MYD88 L265P Mutations, But No Other Variants, Identify a Subpopulation of DLBCL Patients of Activated B-cell Origin, Extranodal Involvement, and Poor Outcome

Deciphering the Prognostic Significance of MYD88 and CD79B Mutations in Diffuse Large B-Cell Lymphoma: Insights into Treatment Outcomes

BACKGROUND

The clinical and genetic characteristics, as well as treatment outcomes, of diffuse large B-cell lymphoma (DLBCL) patients with different MYD88 and CD79B mutation status merit further investigation.

OBJECTIVE

This study aims to investigate the distinctions in clinical manifestations, genetic characteristics, and treatment outcomes among MYD88-CD79Bco-mut, MYD88/CD79Bsingle-mut, and MYD88-CD79Bco-wt DLBCL patients.

PATIENTS AND METHODS

Clinical and genetic characteristics, along with treatment outcomes among 2696 DLBCL patients bearing MYD88-CD79Bco-mut, MYD88/CD79Bsingle-mut, and MYD88-CD79Bco-wt treated with R-CHOP/R-CHOP-like regimens from the Cancer Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College and six external cohorts were analyzed. Potential molecular mechanisms were investigated through Gene Set Enrichment Analysis and xCell methodology.

RESULTS

In the MCD subtype, patients with MYD88-CD79Bco-mut showed comparable progression-free survival (PFS) and overall survival (OS) compared to MYD88/CD79Bsingle-mut or MYD88-CD79Bco-wt. However, in the non-MCD subtype, patients with MYD88-CD79Bco-mut exhibited significantly inferior OS than MYD88/CD79Bsingle-mut or MYD88-CD79Bco-wt, while there was no significant OS difference between MYD88/CD79Bsingle-mut and MYD88-CD79Bco-wt (median OS: 68.8 [95% CI 22-NA] vs NA [95% CI 112-NA] vs 177.7 [95% CI 159-NA] months; MYD88-CD79Bco-mut vs MYD88/CD79Bsingle-mut: p = 0.02; MYD88-CD79Bco-mut vs MYD88-CD79Bco-wt: p = 0.03; MYD88/CD79Bsingle-mut vs MYD88-CD79Bco-wt: p = 0.33). Regarding patients with MYD88-CD79Bco-mut, there was no significant difference in PFS and OS between the MCD and non-MCD subtypes. Within the MYD88-CD79Bco-mut group, patients with PIM1mut had better PFS than PIM1wt (median PFS: 8.34 [95% CI 5.56-NA] vs 43.8 [95% CI 26.4-NA] months; p = 0.02). Possible mechanisms contributing to the superior PFS of PIM1mut patients may include activated lymphocyte-mediated immunity and interferon response, a higher proportion of natural killer T cells and plasmacytoid dendritic cells, as well as suppressed angiogenesis and epithelial-mesenchymal transition, along with lower fibroblast and stromal score.

CONCLUSIONS

In the MCD subtype, patients with MYD88-CD79Bco-mut showed comparable PFS and OS compared to MYD88/CD79Bsingle-mut or MYD88-CD79Bco-wt, while in the non-MCD subtype, they exhibited significantly inferior OS. There was no significant disparity in PFS and OS of MYD88-CD79Bco-mut between the MCD and non-MCD subtypes. The presence of PIM1mut within the MYD88-CD79Bco-mut group correlated with better PFS, which may result from an intricate interplay of immune processes and tumor microenvironment alterations.

A single-centre, real-world study of BTK inhibitors for the initial treatment of MYD88mut /CD79Bmut diffuse large B-cell lymphoma

BACKGROUND

MCD (MYD88L265P /CD79Bmut ) diffuse large B-cell lymphoma has a poor prognosis. There is no published clinical research conclusion regarding zanubrutinib or orelabrutinib for the initial treatment of MCD DLBCL.

AIMS

This study aimed to analyse the efficacy and safety of Bruton's tyrosine kinase inhibitor (BTKi) (zanubrutinib or orelabrutinib) therapy for newly diagnosed DLBCL patients with MYD88mut and/or CD79Bmut .

MATERIALS AND METHODS

Twenty-three newly diagnosed DLBCL patients with MYD88mut and/or CD79Bmut from June 2020 to June 2022 received BTKi combined with rituximab plus cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP) or rituximab + lenalidomide (R2 ). A control group of 17 patients with MYD88mut and/or CD79Bmut DLBCL who received the standard R-CHOP therapy was also assessed. We retrospectively analysed clinical characteristics, safety, overall response rate (ORR), complete response (CR) rate and progression-free survival (PFS) of the two groups.

RESULTS

The main clinical features were a high International Prognostic Index (IPI) score (≥3, 22/40, 55%) and a high rate of extranodal involvement (27/40,67.5%). Among the 23 DLBCL patients, 18 received BTKi + R-CHOP, and five elderly DLBCL patients were treated with BTKi + R2 . Compared with those in the control group (ORR 70.6%, CRR 52.9%, 1-year PFS rate 41.2%), improved ORR, CRR and PFS results were observed in the BTKi + R-CHOP group (100%, 94.4% and 88.9%, p = 0.019, 0.007, and 0.0001). In subgroup analyses based on genetic subtypes, cell origin, dual expression or IPI score, patients in the BTKi + R-CHOP group had better PFS than patients in the control group. In the BTKi + R-CHOP group, no significant difference was found in ORR, CRR and PFS based on subtype analysis, while BTKi-type subgroups exhibited statistically significant differences in 1-year PFS (p = 0.028). There were no significant differences in grade 3-4 haematological toxicity (p = 1) and grade 3-4 non-haematological toxicity (p = 0.49) between the BTKi + R-CHOP and R-CHOP treatment groups. In the BTKi + R2 group, the ORR was 100%, the CRR was 80%, and the 1-year PFS rate was 80%. The incidences of grade 3-4 haematologic toxicity and non-haematological toxicity were both 40%. No bleeding or cardiovascular events of grade 3 or higher occurred in any patients.

DISCUSSION

The efficacy of BTKi combined with R-CHOP was similar to previous reports, which was significantly better than R-CHOP alone. It is necessary to fully consider that 14 patients in the BTKi + R-CHOP group received a BTKi as maintenance therapy when evaluating efficacy. Meanwhile, the addition of a BTKi may improve the prognosis of non-GCB, DEL or high-IPI-score DLBCL patients with MYD88mut and/or CD79Bmut . In our study, five elderly DLBCL patients with MYD88mut and/or CD79Bmut were achieved better ORR, CRR, PFS than the historical data of R-miniCHOP treatment and Ibrutinib + R2 treatment. However, the efficacy and benefit of BTKis for this type of DLBCL need to be further analysed using a larger sample size.

