclophosphamide, and dexamethasone (VCD) and 5 cycles of Venetoclax-VCD, followed by an unsuccessful stem cell mobilization. One cycle of daratumumab in combination with bortezomib, lenalidomide, and dexamethasone (VRD) was then given. The patient achieved complete remission. She underwent allogeneic stem cell transplantation of an HLA-matched sibling donor. Post-transplant marrow assessment showed disease remission and absence of t(11;14) and 17p deletions. She was administered pamidronate and lenalidomide maintenance. She remained clinically well with a good performance status and no active graft-versus-host disease 18 months after transplant. CONCLUSIONS The success of our patient in achieving complete remission has highlighted the efficacy and safety of this novel therapy in the front-line management of PCL.

Genetic and Clinical Characteristics of Korean Chronic Lymphocytic Leukemia Patients with High Frequencies of MYD88 Mutations

Chronic lymphocytic leukemia (CLL) is the most common adult leukemia in Western countries. However, CLL is relatively rare in Asia; its genetic features are rarely studied. Here, we aimed to genetically characterize Korean CLL patients and to elucidate the genetic and clinical associations based on data obtained from 113 patients at a single Korean institute. We used next-generation sequencing to explore the multi-gene mutational data and immunoglobulin heavy chain variable gene clonality with somatic hypermutation (SHM). MYD88 (28.3%), including L265P (11.5%) and V217F (13.3%), was the most frequently mutated gene, followed by KMT2D (6.2%), NOTCH1 (5.3%), SF3B1 (5.3%), and TP53 (4.4%). MYD88-mutated CLL was characterized by SHM and atypical immunophenotype with fewer cytogenetic abnormalities. The 5-year time to treatment (TTT) of the overall cohort was 49.8% ± 8.2% (mean ± standard deviation) and the 5-year overall survival was 86.2% ± 5.8%. Patients with SHM, isolated del(13q), TP53-wild type, and NOTCH1-wild type showed better results than those without these conditions. In the subgroup analyses, patients with SHM and L265P presented shorter TTT than patients with SHM but not L265P. In contrast, V217F was associated with a higher SHM percentage and showed a favorable prognosis. Our study revealed the distinct characteristics of Korean CLL patients with high frequencies of MYD88 mutations and their clinical relevance.

Aqueous Humor-Derived MYD88 L265P Mutation Analysis in Vitreoretinal Lymphoma: A Potential Less Invasive Method for Diagnosis and Treatment Response Assessment

PURPOSE

To investigate whether MYD88 L265P mutation, which is frequently present in vitreoretinal lymphoma, can be detected in aqueous humor, a specimen that can be obtained in a clinic setting, potentially mitigating the need for more invasive vitrectomy procedures, and whether this approach can be used to monitor treatment response.

DESIGN

Observational case series.

SUBJECTS

Patients who were diagnosed with biopsy-confirmed or clinically diagnosed vitreoretinal lymphoma or biopsy-confirmed vitritis.

METHODS

We evaluated aqueous humor-derived (AHD) MYD88 L265P mutation during vitreous biopsy or at the initial presentation in the clinic if vitreous biopsy was not feasible. Demographic or clinical features of patients were retrospectively reviewed. Aqueous humor-derived MYD88 L265P mutation was re-evaluated after patients completed a course of intravitreal methotrexate and rituximab injection therapy. The NM_002468.4: c.794T>C (p.L265P) mutation in the MYD88 gene was evaluated in AHD cellular and cell-free DNA using allele-specific polymerase chain reaction.

MAIN OUTCOME MEASURES

Detection of AHD MYD88 L265P mutation at the initial diagnosis and to monitor the treatment response.

RESULTS

Aqueous humor from 18 eyes of 14 patients with biopsy-confirmed or clinically diagnosed vitreoretinal lymphoma and 3 eyes of 3 patients with biopsy-confirmed vitritis were evaluated. Aqueous humor-derived MYD88 L265P mutation was detected in cell-based and cell-free DNA from 15 (83%) of 18 eyes with biopsy-confirmed or clinically diagnosed vitreoretinal lymphoma but not identified in any of the 3 eyes with vitritis. The mutation was less readily detectable in cellular DNA (10 of 18) compared with cell-free DNA (15 of 18). Furthermore, aqueous sampling after intravitreal methotrexate and rituximab injection therapy revealed absence of this mutation after complete response in 7 eyes. The mutation was detected in 1 eye that developed recurrence in a posttreatment window of 6 months. After a mean of follow-up of 9 months, there was no clinical evidence of vitreoretinal lymphoma recurrence in the 7 eyes with no detectable AHD MYD88 L265P mutation.

