A three-signal model of T-cell lymphoma pathogenesis

The OX40-TRAF6 axis promotes CTLA-4 degradation to augment antitumor CD8+ T-cell immunity

Immune checkpoint blockade (ICB), including anti-cytotoxic T-lymphocyte associated protein 4 (CTLA-4), benefits only a limited number of patients with cancer. Understanding the in-depth regulatory mechanism of CTLA-4 protein stability and its functional significance may help identify ICB resistance mechanisms and assist in the development of novel immunotherapeutic modalities to improve ICB efficacy. Here, we identified that TNF receptor-associated factor 6 (TRAF6) mediates Lys63-linked ubiquitination and subsequent lysosomal degradation of CTLA-4. Moreover, by using TRAF6-deficient mice and retroviral overexpression experiments, we demonstrated that TRAF6 promotes CTLA-4 degradation in a T-cell-intrinsic manner, which is dependent on the RING domain of TRAF6. This intrinsic regulatory mechanism contributes to CD8+ T-cell-mediated antitumor immunity in vivo. Additionally, by using an OX40 agonist, we demonstrated that the OX40-TRAF6 axis is responsible for CTLA-4 degradation, thereby controlling antitumor immunity in both tumor-bearing mice and patients with cancer. Overall, our findings demonstrate that the OX40-TRAF6 axis promotes CTLA-4 degradation and is a potential therapeutic target for the improvement of T-cell-based immunotherapies.

Successful anti-tumor effects with two novel bifunctional chemotherapeutic compounds that combine a LAT1 substrate with cytotoxic moieties in aggressive T-cell lymphomas

T-cell lymphomas are aggressive neoplasms characterized by poor responses to current chemotherapeutic agents. Expression of the l-type amino acid transporter 1 (LAT 1, SLC7A5) allows for the expansion of healthy T-cell counterparts, and upregulation of LAT1 has been reported in precursor T-cell acute leukemia. Therefore, the expression of LAT1 was evaluated in a cohort of cutaneous and peripheral T-cell lymphomas. The findings demonstrated that LAT1 is upregulated in aggressive variants and absent in low-grade or indolent disease such as mycosis fungoides. In addition, upregulated LAT1 expression was seen in a large proportion of aggressive peripheral T-cell lymphomas, including peripheral T-cell lymphoma not otherwise specific (PTCL-NOS) and angioimmunoblastic T-cell lymphoma (AITL). The anti-tumor effects of two novel non-cleavable and bifunctional compounds, QBS10072S and QBS10096S, that combine a potent cytotoxic chemotherapeutic domain (tertiary N-bis(2-chloroethyl)amine) with the structural features of a selective LAT1 substrate (aromatic β-amino acid) were tested in vitro and in vivo in T-cell lymphoma cell lines. The findings demonstrated decreased survival of T-cell lymphoma lines with both compounds. Overall, the results demonstrate that LAT1 is a valuable biomarker for aggressive T-cell lymphoma counterparts and QBS10072S and QBS10096S are successful therapeutic options for these aggressive diseases.

Role of cytokine in malignant T-cell metabolism and subsequent alternation in T-cell tumor microenvironment

T cells are an important component of adaptive immunity and T-cell-derived lymphomas are very complex due to many functional sub-types and functional elasticity of T-cells. As with other tumors, tissues specific factors are crucial in the development of T-cell lymphomas. In addition to neoplastic cells, T- cell lymphomas consist of a tumor micro-environment composed of normal cells and stroma. Numerous studies established the qualitative and quantitative differences between the tumor microenvironment and normal cell surroundings. Interaction between the various component of the tumor microenvironment is crucial since tumor cells can change the microenvironment and vice versa. In normal T-cell development, T-cells must respond to various stimulants deferentially and during these courses of adaptation. T-cells undergo various metabolic alterations. From the stage of quiescence to attention of fully active form T-cells undergoes various stage in terms of metabolic activity. Predominantly quiescent T-cells have ATP-generating metabolism while during the proliferative stage, their metabolism tilted towards the growth-promoting pathways. In addition to this, a functionally different subset of T-cells requires to activate the different metabolic pathways, and consequently, this regulation of the metabolic pathway control activation and function of T-cells. So, it is obvious that dynamic, and well-regulated metabolic pathways are important for the normal functioning of T-cells and their interaction with the microenvironment. There are various cell signaling mechanisms of metabolism are involved in this regulation and more and more studies have suggested the involvement of additional signaling in the development of the overall metabolic phenotype of T cells. These important signaling mediators include cytokines and hormones. The impact and role of these mediators especially the cytokines on the interplay between T-cell metabolism and the interaction of T-cells with their micro-environments in the context of T-cells lymphomas are discussed in this review article.

