Targetable genetic features of primary testicular and primary central nervous system lymphomas

Novel Therapies for Primary Central Nervous System Lymphomas

PURPOSE OF REVIEW

Primary Central Nervous System Lymphoma (PCNSL) is an aggressive form of lymphoma that can involve the brain, spinal cord, leptomeninges and eyes. PCNSL prognosis continues to be poor, with 5-year survival rates of 30-40%. Therapeutic options are especially limited for relapsed/refractory (r/r) PCNSL. In recent years, studies shed light on the pathogenesis and oncogenic pathways driving PCNSL, leading to the development of novel therapeutics. In this review, we discuss the evidence supporting these novel agents and present ongoing clinical studies.

RECENT FINDINGS

Key oncogenic drivers of PCNSL include activation of the NFkB pathway, cell cycle dysregulation, somatic hypermutation and immune evasion, leading to the investigation of targeted therapeutics and immunotherapeutics to inhibit these pathways. Such approaches include BTK inhibitors, mTOR/PI3K inhibitors, immunomodulatory agents (IMIDs), immune checkpoint inhibitors and CD19-based CAR T-cells. The therapeutic repertoire for PCNSL is rapidly evolving, and a multi-modality approach including intensive chemotherapy regimens and novel therapies will likely be utilized in the future.

Identification, risk factors, and clinical course of CNS relapse in DLBCL patients across 19 prospective phase 2 and 3 trials-a LYSA and GLA/ DSHNHL collaboration

Progression or relapse in the central nervous system (CNS) remains a rare but mostly fatal event for patients with diffuse large B-cell lymphoma (DLBCL). In a retrospective analysis of 5189 patients treated within 19 prospective German and French phase 2/3 trials, we identified 159 patients experiencing a CNS event (relapse: 62%, progression: 38%). Intracerebral, meningeal, intraspinal, or combined involvement was reported in 44%, 31%, 3%, and 22% of patients, respectively. 62 of 155 evaluable patients (40%) showed concurrent systemic progression/ relapse. 82% of all CNS events occurred within two years after study inclusion or randomization. 87% of patients showed extranodal involvement outside the CNS. Patients generally had poor outcomes with a median overall survival (OS) of 3.4 months (95% CI 2.9-4.2) and a 2-year OS of 15% (10-22%). Outcomes did not differ depending on the site or time point of CNS events. Patients with isolated CNS events demonstrated significantly better OS (p = 0.023). Twenty-five patients were consolidated with autologous or allogeneic stem cell transplantation and achieved a 3-year OS of 36% (20-66%). This large study including more than 5000 DLBCL patients highlights the unmet medical need to improve the outcome of DLBCL patients suffering from CNS relapse.

Testicular large B-cell lymphoma is genetically similar to PCNSL and distinct from nodal DLBCL

Testicular large B-cell lymphoma (TLBCL) is an infrequent and aggressive lymphoma arising in an immune-privileged site and has recently been recognized as a distinct entity from diffuse large B-cell lymphoma (DLBCL). We describe the genetic features of TLBCL and compare them with published series of nodal DLBCL and primary large B-cell lymphomas of the CNS (PCNSL). We collected 61 patients with TLBCL. We performed targeted next-generation sequencing, copy number arrays, and fluorescent in situ hybridization to assess chromosomal rearrangements in 40 cases with available material. Seventy percent of the cases showed localized stages. BCL6 rearrangements were detected in 36% of cases, and no concomitant BCL2 and MYC rearrangements were found. TLBCL had fewer copy number alterations (p < 0.04) but more somatic variants (p < 0.02) than nodal DLBCL and had more frequent 18q21.32-q23 (BCL2) gains and 6q and 9p21.3 (CDKN2A/B) deletions. PIM1, MYD88 L265P , CD79B, TBL1XR1, MEF2B, CIITA, EP300, and ETV6 mutations were more frequent in TLBCL, and BCL10 mutations in nodal DLBCL. There were no major genetic differences between TLBCL and PCNSL. Localized or disseminated TLBCL displayed similar genomic profiles. Using LymphGen, the majority of cases were classified as MCD. However, we observed a subgroup of patients classified as BN2, both in localized and disseminated TLBCL, suggesting a degree of genetic heterogeneity in the TLBCL genetic profile. TLBCL has a distinctive genetic profile similar to PCNSL, supporting its recognition as a separate entity from DLBCL and might provide information to devise targeted therapeutic approaches.

Sintilimab (anti-PD-1 antibody) combined with high-dose methotrexate, temozolomide, and rituximab (anti-CD20 antibody) in primary central nervous system lymphoma: a phase 2 study

Primary central nervous system lymphoma (PCNSL) is a rare and frequently fatal lymphoma subtype. The programmed death-1 (PD-1) pathway has emerged as a potential therapeutic target, but the effectiveness of PD-1 antibody sintilimab in combination with immunochemotherapy as a frontline treatment for PCNSL remains to be determined. In this phase 2 trial (ChiCTR1900027433) with a safety run-in, we included patients aged 18-70 with newly diagnosed PCNSL. Participants underwent six 21-day cycles of a SMTR regimen, which includes sintilimab (200 mg, Day 0), rituximab (375 mg/m2, Day 0), methotrexate (3.0 g/m2, Day 1 or 1.0 g/m2 for patients aged ≥65 years), and temozolomide (150 mg/m2/d, Days 1-5). Among 27 evaluable patients, the overall response rate (ORR) was 96.3% (95% confidence interval: 81-99.9%), with 25 complete responses. At a median follow-up of 24.4 months, the medians for duration of response, progression-free survival (PFS), and overall survival were not reached. The most common grade 3-4 treatment-related toxicities were increased levels of alanine aminotransferase (17.9%) and aspartate aminotransferase (14.3%). Additionally, baseline levels of interferon-α and the IL10/IL6 ratio in cerebrospinal fluid emerged as potential predictors of PFS, achieving areas under the curve of 0.88 and 0.84, respectively, at 2 years. Whole-exome sequencing revealed a higher prevalence of RTK-RAS and PI3K pathway mutations in the durable clinical benefit group, while a greater frequency of Notch and Hippo pathway mutations in the no durable benefit group. These findings suggest the SMTR regimen is highly efficacious and tolerable for newly diagnosed PCNSL, warranting further investigation.

Molecular Determinants of Sensitivity to Polatuzumab Vedotin in Diffuse Large B-Cell Lymphoma

Polatuzumab vedotin (Pola-V) is an antibody-drug conjugate directed to the CD79B subunit of the B-cell receptor (BCR). When combined with conventional immunochemotherapy, Pola-V improves outcomes in diffuse large B-cell lymphoma (DLBCL). To identify determinants of Pola-V sensitivity, we used CRISPR-Cas9 screening for genes that modulated Pola-V toxicity for lymphomas or the surface expression of its target, CD79B. Our results reveal the striking impact of CD79B glycosylation on Pola-V epitope availability on the lymphoma cell surface and on Pola-V toxicity. Genetic, pharmacological, and enzymatic approaches that remove sialic acid from N-linked glycans enhanced lymphoma killing by Pola-V. Pola-V toxicity was also modulated by KLHL6, an E3 ubiquitin ligase that is recurrently inactivated in germinal center derived lymphomas. We reveal how KLHL6 targets CD79B for degradation in normal and malignant germinal center B cells, thereby determining expression of the surface BCR complex. Our findings suggest precision medicine strategies to optimize Pola-V as a lymphoma therapeutic. Significance: These findings unravel the molecular basis of response heterogeneity to Pola-V and identify approaches that might be deployed therapeutically to enhance the efficacy of CD79B-specific tumor killing. In addition, they reveal a novel post-translational mechanism used by normal and malignant germinal center B cells to regulate expression of the BCR. See related commentary by Leveille, p. 1577 See related article by Meriranta et al.

Systemic diffuse large B-cell lymphoma involving the central nervous system has high rates of defective antigen presentation and immune surveillance

Not available.

