MyD88 Mutation in Elderly Predicts Poor Prognosis in Primary Central Nervous System Lymphoma: Multi-Institutional Analysis

Expression of MYD88 L265P Mutation in Subtypes of Diffuse Large B-Cell Lymphoma in the Pakistani Population

MYD88 L265P mutation is a gain-of-function driver mutation. It is observed in a significant proportion of Waldenstrom macroglobulinemia and activated B-cell subtype of diffuse large B-cell lymphoma (DLBCL; non-germinal center subtype). The incidence of this mutation in the subtypes of DLBCL has not yet been documented in the Pakistani population. This study aimed to ascertain the frequency and association of MYD88 L265P mutation within 2 subtypes of DLBCL, germinal center B-cell-like (GCB) and non-GCB B-cell lymphoma (non-GCB), in the local population. This cross-sectional study was conducted at the Armed Forces Institute of Pathology, Punjab, Pakistan. All newly diagnosed cases of DLBCL were included in the study. We analyzed 82 biopsy-proven cases of DLBCL (28 cases of GCB subtype and 54 cases of non-GCB subtype). DNA was extracted from formalin-fixed paraffin-embedded tissue blocks, and a conventional polymerase chain reaction was used to detect the MYD88 L265P mutation. The MYD88 L265P mutation was detected in 01 of 28 (3.6%) cases of the GCB subtype (95% CI: 0%-10%) and in 12 of 54 (22.2%) cases of the non-GCB subtype (95% CI: 11%-33%). Pearsos χ2 test revealed a statistically significant association of MYD88 L265P mutation with non-GCB subtype of DLBCL (P = 0.024). This association will assist in identifying a target population that may benefit from MYD88-specific treatment regimens. This may exponentially improve the outcome of patients with DLBCL harboring this mutation.

Targeted multiplex validation of CSF proteomic biomarkers: implications for differentiation of PCNSL from tumor-free controls and other brain tumors

Introduction

Primary central nervous system lymphoma (PCNSL) is a rare type of non-Hodgkin's lymphoma that affects brain parenchyma, eyes, cerebrospinal fluid, and spinal cord. Diagnosing PCNSL can be challenging because imaging studies often show similar patterns as other brain tumors, and stereotactic brain lesion biopsy conformation is invasive and not always possible. This study aimed to validate a previous proteomic profiling (PMID: 32610669) of cerebrospinal fluid (CSF) and develop a CSF-based proteomic panel for accurate PCNSL diagnosis and differentiation.

Methods

CSF samples were collected from patients of 30 PCNSL, 30 other brain tumors, and 31 tumor-free/benign controls. Liquid chromatography tandem-mass spectrometry targeted proteomics analysis was used to establish CSF-based proteomic panels.

Results

Final proteomic panels were selected and optimized to diagnose PCNSL from tumor-free controls or other brain tumor lesions with an area under the curve (AUC) of 0.873 (95%CI: 0.723-0.948) and 0.937 (95%CI: 0.807- 0.985), respectively. Pathways analysis showed diagnosis panel features were significantly enriched in pathways related to extracellular matrices-receptor interaction, focal adhesion, and PI3K-Akt signaling, while prion disease, mineral absorption and HIF-1 signaling were significantly enriched with differentiation panel features.

Discussion

This study suggests an accurate clinical test panel for PCNSL diagnosis and differentiation with CSF-based proteomic signatures, which may help overcome the challenges of current diagnostic methods and improve patient outcomes.

Genomic Profiling of Primary Diffuse Large B-Cell Lymphoma of the Central Nervous System Suggests Novel Potential Therapeutic Targets