CONCLUSION

This study suggests that newly diagnosed DLBCL patients with MYD88mut and/or CD79Bmut may benefit from BTKis according to real-world clinical data.

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.

Evaluation and Management of Disease Transformation in Waldenström Macroglobulinemia

Histologic transformation (HT) to diffuse large B-cell lymphoma occurs rarely in Waldenström macroglobulinemia, with higher incidence in MYD88 wild-type patients. HT is suspected clinically when rapidly enlarging lymph nodes, elevated lactate dehydrogenase levels, or extranodal disease occur. Histologic assessment is required for diagnosis. HT carries a worse prognosis compared with nontransformed Waldenström macroglobulinemia. A validated prognostic score based on three adverse risk factors stratifies three risk groups. The most common frontline treatment is chemoimmunotherapy, such as R-CHOP. Central nervous system prophylaxis should be considered if feasible and consolidation with autologous transplant should be discussed in fit patients responding to chemoimmunotherapy.

Design, synthesis and pharmacological evaluation of 2,3-dihydrobenzofuran IRAK4 inhibitors for the treatment of diffuse large B-cell lymphoma

Interleukin-1 receptor associated kinase 4 (IRAK4) is a critical mediator of MYD88 L265P-induced NF-κB activation, indicating it is a promising therapeutic target for diffuse large B-cell lymphoma (DLBCL). Herein we report the discovery of a series of 2,3-dihydrobenzofuran IRAK4 inhibitors through structure-based drug design. The representative compound 22 exhibited strong IRAK4 inhibitory potency (IRAK4 IC₅₀ = 8.7 nM), favorable kinase selectivity and high antiproliferative activity against the MYD88 L265P DLBCL cell line (OCI-LY10 IC₅₀ = 0.248 μM). Compound 22 also exhibited the ability to inhibit the activation of IRAK4 signaling pathway and induce apoptosis in MYD88 L265P DLBCL cell line. In combination with Bruton's tyrosine kinase (BTK) inhibitor ibrutinib, 22 showed enhanced apoptosis-inducing effect and antiproliferative potency. The most advanced compound 22 in this inhibitor series holds promise for further development into efficacious and selective IRAK4 inhibitors for the treatment of DLBCL.

MYD88L265P and MYD88other variants show different molecular characteristics and prognostic significance in diffuse large B-cell lymphoma

PURPOSE

This study aims to investigate the clinical and molecular differences between diffuse large B-cell lymphoma (DLBCL) patients with MYD88^L265P and MYD88^other.

METHODS

DLBCL patients with MYD88 variations were collected from the Cancer Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College (CHCAMS), and Suzhou Municipal Hospital from February 6th, 2007 to May 20th, 2022. Clinicopathological parameters and treatment outcomes between MYD88^L265P and MYD88^other were investigated.

RESULTS

A total of 132 patients with MYD88 variations from a cohort of 475 DLBCL patients were included, among which, 78 were MYD88^L265P, while 54 were MYD88^other. MYD88^L265P was more common in non-GCB subtype than MYD88^other (83% vs. 60%, P = 0.004). Besides, MYD88^L265P was significantly related to higher proportion of testicle/ central nervous system involvement (31% vs. 6%, P < 0.001), PIM1 mutation (71% vs. 39%, P < 0.001), and PIM1 hypermutation (28% vs. 11%, P = 0.018), compared with MYD88^other. Compared with MYD88^L265P, MYD88^other were more likely to have higher percentage of advanced stage (60% vs. 42%, P = 0.044), extranodal site ≥ 2 (45% vs. 28%, P = 0.044), elevated LDH (55% vs. 35%, P = 0.033), positive CD10 expression (36% vs. 16%, P = 0.009), BCL-6 translocation (20% vs. 8%, P = 0.033), and NOTCH pathway gene alteration (24% vs. 13%, P = 0.040). In non-GCB DLBCL subtype, patients with MYD88^other were significantly associated with worse progression free survival (PFS) than those with MYD88^L265P when treated initially with R-CHOP/R-CHOP-like regimen (P = 0.010).

CONCLUSION

The findings of this study indicate that DLBCL patients with MYD88^L265P and MYD88^other are likely to be two subgroups with different clinical and molecular characteristics. The survival of patients with MYD88^other is not superior than those with MYD88^L265P, even poorer when focusing on the non-GCB subtype.

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

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

A novel IRAK4/PIM1 inhibitor ameliorates rheumatoid arthritis and lymphoid malignancy by blocking the TLR/MYD88-mediated NF-κB pathway

Interleukin-1 receptor-associated kinase 4 (IRAK4) is a pivotal enzyme in the Toll-like receptor (TLR)/MYD88 dependent signaling pathway, which is highly activated in rheumatoid arthritis tissues and activated B cell-like diffuse large B-cell lymphoma (ABC-DLBCL). Inflammatory responses followed by IRAK4 activation promote B-cell proliferation and aggressiveness of lymphoma. Moreover, proviral integration site for Moloney murine leukemia virus 1 (PIM1) functions as an anti-apoptotic kinase in propagation of ABC-DLBCL with ibrutinib resistance. We developed a dual IRAK4/PIM1 inhibitor KIC-0101 that potently suppresses the NF-κB pathway and proinflammatory cytokine induction in vitro and in vivo. In rheumatoid arthritis mouse models, treatment with KIC-0101 significantly ameliorated cartilage damage and inflammation. KIC-0101 inhibited the nuclear translocation of NF-κB and activation of JAK/STAT pathway in ABC-DLBCLs. In addition, KIC-0101 exhibited an anti-tumor effect on ibrutinib-resistant cells by synergistic dual suppression of TLR/MYD88-mediated NF-κB pathway and PIM1 kinase. Our results suggest that KIC-0101 is a promising drug candidate for autoimmune diseases and ibrutinib-resistant B-cell lymphomas.