CONCLUSIONS

This investigational study suggests that AHD MYD88 L265P can be detected in eyes with lymphoma and may thus serve as a surrogate, less invasive biopsy in the diagnosis and follow-up of vitreoretinal lymphoma, particularly when cell-free DNA is evaluated.

B cell receptor (BCR) endocytosis

The B cell receptor (BCR) interacts with foreign antigens to mediate B cell activation and secretion of antibodies. B cell activation begins with initiation of signaling pathways, such as NFAT, NF-κB, and MAPK, and endocytosis of the BCR-antigen complex. Many studies have investigated the signaling pathways associated with BCR activation, and this work has led to significant advances in drug therapies to treat cancer and autoimmune diseases that are linked to aberrant BCR signaling. Less is known, however, about the mechanisms of BCR endocytosis and the role endocytosis plays in B cell pathogenesis. This chapter will review key characteristics of the BCR, including a review of signaling pathways, and endocytic mechanisms associated with the activated BCR. We will also review recent studies investigating the role of BCR endocytosis disease pathogenesis.

MYD88 L265P Mutation Detection by ddPCR: Recommendations for Screening and Minimal Residual Disease Monitoring : ddPCR for Highly Sensitive Detection of MYD88 L265P Mutation

MYD88^L265P is a gain-of-function mutation, arising from the missense alteration c.794T>C, that frequently occurs in B-cell malignancies such as Waldenstrom macroglobulinemia and less frequently in IgM monoclonal gammopathy of undetermined significance (IgM-MGUS) or other lymphomas. MYD88^L265P has been recognized as a relevant diagnostic flag, but also as a valid prognostic and predictive biomarker, as well as an investigated therapeutic target. Up until now, allele-specific quantitative PCR (ASqPCR) has been widely used for MYD88^L265P detection providing a higher level of sensitivity than Sanger sequencing. However, the recently developed droplet digital PCR (ddPCR) shows a deeper sensitivity, compared to ASqPCR, that is necessary for screening low infiltrated samples. Actually, ddPCR could represent an improvement in daily laboratory practice since it allows mutation detection in unselected tumor cells, allowing to bypass the time-consuming and costly B-cell selection procedure. ddPCR accuracy has been recently proved to be suitable also for mutation detection in "liquid biopsy" samples that might be used as a noninvasive and patient-friendly alternative to bone marrow aspiration especially during the disease monitoring. The relevance of MYD88^L265P, both in daily management of patients and in prospective clinical trials investigating the efficacy of novel agents, makes crucial to find a sensitive, accurate, and reliable molecular technique for mutation detection. Here, we propose a protocol for MYD88^L265P detection by ddPCR.

Clinical significance of MYD88 non-L265P mutations in diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is a group of heterogeneous tumors with different molecular traits and clinical features. MYD88 is an oncogene that activates the nuclear factor κB pathway in DLBCL. MYD88 L265P mutation frequently occurs in DLBCL with poor prognosis, while the clinical significance of non-L265P mutations needs to be clarified. Next-generation sequencing was performed on a cohort of 356 patients with DLBCL to investigate the impact of MYD88 mutation. Ten MYD88 mutated variants were detected in 32% (114/356) of the cases. V217F, S219C, S222R, M232T, S243N, and T294P were identified as pathogenic variants. MYD88 non-L265P mutations occurred less than L265P mutation in DLBCL of the central nervous system and breast tissue. The coexistence of MYD88 non-L265P mutations with PIM1 mutation was also less than that of L265P mutation. The progression-free survival in patients with DLBCL with MYD88 non-L265P mutation was statistically better than in patients with MYD88 L265P mutation. The interpretation of variants of MYD88 mutation offers a precise guide for the management of DLBCL.

Evidence-based review of genomic aberrations in diffuse large B cell lymphoma, not otherwise specified (DLBCL, NOS): Report from the cancer genomics consortium lymphoma working group

Diffuse large B cell lymphoma, not otherwise specified (DLBCL, NOS) is the most common type of non-Hodgkin lymphoma (NHL). The 2016 World Health Organization (WHO) classification defined DLBCL, NOS and its subtypes based on clinical findings, morphology, immunophenotype, and genetics. However, even within the WHO subtypes, it is clear that additional clinical and genetic heterogeneity exists. Significant efforts have been focused on utilizing advanced genomic technologies to further subclassify DLBCL, NOS into clinically relevant subtypes. These efforts have led to the implementation of novel algorithms to support optimal risk-oriented therapy and improvement in the overall survival of DLBCL patients. We gathered an international group of experts to review the current literature on DLBCL, NOS, with respect to genomic aberrations and the role they may play in the diagnosis, prognosis and therapeutic decisions. We comprehensively surveyed clinical laboratory directors/professionals about their genetic testing practices for DLBCL, NOS. The survey results indicated that a variety of diagnostic approaches were being utilized and that there was an overwhelming interest in further standardization of routine genetic testing along with the incorporation of new genetic testing modalities to help guide a precision medicine approach. Additionally, we present a comprehensive literature summary on the most clinically relevant genomic aberrations in DLBCL, NOS. Based upon the survey results and literature review, we propose a standardized, tiered testing approach which will help laboratories optimize genomic testing in order to provide the maximum information to guide patient care.