Primary diffuse large B-cell lymphoma of the primary central nervous system (CNS-DLBCL) is an aggressive disease, with dismal prognosis despite the use of high-dose methotrexate-based polychemotherapy. Our study aimed to expand the biologic profiles of CNS-DLBCL and to correlate them with clinical/imaging findings to gain diagnostic insight and possibly identify new therapeutic targets. We selected 61 CNS-DLBCL whose formalin-fixed paraffin-embedded samples were available at first diagnosis. These were investigated by immunohistochemistry, cMYC rearrangements were explored by fluorescence in situ hybridization, and CNS-DLBCL mutated genes were evaluated by next-generation sequencing. CD10, BCL6, and IRF4 were observed in 16%, 83.6%, and 93% of cases, respectively. As typical of CNS lymphoma, 10 (16.4%) of 61 cases were classified as germinal center (GCB) type and 51 (83.6%) of 61 as non-germinal center (non-GCB) type according to the Hans algorithm. Double-expression status for BCL2 and cMYC was detected in 36 (59%) of 61 cases whereas 25 (41%) of 61 were non-DE. Rearrangement of the cMYC gene was detected in 2 cases, associated with BCL6 translocation only in 1 case MYD88, PIM1, CD79B, and TP53 were mutated in 54.5%, 53.5%, 30.2%, and 18.4% cases, respectively. Novel mutations not previously reported in CNS-DLBCL were found: AIP in 23.1%, PI3KCA in 15%, NOTCH1 in 11.4%, GNAS in 8.1%, CASP8 in 7.9%, EGFR in 6.4%, PTEN in 5.1, and KRAS in 2.6% of cases. Survival was significantly longer for patients with mutated MYD88 (8.7 months vs 1.7 months; log-rank test = 5.43; P = .020) and for patients with mutated CD79B (10.8 months vs 2.5 months; log-rank test = 4.64; P = .031). MYD88 and CD79B predicted a longer survival in patients affected by CNS-DLBCL. Notably, we identified novel mutations that enrich the mutational landscape of CNS-DLBCL, suggest a role of PTEN-PI3K-AKT and receptor tyrosine kinase-RAS-mitogen-activated protein kinase signaling in a subset of CNS-DLBCL, and provide new potential therapeutic targets.

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.

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.

Frequent Gene Mutations and Their Possible Roles in the Pathogenesis, Treatment and Prognosis of Primary Central Nervous System Lymphoma

Primary central nervous system lymphoma (PCNSL) is a rare extranodal non-Hodgkin lymphoma with poor prognosis. In recent years, the emergence of genetic subtypes of systematic diffuse large B-cell lymphoma has highlighted the importance of molecular genetics, but large-scale research on the molecular genetics of PCNSL is lacking. Herein, we summarize the frequent gene mutations and discuss the possible pathogenesis of PCNSL. Myeloid differentiation primary response gene 88 (MYD88) and CD79B mutations, which cause abnormal activation of noncanonical nuclear factor-κB, are prominent genetic abnormalities in PCNSL. They are considered to play a major role in the pathogenesis of PCNSL. Other genes, such as caspase recruitment domain family member 11 (CARD11), tumor necrosis factor alpha induced protein 3 (TNFAIP3), transducin (β)-like 1 X-linked receptor 1, cyclin dependent kinase inhibitor 2A, PR domain zinc finger protein 1, and proviral insertion in murine malignancies 1, are also frequently mutated. Notably, the pathogenesis of immune insufficiency-associated PCNSL is related to Epstein-Barr virus infection, and its progression may be affected by different signaling pathways. The different mutational patterns in different studies highlight the heterogeneity of PCNSL. However, existing research on the molecular genetics of PCNSL is still limited, and further research into PCNSL is required to clarify the genetic characteristics of PCNSL.

CD79B Y196 mutation is a potent predictive marker for favorable response to R-MPV in primary central nervous system lymphoma

BACKGROUND

Rituximab, high-dose methotrexate (HD-MTX), procarbazine and vincristine (R-MPV), has significantly prolonged the survival of patients with primary central nervous system lymphoma (PCNSL), but predictive factors for response to R-MPV have not yet been investigated. Herein, we investigated the correlation of MYD88 L265P and CD79B Y196 mutations, which are the most frequently found molecular alterations in PCNSL, with prognosis of patients with PCNSL treated with R-MPV.

METHODS

We investigated the long-term clinical course and status of MYD88 and CD79B genes in 85 patients with PCNSL treated with R-MPV or HD-MTX treatment, and the correlation of these genetic mutations with prognosis.

RESULTS

R-MPV achieved an excellent tumor control rate (61.6% and 69.9% of 5-year progression-free and overall survival rates, respectively). While MYD88 L265P mutation had no significant effect on survival, patients with CD79B Y196 mutations exhibited prolonged survival (p < 0.05). However, the association of CD79B Y196 mutation with a better prognosis was not observed in the HD-MTX cohort, which indicated that CD79B Y196 mutation was a predictive marker for a favorable response to R-MPV. Furthermore, we established an all-in-one rapid genotyping system for these genetic mutations.