Clinical Presentation, Management, and Outcome in Neurolymphomatosis: A Systematic Review

BACKGROUND AND OBJECTIVES

Neurolymphomatosis (NL) refers to lymphomatous infiltration of the peripheral nervous system (PNS). NL diagnosis and treatment are challenging given the broad differential diagnosis of peripheral neuropathy, the lack of larger cohorts, and the subsequent unavailability of prognostic factors or consensus therapy. This study aimed to define characteristics and prognostic factors of NL.

METHODS

A systematic review of the literature (2004-2023) was performed using PubMed and Scopus databases and reported following PRISMA guidelines. Studies reporting individual patient data on cases with definitive NL diagnosis were included. Clinical, radiologic, pathologic, and outcome information were extracted. Univariable and multivariable survival analyses were performed using log-rank tests and Cox proportional hazard models.

RESULTS

A total of 459 NL cases from 264 studies were accumulated. NL was the first manifestation of malignancy (primary NL) in 197 patients. PNS relapse of known non-Hodgkin lymphoma (secondary NL) occurred in 262 cases after a median 12 months. NL predominantly presented with rapidly deteriorating, asymmetric painful polyneuropathy. Infiltrated structures included peripheral nerves (56%), nerve roots (52%), plexus (33%), and cranial nerves (32%). Diagnosis was established at a median of 3 months after symptom onset with substantial delays in primary NL. It mainly relied on PNS biopsy or FDG-PET, which carried high diagnostic yields (>90%). Postmortem diagnoses were rare (3%). Most cases were classified as B-cell (90%) lymphomas. Tumor-directed therapy was administered in 96% of patients and typically consisted of methotrexate or rituximab-based polychemotherapy. The median overall survival was 18 months. Primary NL without concurrent systemic disease outside the nervous system (hazard ratio [HR]: 0.44; 95% CI 0.25-0.78; p = 0.005), performance status (ECOG <2, HR: 0.30; 95% CI 0.18-0.52; p < 0.0001), and rituximab-based treatment (HR: 0.46; 95% CI 0.28-0.73; p = 0.001) were identified as favorable prognostic markers on multivariable analysis when adjusting for clinical and sociodemographic parameters.

DISCUSSION

Advances in neuroimaging modalities, particularly FDG-PET, facilitate NL diagnosis and offer a high diagnostic yield. Yet, diagnostic delays in primary NL remain common. Rituximab-based therapy improves NL outcome. Findings may assist clinicians in early recognition, prognostic stratification, and treatment of NL.

Comparative analyses of immune cells and alpha-smooth muscle actin-positive cells under the immunological microenvironment between with and without dense fibrosis in primary central nervous system lymphoma

Histopathologic examinations of primary central nervous system lymphoma (PCNSL) reveal concentric accumulation of lymphocytes in the perivascular area with fibrosis. However, the nature of this fibrosis in "stiff" PCNSL remains unclear. We have encountered some PCNSLs with hard masses as surgical findings. This study investigated the dense fibrous status and tumor microenvironment of PCNSLs with or without stiffness. We evaluated by silver-impregnation nine PCNSLs with stiffness and 26 PCNSLs without stiffness. Six of the nine stiff PCNSLs showed pathological features of prominent fibrosis characterized by aggregation of reticulin fibers, and collagen accumulations. Alpha-smooth muscle actin (αSMA)-positive spindle cells as a cancer-associated fibroblast, the populations of T lymphocytes, and macrophages were compared between fibrous and control PCNSLs. Fibrous PCNSLs included abundant αSMA-positive cells in both intra- and extra-tumor environments (5/6, 87% and 3/6, 50%, respectively). Conversely, only one out of the seven control PCNSL contained αSMA-positive cells in the intra-tumoral area. Furthermore, the presence of extra-tumoral αSMA-positive cells was associated with infiltration of T lymphocytes and macrophages. In conclusion, recognizing the presence of dense fibrosis in PCNSL can provide insights into the tumor microenvironment. These results may help stratify patients with PCNSL and improve immunotherapies for these patients.

Targets and treatments in primary CNS lymphoma

Primary central nervous system lymphoma (PCNSL) is a rare and highly aggressive lymphoma entirely localized in the central nervous system or vitreoretinal space. PCNSL generally initially responds to methotrexate-containing chemotherapy regimens, but progressive or relapsing disease is common, and the prognosis is poor for relapsed or refractory (R/R) patients. PCNSL is often characterized by activation of nuclear factor kappa B (NF-κB) due to mutations in the B-cell receptor (BCR) or toll-like receptor (TLR) pathways, as well as immune evasion. Targeted treatments that inhibit key PCNSL mechanisms and pathways are being evaluated; inhibition of Bruton's tyrosine kinase (BTK) downstream of BCR activation has demonstrated promising results in treating R/R disease. This review will summarize the evidence and potential for targeted therapeutic agents to improve treatment outcomes in PCNSL. This includes immunotherapeutic and immunomodulatory approaches and inhibitors of the key pathways driving PCNSL, such as aberrant BCR and TLR signaling.

Immune checkpoint inhibitors targeting PD-1/PD-L1 in the treatment of human lymphomas

Non-Hodgkin lymphomas (NHLs) encompass a diverse group of malignancies arising from B cells, T cells, and natural killer (NK) cells at various stages of differentiation. Conversely, classical Hodgkin lymphomas (cHLs) primarily feature Reed-Sternberg cells (RSCs) amid a background of reactive immune cells. Immunomodulatory pathways, notably the PD-1/PD-L1 axis, play pivotal roles in tumor immune evasion across both NHLs and cHLs. Elevated expression of PD-1 and PD-L1 is observed in a spectrum of lymphomas, influencing prognosis and treatment response. Therapeutically, immune checkpoint inhibitors (ICIs) targeting PD-1/PD-L1 have revolutionized lymphoma management, particularly in relapsed/refractory cases. Nivolumab and pembrolizumab, among others, have demonstrated efficacy in various B-cell lymphomas, with promising outcomes in cHL. Combination strategies incorporating ICIs with conventional chemotherapy or targeted agents show enhanced efficacy and are being explored extensively. In this review we discuss the most important features of the tumor microenvironment of NHLs and cHLs, address the therapeutic approaches with ICIs and try to outline future perspectives.

Bruton's tyrosine kinase (BTK) inhibitors for the treatment of primary central nervous system lymphoma (PCNSL): current progress and latest advances

The incidence of primary central nervous system lymphoma (PCNSL) has steadily increased, particularly in elderly patients. Although highly responsive to first-line chemotherapy and radiotherapy, approximately 50% of patients relapse or become refractory within 1 year. Prognosis following relapse is dismal and no standard salvage therapy exists. Bruton's tyrosine kinase (BTK), a key regulator of the B-cell receptor (BCR) pathway, has emerged as a promising therapeutic target. The first BTK inhibitor ibrutinib has been evaluated in the relapsed/refractory PCNSL setting, with overall response rates of 51.9%-89.0% and median progression-free survival of 4.6-4.8 months. However, ibrutinib inhibits several kinases in addition to BTK, leading to off-target effects. Second-generation BTK inhibitors have since been developed, which afford greater selectivity for BTK and fewer off-target effects. We review current practices in the diagnosis and evaluation of PCNSL, as well as clinical trials of BTK inhibitors in PCNSL and future developments in PCNSL treatment.

Novel Targets and Advanced Therapies in Diffuse Large B Cell Lymphomas

Since the introduction of rituximab in the late 1990s, significant progress has been made in advancing targeted therapies for B cell lymphomas, improving patients' chance of being cured and clinicians' therapeutic armamentarium. A better understanding of disease biology and pathogenic pathways, coupled with refinements in immunophenotypic and molecular diagnostics, have been instrumental in these achievements. While traditional chemotherapy remains fundamental in most cases, concerns surrounding chemorefractoriness and cumulative toxicities, particularly the depletion of the hemopoietic reserve, underscore the imperative for personalized treatment approaches. Integrating targeted agents, notably monoclonal antibodies, alongside chemotherapy has yielded heightened response rates and prolonged survival. A notable paradigm shift is underway with innovative-targeted therapies replacing cytotoxic drugs, challenging conventional salvage strategies like stem cell transplantation. This review examines the landscape of emerging targets for lymphoma cells and explores innovative therapies for diffuse large B cell lymphoma (DLBCL). From Chimeric Antigen Receptor-T cells to more potent monoclonal antibodies, antibody-drug conjugates, bispecific antibodies, checkpoint inhibitors, and small molecules targeting intracellular pathways, each modality offers promising avenues for therapeutic advancement. This review aims to furnish insights into their potential implications for the future of DLBCL treatment strategies.