Whole-exome sequencing analysis identifies distinct mutational profile and novel prognostic biomarkers in primary gastrointestinal diffuse large B-cell lymphoma

Background

Diffuse large B-cell lymphoma (DLBCL) is the most common aggressive non-Hodgkin lymphoma, and about 10% of DLBCL cases primarily occur in the gastrointestinal tract. Previous reports have revealed that primary gastrointestinal-DLBCL (pGI-DLBCL) harbors different genetic mutations from other nodal or extranodal DLBCL. However, the exonic mutation profile of pGI-DLBCL has not been fully addressed.

Methods

We performed whole-exome sequencing of matched tumor tissues and blood samples from 53 pGI-DLBCL patients. The exonic mutation profiles were screened, and the correlations between genetic mutations and clinicopathological characteristics were analyzed.

Results

A total of 6,588 protein-altering events were found and the five most frequent mutated genes in our pGI-DLBCL cohort were IGLL5 (47%), TP53 (42%), BTG2 (28%), P2RY8 (26%) and PCLO (23%). Compared to the common DLBCL, significantly less or absence of MYD88 (0%), EZH2 (0%), BCL2 (2%) or CD79B (8%) mutations were identified in pGI-DLBCL. The recurrent potential driver genes were mainly enriched in pathways related to signal transduction, infectious disease and immune regulation. In addition, HBV infection had an impact on the mutational signature in pGI-DLBCL, as positive HBsAg was significantly associated with the TP53 and LRP1B mutations, two established tumor suppressor genes in many human cancers. Moreover, IGLL5 and LRP1B mutations were significantly correlated with patient overall survival and could serve as two novel prognostic biomarkers in pGI-DLBCL.

Conclusions

Our study provides a comprehensive view of the exonic mutation profile of the largest pGI-DLBCL cohort to date. The results could facilitate the clinical development of novel therapeutic and prognostic biomarkers for pGI-DLBCL.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40164-022-00325-7.

Transformed Waldenström Macroglobulinemia: Update on Diagnosis, Prognosis and Treatment

Histological transformation (HT) to an aggressive lymphoma results from a rare evolution of Waldenström macroglobulinemia (WM). A higher incidence of transformation events has been reported in MYD88 wild-type WM patients. HT in WM can be histologically heterogeneous, although the diffuse large B-cell lymphoma of activated B-cell subtype is the predominant pathologic entity. The pathophysiology of HT is largely unknown. The clinical suspicion of HT is based on physical deterioration and the rapid enlargement of the lymph nodes in WM patients. Most transformed WM patients present with elevated serum lactate dehydrogenase (LDH) and extranodal disease. A histologic confirmation regarding the transformation to a higher-grade lymphoma is mandatory for the diagnosis of HT, and the choice of the biopsy site may be dictated by the findings of the 18fluorodeoxyglucose-positron emission tomography/computed tomography. The prognosis of HT in WM is unfavorable, with a significantly inferior outcome compared to WM patients without HT. A validated prognostic score based on 3 adverse risk factors (elevated LDH, platelet count < 100 × 109/L and any previous treatment for WM) stratifies patients into 3 risk groups. The most common initial treatment used is a chemo-immunotherapy (CIT), such as R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone). The response duration is short and central nervous system relapses are frequent. Whether autologous stem cell transplantation could benefit fit patients responding to CIT remains to be studied.

MYD88 Mutations: Transforming the Landscape of IgM Monoclonal Gammopathies

The MYD88 gene has a physiological role in the innate immune system. Somatic mutations in MYD88, including the most common L265P, have been associated with the development of certain types of lymphoma. MYD88L265P is present in more than 90% of patients with Waldenström's macroglobulinemia (WM) and IgM monoclonal gammopathy of undetermined significance (IgM-MGUS). The absence of MYD88 mutations in WM patients has been associated with a higher risk of transformation into aggressive lymphoma, resistance to certain therapies (BTK inhibitors), and shorter overall survival. The MyD88 signaling pathway has also been used as a target for specific therapies. In this review, we summarize the clinical applications of MYD88 testing in the diagnosis, prognosis, follow-up, and treatment of patients. Although MYD88L265P is not specific to WM, few tumors present a single causative mutation in a recurrent position. The role of the oncogene in the pathogenesis of WM is still unclear, especially considering that the mutation can be found in normal B cells of patients, as recently reported. This may have important implications for early lymphoma detection in healthy elderly individuals and for the treatment response assessment based on a MYD88L265P analysis.

Neo-Splicetopes in Tumor Therapy: A Lost Case?

Proteasome generates spliced peptides by ligating two distant cleavage products in a reverse proteolysis reaction. The observation that CD8+ T cells recognizing a spliced peptide induced T cell rejection in a melanoma patient following adoptive T cell transfer (ATT), raised some hopes with regard to the general therapeutic and immune relevance of spliced peptides. Concomitantly, the identification of spliced peptides was also the start of a controversy with respect to their frequency, abundancy and their therapeutic applicability. Here I review some of the recent evidence favoring or disfavoring an immune relevance of splicetopes and discuss from a theoretical point of view the potential usefulness of tumor specific splicetopes and why against all odds it still may seem worth trying to identify such tumor and patient-specific neosplicetopes for application in ATT.

MYD88L265P and CD79B double mutations type (MCD type) of diffuse large B-cell lymphoma: mechanism, clinical characteristics, and targeted therapy

MYD88/CD79B-mutated (MCD) genotype is a genetic subgroup of diffuse large B-cell lymphoma (DLBCL) with the co-occurrence of MYD88^L265P and CD79B mutations. MCD genotype is characterized by poor prognosis and extranodal involvement especially in immune-privileged sites. MCD model is dominated by activated B-cell (ABC)-like subtype of DLBCLs. It is generally accepted that the pathogenesis of MCD DLBCL mainly includes chronic active B-cell receptor (BCR) signaling and oncogenic MYD88 mutations, which drives pathological nuclear factor kappa B (NF-κB) activation in MCD lymphoid malignancies. CD79B and MYD88^L265P mutations are frequently and contemporaneously founded in B-cell malignancies. The collaboration of the two mutations may explain the unique biology of MCD. Meanwhile, standard immunochemotherapy combine with different targeted therapies worth further study to improve the prognosis of MCD, according to genetic, phenotypic, and clinical features of MCD type. In this review, we systematically described mechanism, clinical characteristics, and targeted therapy of MCD DLBCL.