SOHO State of the Art Updates and Next Questions | New Pathways and New Targets in PTCL: Staying on Target

While the peripheral T-cell lymphomas (PTCL) remain a therapeutic challenge, and increasingly account for a disproportionate number of lymphoma-related deaths, improved understanding of disease pathogenesis and classification, and the development of novel therapeutic agents over the past decade, all provide reasons for a more optimistic outlook in the next. Despite their genetic and molecular heterogeneity, many PTCL are dependent upon signaling input provided by antigen, costimulatory, and cytokine receptors. While gain-of-function alterations effecting these pathways are recurrently observed in many PTCL, more often than not, signaling remains ligand-and tumor microenvironment (TME)-dependent. Consequently, the TME and its constituents are increasingly recognized as "on target". Utilizing a "3 signal" model, we will review new-and old-therapeutic targets that are relevant for the more common nodal PTCL subtypes.

T-Cell Prolymphocytic Leukemia: Diagnosis, Pathogenesis, and Treatment

T-cell prolymphocytic leukemia (T-PLL) is a rare and aggressive neoplasm of mature T-cells. Most patients with T-PLL present with lymphocytosis, anemia, thrombocytopenia, and hepatosplenomegaly. Correct identification of T-PLL is essential because treatment for this disease is distinct from that of other T-cell neoplasms. In 2019, the T-PLL International Study Group (TPLL-ISG) established criteria for the diagnosis, staging, and assessment of response to treatment of T-PLL with the goal of harmonizing research efforts and supporting clinical decision-making. T-PLL pathogenesis is commonly driven by T-cell leukemia 1 (TCL1) overexpression and ATM loss, genetic alterations that are incorporated into the TPLL-ISG diagnostic criteria. The cooperativity between TCL1 family members and ATM is seemingly unique to T-PLL across the spectrum of T-cell neoplasms. The role of the T-cell receptor, its downstream kinases, and JAK/STAT signaling are also emerging themes in disease pathogenesis and have obvious therapeutic implications. Despite improved understanding of disease pathogenesis, alemtuzumab remains the frontline therapy in the treatment of naïve patients with indications for treatment given its high response rate. Unfortunately, the responses achieved are rarely durable, and the majority of patients are not candidates for consolidation with hematopoietic stem cell transplantation. Improved understanding of T-PLL pathogenesis has unveiled novel therapeutic vulnerabilities that may change the natural history of this lymphoproliferative neoplasm and will be the focus of this concise review.

ITK degradation to block T cell receptor signaling and overcome therapeutic resistance in T cell lymphomas

Interleukin (IL)-2-inducible T cell kinase (ITK) is essential for T cell receptor (TCR) signaling and plays an integral role in T cell proliferation and differentiation. Unlike the ITK homolog BTK, no inhibitors of ITK are currently US Food and Drug Administration (FDA) approved. In addition, recent studies have identified mutations within BTK that confer resistance to both covalent and non-covalent inhibitors. Here, as an alternative strategy, we report the development of BSJ-05-037, a potent and selective heterobifunctional degrader of ITK. BSJ-05-037 displayed enhanced anti-proliferative effects relative to its parent inhibitor BMS-509744, blocked the activation of NF-kB/GATA-3 signaling, and increased the sensitivity of T cell lymphoma cells to cytotoxic chemotherapy both in vitro and in vivo. In summary, targeted degradation of ITK is a novel approach to modulate TCR signal strength that could have broad application for the investigation and treatment of T cell-mediated diseases.

