Prognostic Significance of in situ Phenotypic Marker Expression in Diffuse Large B-cell Lymphomas

Diffuse large B-cell lymphomas (DLBCL) are the most common lymphoid malignancies, and encompass all malignant lymphomas characterized by large neoplastic cells and B-cell derivation. In the last decade, DLBCL has been subjected to intense clinical, phenotypic and molecular studies, and were found to represent a heterogeneous group of tumors. These studies suggested new disease subtypes and variants with distinct clinical characteristics, morphologies, immunophenotypes, genotypes or gene expression profiles, associated with distinct prognoses or unique sensitivities to particular therapy regimens. Unfortunately, the reliability and reproducibility of the molecular results remains unclear due to contradictory reports in the literature resulting from small sample sizes, referral and selection biases, and variable methodologies and cut-off levels used to determine positivity. Here, we review phenotypic studies on the prognostic significance of protein expression profiles in DLBCL and reconsider our own retrospective data on 301 primary DLBCL cases obtained on a previously validated tissue microarray in light of powerful statistical methods of determining optimal cut-off values of phenotypic factors for prediction of outcome

Vascular Endothelial Growth Factor-Related Pathways in Hemato-Lymphoid Malignancies

Angiogenesis is essential for malignant tumor growth. This has been documented for solid tumors, and there is an emerging evidence suggesting that tumor progression of hematolymphoid malignancies also depends on the induction of new blood vessel formation. The most important proangiogenic agent is vascular endothelial growth factor (VEGF), activating VEGF receptors 1 and 2. The available data on angiogenesis in hemato-lymphoid malignancies, such as acute leukemias, myelodysplastic syndromes, myeloproliferative neoplasms, multiple myeloma, and lymphomas, point towards the significance of autocrine and paracrine VEGF-mediated effects for proliferation and survival of leukemia/lymphoma cells in addition to tumor vascularization. Antiangiogenic strategies have become an important therapeutic modality for solid tumors. Several antiangiogenic agents targeting VEGF-related pathways are also being utilized in clinical trials for the treatment of hemato-lymphoid malignancies, and in some instances these pathways have emerged as promising therapeutic targets. This review summarizes recent advances in the basic understanding of the role of angiogenesis in hemato-lymphoid malignancies and the translation of such basic findings into clinical studies

Genetic background and evolution of relapses in aggressive B-cell lymphomas

Relapses of aggressive B-cell lymphomas pose a higher risk to affected patients because of potential treatment resistance and usually rapid tumor growth. Recent advances, such as targeting Bruton tyrosine kinase, have provided promising results in small numbers of cases, but treatment for the majority of patients remains challenging and outcomes are generally poor. A number of recent studies have utilized state-of-the-art genomic technologies in an attempt to better understand tumor genome evolution during relapse and to identify relapse-specific genetic alterations. It has been found that in some settings (e.g. diffuse large B-cell lymphomas in immunocompromised patients, secondary diffuse large B-cell lymphomas as Richter transformations) a significant part of the recurrences are clonally-unrelated de novo neoplasms, which might have distinct genomic and drug sensitivity profiles as well as different prognoses. Similar to earlier findings in indolent lymphomas, genetic tumor evolution of clonally-related relapsing aggressive B-cell lymphomas is predominantly characterized by two patterns: early divergence from a common progenitor and late divergence/linear evolution from a primary tumor. The clinical implications of these distinct patterns are not yet clear and will require additional investigation; however, it is plausible that these two patterns of recurrence are linked to different treatment-resistance mechanisms. Attempts to identify drivers of relapses result in a very heterogeneous list of affected genes and pathways as well as epigenetic mechanisms and suggest many ways of how recurrent tumors can adapt to treatment and expand their malignant properties

Expression of pSTAT5 predicts FLT3 internal tandem duplications in acute myeloid leukemia

Mutations of the Fms-like tyrosine kinase 3 (FLT3) can be detected in a significant number of acute myeloid leukemias (AML). Seventy-five cases of acute myeloid leukemia were evaluated for FLT3-internal tandem duplications (ITD) by polymerase chain reaction. Paraffin-embedded formalin-fixed trephine biopsies of these cases were evaluated for expression of phosphorylated signal transducer and activator of transcription 1 (pSTAT1), pSTAT3, and pSTAT5. Specific expression of pSTAT5 was proven in leukemic blasts in situ by double staining with a blast-specific marker. Expression of pSTAT5 in ≥1% of blasts was highly predictive of FLT3-ITD. Neither expression of pSTAT1 nor pSTAT3 were associated with FLT3 mutations. Altogether we conclude that pSTAT5 expression can precisely be assessed by immunohistochemistry in routinely processed bone marrow trephines, STAT5 is highly likely the preferred second messenger of FLT3-mediated signaling in AML, and expression of pSTAT5 is predictive of FLT3-IT