Mutation profile of diffuse large B-cell lymphoma with relapses in the central nervous system

Introduction. The recurrence of diffuse large B-cell cell lymphoma in the central nervous system in the vast majority of cases is a fatal manifestation of the disease. The study of the lymphoma mutational profile can improve the accuracy of the prognosis of relapse in the central nervous system and justify the selection of patients for preventive treatment. Aim. To evaluate the mutational profile of cases of diffuse large B-cell cell lymphoma with central nervous system damage in relapse based on the results of our own experiment on high-performance sequencing.

Materials and methods. On the Illumina platform, full-exome sequencing of diagnostic samples of diffuse large B-cell cell lymphoma with relapses in the central nervous system was performed. A panel including more than 70 genes was analyzed.

Results. Four main groups of genetic events can be distinguished in the group of studied samples, namely: combined mutations in the NF-kB (MYD88, NOTCH1, CD79B, CARD11) and JAK-STAT (PIM1, STAT6) signaling pathways, as well as aberrations in the main oncosuppressor TP53 and chromatin remodeling system genes (ARID1A, KMT2D, EP300, SMARCA4). A recurrent mutation c. 794T>C, p.L265P MYD88 was detected in the study group. Among other findings, mutations in the CIITA and CD58 genes should be noted, which are important in avoiding tumor cells from immune surveillance.

Conclusion. Despite the apparent heterogeneity of the mutational profile of diffuse large B-cell cell lymphoma with relapses in the central nervous system, in most cases, tumor cells were characterized by genetic disorders leading to the production of a large number of pro-inflammatory cytokines by malignant lymphocytes, as well as aberrations that reduce immunogenicity and contribute to the avoidance of immune surveillance by the tumor.

Primary Vitreoretinal Lymphoma: Current Diagnostic Laboratory Tests and New Emerging Molecular Tools

Primary vitreoretinal lymphoma (PVRL), a rare aggressive malignancy primarily involving the retina and/or the vitreous, is a major diagnostic challenge for clinicians (who commonly misdiagnose it as chronic uveitis) as well as for pathologists (for biological and technical reasons). Delays in diagnosis and treatment are responsible for visual impairments and life-threatening consequences, usually related to central nervous system involvement. The identification of lymphoma cells in vitreous fluid, obtained by vitrectomy, is required for diagnosis. Of note, the scarcity of neoplastic cells in small volumes of vitreous sample, and the fragility of lymphoma cells with degenerative changes caused by previous steroid use for presumed uveitis makes diagnosis based on cytology plus immunophenotyping difficult. Interleukin levels, immunoglobulin heavy chain or T-cell receptor gene rearrangements, and MYD88 mutation are applied in combination with cytology to support diagnosis. We aim to describe the current laboratory technologies for PVRL diagnosis, focusing on the main issues that these methods have. In addition, new emerging diagnostic strategies, such as next-generation sequencing analysis, are discussed. The genetic profile of PVRL remains largely unexplored. Better knowledge of genetic alterations is critical for precision medicine interventions with target-based treatments of this lymphoma for which no standardised treatment protocol currently exists.

Update in Molecular Testing for Intraocular Lymphoma

The diagnosis of primary vitreoretinal lymphoma and central nervous system lymphoma is challenging. In cases with intraocular involvement, vitreous biopsy plays a pivotal role. Several diagnostic tests are employed to confirm a diagnosis and include cytologic evaluation, immunohistochemistry, flow cytometry, and cytokine analysis. The limitations of these conventional diagnostic tests stem from the often paucicellular nature of vitreous biopsy specimens and the fragility of malignant cells ex vivo. Several emerging molecular techniques show promise in improving the diagnostic yield of intraocular biopsy, possibly enabling more accurate and timely diagnoses. This article will review existing diagnostic modalities for intraocular lymphoma, with an emphasis on currently available molecular tests.