Cutaneous Lymphoma and Antibody-Directed Therapies

The introduction of monoclonal antibodies such as rituximab to the treatment of cancer has greatly advanced the treatment scenario in onco-hematology. However, the response to these agents may be limited by insufficient efficacy or resistance. Antibody–drug conjugates are an attractive strategy to deliver payloads of toxicity or radiation with high selectivity toward malignant targets and limited unwanted effects. Primary cutaneous lymphomas are a heterogeneous group of disorders and a current area of unmet need in dermato-oncology due to the limited options available for advanced cases. This review briefly summarizes our current understanding of T and B cell lymphomagenesis, with a focus on recognized molecular alterations that may provide investigative therapeutic targets. The authors reviewed antibody-directed therapies investigated in the setting of lymphoma: this term includes a broad spectrum of approaches, from antibody–drug conjugates such as brentuximab vedotin, to bi-specific antibodies, antibody combinations, antibody-conjugated nanotherapeutics, radioimmunotherapy and, finally, photoimmunotherapy with specific antibody–photoadsorber conjugates, as an attractive strategy in development for the future management of cutaneous lymphoma.

PTCL, NOS: An update on classification, risk-stratification, and treatment

The peripheral T-cell lymphomas (PTCL) are relatively rare, heterogeneous, and therapeutically challenging. While significant therapeutic gains and improved understanding of disease pathogenesis have been realized for selected PTCL subtypes, the most common PTCL in North America remains "not otherwise specified (NOS)" and is an unmet need. However, improved understanding of the genetic landscape and ontogeny for the PTCL subtypes currently classified as PTCL, NOS have been realized, and have significant therapeutic implications, which will be reviewed here.

Drastic transformation of visceral adipose tissue and peripheral CD4 T cells in obesity

Obesity has a pronounced effect on the immune response in systemic organs that results in not only insulin resistance but also altered immune responses to infectious diseases and malignant tumors. Obesity-associated microenvironmental changes alter transcriptional expression and metabolism in T cells, leading to alterations in T-cell differentiation, proliferation, function, and survival. Adipokines, cytokines, and lipids derived from obese visceral adipose tissue (VAT) may also contribute to the systemic T-cell phenotype, resulting in obesity-specific pathogenesis. VAT T cells, which have multiple roles in regulating homeostasis and energy utilization and defending against pathogens, are most susceptible to obesity. In particular, many studies have shown that CD4 T cells are deeply involved in the homeostasis of VAT endocrine and metabolic functions and in obesity-related chronic inflammation. In obesity, macrophages and adipocytes in VAT function as antigen-presenting cells and contribute to the obesity-specific CD4 T-cell response by inducing CD4 T-cell proliferation and differentiation into inflammatory effectors via interactions between major histocompatibility complex class II and T-cell receptors. When obesity persists, prolonged stimulation by leptin and circulating free fatty acids, repetitive antigen stimulation, activating stress responses, and hypoxia induce exhaustion of CD4 T cells in VAT. T-cell exhaustion is characterized by restricted effector function, persistent expression of inhibitory receptors, and a transcriptional state distinct from functional effector and memory T cells. Moreover, obesity causes thymic regression, which may result in homeostatic proliferation of obesity-specific T-cell subsets due to changes in T-cell metabolism and gene expression in VAT. In addition to causing T-cell exhaustion, obesity also accelerates cellular senescence of CD4 T cells. Senescent CD4 T cells secrete osteopontin, which causes further VAT inflammation. The obesity-associated transformation of CD4 T cells remains a negative legacy even after weight loss, causing treatment resistance of obesity-related conditions. This review discusses the marked transformation of CD4 T cells in VAT and systemic organs as a consequence of obesity-related microenvironmental changes.

Cutaneous T-cell lymphomas: 2023 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Cutaneous T-cell lymphomas are a heterogenous group of T-cell neoplasms involving the skin, the majority of which may be classified as Mycosis Fungoides (MF) or Sézary Syndrome (SS).

DIAGNOSIS

The diagnosis of MF or SS requires the integration of clinical and histopathologic data.