Updates of primary central nervous system lymphoma

Lymphoma occurring in the central nervous system is considered primary central nervous system lymphoma (PCNSL), usually without systematic lesions. Over the last few decades, a deep understanding of PCNSL has been lacking due to the low incidence rate, and the overall survival and progression-free survival of patients with PCNSL are lower than those with other types of non-Hodgkin lymphoma. Recently, there have been several advancements in research on PCNSL. Advances in diagnosis of the disease are primarily reflected in the promising diagnostic efficiency of novel biomarkers. Pathogenesis mainly involves abnormal activation of nuclear factor kappa-B signaling pathways, copy number variations, and DNA methylation. Novel therapies such as Bruton's tyrosine kinase inhibitors, immunomodulatory drugs, immune checkpoint inhibitors, and phosphoinositide 3-kinase/mammalian target of rapamycin inhibitors are being evaluated as possible treatment options for PCNSL, especially for relapsed/refractory (R/R) cases. Several clinical trials also indicated the promising feasibility and efficacy of chimeric antigen receptor T-cell therapy for selected R/R PCNSL patients. This review focuses on discussing recent updates, including the diagnosis, pathogenesis, and novel therapy of PCNSL.

Programmed Death Ligand 1 (PD-L1) Expression in Lymphomas: State of the Art

The interaction of programmed death-1 (PD-1) on T lymphocytes with its ligands Programmed Death Ligand 1 (PD-L1) and Programmed Death Ligand 2 (PD-L2) on tumor cells and/or tumor-associated macrophages results in inhibitory signals to the T-cell receptor pathway, consequently causing tumor immune escape. PD-L1/PD-L2 are currently used as predictive tissue biomarkers in clinical practice. Virtually PD-L1 levels expressed by tumor cells are associated with a good response to immune checkpoint blockade therapies targeting the PD-1/PD-L1 axis. These therapies restore T-cell antitumor immune response by releasing T-lymphocytes from the inhibitory effects of tumor cells. Immune checkpoint therapies have completely changed the management of patients with solid cancers. This therapeutic strategy is less used in hematological malignancies, although good results have been achieved in some settings, such as refractory/relapsed classic Hodgkin lymphoma and primary mediastinal large B-cell lymphoma. Variable results have been obtained in diffuse large B-cell lymphoma and T-cell lymphomas. Immunohistochemistry represents the main technique for assessing PD-L1 expression on tumor cells. This review aims to describe the current knowledge of PD-L1 expression in various types of lymphomas, focusing on the principal mechanisms underlying PD-L1 overexpression, its prognostic significance and practical issues concerning the evaluation of PD-L1 immunohistochemical results in lymphomas.

Molecular Subtypes and the Role of TP53 in Diffuse Large B-Cell Lymphoma and Richter Syndrome

Diffuse large B-cell lymphoma (DLBCL) is the most common lymphoid malignancy and a heterogeneous entity comprised of several biologically distinct subtypes. Recently, novel genetic classifications of DLBCL have been resolved based on common mutational patterns indicative of distinct pathways of transformation. However, the complicated and costly nature of the novel classifiers has precluded their inclusion into routine practice. In view of this, the status of the TP53 gene, which is mutated or deleted in 20-30% of the cases, has emerged as an important prognostic factor for DLBCL patients, setting itself apart from other predictors. TP53 genetic lesions are particularly enriched in a genetic subtype of DLBCL that shares genomic features with Richter Syndrome, highlighting the possibility of a subset of DLBCL arising from the transformation of an occult chronic lymphocytic leukemia-like malignancy, such as monoclonal B-cell lymphocytosis. Patients with TP53-mutated DLBCL, including those with Richter Syndrome, have a particularly poor prognosis and display inferior responses to standard chemoimmunotherapy regimens. The data presented in this manuscript argue for the need for improved and more practical risk-stratification models for patients with DLBCL and show the potential for the use of TP53 mutational status for prognostication and, in prospect, treatment stratification in DLBCL.

Liquid biopsy for improving diagnosis and monitoring of CNS lymphomas: A RANO review

BACKGROUND

The utility of liquid biopsies is well documented in several extracranial and intracranial (brain/leptomeningeal metastases, gliomas) tumors.

METHODS

The RANO (Response Assessment in Neuro-Oncology) group has set up a multidisciplinary Task Force to critically review the role of blood and cerebrospinal fluid (CSF)-liquid biopsy in CNS lymphomas, with a main focus on primary central nervous system lymphomas (PCNSL).

RESULTS

Several clinical applications are suggested: diagnosis of PCNSL in critical settings (elderly or frail patients, deep locations, and steroid responsiveness), definition of minimal residual disease, early indication of tumor response or relapse following treatments, and prediction of outcome.

CONCLUSIONS

Thus far, no clinically validated circulating biomarkers for managing both primary and secondary CNS lymphomas exist. There is need of standardization of biofluid collection, choice of analytes, and type of technique to perform the molecular analysis. The various assays should be evaluated through well-organized central testing within clinical trials.

Genomic landscape and distinct molecular subtypes of primary testicular lymphoma

Primary testicular lymphoma (PTL) is a rare lymphoma predominantly occurring in the elderly male population. It is characterized by a limited response to treatment and a heightened tendency towards relapse. Histologically, approximately 90% of PTL cases are classified as diffuse large B-cell lymphomas (DLBCL). Genetic features of PTL were delineated in a limited scope within several independent studies. Some of the articles which analyzed the genetic characterization of DLBCL have incorporated PTL samples, but these have been constrained by small sample sizes. In addition, there have been an absence of independent molecular typing studies of PTL. This report summarizes the common mutational features, copy number variations (CNVs) and molecular typing of PTL patients, based on whole-exome sequencing (WES) conducted on a cohort of 25 PTL patients. Among them, HLA, CDKN2A and MYD88 had a high mutation frequency. In addition, we found two core mutational characteristics in PTL including mutation in genes linked to genomic instability (TP53 and CDKN2A) and mutation in immune-related genes (HLA, MYD88, CD79B). We performed molecular typing of 25 PTL patients into C1 subtype with predominantly TP53 mutations and C2 subtype with predominantly HLA mutations. Notably, mutations in the TP53 gene predicted a poor outcome in most types of lymphomas. However, the C1 subtype, dominated by TP53 mutations, had a better prognosis compared to the C2 subtype in PTL. C2 subtype exhibited a worse prognosis, aligning with our finding that the mechanism of immune escape in PTL was primarily the deletions of HLA rather than PD-L1/PD-L2 alterations, a contrast to other DLBCLs. Moreover, we calculated the tumor mutation burden (TMB) and identified that TMB can predict prognosis and recurrence rate in PTL. Our study underscores the significance of molecular typing in PTL based on mutational characteristics, which plays a crucial role in prognostication and guiding therapeutic strategies for patients.

The Molecular Landscape of Primary CNS Lymphomas (PCNSLs) in Children and Young Adults

Pediatric brain tumors are often noted to be different from their adult counterparts in terms of molecular features. Primary CNS lymphomas (PCNSLs) are mostly found in elderly adults and are uncommon in children and teenagers. There has only been scanty information about the molecular features of PCNSLs at a young age. We examined PCNSLs in 34 young patients aged between 7 and 39 years for gene rearrangements of BCl2, BCL6, CCND1, IRF4, IGH, IGL, IGK, and MYC, homozygous deletions (HD) of CDKN2A, and HLA by FISH. Sequencing was performed using WES, panel target sequencing, or Sanger sequencing due to the small amount of available tissues. The median OS was 97.5 months and longer than that for older patients with PCNSLs. Overall, only 14 instances of gene rearrangement were found (5%), and patients with any gene rearrangement were significantly older (p = 0.029). CDKN2A HD was associated with a shorter OS (p < 0.001). Only 10/31 (32%) showed MYD88 mutations, which were not prognostically significant, and only three of them were L265P mutations. CARD11 mutations were found in 8/24 (33%) cases only. Immunophenotypically, the cases were predominantly GCB, in contrast to older adults (61%). In summary, we showed that molecular findings identified in the PCNSLs of the older patients were only sparingly present in pediatric and young adult patients.