Butyrate-producing Eubacterium rectale suppresses lymphomagenesis by alleviating the TNF-induced TLR4/MyD88/NF-κB axis

Microbiota-induced tumorigenesis is well established in solid tumors of the gastrointestinal tract but rarely explored in hematologic malignancies. To determine the role of gut microbiota in lymphoma progression, we performed metagenomic sequencing on human primary gastrointestinal B cell lymphomas. We identified a distinct microbiota profile of intestinal lymphoma, with significantly decreased symbiotic microbes, particularly the genus Eubacterium and notably butyrate-producing Eubacterium rectale. Transfer of E. rectale-deficit microbiota of intestinal lymphoma patients to mice caused inflammation and tumor necrosis factor (TNF) production. Conversely, E. rectale treatment reduced TNF levels and the incidence of lymphoma in sensitized Eμ-Myc mice. Moreover, lipopolysaccharide from the resident microbiota of lymphoma patients and mice synergizes with TNF signaling and reinforces the NF-κB pathway via the MyD88-dependent TLR4 signaling, amalgamating in enhanced intestinal B cell survival and proliferation. These findings reveal a mechanism of inflammation-associated lymphomagenesis and a potential clinical rationale for therapeutic targeting of gut microbiota.

Occurrence of MYD88L265P and CD79B mutations in diffuse large b cell lymphoma with bone marrow infiltration: A case report

BACKGROUND

Over the past 20 years, we have gained a deep understanding of the biological heterogeneity of diffuse large B cell lymphoma (DLBCL) and have developed a range of new treatment programs based on the characteristics of the disease, bringing us to the era of immune-chemotherapy. However, the effectiveness and molecular mechanisms of targeted-immunotherapy remain unclear in DLBCL. Targeted-immunotherapy may be beneficial for specific subgroups of patients, thus requiring biomarker assessment.

CASE SUMMARY

Here, we report a case of MCD subtype DLBCL with MYD88L265P and CD79B mutations, considered in the initial stage as lymphoplasmic lymphoma (LPL) or Waldenstrom macroglobulinemia (WM). Flow cytometry supported this view; however, the immunohistochemical results of the lymph nodes overturned the above diagnosis, and the patient was eventually diagnosed with MCD subtype DLBCL. The presence of a monoclonal IgM component in the serum and infiltration of small lymphocytes with a phenotype compatible with WM into the bone marrow led us to propose a hypothesis that the case we report may have transformed from LPL/WM.

CONCLUSION

This highlights the possible transformation from WM to DLBCL, CD79B mutation may be a potential biomarker for predicting this conversion.

[Distribution and prognostic value of LymphGen genotyping in patients with diffuse large B-cell lymphoma]

Objective: To investigate the distribution characteristics of LymphGen genotyping in a diffuse large B-cell lymphoma (DLBCL) population and verify its prognostic value. Methods: We collected the clinical data and paraffin-embedded tumor tissue samples of 155 patients with newly diagnosed DLBCL in the People's Hospital of Xinjiang Uygur Autonomous Region from June 2014 to December 2020. DNA was extracted from tumor tissue and 475 gene mutations were detected by next-generation sequencing technology. We investigated the distribution of LymphGen genotyping in the DLBCL population, patients with different COO genotypes in the Xinjiang region, and their effects on PFS and OS. Results: ①Among 155 patients, 105 patients (67.7%) could be genotyped, including 14 (9.0%) for MCD, 26 (16.8%) for BN2, 10 (6.5%) for N1, 8 (5.2%) for EZB, 27 (17.4%) for A53, and 20 (12.9%) for ST2. ②The distribution of each gene subtype was different in different cell origin (COO) types (P=0.021) . ST2 was dominant in the germinal center type (GCB) group (28.8%) , and A53 and MCD were dominant in the non-GCB group (35.8%, 17.0%) . The BN2 type was the most common in both groups (23.1%, 26.4%) . ③There were statistically significant differences in progression-free survival (PFS) and overall survival (OS) among different gene subtypes (P=0.031 and 0.005, respectively) . N1 and A53 had poor prognosis. The 2-year PFS and OS rates of N1 were both (21.3±18.4) %, and the 3-year PFS and OS rates of A53 were (60.9±11.3) %, (46.8±10.9) %, respectively. ④ The 3-year PFS and OS rates of MCD were the best, but the 5-year PFS and OS rates were worse. ⑤In the ROC curve of LymphGen genotyping for OS prediction, the AUC was 0.66, showing a certain degree of differentiation. Conclusion: LymphGen genotyping in the DLBCL population was different from previous reports and was of great significance for the prognosis of patients with DLBCL.

From Biology to Treatment of Monoclonal Gammopathies of Neurological Significance

Monoclonal gammopathy and peripheral neuropathy are common diseases of elderly patients, and almost 10% of patients with neuropathy of unknown cause have paraprotein. However, growing evidence suggests that several hematological malignancies synthesize and release monoclonal proteins that damage the peripheral nervous system through different mechanisms. The spectrum of the disease varies from mild to rapidly progressive symptoms, sometimes affecting not only sensory nerve fibers, but also motor and autonomic fibers. Therefore, a multidisciplinary approach, mainly between hematologists and neurologists, is recommended in order to establish the correct diagnosis of monoclonal gammopathy of neurological significance and to tailor therapy based on specific genetic mutations. In this review, we summarize the spectrum of monoclonal gammopathies of neurological significance, their distinctive clinical and neurophysiological phenotypes, the most relevant pathophysiological events and new therapeutic approaches.