RISK-ADAPTED THERAPY

TNMB (tumor, node, metastasis, blood) staging remains the most important prognostic factor in MF/SS and forms the basis for a "risk-adapted," multidisciplinary approach to treatment. For patients with disease limited to the skin, expectant management or skin-directed therapies is preferred, as both disease-specific and overall survival for these patients is favorable. In contrast, patients with advanced-stage disease with significant nodal, visceral or the blood involvement are generally approached with systemic therapies, including biologic-response modifiers, histone deacetylase inhibitors, or antibody-based strategies, in an escalating fashion. In highly-selected patients, allogeneic stem-cell transplantation may be considered, as this may be curative in some patients.

Challenges in nodal peripheral T-cell lymphomas: from biological advances to clinical applicability

T cell lymphomas are a heterogenous group with varying biological and clinical features that tend to have poor outcomes with a few exceptions. They account for 10-15% of all non-Hodgkin lymphomas (NHL), and 20% of aggressive NHL. There has been little change in the overall prognosis of T cell lymphomas over the last 2 decades. Most subtypes carry an inferior prognosis when compared to the B cell lymphomas, with a 5-year OS of 30%. Gene expression profiling and other molecular techniques has enabled a deeper understanding of these differences in the various subtypes as reflected in the latest 5th WHO and ICC classification of T cell lymphomas. It is becoming increasingly clear that therapeutic approaches that target specific cellular pathways are needed to improve the clinical outcomes of T cell lymphomas. This review will focus on nodal T cell lymphomas and describe novel treatments and their applicability to the various subtypes.

Classification and challenges in the histopathological diagnosis of peripheral T-cell lymphomas, emphasis on the WHO-HAEM5 updates

Mature T-cell lymphomas represent neoplastic expansions of T-cell lymphocytes with a post-thymic derivation. Most of these tumors feature aggressive clinical behavior and challenging histopathological diagnosis and classification. Novel findings in the genomic landscape of T-cell lymphomas are helping to improve the understanding of the biology and the molecular mechanisms that underly its clinical behavior. The most recent WHO-HAEM5 classification of hematolymphoid tumors introduced novel molecular and histopathological findings that will aid in the diagnostic classification of this group of neoplasms. The current review article summarizes the most relevant diagnostic features of peripheral T-cell lymphomas with an emphasis on the updates that are incorporated at the WHO-HAEM5.

Targeting Lymphoma-associated Macrophage Expansion via CSF1R/JAK Inhibition is a Therapeutic Vulnerability in Peripheral T-cell Lymphomas

The reciprocal relationship between malignant T cells and lymphoma-associated macrophages (LAM) within the tumor microenvironment (TME) is unique, as LAMs are well poised to provide ligands for antigen, costimulatory, and cytokine receptors that promote T-cell lymphoma growth. Conversely, malignant T cells promote the functional polarization and homeostatic survival of LAM. Therefore, we sought to determine the extent to which LAMs are a therapeutic vulnerability in these lymphomas, and to identify effective therapeutic strategies for their depletion. We utilized complementary genetically engineered mouse models and primary peripheral T-cell lymphoma (PTCL) specimens to quantify LAM expansion and proliferation. A high-throughput screen was performed to identify targeted agents that effectively deplete LAM within the context of PTCL. We observed that LAMs are dominant constituents of the TME in PTCL. Furthermore, their dominance was explained, at least in part, by their proliferation and expansion in response to PTCL-derived cytokines. Importantly, LAMs are a true dependency in these lymphomas, as their depletion significantly impaired PTCL progression. These findings were extrapolated to a large cohort of human PTCL specimens where LAM proliferation was observed. A high-throughput screen demonstrated that PTCL-derived cytokines led to relative resistance to CSF1R selective inhibitors, and culminated in the identification of dual CSF1R/JAK inhibition as a novel therapeutic strategy to deplete LAM in these aggressive lymphomas. Malignant T cells promote the expansion and proliferation of LAM, which are a bone fide dependency in these lymphomas, and are effectively depleted with a dual CSF1R/JAK inhibitor.

Significance

LAMs are a therapeutic vulnerability, as their depletion impairs T-cell lymphoma disease progression. Pacritinib, a dual CSF1R/JAK inhibitor, effectively impaired LAM viability and expansion, prolonged survival in preclinical T-cell lymphoma models, and is currently being investigated as a novel therapeutic approach in these lymphomas.