A prognostic index predicting survival in transformed Waldenström macroglobulinemia

Histological transformation into diffuse large B-cell lymphoma is a rare complication in patients with Waldenström macroglobulinemia (WM) and is usually associated with a poor prognosis. The objective of this study was to develop and validate a prognostic index for survival of patients with transformed WM. Through this multicenter, international collaborative effort, we developed a scoring system based on data from 133 patients with transformed WM who were evaluated between 1995 and 2016 (training cohort). Univariate and multivariate analyses were used to propose a prognostic index with 2-year survival after transformation as an endpoint. For external validation, a dataset of 67 patients was used to evaluate the performance of the model (validation cohort). By multivariate analysis, three adverse covariates were identified as independent predictors of 2-year survival after transformation: elevated serum lactate dehydrogenase (2 points), platelet count <100x109/L (1 point) and any previous treatment for WM (1 point). Three risk groups were defined: low-risk (0-1 point, 24% of patients), intermediate-risk (2-3 points, 59%; hazard ratio = 3.4) and high-risk (4 points, 17%; hazard ratio = 7.5). Two-year survival rates were 81%, 47%, and 21%, respectively (P<0.0001). This model appeared to be a better discriminant than either the International Prognostic Index or the revised International Prognostic Index. We validated this model in an independent cohort. This easy-to-compute scoring index is a robust tool that may allow identification of groups of transformed WM patients with different outcomes and could be used for improving the development of risk-adapted treatment strategies.

High-affinity T-cell receptor specific for MyD88 L265P mutation for adoptive T-cell therapy of B-cell malignancies

BACKGROUND

Adoptive transfer of engineered T cells has shown remarkable success in B-cell malignancies. However, the most common strategy of targeting lineage-specific antigens can lead to undesirable side effects. Also, a substantial fraction of patients have refractory disease. Novel treatment approaches with more precise targeting may be an appealing alternative. Oncogenic somatic mutations represent ideal targets because of tumor specificity. Mutation-derived neoantigens can be recognized by T-cell receptors (TCRs) in the context of MHC-peptide presentation.

METHODS

Here we have generated T-cell lines from healthy donors by autologous in vitro priming, targeting a missense mutation on the adaptor protein MyD88, changing leucine at position 265 to proline (MyD88 L265P), which is one of the most common driver mutations found in B-cell lymphomas.

RESULTS

Generated T-cell lines were selectively reactive against the mutant HLA-B*07:02-restricted epitope but not against the corresponding wild-type peptide. Cloned TCRs from these cell lines led to mutation-specific and HLA-restricted reactivity with varying functional avidity. T cells engineered with a mutation-specific TCR (TCR-T cells) recognized and killed B-cell lymphoma cell lines characterized by intrinsic MyD88 L265P mutation. Furthermore, TCR-T cells showed promising therapeutic efficacy in xenograft mouse models. In addition, initial safety screening did not indicate any sign of off-target reactivity.

CONCLUSION

Taken together, our data suggest that mutation-specific TCRs can be used to target the MyD88 L265P mutation, and hold promise for precision therapy in a significant subgroup of B-cell malignancies, possibly achieving the goal of absolute tumor specificity, a long sought-after dream of immunotherapy.

The Positivity of Phosphorylated STAT3 Is a Novel Marker for Favorable Prognosis in Germinal Center B-Cell Type of Diffuse Large B-Cell Lymphoma

On the basis of immunohistochemistry, diffuse large B-cell lymphoma (DLBCL) is categorized as a germinal center B-cell (GCB) or non-GCB subtype. Recent integrated genomic analyses have highlighted the importance of the JAK-STAT3 pathway in the molecular pathogenesis of DLBCL. However, its relevance to clinical outcomes remains controversial. Therefore, we evaluated the extent of the nuclear expression of phosphorylated STAT3 (pSTAT3), a surrogate marker of signal transducer and activator of transcription 3 (STAT3) activation, by immunohistochemistry. We also analyzed the potential relationship between pSTAT3 positivity (defined as ≥40% positive neoplastic cells) and clinicopathologic characteristics in 294 patients with DLBCL. pSTAT3 was detected in 122 patients (42%), with a higher rate in the non-GCB subtype than in the GCB subtype (57% vs. 28%, P<0.001). Factors potentially activating STAT3, MYD88L265P, and Epstein-Barr virus-encoded small RNA were identified in the pSTAT3-positive non-GCB subtype, whereas the pSTAT3-positive GCB subtype often showed STAT3 mutations and lacked EZH2 mutations and the rearrangements of BCL2 and MYC. Multivariate analyses revealed that the pSTAT3-positive GCB subtype showed a favorable prognosis (HR: 0.17; 95% confidence interval, 0.04-0.7; P=0.014). These findings suggest that pSTAT3 positivity may have a unique impact on the clinicopathologic characteristics of DLBCL, making it a promising novel marker for the favorable prognosis of patients with the GCB subtype.

Diffuse Large B-Cell Lymphoma: Recognition of Markers for Targeted Therapy

Diffuse large B-cell lymphomas (DLBCL)s, the most common type of Non-Hodgkin’s Lymphoma, constitute a heterogeneous group of disorders including different disease sites, strikingly diverse molecular features and a profound variability in the clinical behavior. Molecular studies and clinical trials have partially revealed the underlying causes for this variability and have made possible the recognition of some molecular variants susceptible of specific therapeutic approaches. The main histogenetic groups include the germinal center, activated B cells, thymic B cells and terminally differentiated B cells, a basic scheme where the large majority of DLBCL cases can be ascribed. The nodal/extranodal origin, specific mutational changes and microenvironment peculiarities provide additional layers of complexity. Here, we summarize the status of the knowledge and make some specific proposals for addressing the future development of targeted therapy for DLBC cases.

Generation and Surgical Analysis of Genetic Mouse Models to Study NF-κB-Driven Pathogenesis of Diffuse Large B Cell Lymphoma

Enforced activation of NF-κB signaling can be achieved by constitutive NF-κB-inducing kinases, IKK2 and NIK, or via lymphoma-associated mutants of MYD88, CARD11, and CD79B. In order to model Diffuse Large B Cell Lymphoma (DLBCL) in mice, conditional alleles for these proteins are combined with alleles targeting Cre recombinase expression in mature B cells. However, unopposed NF-κB signaling promotes plasmablast differentiation, and as a consequence the model system must be complemented with further mutations that block differentiation, such as Prdm1/BLIMP1 inactivation or overexpression of BCL6. Here, we describe the currently available tools for DLBCL models in mice and their relative advantages and drawbacks. Furthermore, we describe methods to monitor lymphomagenesis, using ultrasound tomography of the spleen, and the technique of partial splenectomy surgery with recovery. These powerful techniques allow paired comparison of individual lymphoma cases before and after interventions, including therapies, and to study the evolution of lymphoma over time. NF-κB activation also promotes widespread nodal involvement with lymphoma and we describe the post-mortem dissection of major nodal groups.