CONCLUSIONS

In conclusion, CD79B Y196 mutation is a potent predictive marker for favorable response to R-MPV in PCNSL. The rapid identification of MYD88 L265P and CD79B Y196 mutations can be helpful not only for the accurate molecular diagnosis of PCNSL but also for the prediction of response to R-MPV.

A genetically distinct pediatric subtype of primary CNS large B-cell lymphoma is associated with favorable clinical outcome

Primary central nervous system large B-cell lymphoma (PCNS-LBCL) occurs typically in older adults and only rarely in the pediatric population. The genomic landscape of PCNS-LBCL in children and young adults (YA) is not well-characterized. In this multi-institutional study, targeted next-generation DNA sequencing and chromosomal copy number analysis was performed on a cohort of 12 pediatric and YA (age<40 years) PCNS-LBCL patients without known immunodeficiency and correlated with clinicopathologic data. Based on genomic features, we identified two subgroups: a unique "Pediatric type, MYD88-wildtype" group (median age 14 years, range 7-25 years) was characterized by absence of MYD88 mutations but frequent genetic alterations in TP53 (6/8, 75%), NFKBIE (4/8, 50%), and GNA13 (4/8, 50%); and an "adult type, MYD88-mutant" group (median age 35 years, range 25-38 years) was defined by MYD88 hotspot mutations (4/4, 100%), with frequent PRDM1 mutation/deletion (3/4, 75%), CDKN2A/B homozygous deletion (3/4, 75%), and deletions of the HLA gene cluster (2/4, 50%). Kaplan-Meier analysis demonstrated that patients with pediatric type, MYD88-wildtype PCNS-LBCL had favorable outcomes (median survival: >100 months; 5-year-overall survival: 100%). In conclusion, we have identified a new pediatric type of PCNS-LBCL that is molecularly distinct from PCNS-LBCL occurring in adults, based on an absence of MYD88 mutation, CDKN2A/B homozygous deletion, deletion of HLA gene cluster, and paucity of CD79B and PRDM1 mutations, along with an enrichment for TP53, NFKBIE, and GNA13 mutations. Patients with pediatric type, MYD88-wildtype PCNS-LBCL often have long-term survival compared to their adult counterparts.

Primary central nervous system lymphomas with massive intratumoral hemorrhage: Clinical, radiological, pathological, and molecular features of six cases

Primary central nervous system lymphomas (PCNSLs) rarely exhibit intratumoral hemorrhage. The differential diagnosis of hemorrhagic neoplasms of the central nervous system (CNS) currently includes metastatic carcinomas, melanomas, choriocarcinomas, oligodendrogliomas, and glioblastomas. Here we present the clinical, radiological, pathological, and molecular genetic features of six cases of PCNSL associated with intratumoral hemorrhage. The median age of patients was 75 years, with male predominance. While conventional PCNSLs were associated with low cerebral blood volume (CBV), perfusion magnetic resonance imaging (MRI) revealed elevated CBV in three cases, consistent with vascular proliferation. All six cases were diagnosed pathologically as having diffuse large B-cell lymphoma (DLBCL) with a non-germinal center B-cell-like (non-GCB) phenotype; marked histiocytic infiltrates and abundant non-neoplastic T-cells were observed in most cases. Expression of vascular endothelial growth factor and CD105 in the lymphoma cells and the small vessels, respectively, suggested angiogenesis within the neoplasms. Neoplastic cells were immunohistochemically negative for programmed cell death ligand 1 (PD-L1), while immune cells in the microenvironment were positive for PD-L1. Mutations in the MYD88 gene (MYD88) (L265P) and the CD79B gene (CD79B) were detected in five and one case, respectively. As therapeutic modalities used for PCNSLs differ from those that target conventional hemorrhagic neoplasms, full tissue diagnoses of all hemorrhagic CNS tumors are clearly warranted.