Hodgkin's Lymphoma and Paraneoplastic Phenomena in the Central Nervous System: A Case Report and Review of the Literature

A 25-year-old male patient presented to our Ear, Nose and Throat clinic with a history of nausea, vomiting, headache, vertigo and weight loss of 5 kg over the preceding 3 months. An enlarged cervical lymph node was detected at clinical examination. Lymph node biopsy showed nodular lymphocyte-predominant Hodgkin's lymphoma (NLPHL, nodular paragranuloma). Because of the neurological symptoms a cerebral MRI scan was performed and revealed an intense perivascular, bilateral, contrast-medium enhancing lesion of the temporal lobes suggestive of cerebral vasculitis. Cerebrospinal fluid analysis showed an increased number of mononuclear cells, but there was no indication for neurotropic viral or bacterial infections. EEG revealed a left temporal epileptic focus, and anti-epileptic therapy was initiated. NLPHL was treated with 2 cycles of ABVD chemotherapy and 20 Gy involved-field radiotherapy. Steroid therapy (prednisone 100 mg q.d.) for the presumed paraneoplastic neurological manifestation was started 1 week before chemotherapy and led to the rapid disappearance of complaints. Because of renewed onset of nausea and vertigo after 3 weeks of treatment with ABVD chemotherapy and 4 weeks of treatment with steroids, a follow-up brain MRI and EEG were performed and demonstrated complete disappearance of the ‘vasculitic’ changes without additional pathologic findings. Five months after therapy, the patient is without neurological symptoms and a PET-CT showed a complete remission. This case is a unique example of paraneoplastic central nervous system (CNS) involvement in a patient with newly diagnosed NLPHL. We present a review of the literature on paraneoplastic CNS symptoms in Hodgkin's lymphoma

Lymphadenectomy Specimens in a Large Retrospective Cohort of Pediatric Patients Reveal No in situ Lymphomas but a Broad Spectrum of Reactive Changes.

OBJECTIVES While the incidence and prevalence of in situ follicular neoplasia (ISFN) and in situ mantle cell neoplasia (ISMCN) in adults are well documented, little is known about these early (precursor) lesions in pediatric populations. The aim of this study was to analyze so-called 'reactive' lymph nodes harvested for the purpose of staging solid tumors, unexplained lymphadenopathies, or presumed inflammatory processes or in conjunction with other surgical interventions in children and adolescents aged <18 years, with special attention to ISFN and ISMCN. METHODS Formalin-fixed, paraffin-embedded reactive lymph node samples from an unselected pediatric population from two catchment areas in Switzerland were retrospectively analyzed for the presence of ISFN and ISMCN and specific reactive lymph node patterns. RESULTS While a diverse range of histopathological patterns of reactive lymph node changes with a particular periodic increase in mycobacterioses could be observed in this pediatric population, not a single case of ISFN or ISMCN was found. CONCLUSIONS Early histological lymphomagenesis equivalents in the form of in situ lymphomas are exceedingly rare events in children and young adolescents. The spectrum of reactive lymph node changes is large, with differences possibly determined by regional variations in geography, demographics, catchment areas, seasons, and years, respectively

Treg-selective IL-2 starvation synergizes with CD40 activation to sustain durable responses in lymphoma models