Genomic Alterations and MYD88MUT Variant Mapping in Patients with Diffuse Large B-Cell Lymphoma and Response to Ibrutinib

BACKGROUND

Diffuse large B-cell lymphoma (DLBCL) is a clinically heterogeneous malignancy. Following front-line immunochemotherapy, 30-40% of DLBCL patients develop relapsed or refractory (r/r) disease, which can be treated with ibrutinib. It has been previously reported that MYD88^MUT affects the response to ibrutinib in patients with r/r DLBCL.

OBJECTIVE

Here, we aimed to gather understanding of MYD88^MUT in r/r DLBCL patients and to evaluate its influence on response to ibrutinib.

PATIENTS AND METHODS

In this study, tissue samples from DLBCL patients (n = 212) were retrospectively collected and sequenced by target-capturing panels of either 413 or 112 genes that are frequently mutated in non-Hodgkin's lymphoma. Sixty patients with MYD88 mutations and available clinical information were included for further analysis.

RESULTS

Seven MYD88^MUT variants were identified, L265P (65.0%, n = 39), S219C (13.3%, n = 8), S243N (8.3%, n = 5), P258L (6.7%, n = 4), F283V (1.7%, n = 1), P141R (1.7%, n = 1), and V217F (1.7%, n = 1). One patient had MYD88 amplification. In addition, mutations in PIM1 (67%, n = 40), IGH fusion (48%, n = 29), CD79B (43%, n = 26), KMT2D (30%, n = 18), and TP53 (27%, n = 17) were identified. For patients with L265P, IRF4 (p = 0.011) was frequently mutated. Otherwise, TET2 (p = 0.016), NOTCH2 (p = 0.044), MET (p = 0.037), SOCS1 (p = 0.011), TNFRSF14 (p = 0.011), EZH2 (p = 0.037), and BCL6 (p < 0.001) mutations were associated with MYD88^MUT non-L265P variants. The incidence rate of MYD88^MUT L265P was significantly higher with central nervous system involvement (p = 0.034). Four out of nine MYD88^MUT patients responded to ibrutinib containing treatment, and this included those with MYD88^MUT/CD79B^WT.

CONCLUSIONS

This study adds clinical observations with MYD88^MUT patients, further helping to understand the genetic features and possible correlation of MYD88^MUT with response to ibrutinib.

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

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

Clinicopathological characterization of chronic lymphocytic leukemia with MYD88 mutations: L265P and non-L265P mutations are associated with different features

MYD88 mutations in chronic lymphocytic leukemia (CLL) are not well characterized. Earlier reports yielded conflicting results in terms of clinicopathologic presentation and prognostic impact of MYD88 mutations in CLL patients. In addition, the morphological and immunophenotypic features of CLL cases carrying MYD88 mutations have not been explored. Finally, the clinical or biologic implications of the canonical L265P MYD88 mutation vs. mutations in other sites of MYD88 within the context of CLL are also unknown. In this study, a cohort of 1779 CLL patients underwent mutational analysis, and 56 (3.1%) cases were found to have MYD88 mutations, including 38 with L265P mutations (designated here as group A) and 18 with non-L265P mutations (group B). Cases with wild type MYD88 were included as controls. There was no morphological difference in cases with and without MYD88 mutations. Immunophenotypically, cases with mutated MYD88 (both groups A and B) more frequently had an atypical immunophenotype when compared to wild type cases. Group A patients were younger and were associated with variable favorable prognostic factors, including less elevated β2-microglobulin level, negative CD38 and ZAP70, higher frequency of mutated IGHV and isolated del(13q14.3), and lower frequency of del(11q22.3) and mutations of NOTCH1 and SF3B1. In contrast, group B patients were more similar to CLL patients with wild type MYD88. There was no difference in time to first treatment when comparing MYD88-mutated vs. wild type CLL patients before and after stratification according to IGHV mutation status. In summary, MYD88 mutations are uncommon in CLL and cases with L265P mutation have distinctive clinical, immunophenotypic, cytogenetic, and molecular features. There is no significant impact of MYD88 mutations on time to first treatment in CLL.

MYD88 L265P mutation detected by digital PCR as a prognostic factor in patients with diffuse large B-cell lymphoma in rituximab era

The central nervous system (CNS) relapse in patients with diffuse large B cell lymphoma (DLBCL) is fatal as there are no effective rescue treatments. To test if the presence of the MYD88 L265P mutation is a prognostic factor for secondary CNS relapse, we carried out the digital PCR analysis of 134 samples from patients with DLBCL at diagnosis. The MYD88 L265P mutations were detected in 22 (16.4%) patients, particularly in those with a non-GC subtype, CD5-positive, high absolute monocyte count, extra-nodal lymphoma, and B symptoms. Nine patients showed low signal in digital PCR but were deemed positive for the MYD88 L265P mutation by the nested allele-specific PCR. The remaining 103 patients were negative according to the results of both the PCR analyses. With a median follow-up period of 64 months, the carriers of MYD88 L265P mutation exhibited inferior CNS relapse-free survival at 5 years (53.2% versus 96% and 100%, respectively, P < 0.001) with a significant effect of the mutation demonstrated by the multivariate analysis (hazard ratio 5.1; 95% CI 1.2-22.9, P = 0.02). This suggests that the MYD88 L265P mutation plays a critical role in the progression of DLBCL to CNS.