Sinonasal DLBCL: molecular profiling identifies subtypes with distinctive prognosis and targetable genetic features

ABSTRACT

Primary sinonasal diffuse large B-cell lymphoma (PSDLBCL) is a rare lymphoma with a variable prognosis and a unique relapse/dissemination pattern involving the central nervous system and skin. The underlying molecular mechanisms leading to this heterogeneity and progression pattern remain uncharted, hampering patient-tailored treatment. To investigate associated mechanisms, we analyzed clinical data and used immunohistochemistry, gene-expression profiling, cytogenetics, and next-generation sequencing in a cohort of 117 patients with PSDLBCL. The distribution in cell-of-origin (COO) was 68 (58%) activated B-cell (ABC), 44 (38%) germinal center B-cell (GCB), and 5 (4%) unclassifiable. COO was significantly associated with progression-free survival (PFS) and lymphoma-specific mortality (LSM) in both the overall cohort (5-year PFS: ABC, 43% vs GCB, 73%; LSM: ABC, 45% vs GCB, 14%) and in the subgroup of patients receiving immunochemotherapy (5-year PFS: ABC, 55% vs GCB, 85%; LSM: ABC, 28% vs GCB, 0%). ABC lymphomas were mainly MCD class, showing a high prevalence of MYD88 (74%) and CD79B (35%) mutations compared with GCB lymphomas (MYD88 23%; CD79B 10%) (P < .01). The ABC subtype frequently displayed cMYC/BCL2 coexpression (76% vs 18% GCB; P < .001) and HLA-II loss (48% vs 10% GCB; P < .001). PD-L1 expression and copy-number alterations were rare. All lymphomas were Epstein-Barr virus-negative. Our data suggest molecular profiling as a potent tool for detecting prognostic subgroups in PSDLBCL, exposing links to known relapse/dissemination sites. The ABC subgroup's MCD genetic features, shared with lymphomas at other nonprofessional lymphoid sites, make them potential candidates for targeted B-cell and toll-like receptor signaling therapy.

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.

Genetic alterations in mature B- and T-cell lymphomas - a practical guide to WHO-HAEM5

The identification of recurrent genomic alterations in tumour cells has a significant role in the classification of mature B- and T-cell lymphomas. Following the development of new technologies, such as next generation sequencing and the improvement of classical technologies such as conventional and molecular cytogenetics, a huge catalogue of genomic alterations in lymphoid neoplasms has been established. These alterations are relevant to refine the taxonomy of the classification of lymphomas, to scrutinize the differential diagnosis within different lymphoma entities and to help assessing the prognosis and clinical management of the patients. Consequently, here we describe the key genetic alterations relevant in mature B- and T-cell lymphomas.

IELSG30 phase 2 trial: intravenous and intrathecal CNS prophylaxis in primary testicular diffuse large B-cell lymphoma

ABSTRACT

Primary testicular diffuse large B-cell lymphoma (PTL) is characterized by high risk of contralateral testis and central nervous system (CNS) relapse. Chemoimmunotherapy with intrathecal (IT) CNS prophylaxis and contralateral testis irradiation eliminates contralateral recurrences and reduces CNS relapses. The IELSG30 phase 2 study investigated feasibility and activity of an intensified IT and IV CNS prophylaxis. Patients with stage I/II PTL who had not received treatment received 2 cycles of IV high-dose methotrexate (MTX) (1.5 g/m2) after 6 cycles of the R-CHOP regimen (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone, every 21 days). IT liposomal cytarabine was administered on day 0 of cycles 2 to 5 of 21-day R-CHOP regimen. Contralateral testis radiotherapy (25-30 Gy) was recommended. Fifty-four patients (median age: 66 years) with stage I (n = 32) or II (n = 22) disease were treated with R-CHOP, 53 received at least 3 doses of IT cytarabine, 48 received at least 1 dose of IV MTX, and 50 received prophylactic radiotherapy. No unexpected toxicity occurred. At a median follow-up of 6 years, there was no CNS relapse; 7 patients progressed, and 8 died, with 5-year progression-free and overall survival rates of 91% (95% confidence interval [CI], 79-96) and 92% (95% CI, 81-97), respectively. Extranodal recurrence was documented in 6 patients (in 2 without nodal involvement). In 4 cases, the relapse occurred >6 years after treatment. Causes of death were lymphoma (n = 4), second primary malignancy (n = 1), cerebral vasculopathy (n = 1), unknown (n = 2). Intensive prophylaxis was feasible and effective in preventing CNS relapses. Late relapses, mainly at extranodal sites, represented the most relevant pattern of failure. This trial was registered at www.clinicaltrials.gov as #NCT00945724.

Predictive and prognostic molecular biomarkers in lymphomas

Recent advances in molecular diagnostics have markedly expanded our understanding of the genetic underpinnings of lymphomas and catalysed a transformation in not just how we classify lymphomas, but also how we treat, target, and monitor affected patients. Reflecting these advances, the World Health Organization Classification, International Consensus Classification, and National Comprehensive Cancer Network guidelines were recently updated to better integrate these molecular insights into clinical practice. We summarise here the molecular biomarkers of lymphomas with an emphasis on biomarkers that have well-supported prognostic and predictive utility, as well as emerging biomarkers that show promise for clinical practice. These biomarkers include: (1) diagnostic entity-defining genetic abnormalities [e.g., B-cell acute lymphoblastic leukaemia (B-ALL) with KMT2A rearrangement]; (2) molecular alterations that guide patients' prognoses (e.g., TP53 loss frequently conferring worse prognosis); (3) mutations that serve as the targets of, and often a source of acquired resistance to, small molecular inhibitors (e.g., ABL1 tyrosine kinase inhibitors for B-ALL BCR::ABL1, hindered by ABL1 kinase domain resistance mutations); (4) the growing incorporation of molecular measurable residual disease (MRD) in the management of lymphoma patients (e.g., molecular complete response and sequencing MRD-negative criteria in multiple myeloma). Altogether, our review spans the spectrum of lymphoma types, from the genetically defined subclasses of precursor B-cell lymphomas to the highly heterogeneous categories of small and large cell mature B-cell lymphomas, Hodgkin lymphomas, plasma cell neoplasms, and T/NK-cell lymphomas, and provides an expansive summary of our current understanding of their molecular pathology.

Diffuse large B-cell lymphoma involving the central nervous system: biologic rationale for targeted therapy

Diffuse large B-cell lymphoma (DLBCL) is an aggressive B-cell lymphoma curable even in advanced stages. DLBCL involving the central nervous system (CNS) is more difficult to cure and fewer treatment options exist. Primary CNS lymphoma (PCNSL) refers to aggressive lymphomas confined to the CNS, and are almost always DLBCL. Standard approaches for PCNSL use high-dose methotrexate-based combinations as induction therapy and younger patients often receive dose-intensive consolidation. However, dose-intensive therapies are not suitable for all patients, and older patients have fewer effective treatment options. Patients with relapsed or chemotherapy-refractory disease have a very poor prognosis. Secondary CNS lymphoma (SCNSL) describes aggressive lymphomas involving the CNS at initial presentation or relapses within the CNS after treatment for systemic DLBCL. Isolated CNS relapse is often managed as PCNSL, but patients with synchronous involvement of DLBCL in both the periphery and the CNS pose a unique clinical challenge. Insights into the molecular circuitry of DLBCL have identified distinct genetic subtypes including cases with a predilection for CNS invasion. PCNSL and subsets of SCNSL are characterized by chronically activated B-cell receptor and NFκB signaling along with genetic evidence of immune evasion which may be exploited therapeutically. Improved mechanistic understanding of targetable pathways underpinning CNS lymphomas has led to numerous clinical trials testing targeted agent combinations and immunotherapy approaches with promising early results. Biologically rational strategies may further improve the cure rate of CNS lymphomas, either by overcoming intrinsic or acquired treatment resistance and/or by being broadly applicable to patients of all ages.