GATA-3 is a proto-oncogene in T-cell lymphoproliferative neoplasms

Neoplasms originating from thymic T-cell progenitors and post-thymic mature T-cell subsets account for a minority of lymphoproliferative neoplasms. These T-cell derived neoplasms, while molecularly and genetically heterogeneous, exploit transcription factors and signaling pathways that are critically important in normal T-cell biology, including those implicated in antigen-, costimulatory-, and cytokine-receptor signaling. The transcription factor GATA-3 regulates the growth and proliferation of both immature and mature T cells and has recently been implicated in T-cell neoplasms, including the most common mature T-cell lymphoma observed in much of the Western world. Here we show that GATA-3 is a proto-oncogene across the spectrum of T-cell neoplasms, including those derived from T-cell progenitors and their mature progeny, and further define the transcriptional programs that are GATA-3 dependent, which include therapeutically targetable gene products. The discovery that p300-dependent acetylation regulates GATA-3 mediated transcription by attenuating DNA binding has novel therapeutic implications. As most patients afflicted with GATA-3 driven T-cell neoplasms will succumb to their disease within a few years of diagnosis, these findings suggest opportunities to improve outcomes for these patients.

Notch Signaling Promotes Mature T-Cell Lymphomagenesis

Peripheral T-cell lymphomas (PTCL) are agressive lymphomas that develop from mature T cells. The most common PTCLs are genetically, molecularly, and clinically diverse and are generally associated with dismal outcomes. While Notch signaling plays a critically important role in both the development of immature T cells and their malignant transformation, its role in PTCL is poorly understood, despite the increasingly appreciated function of Notch in regulating the proliferation and differentiation of mature T cells. Here, we demonstrate that Notch receptors and their Delta-like family ligands (DLL1/DLL4) play a pathogenic role in PTCL. Notch1 activation was observed in common PTCL subtypes, including PTCL-not otherwise specified (NOS). In a large cohort of PTCL-NOS biopsies, Notch1 activation was significantly associated with surrogate markers of proliferation. Complementary genetically engineered mouse models and spontaneous PTCL models were used to functionally examine the role of Notch signaling, and Notch1/Notch2 blockade and pan-Notch blockade using dominant-negative MAML significantly impaired the proliferation of malignant T cells and PTCL progression in these models. Treatment with DLL1/DLL4 blocking antibodies established that Notch signaling is ligand-dependent. Together, these findings reveal a role for ligand-dependent Notch signaling in driving peripheral T-cell lymphomagenesis.

SIGNIFICANCE

This work demonstrates that ligand-dependent Notch activation promotes the growth and proliferation of mature T-cell lymphomas, providing new therapeutic strategies for this group of aggressive lymphomas.

T and NK cell lymphoma cell lines do not rely on ZAP-70 for survival

B-cell receptor (BCR) signalling is critical for the survival of B-cell lymphomas and is a therapeutic target of drugs such as Ibrutinib. However, the role of T-cell receptor (TCR) signalling in the survival of T/Natural Killer (NK) lymphomas is not clear. ZAP-70 (zeta associated protein-70) is a cytoplasmic tyrosine kinase with a critical role in T-cell receptor (TCR) signalling. It has also been shown to play a role in normal NK cell signalling and activation. High ZAP-70 expression has been detected by immunohistochemistry in peripheral T cell lymphoma (PTCL) and NK cell lymphomas (NKTCL). We therefore, studied the role of TCR pathways in mediating the proliferation and survival of these malignancies through ZAP-70 signalling. ZAP-70 protein was highly expressed in T cell lymphoma cell lines (JURKAT and KARPAS-299) and NKTCL cell lines (KHYG-1, HANK-1, NK-YS, SNK-1 and SNK-6), but not in multiple B-cell lymphoma cell lines. siRNA depletion of ZAP-70 suppressed the phosphorylation of ZAP-70 substrates, SLP76, LAT and p38MAPK, but did not affect cell viability or induce apoptosis in these cell lines. Similarly, while stable overexpression of ZAP-70 mediates increased phosphorylation of target substrates in the TCR pathway, it does not promote increased survival or growth of NKTCL cell lines. The epidermal growth factor receptor (EGFR) inhibitor Gefitinib, which has off-target activity against ZAP-70, also did not show any differential cell kill between ZAP-70 overexpressing (OE) or knockdown (KD) cell lines. Whole transcriptome RNA sequencing highlighted that there was very minimal differential gene expression in three different T/NK cell lines induced by ZAP-70 KD. Importantly, ZAP-70 KD did not significantly enrich for any downstream TCR related genes and pathways. Altogether, this suggests that high expression and constitutive signalling of ZAP-70 in T/NK lymphoma is not critical for cell survival or downstream TCR-mediated signalling and gene expression. ZAP-70 therefore may not be a suitable therapeutic target in T/NK cell malignancies.