Molecular profiling of Chinese R-CHOP treated DLBCL patients: Identifying a high-risk subgroup

Diffuse large B-cell lymphoma (DLBCL) is a clinically aggressive and heterogenous disease. Although most patients can be cured by immunochemotherapy, 30% to 40% patient will ultimately develop relapsed or refractory disease. Here, we investigated the molecular landscapes of patients with diverse responses to R-CHOP. We performed capture-based targeted sequencing on baseline samples of 105 DLBCL patients using a panel consisting of 112 lymphoma-related genes. Subsequently, 81 treatment-naïve patients with measurable disease and followed for over 1 year were included for survival analysis. Collectively, the most commonly seen mutations included IGH fusion (69%), PIM1(33%), MYD88 (29%), BCL2 (29%), TP53 (29%), CD79B (25%) and KMT2D (24%). Patients with TP53 mutations were more likely to have primary refractory disease (87.0% vs 50.0%, P = .009). For those with TP53 disruptive mutations, 91.7% patients were in the primary refractory group. Interestingly, BCL-2 somatic hypermutation was only seen in patients without primary refractory disease (P = .014). In multivariate analysis, BCL-2 amplification (hazard ratio [HR] = 2.94, P = .022), B2M mutation (HR = 2.99, P = .017) and TP53 mutation (HR = 3.19, P < .001) were independently associated with shorter time to progression (TTP). Furthermore, TP53 mutations was correlated with worse overall survival (P = .049). Next, we investigated mutation landscape in patients with wild-type (WT) TP53 (n = 58) and found that patients harboring MYD88 L265P had significantly inferior TTP than those with WT or non-265P (P = .046). Our study reveals the mutation spectrum of treatment-naive Chinese DLBCL patients. It also confirms the clinical significance of TP53 mutations and indicates the prognostic value of MYD88 L265P in TP53 WT patients.

MYD88 mutations identify a molecular subgroup of diffuse large B-cell lymphoma with an unfavorable prognosis

The 2016 World Health Organization classification defines diffuse large B-cell lymphoma (DLBCL) subtypes based on Epstein-Barr virus (EBV) infection and oncogenic rearrangements of MYC/BCL2/BCL6 as drivers of lymphomagenesis. A subset of DLBCL, however, is characterized by activating mutations in MYD88/CD79B We investigated whether MYD88/CD79B mutations could improve the classification and prognostication of DLBCL. In 250 primary DLBCL, MYD88/CD79B mutations were identified by allele-specific polymerase chain reaction or next-generation-sequencing, MYC/BCL2/BCL6 rearrangements were analyzed by fluorescence in situ hybridization, and EBV was studied by EBV-encoded RNA in situ hybridization. Associations of molecular features with clinicopathologic characteristics, outcome, and prognosis according to the International Prognostic Index (IPI) were investigated. MYD88 and CD79B mutations were identified in 29.6% and 12.3%, MYC, BCL2, and BCL6 rearrangements in 10.6%, 13.6%, and 20.3%, and EBV in 11.7% of DLBCL, respectively. Prominent mutual exclusivity between EBV positivity, rearrangements, and MYD88/CD79B mutations established the value of molecular markers for the recognition of biologically distinct DLBCL subtypes. MYD88-mutated DLBCL had a significantly inferior 5-year overall survival than wild-type MYD88 DLBCL (log-rank; P=0.019). DLBCL without any of the studied aberrations had superior overall survival compared to cases carrying ≥1 aberrancy (log-rank; P=0.010). MYD88 mutations retained their adverse prognostic impact upon adjustment for other genetic and clinical variables by multivariable analysis and improved the prognostic performance of the IPI. This study demonstrates the clinical utility of defining MYD88-mutated DLBCL as a distinct molecular subtype with adverse prognosis. Our data call for sequence analysis of MYD88 in routine diagnostics of DLBCL to optimize classification and prognostication, and to guide the development of improved treatment strategies.

Genetic alterations and their clinical implications in DLBCL

Diffuse large B cell lymphoma (DLBCL) is a highly heterogeneous lymphoid neoplasm with variations in gene expression profiles and genetic alterations, which lead to substantial variations in clinical course and response to therapy. The advent of high-throughput genome sequencing platforms, and especially whole-exome sequencing, has helped to define the genetic landscape of DLBCL. In the past 10 years, these studies have identified many genetic alterations in DLBCL, some of which are specific to B cell lymphomas, whereas others can also be observed in other types of cancer. These aberrations result in altered activation of a wide range of signalling pathways and other cellular processes, including those involved in B cell differentiation, B cell receptor signalling, activation of the NF-κB pathway, apoptosis and epigenetic regulation. Further elaboration of the genetics of DLBCL will not only improve our understanding of disease pathogenesis but also provide further insight into disease classification, prognostication and therapeutic targets. In this Review, we describe the current understanding of the prevalence and causes of specific genetic alterations in DLBCL and their role in disease development and progression. We also summarize the available clinical data on therapies designed to target the aberrant pathways driven by these alterations.

Molecular Genetics in the Diagnosis and Biology of Lymphoid Neoplasms

OBJECTIVES

The 2017 Workshop of the Society for Hematopathology/European Association for Haematopathology reviewed the role of molecular genetics in the diagnosis and biology of lymphoid neoplasms.

METHODS

The Workshop Panel reviewed 82 cases.

RESULTS

Molecular genetic testing reveals alterations that expand the spectrum of diseases such as DUSP22 rearrangement in ALK-negative anaplastic large cell lymphoma, large B-cell lymphoma with IRF4 rearrangement, MYD88 mutations in B-cell lymphomas, Burkitt-like lymphoma with 11q aberrations, and diagnostic criteria for high-grade B-cell lymphomas. Therapeutic agents and natural tumor progression may be associated with transcriptional reprogramming that lead to transdifferentiation and lineage switch.

CONCLUSIONS

Application of emerging technical advances has revealed the complexity of genetic events in lymphomagenesis, progression, and acquired resistance to therapies. They also contribute to enhanced understanding of the biology of indolent vs aggressive behavior, clonal evolution, tumor progression, and transcriptional reprogramming associated with transdifferentiation events that may occur subsequent to therapy.

Glutaminolysis Mediated by MALT1 Protease Activity Facilitates PD-L1 Expression on ABC-DLBCL Cells and Contributes to Their Immune Evasion

Previous studies have demonstrated that programmed death-1 ligand 1 (PD-L1) expressed in an aggressive activated B-cell (ABC)/non-germinal center B cell–like (GCB) subtype of diffuse large B-cell lymphoma (DLBCL) is associated with inhibition of the tumor-associated T cell response. However, the molecular mechanism underlying PD-L1 expression in ABC-DLBCL remains unclear. Here, we report that MALT1 protease activity is required for ABC-DLBCL cells to evade cytotoxity of Vγ9Vδ2 T lymphocytes by generating substantial PD-L1⁺ ABC-DLBCL cells. While, NF-κB was dispensable for the PD-L1 expression induced by MALT1 protease activity in ABC-DLBCL cells. Furthermore, we showed that GLS1 expression was profoundly reduced by MALT1 protease activity inhibition, which resulted in insufficiency of glutaminolysis-derived mitochondrial bioenergetics. Activation of the PD-L1 transcription factor STAT3, which was strongly suppressed by glutaminolysis blockade, was rescued in a TCA (tricarboxylic acid) cycle-dependent manner by glutamate addition. Collectively, MALT1 protease activity coupled with glutaminolysis-derived mitochondrial bioenergetics plays an essential role in PD-L1 expression on ABC-DLBCL cells under immunosurveillance stress. Thus, our research sheds light on a mechanism underlying PD-L1 expression and highlights a potential therapeutic target to vanquish immune evasion by ABC-DLBCL cells.