Preneoplastic somatic mutations including MYD88L265P in lymphoplasmacytic lymphoma

Normal cell counterparts of solid and myeloid tumors accumulate mutations years before disease onset; whether this occurs in B lymphocytes before lymphoma remains uncertain. We sequenced multiple stages of the B lineage in elderly individuals and patients with lymphoplasmacytic lymphoma, a singular disease for studying lymphomagenesis because of the high prevalence of mutated MYD88. We observed similar accumulation of random mutations in B lineages from both cohorts and unexpectedly found MYD88^L265P in normal precursor and mature B lymphocytes from patients with lymphoma. We uncovered genetic and transcriptional pathways driving malignant transformation and leveraged these to model lymphoplasmacytic lymphoma in mice, based on mutated MYD88 in B cell precursors and BCL2 overexpression. Thus, MYD88^L265P is a preneoplastic event, which challenges the current understanding of lymphomagenesis and may have implications for early detection of B cell lymphomas.

Ibrutinib in Refractory or Relapsing Primary Central Nervous System Lymphoma: A Systematic Review

Primary Central Nervous System Lymphoma (PCNSL) is a rare variant of Non-Hodgkin Lymphoma (NHL) representing 1–2% of all NHL cases. PCNSL is defined as a lymphoma that occurs in the brain, spinal cord, leptomeninges, or eyes. Efforts to treat PCNSL by traditional chemotherapy and radiotherapy have generally been unsuccessful as a significant proportion of patients have frequent relapses or are refractory to treatment. The prognosis of patients with Refractory or Relapsed (R/R) PCNSL is abysmal. The optimal treatment for R/R PCNSL is poorly defined as there are only a limited number of studies in this setting. Several studies have recently shown that ibrutinib, a Bruton tyrosine kinase (BTK) inhibitor, has promising results in the treatment of R/R PCNSL. However, these are preliminary studies with a limited sample size. In this systematic review, we explored and critically appraised the evidence about the efficacy of the novel agent ibrutinib in treating R/R PCNSL.

CD5-Negative, CD10-Negative Low-Grade B-Cell Lymphoproliferative Disorders of the Spleen

CD5-negative, CD10-negative low-grade B-cell lymphoproliferative disorders (CD5-CD10-LPD) of the spleen comprise a fascinating group of indolent, neoplastic, mature B-cell proliferations that are essential to accurately identify but can be difficult to diagnose. They comprise the majority of B-cell LPDs primary to the spleen, commonly presenting with splenomegaly and co-involvement of peripheral blood and bone marrow, but with little to no involvement of lymph nodes. Splenic marginal zone lymphoma is one of the prototypical, best studied, and most frequently encountered CD5-CD10-LPD of the spleen and typically involves white pulp. In contrast, hairy cell leukemia, another well-studied CD5-CD10-LPD of the spleen, involves red pulp, as do the two less common entities comprising so-called splenic B-cell lymphoma/leukemia unclassifiable: splenic diffuse red pulp small B-cell lymphoma and hairy cell leukemia variant. Although not always encountered in the spleen, lymphoplasmacytic lymphoma, a B-cell lymphoproliferative disorder consisting of a dual population of both clonal B-cells and plasma cells and the frequent presence of the MYD88 L265P mutation, is another CD5-CD10-LPD that can be seen in the spleen. Distinction of these different entities is possible through careful evaluation of morphologic, immunophenotypic, cytogenetic, and molecular features, as well as peripheral blood and bone marrow specimens. A firm understanding of this group of low-grade B-cell lymphoproliferative disorders is necessary for accurate diagnosis leading to optimal patient management.

Protein overexpression of toll-like receptor 4 and myeloid differentiation factor 88 in oral squamous cell carcinoma and clinical significance

Oral squamous cell carcinoma (OSCC) is the most common type of malignancy of the head and neck. In the present study, the expression of Toll-like receptor 4 (TLR4) and myeloid differentiation primary response gene 88 (MyD88) was evaluated in 55 OSCC tissues and their corresponding adjacent tissues using immunohistochemistry and reverse-transcription quantitative PCR. The results indicated that TLR4 and MyD88 were overexpressed in OSCC. Furthermore, high expression of MyD88 was negatively associated with a poor degree of differentiation, recurrence and metastasis of the tumor and was positively associated with underlying disease, including hypertension, heart disease and diabetes mellitus. Furthermore, high expression of TLR4 was positively associated with a long growth time of the tumor. In conclusion, the present study evaluated the expression levels of TLR4 and MyD88 in OSCC, as well as the association between them and clinicopathological factors, to provide markers for the prognosis and treatment of OSCC. These two genes may serve as biomarkers to optimize OSCC treatment, setting a new direction for stratifying patients and developing precise and personalized treatment regimens; the TLR4/MyD88 pathway may serve as a potential therapeutic target in the future.