Primary central nervous system lymphoma: status and advances in diagnosis, molecular pathogenesis, and treatment

Primary central nervous system lymphoma (PCNSL) is a rare group of extra-nodal non-Hodgkin lymphoma which is confined to the central nervous system or eyes. This article aims to present a brief profile of PCNSL diagnosis and treatment in immunocompetent patients. The authors retrieved information from the PubMed database up to September 2019. The annual incidence of PCNSL increased over the last four decades. The prognosis of PCNSL has improved mainly due to the introduction and wide-spread use of high-dose methotrexate, which is now the backbone of all first-line treatment polychemotherapy regimens. Gene expression profiling and next-generation sequencing analyses have revealed mutations that induce activation of nuclear factor-κB, B cell antigen receptor, and Janus kinases/signal transducer and activator of transcription proteins signal pathways. Some novel agents are investigated in the treatment of relapsed PCNSL including immunotherapy and targeted therapy. In particular, lenalidomide and ibrutinib have demonstrated durable efficiency. Treatment of PCNSL has evolved in the last 40 years and survival outcomes have improved in most patient groups, but there is still room to improve outcome by optimizing current chemotherapy and novel agents.

Diagnosis, prognosis and treatment of primary central nervous system lymphoma in the elderly population (Review)

Primary central nervous system lymphoma (PCNSL) is a rare subtype of extranodal non-Hodgkin lymphoma that is unique and different from systemic diffuse large B-cell lymphomas. The median age at diagnosis of PCNSL is 65 years and its incidence is rising rapidly in the elderly population. A total of ≥20% of all patients with PCNSL are ≥80 years old. Notably, age has been identified as an independent poor prognostic factor for PCNSL. Elderly patients have an inferior prognosis to that of younger patients and are more severely affected by iatrogenic toxicity; therefore, elderly patients represent a unique and vulnerable treatment subgroup. The present review summarized the available literature to provide an improved understanding of the epidemiology, clinical characteristics, diagnosis, prognosis and management of PCNSL in the elderly population. Notably, the incidence of PCNSL in immunocompetent elderly patients, predominantly in men, is increasing. For the diagnosis of CNSL, imaging-guided stereotactic biopsy is considered the gold standard. When stereotactic biopsy is not possible or conclusive, certain biomarkers have been described that can help establish a diagnosis. PCNSL has a very poor prognosis in the elderly, even though several prognostic scoring systems exist and several prognostic markers have been reported in patients with PCNSL. Furthermore, the treatment of elderly patients remains challenging; it is unlikely that a novel agent could be used as a curative monotherapy; however, a combination of novel agents with polychemotherapy or its combination with other novel drugs may have therapeutic potential.

Diversity of genetic alterations of primary central nervous system lymphoma in Hispanic versus non-Hispanic patients

PURPOSE

Primary central nervous system lymphoma (PCNSL) is a rare type of non-Hodgkin lymphoma. Previous studies have identified MYD88, CD79b and PIM1 as the most common genetic mutations in PCNSL. The extent to which mutations vary by ethnicity is unknown. The purpose of this study was to describe differences in genetic mutations and survival by Hispanic ethnicity in PCNSL.

METHODS

30 patients with PCNSL were examined for mutations in 275 genes by DNA analysis and 1408 genes by RNA analysis utilizing next generation sequencing.

RESULTS

60% of patients were Hispanic. 125 different mutated genes were detected. The most commonly affected genes were: MYD88 (44%), CARD11 (21%), CD79b (17%), PIM1 (17%) and KMT2D (17%) . MYD88 mutation was less frequent in Hispanic patients (27% vs 66%, P=.02). More Hispanic patients had >3 mutated genes (89% vs 55 %. P=.03). Two-year progression-free survival (PFS) and overall survival (OS) in Hispanic vs. non-Hispanic patients (PFS 60% vs 27%, P=.09), (OS 60% vs 36%, P=.23). MYD88, CARD11, PIM1, and KMT2D were not associated with significant differences in OS or PFS. CD79b mutation correlated with superior 2-yr PFS (P=.04).

CONCLUSIONS

We identified highly recurrent genetic alterations in PCNSL. Our data suggest that heterogeneity in some mutations may be related to ethnicity. There was no statistically significant difference in 2-yr PFS and OS in our Hispanic patients. Studies on larger population may further help to describe differences in tumor biology, and outcomes in Hispanic patients.