Oncogenic MYD88 mutations in lymphoma: novel insights and therapeutic possibilities

Oncogenic MYD88 mutations, most notably the Leu 265 Pro (L265P) mutation, were recently identified as potential driver mutations in various B-cell non-Hodgkin Lymphomas (NHLs). The L265P mutation is now thought to be common to virtually all NHLs and occurs in between 4 and 90% of cases, depending on the entity. Since it is tumor-specific, the mutation, and the pathways it regulates, might serve as advantageous therapeutic targets for both conventional chemotherapeutic intervention, as well as immunotherapeutic strategies. Here, we review recent progress on elucidating the molecular and cellular processes affected by the L265P mutation of MYD88, describe a new in vivo model for MyD88 L265P-mediated oncogenesis, and summarize how these findings could be exploited therapeutically by specific targeting of signaling pathways. In addition, we summarize current and explore future possibilities for conceivable immunotherapeutic approaches, such as L265P-derived peptide vaccination, adoptive transfer of L265P-restricted T cells, and use of T-cell receptor-engineered T cells. With clinical trials regarding their efficacy rapidly expanding to NHLs, we also discuss potential combinations of immune checkpoint inhibitors with the described targeted chemotherapies of L265P signaling networks, and/or with the above immunological approaches as potential ways of targeting MYD88-mutated lymphomas in the future.

Molecular subtypes of diffuse large B cell lymphoma are associated with distinct pathogenic mechanisms and outcomes

Diffuse large B cell lymphoma (DLBCL), the most common lymphoid malignancy in adults, is a clinically and genetically heterogeneous disease that is further classified into transcriptionally defined activated B cell (ABC) and germinal center B cell (GCB) subtypes. We carried out a comprehensive genetic analysis of 304 primary DLBCLs and identified low-frequency alterations, captured recurrent mutations, somatic copy number alterations, and structural variants, and defined coordinate signatures in patients with available outcome data. We integrated these genetic drivers using consensus clustering and identified five robust DLBCL subsets, including a previously unrecognized group of low-risk ABC-DLBCLs of extrafollicular/marginal zone origin; two distinct subsets of GCB-DLBCLs with different outcomes and targetable alterations; and an ABC/GCB-independent group with biallelic inactivation of TP53, CDKN2A loss, and associated genomic instability. The genetic features of the newly characterized subsets, their mutational signatures, and the temporal ordering of identified alterations provide new insights into DLBCL pathogenesis. The coordinate genetic signatures also predict outcome independent of the clinical International Prognostic Index and suggest new combination treatment strategies. More broadly, our results provide a roadmap for an actionable DLBCL classification.

Prognostication of diffuse large B-cell lymphoma in the molecular era: moving beyond the IPI

Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous disease with variable outcomes. Despite the majority of patients being cured with combination chemoimmunotherapy, up to 30% eventually succumb to the disease. Until recently, baseline prognostic assessment has centred on the International Prognostic Index (IPI), although this index is yet to impact strongly on treatment choice. Molecular features such as cell of origin, MYC and BCL-2 genetic alterations and protein overexpression were identified over a decade ago, yet their prognostic value is still not fully elucidated. Adding complexity are the plethora of new clinical, biological and molecular prognostic markers described in the recent literature, most of which lack independent validation, likely act as surrogate markers for those already in common use and have yet to substantially impact on therapeutic decision making. This review comprehensively assesses the value of individual prognostic markers in the clinical setting and their potential to predict response to novel agents, and ways to optimise their use in future research.

Extranodal diffuse large B-cell lymphomas: A retrospective case series and review of the literature

Non-Hodgkin lymphomas commonly show extranodal involvement (25-30%) but primary diffuse large B-cell lymphomas (DLBCL) with extranodal localization represent clinically and molecularly distinct entities. The present study involved retrospective analysis of case records of 4 patients who were diagnosed with extranodal DLBCL between 2010 and 2016 at the Medical Oncology and Hematology Departments of the Ioannina University Hospital, Greece. Median age of presentation was 69 years (range 60-77 years). There were 2 males and 2 females. The sites of DLBCL involvement included adrenal gland, mandible, cervix uteri, and ileum. Two patients had B symptoms while none had bone marrow involvement. After staging workup, all the patients fell into IE stage. The treatment approach included chemotherapy combined with rituximab (R), whereas one patient received additionally irradiation therapy. Post-treatment positron emission tomography-computed tomography scan was performed in 3 patients. In terms of the outcome, 3 patients are alive in complete response, whereas one was lost in follow-up. Further prospective data analyses are required so as to better elucidate the biology and course of extranodal DLBCL.

Authors' Reply

Authors' Reply to the Letter to the Editor by Y. Lynn Wang (MYD88 mutations and sensitivity to ibrutinib therapy).

Molecular heterogeneity in diffuse large B-cell lymphoma and its implications in clinical diagnosis and treatment

Over half of patients with diffuse large B-cell lymphoma (DLBCL) can be cured by standard R-CHOP treatment (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone). However, the remaining patients are refractory and ultimately succumb to progressive or relapsed disease. During the past decade, there has been significant progress in the understanding of molecular mechanisms in DLBCL, largely owing to collaborative efforts in large-scale gene expression profiling and deep sequencing, which have identified genetic alterations critical in lymphomagenesis through activation of key signaling transduction pathways in DLBCL. These discoveries have not only led to the development of targeted therapies, including several currently in clinical trials, but also laid a solid foundation for the future identification of more effective therapies for patients not curable by R-CHOP. This review summarizes the recent advances in our understanding of the molecular characterization and pathogenesis of DLBCL and new treatment directions.