Pembrolizumab With R-CHOP in Previously Untreated DLBCL: Sustained, High Efficacy, and Safety With Long-Term Follow-Up

BACKGROUND

While generally ineffective in relapsed diffuse large B cell lymphoma (DLBCL), immune checkpoint inhibitors (ICIs) may hold greater promise in untreated, immunocompetent patients. We previously reported safety and early efficacy of pembrolizumab plus rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (PR-CHOP) in a phase I trial of untreated DLBCL, noting responses in 90% of patients (complete response 77%) and a 2-year progression-free survival (PFS) of 83%. We herein report long-term safety and efficacy at 5-year follow up.

PATIENTS AND METHODS

Adult patients with untreated DLBCL or grade 3b follicular lymphoma, intended to receive 6 cycles of R-CHOP were eligible. Patients (N = 30) were treated with pembrolizumab 200 mg IV and R-CHOP in 21-day cycles for 6 cycles.

RESULTS

At median follow up of 4.8 years, 5-year PFS was 71% (CI, 54%-94%) and 5-year overall survival was 83% (CI, 71%-98%). Immune-related adverse events (IRAEs) occurred in 7 (23%) patients (10% grade 3/4). Three IRAEs (rash, thyroiditis, rheumatoid arthritis) occurred beyond 3 months of treatment completion. PD-L1 tumor expression was documented in 19 of 23 (83%) tested patients. None of the 19 patients who had any PD-L1 expression have relapsed, whereas 2 out of the 4 patients with no PD-L1 expression have relapsed.

CONCLUSION

PR-CHOP has led to durable responses in most patients, with the best outcomes in PD-L1-expressing disease. Furthermore, the safety profile was manageable, with no consistent pattern of late events. These data support ongoing strategies incorporating ICIs in frontline DLBCL therapy and confirmation of predictive biomarkers including tumor PD-L1 expression.

Diagnostic, Pathologic, and Therapeutic Considerations for Primary CNS Lymphoma

Primary CNS lymphoma (PCNSL) is a rare lymphoma representing 3% of CNS malignancies. The diagnosis is complicated by the unique risks associated with brain biopsy, and the treatment is similarly complicated by the restriction of effective therapeutics able to cross the blood-brain barrier. Currently, the majority of individuals diagnosed with this disease are immunocompetent although immune deficiency related to HIV or immunosuppressive therapy remains an important risk factor. Improvements in both frontline therapy and consolidation options, including the use of hematopoietic stem-cell transplantation, have translated to improved survival. Unfortunately, patients experiencing relapsed or refractory disease often fare poorly. Here, we review key clinical, pathologic, and therapeutic aspects of PCNSL and highlight challenging clinical scenarios that may be encountered by the treating oncologist.

The Diverse Roles of ETV6 Alterations in B-Lymphoblastic Leukemia and Other Hematopoietic Cancers

Genetic alterations of the repressive ETS family transcription factor gene ETV6 are recurrent in several categories of hematopoietic malignancy, including subsets of B-cell and T-cell acute lymphoblastic leukemias (B-ALL and T-ALL), myeloid neoplasms, and mature B-cell lymphomas. ETV6 is essential for adult hematopoietic stem cells (HSCs), contributes to specific functions of some mature immune cells, and plays a key role in thrombopoiesis as demonstrated by familial ETV6 mutations associated with thrombocytopenia and predisposition to hematopoietic cancers, particularly B-ALL. ETV6 appears to have a tumor suppressor role in several hematopoietic lineages, as demonstrated by recurrent somatic loss-of-function (LoF) and putative dominant-negative alterations in leukemias and lymphomas. ETV6 rearrangements contribute to recurrent fusion oncogenes such as the B-ALL-associated transcription factor (TF) fusions ETV6::RUNX1 and PAX5::ETV6, rare drivers such as ETV6::NCOA6, and a spectrum of tyrosine kinase gene fusions encoding hyperactive signaling proteins that self-associate via the ETV6 N-terminal pointed domain. Another subset of recurrent rearrangements involving the ETV6 gene locus appear to function primarily to drive overexpression of the partner gene. This review surveys what is known about the biochemical and genome regulatory properties of ETV6 as well as our current understanding of how alterations in these functions contribute to hematopoietic and nonhematopoietic cancers.

[«Masks» of CNS demyelinating diseases. Primary lymphoma]

Primary central nervous system lymphoma (PCNSL) is a rare neoplasm that can affect the brain, eyes, and, rarely, the spinal cord. Clinical presentation and MRI findings can mimic a variety of diseases, including high-grade gliomas, infectious and granulomatous diseases, and demyelinating diseases. We describe three cases where the diagnosis of PCNSL was difficult due to an ambiguous clinical, radiological and laboratory results. The role of stereotactic biopsy remains leading in differential diagnosis; however, the invasiveness and frequent limitations of this method determine the search for additional biological markers of the disease. New evidence suggests a potential role for cerebrospinal fluid (CSF) cytokine profiles and proteomic analysis in differential diagnosis, disease progression, and treatment response.

[Molecular diagnostics for vitreoretinal lymphoma]

Primary vitreoretinal lymphoma (PVRL) represents a subtype of intraocular lymphomas, which are a subgroup of malignant lymphomas of the eye. PVRL is considered a special form of primary diffuse large cell lymphoma (DLBCL) of the CNS (central nervous system) (PCNSL) and arises primary or secondary to PCNSL. According to the cell of origin (COO) classification of DLBCL, PVRL largely belongs to the activated B‑cell (ABC) type of DLBCL. Based on a recently established genetic-biological classification of DLBCL, PCNSL and thus also PVRL belong to a group of DLBCL of the MYD88/CD79B-mutated (MCD) or cluster 5 subtype, which often shows extranodal manifestations and MYD88 and CD79A mutations as well as CDKN2A deletions.PVRL diagnostics is often complicated as it represents a classic masquerade syndrome. Due to the usually limited material with often large numbers of reactive lymphocytes and/or degenerative changes in the cells, the results of diagnostic tests are difficult to interpret. Classic diagnostic tests include cytology on vitreous aspirates, immunocytochemistry, and clonality analysis.New insights into the spectrum of genetic alterations of vitreoretinal lymphomas (VRL) confirm the close relationship to PCNSL and could significantly improve pathological diagnosis. Next-generation sequencing panel-based diagnostics allow VRL diagnosis confirmation with little DNA in almost 100% of patients in cases with insufficient cytological evidence or lack of clonality detection. PVRL, as well as secondary vitreoretinal lymphomas after PCNSL or extracerebral DLBCL, have high mutation frequencies in characteristically mutated genes in PCNSL or MCD/cluster 5 type DLBCL. Supporting diagnostics, mutation detection can also be performed on cell-free DNA from the vitreous supernatant.

Primary breast diffuse large B-cell lymphoma in the rituximab era: A retrospective study of the Chinese Southwest Oncology Group

BACKGROUND

Primary breast diffuse large B-cell lymphoma (PB-DLBCL) is a rare subtype of extranodal DLBCL, and the standard treatment remains controversial. In this study, we aimed to define the optimal treatment management in the rituximab era.

METHODS

A total of 5089 newly diagnosed DLBCL patients treated with rituximab-containing immunochemotherapy between 2008 and 2019 from the Chinese Southwest Oncology Group-affiliated institutes were identified, of whom 135 diagnosed with PB-DLBCL were eligible for this analysis.