MYD88 L265P mutation in primary central nervous system lymphoma is associated with better survival: A single-center experience

BACKGROUND

The myeloid differentiation primary response gene (MYD88) mutation in primary central nervous system lymphomas (PCNSL) may be associated with unfavorable prognosis; however, current evidence remains limited. We aimed to characterize PCNSLs by integration of clinicopathological, molecular, treatment, and survival data.

METHODS

We retrospectively identified and validated 57 consecutive patients with PCNSLs according to the 2017 WHO classification of lymphoid neoplasms over 13 years. Formalin-fixed paraffin-embedded tumor samples underwent polymerase chain reaction assay to detect MYD88 mutation. We used Cox regression for survival analysis, including age, treatment, and MYD88 as covariates. We searched the literature for studies reporting demographics, treatment, MYD88, and survival of PCNSL patients and incorporated individual patient data into our analyses.

RESULTS

The median age was 66 years and 56% were women. All 57 patients had PCNSL of non-germinal center cell subtype and the majority (81%) received either single or combined therapies. There were 46 deaths observed over the median follow-up of 10 months. MYD88 mutation status was available in 41 patients of which 36 (88%) were mutated. There was an association between MYD88 mutation and better survival in the multivariable model (hazard ratio [HR] 0.277; 95% confidence interval [CI]: 0.09-0.83; P = .023) but not in a univariable model. After incorporating additional 18 patients from the literature, this association was reproducible (HR 0.245; 95% CI: 0.09-0.64; P = .004).

CONCLUSIONS

Adjusting for confounders, MYD88-mutant PCNSL appears to show improved survival. While further validation is warranted, detection of MYD88 mutation will aid the identification of patients who may benefit from novel targeted therapies.

Consecutive single-institution case series of primary central nervous system lymphoma treated by R-MPV or high-dose methotrexate monotherapy

OBJECTIVE

The optimal regimen for use of high dose-methotrexate-based chemotherapy in primary central nervous system lymphoma is still under debate. We conducted a retrospective study to evaluate the treatment outcome of a combination immunochemotherapy consisting of rituximab, methotrexate, procarbazine and vincristine followed by with or without whole brain radiotherapy and consolidation cytarabine, in comparison with high dose-methotrexate monotherapy followed by full dose whole brain radiotherapy.

METHODS

Newly diagnosed primary central nervous system lymphoma patients treated with either rituximab, methotrexate, procarbazine and vincristine or high dose-methotrexate in Kyorin University Hospital were identified, and the response rates and survival were compared. Toxicities, post-treatment transition of Mini-Mental State Examination, Karnofsky performance status score, Fazekas scale and prognostic factors were analysed in the rituximab, methotrexate, procarbazine and vincristine group.

RESULTS

Ninety-five patients treated with rituximab, methotrexate, procarbazine and vincristine (n = 39) or high dose-methotrexate (n = 56) were analysed. The complete response/complete response unconfirmed rate was significantly higher in the rituximab, methotrexate, procarbazine and vincristine group (74.4 vs. 15.4%, P < 0.001). Accordingly, both median progression-free survival and overall survival were significantly longer in the rituximab, methotrexate, procarbazine and vincristine group (median progression-free survival: unreached vs. 14.75 months, P < 0.001) (median overall survival: unreached vs. 63.15 months, P = 0.005). Although the rate of grade 3/4 hematologic toxicities was high both during rituximab, methotrexate, procarbazine and vincristine and consolidation cytarabine, the rate of grade 3/4 infections was low, and no treatment related deaths were observed. Deterioration in Karnofsky performance status or Mini-Mental State Examination was rare, except on disease recurrence. Although whole brain radiotherapy was associated with Fazekas scale deterioration, its association with Karnofsky performance status or Mini-Mental State Examination deterioration was not significant.

CONCLUSIONS

Rituximab, methotrexate, procarbazine and vincristine was apparently promising in comparison with high dose-methotrexate monotherapy with manageable toxicity in this retrospective study, and further investigation is warranted.