High frequency and prognostic value of MYD88 L265P mutation in diffuse large B-cell lymphoma with R-CHOP treatment

The aim of this study was to analyze the prevalence and prognostic value of myeloid differentiation factor 88 (MYD88) L265P in diffuse large B-cell lymphoma (DLBCL) patients treated with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP). We assessed the MYD88 L265P mutation using an allele-specific semi-nested polymerase chain reaction method in 53 DLBCL patients treated with R-CHOP. The MYD88 L265P mutation was detected in 16 of 53 DLBCL (30.19%) samples from patients treated with R-CHOP. Age and location were statistically significantly associated with MYD88 L265P (P=0.025, 0.033, respectively), while treatment response and tumor recurrence were not. Univariate analysis showed that B symptoms (P=0.004) and Ki-67 (P=0.03) were significantly associated with progression-free survival (PFS), while MYD88 L265P showed no significant association with overall survival and PFS. Multivariate analysis showed that B symptoms were significantly associated with PFS. Our study suggests that the prognostic value of MYD88 L265P in DLBCL patients with R-CHOP requires further research.

Clinical utility of recently identified diagnostic, prognostic, and predictive molecular biomarkers in mature B-cell neoplasms

Genomic profiling studies have provided new insights into the pathogenesis of mature B-cell neoplasms and have identified markers with prognostic impact. Recurrent mutations in tumor-suppressor genes (TP53, BIRC3, ATM), and common signaling pathways, such as the B-cell receptor (CD79A, CD79B, CARD11, TCF3, ID3), Toll-like receptor (MYD88), NOTCH (NOTCH1/2), nuclear factor-κB, and mitogen activated kinase signaling, have been identified in B-cell neoplasms. Chronic lymphocytic leukemia/small lymphocytic lymphoma, diffuse large B-cell lymphoma, follicular lymphoma, mantle cell lymphoma, Burkitt lymphoma, Waldenström macroglobulinemia, hairy cell leukemia, and marginal zone lymphomas of splenic, nodal, and extranodal types represent examples of B-cell neoplasms in which novel molecular biomarkers have been discovered in recent years. In addition, ongoing retrospective correlative and prospective outcome studies have resulted in an enhanced understanding of the clinical utility of novel biomarkers. This progress is reflected in the 2016 update of the World Health Organization classification of lymphoid neoplasms, which lists as many as 41 mature B-cell neoplasms (including provisional categories). Consequently, molecular genetic studies are increasingly being applied for the clinical workup of many of these neoplasms. In this review, we focus on the diagnostic, prognostic, and/or therapeutic utility of molecular biomarkers in mature B-cell neoplasms.

[Diffuse large B-cell lymphoma with concomitant c-MYC and BCL6 gene rearrangements with primary skin involvement: A case report and a review of literature]

Double-hit lymphoma (DHL) is a rare aggressive B-cell lymphoma with concomitant c-MYC, BCL2 or BCL6 gene rearrangements, which is characterized by the high frequency of extranodal lesions and by resistance to chemotherapy. The median survival does not exceed 18 months in patients with this disease. The majority of DHL is represented by с-MYC/BCL2 cases. The combination of c-MYC/BCL6 occurs rarely (5-8%). The paper describes a case of DHL with concomitant c-MYC and BCL6 gene rearrangements, which mimics diffuse large B-cell lymphoma, leg-type.

Clinicopathologic significance of MYD88 L265P mutation in diffuse large B-cell lymphoma: a meta-analysis

The precise clinicopathologic significance of myeloid differentiation primary response gene (MYD88) L265P mutation in diffuse large B-cell lymphomas (DLBCLs) remains elusive. To investigate the frequency and clinicopathologic significance of the MYD88 L265P mutation in DLBCLs, we conducted a meta-analysis of 40 published studies on 2736 DLBCL patients. We collected relevant published research findings identified using the PubMed and Embase databases. The effect sizes of outcome parameters were calculated using a random-effects model. In this meta-analysis, the MYD88 L265P mutation in DLBCL showed a significant difference according to tumor sites. The overall incidence of the MYD88 L265P mutation in DLBCLs, excluding the central nervous system and testicular DLBCLs, was 16.5%. Notably, the MYD88 L265P mutation rates of CNS and testicular DLBCL patients were 60% and 77%, respectively. Interestingly, the MYD88 L265P mutation was more frequently detected in activated B-cell-like (ABC) or non-germinal center B-cell-like (GCB) than GCB subtype (OR = 3.414, p < 0.001). The MYD88 L265P mutation was significantly associated with old age and poor overall survival, but not with sex and clinical stage. This pooled analysis demonstrates that the MYD88 L265P mutation is significantly associated with the tumor sites and molecular subtypes in DLBCL patients.

Biological and Clinical Relevance of Associated Genomic Alterations in MYD88 L265P and non-L265P-Mutated Diffuse Large B-Cell Lymphoma: Analysis of 361 Cases

Purpose:MYD88 mutations, notably the recurrent gain-of-function L265P variant, are a distinguishing feature of activated B-cell like (ABC) diffuse large B-cell lymphoma (DLBCL), leading to constitutive NFκB pathway activation. The aim of this study was to examine the distinct genomic profiles of MYD88-mutant DLBCL, notably according to the presence of the L265P or other non-L265P MYD88 variants.Experimental Design: A cohort of 361 DLBCL cases (94 MYD88 mutant and 267 MYD88 wild-type) was submitted to next-generation sequencing (NGS) focusing on 34 genes to analyze associated mutations and copy number variations, as well as gene expression profiling, and clinical and prognostic analyses.Results: Importantly, we highlighted different genomic profiles for MYD88 L265P and MYD88 non-L265P-mutant DLBCL, shedding light on their divergent backgrounds. Clustering analysis also segregated subgroups according to associated genetic alterations among patients with the same MYD88 mutation. We showed that associated CD79B and MYD88 L265P mutations act synergistically to increase NFκB pathway activation, although the majority of MYD88 L265P-mutant cases harbors downstream NFκB alterations, which can predict BTK inhibitor resistance. Finally, although the MYD88 L265P variant was not an independent prognostic factor in ABC DLBCL, associated CD79B mutations significantly improved the survival of MYD88 L265P-mutant ABC DLBCL in our cohort.Conclusions: This study highlights the relative heterogeneity of MYD88-mutant DLBCL, adding to the field's knowledge of the theranostic importance of MYD88 mutations, but also of associated alterations, emphasizing the usefulness of genomic profiling to best stratify patients for targeted therapy. Clin Cancer Res; 23(9); 2232-44. ©2016 AACR.