RESULTS

PB-DLBCL accounted for 2.7% of all DLBCLs. With a median follow-up of 4.2 years, the 5-year overall survival and progression-free survival rates were 84.8% and 71.6%, respectively. Breast and central nervous system (CNS) relapses were the main cause of treatment failure. We observed that consolidative breast radiotherapy (RT) significantly decreased breast relapse risk (5-year risk, 2.9% vs. 20.1%, p = 0.007). The CNS relapse risk was lower for patients who received high-dose methotrexate (HD-MTX) than for patients who did not (5-year risk, 0% vs. 15.2%, p = 0.015). We further screened the genetic mutation profile of 20 patients from two institutes, and found that MYD88 (25%) and CD79B mutations (25%) frequently occur in PB-DLBCL. In addition, four patients with MYD88 and/or CD79B mutations experienced CNS relapse, while three patients with MYD88 and/or CD79B mutations who received HD-MTX did not experience CNS relapse.

CONCLUSION

Collectively, our results indicate combined modality therapy including rituximab-containing immunochemotherapy and consolidative breast RT is a promising approach for PB-DLBCL, while HD-MTX is useful for preventing CNS relapse.

How I treat secondary CNS involvement by aggressive lymphomas

Secondary central nervous system (CNS) lymphoma (SCNSL) is a rare but clinically challenging scenario with historically disappointing outcomes. SCNSL refers to lymphoma that has spread into the CNS concurrently with systemic disease or CNS relapse during or after frontline immunochemotherapy, presenting with or without systemic lymphoma. Diffuse large B-cell lymphoma (DLBCL) denotes the most common entity, but an increased incidence is observed in other histologies, such as Burkitt lymphoma and mantle-cell lymphoma. The incidence, timing in disease course, location, evidence supporting the use of CNS prophylaxis, and treatment pathways vary according to histology. No randomized data exist to delineate the best treatment approaches with current recommendations based on retrospective and single-arm studies. However, a regimen comprising immunochemotherapy, incorporating agents that cross the blood-brain barrier, followed by thiotepa-containing conditioning and autologous stem-cell transplant outlined in the international MARIETTA study demonstrated improvement in outcomes, representing a major accomplishment in the care of patients with DLBCL with SCNSL. Anti-CD19 chimeric antigen receptor T cell denotes a paradigm shift in the treatment of patients with systemic aggressive lymphomas, with emerging data also demonstrating efficacy without higher neurotoxicity in those with SCNSL. In this manuscript we discuss 5 clinical scenarios and review the evidence supporting our recommendations.

Clinical PD-1/PD-L1 Blockades in Combination Therapies for Lymphomas

Immunotherapy with the programmed cell death protein 1 (PD-1)/PD-1 ligand (PD-L1) blockade has revolutionized the treatment of advanced solid cancers. However, these clinical benefits have been limited to cases of malignant lymphomas, showing promising results for only classic Hodgkin lymphoma (cHL) and primary mediastinal B-cell lymphoma (PMBCL). To bring clinical benefits to more patients with lymphoma, numerous combination therapies involving PD-1/PD-L1 blockade have been tested in clinical trials in both frontline and relapsed/refractory settings. This article reviews the current landscape of combination therapies with PD-1/PD-L1 blockade for lymphoma and discusses the potential therapeutic approaches. An interim analysis of a phase 3 study demonstrated increased progression-free survival with nivolumab combination therapy over the current frontline treatment in patients with advanced-stage cHL. The results of combination therapies for aggressive B-cell lymphomas, except for PMBCL, have been disappointing. Several clinical trials of combined PD-1/PD-L1 blockade and Bruton's tyrosine kinase inhibitors are exploring its efficacy in patients with chronic lymphocytic leukemia (CLL) with Richter transformation. Several T-cell lymphoma subtypes respond to PD-1/PD-L1 blockade monotherapy. Further clinical trials are underway to investigate appropriate combination regimens with PD-1/PD-L1 blockade, especially for cHL, CLL with Richter transformation, and T-cell lymphoma, in both frontline and relapsed/refractory settings.

Next-Generation Sequencing of Vitreoretinal Lymphoma by Vitreous Liquid Biopsy: Diagnostic Potential and Genotype/Phenotype Correlation

Purpose

To determine the diagnostic potential of next-generation sequencing (NGS) in vitreous samples, analyze genotype-phenotype characteristics, and compare NGS of matched vitreous and brain samples in patients with associated central nervous system lymphoma (CNSL).

Methods

A total of 32 patients suspected of vitreoretinal lymphoma (VRL) who underwent diagnostic vitrectomy and NGS were included in this retrospective observational case-series. Fresh vitreous specimens from diagnostic vitrectomy of VRL-suspected patients underwent NGS using a custom panel targeting 747 candidate genes for lymphoma. They also underwent malignancy cytology, interleukin (IL)-10/IL-6, immunoglobulin heavy chain (IGH)/immunoglobulin kappa light chain (IGK) monoclonality testing. MYD88 L265P mutation was examined from anterior chamber tap samples. The diagnosis of VRL was made based on typical clinical characteristics for VRL, as well as malignant cytology, IGH/IGK clonality, or IL-10/IL-6 > 1. Sensitivity and specificity of NGS were compared with conventional diagnostic tests. Brain tissues suspected of lymphoma were collected by stereotactic biopsy and underwent NGS. Genetic variations detected in NGS of vitreous and brain tissue specimens were compared.

Results

The sensitivity values for cytology, IL-10/IL-6 > 1, clonality assays for IGH and IGK, MYD88 L265P detection in anterior chamber tap samples, and vitreous NGS were 0.23, 0.83, 0.68, 0.79, 0.67, and 0.85, with specificity values of 1.00, 0.83, 0.50, 0.25, 0.83, and 0.83, respectively. The sensitivity (0.85) of vitreous NGS was the highest compared to other conventional diagnostic tests for VRL. The most common mutations were MYD88 (91%), CDKN2A (36%), PIM1 (32%), IGLL5 (27%), and ETV6 (23%). Although several gene alterations demonstrated heterogeneity between the brain and eyes, some common mutational profiles were observed in matched vitreous and brain samples.

Conclusions

Overall, NGS of the vitreous demonstrated high sensitivity among conventional diagnostic tests. VRL and CNSL appeared to have both shared and distinct genetic variations, which may suggest site-specific variations from a common origin.

Clonal Relationship and Mutation Analysis in Lymphoplasmacytic Lymphoma/Waldenström Macroglobulinemia Associated With Diffuse Large B-cell Lymphoma

Patients with lymphoplasmacytic lymphoma/Waldenström macroglobulinemia (LPL/WM) occasionally develop diffuse large B-cell lymphoma (DLBCL). This mostly results from LPL/WM transformation, although clonally unrelated DLBCL can also arise. LPL/WM is characterized by activating MYD88L265P (>95%) and CXCR4 mutations (~30%), but the genetic drivers of transformation remain to be identified. Here, in thirteen LPL/WM patients who developed DLBCL, the clonal relationship of LPL and DLBCL together with mutations contributing to transformation were investigated. In 2 LPL/WM patients (15%), high-throughput sequencing of immunoglobulin gene rearrangements showed evidence of >1 clonal B-cell population in LPL tissue biopsies. In the majority of LPL/WM patients, DLBCL presentations were clonally related to the dominant clone in LPL, providing evidence of transformation. However, in 3 patients (23%), DLBCL was clonally unrelated to the major malignant B-cell clone in LPL, of which 2 patients developed de novo DLBCL. In this study cohort, LPL displayed MYD88L265P mutation in 8 out of eleven patients analyzed (73%), while CXCR4 mutations were observed in 6 cases (55%). MYD88WT LPL biopsies present in 3 patients (27%) were characterized by CD79B and TNFAIP3 mutations. Upon transformation, DLBCL acquired novel mutations targeting BTG1, BTG2, CD79B, CARD11, TP53, and PIM1. Together, we demonstrate variable clonal B-cell dynamics in LPL/WM patients developing DLBCL, and the occurrence of clonally unrelated DLBCL in about one-quarter of LPL/WM patients. Moreover, we identified commonly mutated genes upon DLBCL transformation, which together with preserved mutations already present in LPL characterize the mutational landscape of DLBCL occurrences in LPL/WM patients.