Primary Central Nervous System Methotrexate-associated Lymphoproliferative Disorder in a Patient with Rheumatoid Arthritis: Case Report and Review of Literature

Methotrexate (MTX) is an immunosuppressor that is widely used to treat autoimmune diseases, including rheumatoid arthritis (RA). However, it can have serious adverse effects including a lymphoma: MTX-associated lymphoproliferative disorder (MTX-LPD). Extranodal lesions are common in MTX-LPD patients. However, MTX-LPD in the central nervous system (CNS) is extremely rare with few reported cases. Here, we describe a case of primary CNS MTX-LPD in a patient with RA, with a review of the literature. A 68-year-old woman who had received MTX for her RA for more than 10 years was referred to our hospital. Head magnetic resonance imaging (MRI) showed multiple lesions with heterogeneous contrast enhancement scattered throughout both hemispheres. As immunosuppression caused by MTX was suspected, MTX was discontinued, based on a working diagnosis of MTX-LPD. We performed an open biopsy of her right temporal lesion. Histopathologic examination showed atypical CD20+ lymphoid cells, leading to a definitive diagnosis of diffuse large B-cell lymphoma (DLBCL). In situ hybridization of an Epstein-Barr virus-encoded small RNA (EBER) was positive. Sanger sequencing confirmed that both MYD88 L265 and CD79B Y196 mutations were absent. The LPD regressed after stopping MTX. Follow-up head MRI at 8 months after surgery showed no evidence of recurrence. Although primary CNS MTX-LPD is extremely rare, it should be included in the differential diagnosis when a patient receiving MTX develops CNS lesions. Diagnosis by biopsy and MTX discontinuation are required as soon as possible.

Identification of Prognostic Markers in Patients with Primary Vitreoretinal Lymphoma by Clustering Analysis Using Clinical Data

(1) Purpose: Primary vitreoretinal lymphoma (PVRL) is associated with poor prognosis because most of the patients with PVRL develop central nerve system lymphoma. The prognostic biomarker of PVRL is largely unknown. Cluster analysis has been used to identify phenotypic groups within various diseases. In this study, we aimed to describe clinical features of patients with PVRL grouped by clustering analysis and to identify biomarkers for predicting survival prognosis in patients with PVRL. (2) Materials and Methods: Forty patients with PVRL were divided into two groups by clustering analysis using clinical data. Clinical features of the two groups were compared. (3) Result: Clustering analysis classified patients into groups A and B. The survival rate during the follow-up period was significantly lower in group B than in group A (p = 0.03). Serum IgG, serum IgA, vitreous IL-10 and vitreous IL-10 to IL-6 ratio were significantly different between groups A and B (p = 0.03, 0.005, 0.008 and 0.03, respectively). Receiver operating characteristic (ROC) curves generated for the four variables indicated that serum IgA was most suitable for the prediction of prognosis. Patients with serum IgA below 184 mg/dL obtained from the ROC curve had a lower three-year survival rate (p = 0.03) and more episodes of recurrence of lymphoma (3.2 times versus 1.8 times, p = 0.02) compared with patients with serum IgA above 184 mg/dL. (4) Conclusion: The survival rate was significantly different in PVRL patients classified into two groups by clustering analysis. Patients with lower serum IgA had more recurrences and poorer survival than patients with higher IgA.

Prognostic value of MYD88 L265P mutation in diffuse large B cell lymphoma via droplet digital PCR

To assess the prevalence and prognostic value of myeloid differentiation factor 88 (MYD88) expression and mutational status in diffuse large B cell lymphoma (DLBCL), a total cohort of 100 patients with DLBCL were studied using immunohistochemistry (IHC) and droplet digital polymerase chain reaction (DDPCR), and the association between MYD88 expression and clinicopathological parameters was analyzed. Overall, the positive expression rate of MYD88 protein was 38% and the gene mutation rate was 29%. The positive expression and mutation rates were the highest in the primary central nervous system lymphomas (58.33 and 66.67%, respectively). The coincidence rate of the results of MYD88 expression between IHC and DDPCR results was 73% (73/100). Univariate survival analysis showed that age (≥60 years old), high neutrophil/lymphocyte count ratio, low lymphocyte count, c-Myc ≥40%, positive MYD88 protein expression, and gene mutation were associated with poorer prognosis rates. Multivariate survival analysis revealed that MYD88 expression was an independent prognostic factor affecting overall survival. In conclusion, the results of this study demonstrated that MYD88 mutation was a valuable index to evaluate the prognosis of DLBCL. DDPCR can be used as a method for detecting MYD88 mutations, although it was not completely consistent with the results of IHC.