The role of ICOS in allergic disease: Positive or Negative?

With the rapid increase in the incidence of allergic diseases, the mechanisms underlying the development of these diseases have received a great deal of attention, and this is particularly true in regard to the role of ICOS in allergic diseases. Current studies have revealed that ICOS affects the functional activity of multiple immune cells that modulate the adaptive immune system. Additionally, ICOS also plays a crucial role in mediating cellular immunity and coordinating the response of the entire immune system, and thus, it plays a role in allergic reactions. However, the ICOS/ICOS-ligand (ICOS-L) axis functions in a dual role during the development of multiple allergic diseases. In this review, we explore the role of ICOS/ICOSL in the context of different immune cells that function in allergic diseases, and we summarize recent advances in their contribution to these diseases.

Cutaneous T-cell lymphomas: 2021 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Cutaneous T-cell lymphomas are a heterogenous group of T-cell neoplasms involving the skin, the majority of which may be classified as Mycosis Fungoides (MF) or Sézary Syndrome (SS).

DIAGNOSIS

The diagnosis of MF or SS requires the integration of clinical and histopathologic data.

RISK-ADAPTED THERAPY

TNMB (tumor, node, metastasis, blood) staging remains the most important prognostic factor in MF/SS and forms the basis for a "risk-adapted," multi-disciplinary approach to treatment. For patients with disease limited to the skin, expectant management or skin-directed therapies is preferred, as both disease-specific and overall survival for these patients is favorable. In contrast, patients with advanced-stage disease with significant nodal, visceral or blood involvement are generally approached with systemic therapies, including biologic-response modifiers, histone deacetylase inhibitors, or antibody-based strategies, in an escalating fashion. In highly-selected patients, allogeneic stem-cell transplantation may be considered, as this may be curative in some patients.

Follicular Helper CD4+ T Cells, Follicular Regulatory CD4+ T Cells, and Inducible Costimulator and Their Roles in Multiple Sclerosis and Experimental Autoimmune Encephalomyelitis

Follicular helper CD4⁺ T (TFH) cells are a specialized subset of effector T cells that play a central role in orchestrating adaptive immunity. TFH cells mainly promote germinal center (GC) formation, provide help to B cells for immunoglobulin affinity maturation and class-switch recombination of B cells, and facilitate production of long-lived plasma cells and memory B cells. TFH cells express the nuclear transcriptional repressor B cell lymphoma 6 (Bcl-6), the chemokine (C-X-C motif) receptor 5 (CXCR5), the CD28 family members programmed cell death protein-1 (PD-1) and inducible costimulator (ICOS) and are also responsible for the secretion of interleukin-21 (IL-21) and IL-4. Follicular regulatory CD4+ T (TFR) cells, as a regulatory counterpart of TFH cells, participate in the regulation of GC reactions. TFR cells not only express markers of TFH cells but also express markers of regulatory T (Treg) cells containing FOXP3, glucocorticoid-induced tumor necrosis factor receptor (GITR), cytotoxic T lymphocyte antigen 4 (CTLA-4), and IL-10, hence owing to the dual characteristic of TFH cells and Treg cells. ICOS, expressed on activated CD4⁺ effector T cells, participates in T cell activation, differentiation, and effector process. The expression of ICOS is highest on TFH and TFR cells, indicating it as a key regulator of humoral immunity. Multiple sclerosis (MS) is a severe autoimmune disease that affects the central nervous system and results in disability, mediated by autoreactive T cells with evolving evidence of a remarkable contribution from humoral responses. This review summarizes recent advances regarding TFH cells, TFR cells, and ICOS, as well as their functional characteristics in relation to MS.