Checkpoint inhibition in hematologic malignancies

Checkpoint inhibitor therapy has emerged as an effective therapeutic strategy for many types of malignancies, especially in solid tumors. Within the last two decades, numerous monoclonal antibody drugs targeting the CTLA-4 and PD-1/PD-L1 checkpoint pathways have seen FDA approval. Within hematologic malignancies, Hodgkin Lymphoma has seen the greatest clinical benefits thus far with more recent data showing efficacy in the front-line setting. As our understanding of checkpoint inhibition expands, using these pathways as a therapeutic target has shown some utility in the treatment of other hematologic malignancies as well, primarily in the relapsed/refractory settings. Checkpoint inhibition also appears to have a role as a synergistic agent to augment clinical responses to other forms of therapy such as hematopoietic stem cell transplant. Moreover, alternative checkpoint molecules that bypass the well-studied CTLA-4 and PD-1/PD-L1 pathways have emerged as exciting new therapeutic targets. Most excitingly is the use of anti-CD47 blockade in the treatment of high risk MDS and TP-53 mutated AML. Overall, there has been tremendous progress in understanding the benefits of checkpoint inhibition in hematologic malignancies, but further studies are needed in all areas to best utilize these agents. This is a review of the most recent developments and progress in Immune Checkpoint Inhibition in Hematologic Malignancies in the last decade.

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.

Analysis of the genomic landscape of primary central nervous system lymphoma using whole-genome sequencing in Chinese patients

Primary central nervous system lymphoma (PCNSL) is an uncommon non-Hodgkin's lymphoma with poor prognosis. This study aimed to depict the genetic landscape of Chinese PCNSLs. Whole-genome sequencing was performed on 68 newly diagnosed Chinese PCNSL samples, whose genomic characteristics and clinicopathologic features were also analyzed. Structural variations were identified in all patients with a mean of 349, which did not significantly influence prognosis. Copy loss occurred in all samples, while gains were detected in 77.9% of the samples. The high level of copy number variations was significantly associated with poor progression-free survival (PFS) and overall survival (OS). A total of 263 genes mutated in coding regions were identified, including 6 newly discovered genes (ROBO2, KMT2C, CXCR4, MYOM2, BCLAF1, and NRXN3) detected in ⩾ 10% of the cases. CD79B mutation was significantly associated with lower PFS, TMSB4X mutation and high expression of TMSB4X protein was associated with lower OS. A prognostic risk scoring system was also established for PCNSL, which included Karnofsky performance status and six mutated genes (BRD4, EBF1, BTG1, CCND3, STAG2, and TMSB4X). Collectively, this study comprehensively reveals the genomic landscape of newly diagnosed Chinese PCNSLs, thereby enriching the present understanding of the genetic mechanisms of PCNSL.

Differences in mutational signature of diffuse large B-cell lymphomas according to the primary organ

BACKGROUND

Comprehensive molecular subtyping of diffuse large B-cell lymphoma (DLBCL) through genetic profiling has broadened our understanding of DLBCL biology. In this study, we investigated whether DLBCL, not otherwise specified (NOS) shows differences in mutational patterns depending on the primary organ.

PATIENTS AND METHODS

Panel-based next-generation sequencing was performed on 345 DLBCL from various primary organs, and patterns of mutations according to primary organs were analyzed.

RESULTS

DLBCL showed a characteristic mutational signature in several primary organs. Among them, the mutational pattern of DLBCL in the breast and ileocecal area was particularly different from that of other DLBCL NOS. In breast DLBCL, MYD88L265P (57.1%), CD79B mutation (42.9%), and CDKN2A/B loss (71.4%) were found at high frequencies, which were similar to the mutation patterns of DLBCL of immune-privileged sites compared with DLBCL NOS. DLBCL in the ileocecal area showed a characteristic mutation pattern with the most frequent TP53 mutation (52.6%) and 18q21 gain (42.1%). This was also different from the mutational pattern observed in the stomach or other intestines. In discriminant analysis, DLBCL of the breast and ileocecal area tended to form separate genetic constellations from other DLBCL NOS.

CONCLUSION

DLBCL NOS has a characteristic mutational profile that depends on the primary organ. In particular, the mutational signature of DLBCL in the breast and ileocecal area was heterogeneous compared with that of other DLBCL NOS. Further research is needed to determine whether primary DLBCL in the breast and ileocecal area can be classified as an independent subtype.

Extranodal lymphoma: pathogenesis, diagnosis and treatment

Approximately 30% of lymphomas occur outside the lymph nodes, spleen, or bone marrow, and the incidence of extranodal lymphoma has been rising in the past decade. While traditional chemotherapy and radiation therapy can improve survival outcomes for certain patients, the prognosis for extranodal lymphoma patients remains unsatisfactory. Extranodal lymphomas in different anatomical sites often have distinct cellular origins, pathogenic mechanisms, and clinical manifestations, significantly influencing their diagnosis and treatment. Therefore, it is necessary to provide a comprehensive summary of the pathogenesis, diagnosis, and treatment progress of extranodal lymphoma overall and specifically for different anatomical sites. This review summarizes the current progress in the common key signaling pathways in the development of extranodal lymphomas and intervention therapy. Furthermore, it provides insights into the pathogenesis, diagnosis, and treatment strategies of common extranodal lymphomas, including gastric mucosa-associated lymphoid tissue (MALT) lymphoma, mycosis fungoides (MF), natural killer/T-cell lymphoma (nasal type, NKTCL-NT), and primary central nervous system lymphoma (PCNSL). Additionally, as PCNSL is one of the extranodal lymphomas with the worst prognosis, this review specifically summarizes prognostic indicators and discusses the challenges and opportunities related to its clinical applications. The aim of this review is to assist clinical physicians and researchers in understanding the current status of extranodal lymphomas, enabling them to make informed clinical decisions that contribute to improving patient prognosis.

Pathology and new insights in central nervous system lymphomas

PURPOSE OF REVIEW

Primary central nervous system lymphoma (PCNSL) is a rare central nervous system (CNS) malignancy, which represents a heterogenous group of tumors. Among PCNSL, diffuse large B-cell lymphoma of the CNS (CNS-DLBCL) represents the most common tumor type. Multiomics studies have recently revealed the complex genomic landscape of these rare diseases. These findings lead to a potential new molecular and epigenetic classification.

RECENT FINDINGS

Our review is focused on CNS-DLBCL in immunocompetent patients. CNS-DLBCL are derived from self-reactive/polyreactive precursor cells. An early molecular event such as MYD88 mutation leads to escape elimination of precursor cells, which, by a dysregulated GC reaction, acquire auto-/polyreactivity of the B-cell tumoral cells for antigens physiologically expressed in the CNS. Most of CNS-DLBCL tumor cells harbor a non-GCB, ABC-like immunophenotype associated with a late GC (exit) B-cells genotype by gene expression profiling. Various mechanisms of genetic alterations are involved in the pathogenesis of PCNSL, including point mutations [nonsomatic hypermutation (SHM), aberrant SHM (aSHM)], SHM/aSHM, chromosome copy gains or losses, and DNA hypermethylation. Constitutive NFκB activation plays a key role in lymphoma cell proliferation and survival by dysregulation of toll-like receptor (mutations of CARD11 and MYD88 ), BCR ( CD79B ), JAK-STAT, and NFκB signaling pathways.

SUMMARY

Multiomics approaches have succeeded to substantially improve the understanding of the pathogenesis, as well as the molecular and epigenetic events in PCNSL. Challenges remain due to the obvious heterogeneity of CNS-DLBCL, and improvement is needed for their classification.

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.