MYD88 L265P mutation and CDKN2A loss are early mutational events in primary central nervous system diffuse large B-cell lymphomas

The genetic alterations that define primary central nervous system lymphoma (PCNSL) are incompletely elucidated, and the genomic evolution from diagnosis to relapse is poorly understood. We performed whole-exome sequencing (WES) on 36 PCNSL patients and targeted MYD88 sequencing on a validation cohort of 27 PCNSL patients. We also performed WES and phylogenetic analysis of 3 matched newly diagnosed and relapsed tumor specimens and 1 synchronous intracranial and extracranial relapse. Immunohistochemistry (IHC) for programmed death-1 ligand (PD-L1) was performed on 43 patient specimens. Combined WES and targeted sequencing identified MYD88 mutation in 67% (42 of 63) of patients, CDKN2A biallelic loss in 44% (16 of 36), and CD79b mutation in 61% (22 of 36). Copy-number analysis demonstrated frequent regions of copy loss (ie, CDKN2A), with few areas of amplification. CD79b mutations were associated with improved progression-free and overall survival. We did not identify amplification at the PD-1/PD-L1 loci. IHC for PD-L1 revealed membranous expression in 30% (13 of 43) of specimens. Phylogenetic analysis of paired primary and relapsed specimens identified MYD88 mutation and CDKN2A loss as early clonal events. PCNSL is characterized by frequent mutations within the B-cell receptor and NF-κB pathways. The lack of PD-L1 amplifications, along with membranous PD-L1 expression in 30% of our cohort, suggests that PD-1/PD-L1 inhibitors may be useful in a subset of PCNSL. WES of PCNSL provides insight into the genomic landscape and evolution of this rare lymphoma subtype and potentially informs more rational treatment decisions.

High Detection Rate of MYD88 Mutations in Cerebrospinal Fluid From Patients With CNS Lymphomas

PURPOSE

Biopsy is the gold standard for the diagnosis of primary CNS lymphoma (PCNSL). However, surgical biopsy has problems of morbidity related to hemorrhagic complications and false-negative findings, so safer and more reliable diagnostic methods are required. The aim of this study is to detect the MYD88 mutation, an important driver mutation, in the cerebrospinal fluid (CSF) of patients with CNS lymphoma.

PATIENTS AND METHODS

Twenty-six patients with CNS lymphoma (20 primary CNS lymphoma and six CNS relapse from systemic lymphoma) were studied. We extracted cell-free DNA (cfDNA) from CSF by lumbar puncture. cfDNA was extracted from 1 mL of CSF, and Sanger sequencing and droplet digital polymerase chain reaction (ddPCR) were performed. Furthermore, we performed DNA sequencing of MYD88 in 21 cases with available surgically obtained formalin-fixed paraffin-embedded (FFPE) tissue and compared the results.

RESULTS

The median cfDNA amount extracted from 1 mL CSF was 219 ng/mL (25th to 75th percentile, 129 to 333 ng/mL). MYD88 mutations were detected from CSF in 76.9% (20 of 26 cases), and L265P in exon 5 was the most frequent mutation in 19 out of 20 (95.0%) cases. S219C in exon 3 was detected in one case. In four patients, MYD88 mutation was confirmed by ddPCR but not by Sanger sequencing. In all 21 cases with sufficient FFPE tissue for DNA analysis, the detection of MYD88 mutation from cfDNA was consistent with those of tumor-derived DNA from FFPE tissue.

CONCLUSION

This pilot study provided evidence that the somatic driver mutation MYD88 can be reliably detected by combination of Sanger sequencing and ddPCR in the cfDNA taken from 1 mL of CSF in patients with CNS lymphomas.