Expression regulation and function of PD-1 and PD-L1 in T lymphoma cells

T lymphoma cells may constitutively express PD-1 and PD-L1. The relative role of PD-1 and PD-L1 in T lymphoma is incompletely understood. We report here that PD-1+ PDL-1+ human T lymphoma cells exhibit constitutive hyperactivation of the TCR signaling and do not respond to PD-L1-mediated suppression in vitro. Knocking out PD-1 or PD-L1 has no effects on T lymphoma cell apoptosis and proliferation in vitro, but significantly increased tumor-bearing mouse survival. Our findings determine that the constitutively active TCR signaling pathway maintain T lymphoma cell growth in vitro and that both PD-1 and PD-L1 promote T lymphoma growth in vivo.

Effective Cytotoxicity of Dendritic Cells against Established T Cell Lymphomas in Mice

T cell lymphomas arise in mice that constitutively express a single TCR in the absence of NK cells. Upon TCR engagement these lymphomas are able to corrupt tumor surveillance by decreasing NK cell numbers. In this study, we investigate the outcome of interactions between these T cell lymphomas and dendritic cells. Bone marrow–derived dendritic cells mediated effective killing of T cell lymphomas after activation with IFN-γ and TLR ligands in culture. This cytotoxicity was independent of MHC compatibility. Cell lysis was reduced by the presence of the peroxynitrite inhibitors FeTTPS and L-NMMA, whereas inhibitors of apoptosis, death receptors, and degranulation were without effect, suggesting NO metabolites as the main mediators. When injected together with GM-CSF and R848 into lymphoma-bearing mice, in vitro–expanded bone marrow–derived dendritic cells caused significant survival increases. These data show that dendritic cell adaptive immunotherapy can be used as treatment against T cell lymphomas in mice.

Stimulated bone marrow–derived dendritic cells lyse T lymphoma target cells in vitro.

Dendritic cell–mediated cytotoxicity is dependent on peroxynitrite.

Dendritic cell transfers into T lymphoma-bearing mice show antitumor efficacy.

Mycosis Fungoides and Sézary Syndrome: An Integrative Review of the Pathophysiology, Molecular Drivers, and Targeted Therapy

Simple Summary

In the last few years, the field of cutaneous T-cell lymphomas has experienced major advances. In the context of an active translational and clinical research field, next-generation sequencing data have boosted our understanding of the main molecular mechanisms that govern the biology of these entities, thus enabling the development of novel tools for diagnosis and specific therapy. Here, we focus on mycosis fungoides and Sézary syndrome; we review essential aspects of their pathophysiology, provide a rational mechanistic interpretation of the genomic data, and discuss the current and upcoming therapies, including the potential crosstalk between genomic alterations and the microenvironment, offering opportunities for targeted therapies.

Abstract

Primary cutaneous T-cell lymphomas (CTCLs) constitute a heterogeneous group of diseases that affect the skin. Mycosis fungoides (MF) and Sézary syndrome (SS) account for the majority of these lesions and have recently been the focus of extensive translational research. This review describes and discusses the main pathobiological manifestations of MF/SS, the molecular and clinical features currently used for diagnosis and staging, and the different therapies already approved or under development. Furthermore, we highlight and discuss the main findings illuminating key molecular mechanisms that can act as drivers for the development and progression of MF/SS. These seem to make up an orchestrated constellation of genomic and environmental alterations generated around deregulated T-cell receptor (TCR)/phospholipase C, gamma 1, (PLCG1) and Janus kinase/ signal transducer and activator of transcription (JAK/STAT) activities that do indeed provide us with novel opportunities for diagnosis and therapy.