Perspectives on Precision Medicine in Chronic Lymphocytic Leukemia: Targeting Recurrent Mutations-NOTCH1, SF3B1, MYD88, BIRC3

Chronic lymphocytic leukemia (CLL) is highly heterogeneous, with extremely variable clinical course. The clinical heterogeneity of CLL reflects differences in the biology of the disease, including chromosomal alterations, specific immunophenotypic patterns and serum markers. The application of next-generation sequencing techniques has demonstrated the high genetic and epigenetic heterogeneity in CLL. The novel mutations could be pharmacologically targeted for individualized approach in some of the CLL patients. Potential neurogenic locus notch homolog protein 1 (NOTCH1) signalling targeting mechanisms in CLL include secretase inhibitors and specific antibodies to block NOTCH ligand/receptor interactions. In vitro studies characterizing the effect of the splicing inhibitors resulted in increased apoptosis of CLL cells regardless of splicing factor 3B subunit 1 (SF3B1) status. Several therapeutic strategies have been also proposed to directly or indirectly inhibit the toll-like receptor/myeloid differentiation primary response gene 88 (TLR/MyD88) pathway. Another potential approach is targeting nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and inhibition of this prosurvival pathway. Newly discovered mutations and their signalling pathways play key roles in the course of the disease. This opens new opportunities in the management and treatment of CLL.

Continuous MYD88 Activation Is Associated With Expansion and Then Transformation of IgM Differentiating Plasma Cells

Activating mutations of MYD88 (MYD88^L265P being the far most frequent) are found in most cases of Waldenström macroglobulinemia (WM) as well as in various aggressive B-cell lymphoma entities with features of plasma cell (PC) differentiation, such as activated B-cell type diffuse large B-cell lymphoma (DLBCL). To understand how MYD88 activation exerts its transformation potential, we developed a new mouse model in which the MYD88^L252P protein, the murine ortholog of human MYD88^L265P, is continuously expressed in CD19 positive B-cells together with the Yellow Fluorescent Protein (Myd88^L252P mice). In bone marrow, IgM B and plasma cells were expanded with a CD138 expression continuum from IgM^high CD138^low to IgM^low CD138^high cells and the progressive loss of the B220 marker. Serum protein electrophoresis (SPE) longitudinal analysis of 40 Myd88^L252P mice (16 to 56 weeks old) demonstrated that ageing was first associated with serum polyclonal hyper gammaglobulinemia (hyper Ig) and followed by a monoclonal immunoglobulin (Ig) peak related to a progressive increase in IgM serum levels. All Myd88^L252P mice exhibited spleen enlargement which was directly correlated with the SPE profile and was maximal for monoclonal Ig peaks. Myd88^L252P mice exhibited very early increased IgM PC differentiation. Most likely due to an early increase in the Ki67 proliferation index, IgM lymphoplasmacytic (LP) and plasma cells continuously expanded with age being first associated with hyper Ig and then with monoclonal Ig peak. This peak was consistently associated with a spleen LP-like B-cell lymphoma. Clonal expression of both membrane and secreted µ chain isoforms was demonstrated at the mRNA level by high throughput sequencing. The Myd88^L252P tumor transcriptomic signature identified both proliferation and canonical NF-κB p65/RelA activation. Comparison with MYD88^L265P WM showed that Myd88^L252P tumors also shared the typical lymphoplasmacytic transcriptomic signature of WM bone marrow purified tumor B-cells. Altogether these results demonstrate for the first time that continuous MYD88 activation is specifically associated with clonal transformation of differentiating IgM B-cells. Since MYD88^L252P targets the IgM PC differentiation continuum, it provides an interesting preclinical model for development of new therapeutic approaches to both WM and aggressive MYD88 associated DLBCLs.