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

More than 50 subtypes of B-cell non-Hodgkin lymphoma (B-NHL) are recognized in the most recent World Health Organization classification of 2016. The current treatment paradigm, however, is largely based on 'one-size-fits-all' immune-chemotherapy. Unfortunately, this therapeutic strategy is inadequate for a significant number of patients. As such, there is an indisputable need for novel, preferably targeted, therapies based on a biologically driven classification and risk stratification. Sequencing studies identified mutations in the MYD88 gene as an important oncogenic driver in B-cell lymphomas. MYD88 mutations constitutively activate NF-κB and its associated signaling pathways, thereby promoting B-cell proliferation and survival. High frequencies of the hotspot MYD88(L265P) mutation are observed in extranodal diffuse large B-cell lymphoma and Waldenström macroglobulinemia, thereby demonstrating this mutation's potential as a disease marker. In addition, the presence of mutant MYD88 predicts survival outcome in B-NHL subtypes and it provides a therapeutic target. Early clinical trials targeting MYD88 have shown encouraging results in relapsed/refractory B-NHL. Patients with these disorders can benefit from analysis for the MYD88 hotspot mutation in liquid biopsies, as a minimally invasive method to demonstrate treatment response or resistance. Given these clear clinical implications and the crucial role of MYD88 in lymphomagenesis, we expect that analysis of this gene will increasingly be used in routine clinical practice, not only as a diagnostic classifier, but also as a prognostic and therapeutic biomarker directing precision medicine. This review focuses on the pivotal mechanistic role of mutated MYD88 and its clinical implications in B-NHL.

Pathological mutations differentially affect the self-assembly and polymerisation of the innate immune system signalling adaptor molecule MyD88

Background

Higher-order self-assembly of proteins, or “prion-like” polymerisation, is now emerging as a simple and robust mechanism for signal amplification, in particular within the innate immune system, where the recognition of pathogens or danger-associated molecular patterns needs to trigger a strong, binary response within cells. MyD88, an important adaptor protein downstream of TLRs, is one of the most recent candidates for involvement in signalling by higher order self-assembly. In this new light, we set out to re-interpret the role of polymerisation in MyD88-related diseases and study the impact of disease-associated point mutations L93P, R196C, and L252P/L265P at the molecular level.

Results

We first developed new in vitro strategies to characterise the behaviour of polymerising, full-length MyD88 at physiological levels. To this end, we used single-molecule fluorescence fluctuation spectroscopy coupled to a eukaryotic cell-free protein expression system. We were then able to explore the polymerisation propensity of full-length MyD88, at low protein concentration and without purification, and compare it to the behaviours of the isolated TIR domain and death domain that have been shown to have self-assembly properties on their own. These experiments demonstrate that the presence of both domains is required to cooperatively lead to efficient polymerisation of the protein. We then characterised three pathological mutants of MyD88.

Conclusion

We discovered that all mutations block the ability of MyD88 to polymerise fully. Interestingly, we show that, in contrast to L93P and R196C, L252P is a gain-of-function mutation, which allows the MyD88 mutant to form extremely stable oligomers, even at low nanomolar concentrations. Thus, our results shed new light on the digital “all-or-none” responses by the myddosomes and the behaviour of the oncogenic mutations of MyD88.

Characterization of genomic alterations in primary central nervous system lymphomas

PURPOSE

Primary central nervous system lymphoma (PCNSL) is a non-Hodgkin lymphoma that affects the central nervous system (CNS). Although previous studies have reported the most common mutated genes in PCNSL, including MYD88 and CD79b, our understanding of genetic characterizations in primary CNS lymphomas is limited. The aim of this study was to perform a retrospective analysis investigating the most frequent mutation types, and their frequency, in PCNSL.

METHODS

Fifteen patients with a diagnosis of PCNSL from our institution were analyzed for mutations in 406 genes and rearrangements in 31 genes by next generation sequencing (NGS).

RESULTS

Missense mutations were identified as the most common mutation type (32%) followed by frame shift mutations (23%). The highest mutation rate was reported in the MYD88 (33.3%), CDKN2A/B (33.3%), and TP53 (26.7%) genes. Intermediate tumor mutation burden (TMB) and high TMB was detected in 13.3% and 26.7% of PCNSL, respectively. The most frequent gene rearrangement involved the IGH-BCL6 genes (20%).

CONCLUSIONS

This study shows the most common genetic alterations in PCNSL as determined by a commercial next generation sequencing assay. MYD88 and CD79b are frequently mutated in PCNSL, IGH-BCL6 is the most frequent gene rearrangement and approximately 1/4 of cases show a high TMB. Mutations in multiple genes, in addition to high TMB and gene rearrangements, highlights the complex molecular heterogeneity of PCNSL. Knowledge about genetic alterations in PCNSL can inform the development of novel targets for diagnosis and treatment.