Integrated genetic analyses of immunodeficiency-associated Epstein-Barr virus- (EBV) positive primary CNS lymphomas

Immunodeficiency-associated primary CNS lymphoma (PCNSL) represents a distinct clinicopathological entity, which is typically Epstein-Barr virus-positive (EBV+) and carries an inferior prognosis. Genetic alterations that characterize EBV-related CNS lymphomagenesis remain unclear precluding molecular classification and targeted therapies. In this study, a comprehensive genetic analysis of 22 EBV+ PCNSL, therefore, integrated clinical and pathological information with exome and RNA sequencing (RNASeq) data. EBV+ PCNSL with germline controls carried a median of 55 protein-coding single nucleotide variants (SNVs; range 24-217) and 2 insertions/deletions (range 0-22). Genetic landscape was largely shaped by aberrant somatic hypermutation with a median of 41.01% (range 31.79-53.49%) of SNVs mapping to its target motifs. Tumors lacked established SNVs (MYD88, CD79B, PIM1) and copy number variants (CDKN2A, HLA loss) driving EBV- PCNSL. Instead, EBV+ PCNSL were characterized by SOCS1 mutations (26%), predicted to disinhibit JAK/STAT signaling, and mutually exclusive gain-of-function NOTCH pathway SNVs (26%). Copy number gains were enriched on 11q23.3, a locus directly targeted for chromosomal aberrations by EBV, that includes SIK3 known to protect from cytotoxic T-cell responses. Losses covered 5q31.2 (STING), critical for sensing viral DNA, and 17q11 (NF1). Unsupervised clustering of RNASeq data revealed two distinct transcriptional groups, that shared strong expression of CD70 and IL1R2, previously linked to tolerogenic tumor microenvironments. Correspondingly, deconvolution of bulk RNASeq data revealed elevated M2-macrophage, T-regulatory cell, mast cell and monocyte fractions in EBV+ PCNSL. In addition to novel insights into the pathobiology of EBV+ PCNSL, the data provide the rationale for the exploration of targeted therapies including JAK-, NOTCH- and CD70-directed approaches.

The oncogenic human B-cell lymphoma MYD88 L265P mutation genocopies activation by phosphorylation at the Toll/interleukin-1 receptor (TIR) domain

MYD88 is the key signaling adaptor-protein for Toll-like and interleukin-1 receptors. A somatic L265P mutation within the Toll/interleukin-1 receptor (TIR) domain of MYD88 is found in 90% of Waldenström macroglobulinemia cases and in a significant subset of diffuse large B-cell lymphomas. MYD88-L265P strongly promotes NF-κB pathway activation, JAK-STAT signaling and lymphoma cell survival. Previous studies have identified other residues of the TIR-domain crucially involved in NF-κB activation, including serine 257 (S257), indicating a potentially important physiological role in the regulation of MYD88 activation. Here, we demonstrate that MYD88 S257 is phosphorylated in B-cell lymphoma cells and that this phosphorylation is required for optimal TLR-induced NF-κB activation. Furthermore, we demonstrate that a phosphomimetic MYD88-S257D mutant promotes MYD88 aggregation, IRAK1 phosphorylation, NF-κB activation and cell growth to a similar extent as the oncogenic L265P mutant. Lastly, we show that expression of MYD88-S257D can rescue cell growth upon silencing of endogenous MYD88-L265P expression in lymphoma cells addicted to oncogenic MYD88 signaling. Our data suggest that the L265P mutation promotes TIR domain homodimerization and NF-κB activation by copying the effect of MY88 phosphorylation at S257, thus providing novel insights into the molecular mechanism underlying the oncogenic activity of MYD88-L265P in B-cell malignancies.

Multi-scale spatial modeling of immune cell distributions enables survival prediction in primary central nervous system lymphoma

To understand the clinical significance of the tumor microenvironment (TME), it is essential to study the interactions between malignant and non-malignant cells in clinical specimens. Here, we established a computational framework for a multiplex imaging system to comprehensively characterize spatial contexts of the TME at multiple scales, including close and long-distance spatial interactions between cell type pairs. We applied this framework to a total of 1,393 multiplex imaging data newly generated from 88 primary central nervous system lymphomas with complete follow-up data and identified significant prognostic subgroups mainly shaped by the spatial context. A supervised analysis confirmed a significant contribution of spatial context in predicting patient survival. In particular, we found an opposite prognostic value of macrophage infiltration depending on its proximity to specific cell types. Altogether, we provide a comprehensive framework to analyze spatial cellular interaction that can be broadly applied to other technologies and tumor contexts.

Utility of cerebrospinal fluid liquid biopsy in distinguishing CNS lymphoma from cerebrospinal infectious/demyelinating diseases

BACKGROUND

Distinguishing between central nervous system lymphoma (CNSL) and CNS infectious and/or demyelinating diseases, although clinically important, is sometimes difficult even using imaging strategies and conventional cerebrospinal fluid (CSF) analyses. To determine whether detection of genetic mutations enables differentiation between these diseases and the early detection of CNSL, we performed mutational analysis using CSF liquid biopsy technique.

METHODS

In this study, we extracted cell-free DNA from the CSF (CSF-cfDNA) of CNSL (N = 10), CNS infectious disease (N = 10), and demyelinating disease (N = 10) patients, and performed quantitative mutational analysis by droplet-digital PCR. Conventional analyses were also performed using peripheral blood and CSF to confirm the characteristics of each disease.

RESULTS

Blood hemoglobin and albumin levels were significantly lower in CNSL than CNS infectious and demyelinating diseases, CSF cell counts were significantly higher in infectious diseases than CNSL and demyelinating diseases, and CSF-cfDNA concentrations were significantly higher in infectious diseases than CNSL and demyelinating diseases. Mutation analysis using CSF-cfDNA detected MYD88L265P and CD79Y196 mutations in 60% of CNSLs each, with either mutation detected in 80% of cases. Mutual existence of both mutations was identified in 40% of cases. These mutations were not detected in either infectious or demyelinating diseases, and the sensitivity and specificity of detecting either MYD88/CD79B mutations in CNSL were 80% and 100%, respectively. In the four cases biopsied, the median time from collecting CSF with the detected mutations to definitive diagnosis by conventional methods was 22.5 days (range, 18-93 days).

CONCLUSIONS

These results suggest that mutation analysis using CSF-cfDNA might be useful for differentiating CNSL from CNS infectious/demyelinating diseases and for early detection of CNSL, even in cases where brain biopsy is difficult to perform.

Treatment Strategies and Prognostic Factors in Secondary Central Nervous System Lymphoma: A Multicenter Study of 124 Patients

Secondary central nervous system lymphoma (SCNSL) is a rare and difficult to treat type of Non-Hodgkin lymphoma characterized by systemic and central nervous system (CNS) disease manifestations. In this study, 124 patients with SCNSL intensively treated and with clinical long-term follow-up were included. Initial histopathology, as divided in low-grade, other aggressive, and diffuse large B-cell lymphoma (DLBCL), was of prognostic significance. Overall response to induction treatment was a prognostic factor with early responding DLBCL-SCNSL in comparison to those non-responding experiencing a significantly better progression-free survival (PFS) and overall survival (OS). However, the type of induction regime was not prognostic for survival. Following consolidating high-dose chemotherapy and autologous stem cell transplantation (HDT-ASCT), DLBCL-SCNSL patients had better median PFS and OS. The important role of HDT-ASCT was further highlighted by favorable responses and survival of patients not responding to induction therapy and by excellent results in patients with de novo DLBCL-SCNSL (65% long-term survival). SCNSL identified as a progression of disease within 6 months of initial systemic lymphoma presentation represented a previously not appreciated subgroup with particularly dismal outcome. This temporal stratification model of SCNSL diagnosis revealed CNS progression of disease within 6 months as a promising candidate prognosticator for future studies.

Clinical applications of circulating tumor DNA in central nervous system lymphoma

Detection and characterization of circulating tumor DNA (ctDNA) in body fluids have the potential to revolutionize management of patients with lymphoma. Minimal access to malignant DNA through a simple blood draw or lumbar puncture is particularly appealing for CNS lymphomas (CNSL), which cannot be easily or repeatedly sampled without invasive surgeries. Profiling of ctDNA provides a real-time snapshot of the genetic composition in patients with CNSL and enables ultrasensitive quantification of lymphoma burden at any given time point during the course of the disease. Here, we broadly review technical challenges of ctDNA identification in CNSL, recent advances of innovative liquid biopsy technologies, potential clinical applications of ctDNA and how it may improve CNSL risk stratification, outcome prediction, and monitoring of measurable residual disease. Finally, we discuss clinical trials and scenarios in which ctDNA could be implemented to guide risk-adapted and personalized treatment decisions.