Transformation to diffuse large B-cell lymphoma with germinal center B-cell like subtype and discordant light chain expression in a patient with Waldenström macroglobulinemia/lymphoplasmacytic lymphoma

Waldenström macroglobulinemia (WM)/lymphoplasmacytic lymphoma (LPL) is a rare indolent B-cell neoplasm, and a gain-of-function mutation in the myeloid differentiation primary response 88 (MYD88), L265P, is a commonly recurring mutation in patients with WM/LPL. Histological transformation of WM/LPL to an aggressive lymphoma such as diffuse large B-cell lymphoma (DLBCL) is rare, and transformed DLBCL has a worse prognosis than de novo DLBCL, partly because transformed DLBCL is mostly classified as non-germinal center B-cell-like (non-GCB) subtype. We herein describe a 75-year-old man with DLBCL with a history of WM/LPL. DLBCL in this patient showed the GCB subtype, and the light chain restriction of DLBCL was different from that of the antecedent WM/LPL, indicating that the two types of lymphoma cells had distinctive origins. However, DLBCL in this patient harbored the MYD88 L265P mutation, and polymerase chain reaction and Sanger sequencing of the DLBCL and WM/LPL for immunoglobulin heavy chain gene rearrangement suggested a clonal relationship between the two lymphomas. Since the outcome of transformed DLBCL is worse than for de novo DLBCL, it is important to evaluate the clonal relationship between primary WM/LPL and the corresponding transformed DLBCL, even if the DLBCL expresses a GCB subtype or discordant light chain restriction.

Development of molecular intervention strategies for B-cell lymphoma

INTRODUCTION

There are many genetic mutations involved in B-cell lymphomagenesis. These mutations contribute to the prognosis of B-cell lymphomas and can be used for and targeted for intervention.

AREAS COVERED

This review provides an overview of targeted gene therapies for B-cell lymphoma that were newly approved or are under clinical development. These include, TP53 mutations and related pathways, such as BTK inhibitors, MDM2/4 inhibitors, and XPO1 inhibitors; new drugs targeting EZH2 mutations through competitive inhibition, such as tazemetostat and GSK126; BCL-2-targeted therapeutics, including venetoclax and ABT-263; BTK, IRAK 1/4, HCK, and myddosome complex that targets the MYD88 mutation and the related pathways. In addition, we have also discussed gene mutations that have been reported as potential therapeutic targets, such as TNFAIP3, CARD11.

EXPERT OPINION

The mechanisms underlying the role of several genetic mutations in lymphomagenesis have been reported, and several studies have designed and developed drugs targeting these mutations. Many of these drugs have been approved for clinical use, while several are still under clinical development. Recent studies have identified additional genetic mutations and gene targets for BCL-2 treatment; however, effective molecular interventions targeting these new targets are yet to be developed.

Influence of oncogenic mutations and tumor microenvironment alterations on extranodal invasion in diffuse large B-cell lymphoma

BACKGROUND

Diffuse large B-cell lymphoma (DLBCL) is an aggressive subtype of lymphoma, and multiple extranodal involvement (ENI) indicates adverse clinical outcomes. The aim of this study was to investigate the influence of oncogenic mutations and tumor microenvironment alterations on ENI in DLBCL.

METHODS

The clinical features of 1960 patients with newly diagnosed DLBCL were analyzed, and DNA and RNA sequencing was performed on 670 and 349 patients, respectively. Oncogenic mutations and tumor microenvironment alterations were compared according to ENI and evaluated in zebrafish patient-derived tumor xenograft models.

RESULTS

Multiple ENI was significantly associated with poor performance status, advanced stage, elevated serum lactate dehydrogenase, low response rate, and inferior prognosis. Lymphoma invasion of the bones, spleen, bone marrow, liver, and central nervous system were independent unfavorable prognostic factors. MYD88 was frequently mutated in patients with multiple ENI, co-occurred with mutations in CD79B, PIM1, TBL1XR1, BTG1, MPEG1, and PRDM1, and correlated with invasion of the bones, kidney/adrenal glands, breasts, testes, skin, and uterus/ovaries. For tumor microenvironment alterations, patients with multiple ENI showed higher regulatory T-cell (Treg)-recruiting activity, but lower extracellular matrix-encoding gene expression, than those without ENI and with single ENI. Elevated Treg-recruiting activity was related to mutations in B2M, SGK1, FOXO1, HIST1H1E, and ARID1A, and correlated with invasion of the bone marrow and thyroid. Additionally, mutations in MYD88, PIM1, TBL1XR1, SGK1, FOXO1, HIST1H1E, and ARID1A were associated with decreased major histocompatibility complex class I expression. Zebrafish models further revealed relationships between MYD88 mutations and invasion of the kidneys and gonads, as well as B2M mutations and invasion of the bone marrow. Increased CXCR4 expression is linked to bone marrow invasion in an organotropic way.

CONCLUSIONS

Our findings thus contribute to an improved understanding of the biological behavior of multiple ENI and provide a clinical rationale for targeting ENI in DLBCL.