BACKGROUND: Roughly half of all diffuse large B-cell lymphomas (DLBCLs) are infiltrated by large numbers of regulatory T-cells (Tregs). Although the presence of 'effector' Tregs in particular is associated with an inferior prognosis in patients on standard rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) immunochemotherapy, the role of this cell type during lymphoma initiation and progression is poorly understood. METHODS: Here, we use tissue microarrays containing prospectively collected DLBCL patient specimens, as well as data from publicly available cohorts to explore the mutational landscape of Treg-infiltrated DLBCL. We further take advantage of a model of MYC-driven lymphoma to mechanistically dissect the contribution of Tregs to lymphoma pathogenesis and to develop a strategy of Treg-selective interleukin-2 (IL-2) starvation to improve immune control of MYC-driven lymphoma. RESULTS: We find that all genetic DLBCL subtypes, except for one characterized by co-occurring MYD88/CD79 mutations, are heavily infiltrated by Tregs. Spectral flow cytometry and scRNA-sequencing reveal the robust expression of functional and immunosuppressive markers on Tregs infiltrating MYC-driven lymphomas; notably, we find that intratumoral Tregs arise due to local conversion from naïve CD4$^{+}$ precursors on tumor contact. Treg ablation in Foxp3$^{iDTR}$ mice, or by antibody-mediated Treg-selective blockade of IL-2 signaling, strongly reduces the lymphoma burden. We identify lymphoma B-cells as a major source of IL-2, and show that the effects of Treg depletion are reversed by the simultaneous depletion of Foxp3-negative CD4$^{+}$ T-cells, but not CD8$^{+}$ T-cells or natural killer (NK) cells. The inhibition of ATP hydrolyzation and adenosine production by Tregs at least partly phenocopies the effects of Treg depletion. Treg depletion further synergizes with pro-apoptotic CD40 activation to sustain durable responses. CONCLUSION: The combined data implicate Tregs as a potential therapeutic target in DLBCL, especially in combination with other immunotherapies

Ipilimumab and Pembrolizumab Mixed Response in a 41-Year-Old Patient with SMARCA4-Deficient Thoracic Sarcoma: An Interdisciplinary Case Study

SMARCA4-deficient thoracic sarcoma is a newly described entity of thoracic sarcomas with a poor prognosis, defined by poorly differentiated epithelioid to rhabdoid histomorphology and SMARCA4 gene inactivation. We present a case of a SMARCA4-deficient thoracic sarcoma in a 41-year-old male with a smoking history who presented with an upper anterior mediastinal mass, after seeking medical evaluation for increasing thoracic pain, odynophagia, and dizziness. The biopsy confirmed a large cell tumor with an epithelioid to rhabdoid histomorphology, positive for EMA, CD99, vimentin, TLE1, INI1, PAS-positive cytoplasmic granules, and PD-L1 (100% of tumor cells). High TMB and HRD scores were displayed in the tumor. The histology and immunophenotype of the mass were in line with the diagnosis of SMARCA4-deficient thoracic sarcoma. In the course of his treatment, the patient showcased a partial response to pembrolizumab and the combination of pembrolizumab and ipilimumab. This case report highlights the importance of recognizing SMARCA4-deficient thoracic sarcoma as an individual entity and supports the importance of checkpoint inhibition therapy for SMARCA4-deficient thoracic sarcomas, particularly in cases with a high TMB and PD-L1 expression

Inhibitors of Bcl-2 and Bruton's tyrosine kinase synergize to abrogate diffuse large B-cell lymphoma growth in vitro and in orthotopic xenotransplantation models

Numerous targeted therapies have been developed for diffuse large B-cell lymphoma, but the results of late-stage clinical trials were mostly disappointing and have led to very few new regulatory approvals. Here, we use single and combinatorial drug response profiling to show that the combined inhibition of the anti-apoptotic protein Bcl-2 and of the tyrosine kinase BTK with the small molecules venetoclax and ibrutinib efficiently kills DLBCL cells in vitro. High Bcl-2 expression due to either BCL2 amplifications or translocations, in conjunction with chronic active BCR signaling accurately predict responses to dual Bcl-2/BTK inhibition. Orthotopic xenotransplantation and patient-derived xenograft models confirm that the combinatorial is superior to single-agent treatment in reducing the lymphoma burden. Combinatorial treatment further efficiently overcomes both primary and acquired resistance to venetoclax, which we could link to reduced expression of the Bcl-2 family members Bcl-X$_{L}$ and Bcl-2A1 under ibrutinib. We found in a Swiss DLBCL cohort that ~15% of patients are projected to respond to the venetoclax/ibrutinib combination based on their high Bcl-2 expression and nuclear NF-κB localization. Our data show that drug sensitivities exposed by drug response profiling can be attributed to specific mutational signatures and immunohistochemical biomarkers, and point to combined Bcl-2/BTK inhibition as a promising therapeutic strategy in DLBCL