Eupafolin alleviates cerebral ischemia/reperfusion injury in rats via blocking the TLR4/NF‑κB signaling pathway

Eupatorium perfoliatum L. (E. perfoliatium) has been used traditionally for treating fever, malaria and inflammation‑associated diseases. Eupafolin, the extract of E. perfoliatium, was also reported to suppress inflammation. The present study aimed to investigate the protective effects of eupafolin on cerebral ischemia/reperfusion (I/R) injury in rats and its possible underlying mechanisms. Cerebral I/R injury was induced in rats by middle cerebral artery occlusion (MCAO) for 1.5 h, followed by reperfusion. The rats were randomly assigned into six groups: Control, model, 10 mg/kg eupafolin, 20 mg/kg eupafolin, 50 mg/kg eupafolin and 20 mg/kg nimodipine. Eupafolin and nimodipine were intragastrically administrated to the rats 1 week before MCAO induction. Following reperfusion for 24 h, the neurological deficit was scored, and brain samples were harvested for evaluating encephaledema, infarct volume, oxidative stress, apoptosis, inflammation and the expression of TLR4/NF‑κB signaling. The results revealed that eupafolin decreased the neurological score, relieved encephaledema and decreased infarct volume. Eupafolin also attenuated oxidative stress, neuronal apoptosis and inflammation, with decreases in lactate dehydrogenase, malondialdehyde, TUNEL‑positive cells, Bax and caspase‑3, along with TNF‑α, IL‑1β and IL‑6, but increases in superoxide dismutase and Bcl‑2 levels. Furthermore, eupafolin may decrease the expression of TLR4 downstream proteins and proteins involved in the NF‑κB pathway. Treatment with TLR4 agonist‑LPS significantly blunted the protective effect of eupafolin on encephaledema and cerebral infarct. Meanwhile, 20 mg/kg eupafolin showed nearly equivalent effects to the positive‑control drug nimodipine. In conclusion, eupafolin protected against cerebral I/R injury in rats and the underlying mechanism may be associated with the suppression of apoptosis and inflammation via inhibiting the TLR4/ NF‑κB signaling pathway.

Oncogenic Mutations of MYD88 and CD79B in Diffuse Large B-Cell Lymphoma and Implications for Clinical Practice

Diffuse large B-cell lymphoma (DLBCL) is the most common non-Hodgkin's lymphoma in adults. Despite the recognition of transcriptional subtypes with distinct functional characteristics, patient outcomes have not been substantially altered since the advent of chemoimmunotherapy (CIT) twenty years ago. Recently, a few pivotal studies added to the disease heterogeneity by describing several activating mutations, which have been associated with disease presentation, B-cell function and behavior, and final outcome. DLBCL arises from antigen exposed B-cells, with the B-cell receptor (BCR) playing a central role. BCR-activity related mutations, such as CD79B and MYD88, are responsible for chronic activation of the BCR in a substantial subset of patients. These mutations, often coexisting in the same patient, have been found in a substantial subset of patients with immune-privileged (IP) sites DLBCLs, and are drivers of lymphoma development conferring tissue-specific homing properties. Both mutations have been associated with disease behavior, including tumor response either to CIT or to BCR-targeted therapy. The recognition of CD79B and MYD88 mutations will contribute to the heterogeneity of the disease, both in recognizing the BCR as a potential therapeutic target and in providing genetic tools for personalized treatment.

Targeting pathogenic mechanisms in marginal zone lymphoma: from concepts and beyond

Marginal zone lymphoma (MZL) represents a group of three distinct though overlapping lymphoid malignancies that includes extranodal, nodal and splenic marginal lymphoma. MZL patients usually present an indolent clinical course, although the disease remains largely incurable, save early stage disease that might be irradiated. Therapeutic advances have been limited due to the small patient population, and have largely been adapted from other indolent lymphomas. Here, we discuss the numerous targets and pathways which may offer the prospect of directly inhibiting the mechanisms identified promoting and sustaining marginal zone lymphomagenesis. In particular, we focus on the agents that may have at least a theoretical application in the disease. Various dysregulated pathways converge to produce an overarching stimulation of nuclear factor κB (NF-κB) and the MYD88-IRAK4 axis, which can be thus leveraged or targeting B-cell receptor signaling through BTK inhibitors (such as ibrutinib, zanubrutinib, acalabrutinib) and PI3K inhibitors (such as idelalisib, copanlisib, duvelisib umbralisib) or via more novel agents in development such as MALT1 inhibitors, SMAC mimetics, NIK inhibitors, IRAK4 or MYD88 inhibitors. NOTCH signaling is also crucial for marginal zone cells, but no clinical data are available with NOTCH inhibitors such as the γ-secretase inhibitor PF-03084014 or the NICD inhibitor CB-103. The hypermethylation phenotype, the overexpression of the PRC2-complex or the presence of TET2 mutations reported in MZL subsets make epigenetic agents (demethylating agents, EZH2 inhibitors, HDAC inhibitors) also potential therapeutic tools for MZL patients.