Cytoskeleton Dynamics in Peripheral T Cell Lymphomas: An Intricate Network Sustaining Lymphomagenesis

Defects in cytoskeleton functions support tumorigenesis fostering an aberrant proliferation and promoting inappropriate migratory and invasive features. The link between cytoskeleton and tumor features has been extensively investigated in solid tumors. However, the emerging genetic and molecular landscape of peripheral T cell lymphomas (PTCL) has unveiled several alterations targeting structure and function of the cytoskeleton, highlighting its role in cell shape changes and the aberrant cell division of malignant T cells. In this review, we summarize the most recent evidence about the role of cytoskeleton in PTCLs development and progression. We also discuss how aberrant signaling pathways, like JAK/STAT3, NPM-ALK, RhoGTPase, and Aurora Kinase, can contribute to lymphomagenesis by modifying the structure and the signaling properties of cytoskeleton.

Integrative Statistics, Machine Learning and Artificial Intelligence Neural Network Analysis Correlated CSF1R with the Prognosis of Diffuse Large B-Cell Lymphoma

Tumor-associated macrophages (TAMs) of the immune microenvironment play an important role in the Diffuse Large B-cell Lymphoma (DLBCL) pathogenesis. This research aimed to characterize the expression of macrophage colony-stimulating factor 1 receptor (CSF1R) at the gene and protein level in correlation with survival. First, the immunohistochemical expression of CSF1R was analyzed in a series of 198 cases from Tokai University Hospital and two patterns of histological expression were found, a TAMs, and a diffuse B-lymphocytes pattern. The clinicopathological correlations showed that the CSF1R + TAMs pattern associated with a poor progression-free survival of the patients, disease progression, higher MYC proto-oncogene expression, lower MDM2 expression, BCL2 translocation, and a MYD88 L265P mutation. Conversely, a diffuse CSF1R + B-cells pattern was associated with a favorable progression-free survival. Second, the histological expression of CSF1R was also correlated with 10 CSF1R-related markers including CSF1, STAT3, NFKB1, Ki67, MYC, PD-L1, TNFAIP8, IKAROS, CD163, and CD68. CSF1R moderately correlated with STAT3, TNFAIP8, CD68, and CD163 in the cases with the CSF1R + TAMs pattern. In addition, machine learning modeling predicted the CSF1R immunohistochemical expression with high accuracy using regression, generalized linear, an artificial intelligence neural network (multilayer perceptron), and support vector machine (SVM) analyses. Finally, a multilayer perceptron analysis predicted the genes associated with the CSF1R gene expression using the GEO GSE10846 DLBCL series of the Lymphoma/Leukemia Molecular Profiling Project (LLMPP), with correlation to the whole set of 20,683 genes as well as with an immuno-oncology cancer panel of 1790 genes. In addition, CSF1R positively correlated with SIRPA and inversely with CD47. In conclusion, the CSF1R histological pattern correlated with the progression-free survival of the patients of the Tokai series, and predictive analytics is a feasible strategy in DLBCL.

A novel lncRNA TCLlnc1 promotes peripheral T cell lymphoma progression through acting as a modular scaffold of HNRNPD and YBX1 complexes

Long noncoding RNAs (lncRNAs) play an essential role in tumor progression. Few researches focused on the clinical and biological relevance of lncRNAs in peripheral T cell lymphoma (PTCL). In this research, a novel lncRNA (ENST00000503502) was identified overexpressed in the main subtypes of PTCL, and designated as T cell lymphoma-associated lncRNA1 (TCLlnc1). Serum TCLlnc1 was associated with extranodal involvement, high-risk International Prognostic Index, and poor prognosis of the patients. Both in vitro and in vivo, overexpression of TCLlnc1 promoted T-lymphoma cell proliferation and migration, both of which were counteracted by the knockdown of TCLlnc1 using small interfering RNAs. As the mechanism of action, TCLlnc1 directly interacted with transcription activator heterogeneous nuclear ribonucleoprotein D (HNRNPD) and Y-box binding protein-1 (YBX1) by acting as a modular scaffold. TCLlnc1/HNRNPD/YBX1 complex upregulated transcription of TGFB2 and TGFBR1 genes, activated the tumor growth factor-β signaling pathway, resulting in lymphoma progression, and might be a potential target in PTCL.

Novel therapies targeting cutaneous T cell lymphomas and their microenvironment

Cutaneous T-cell lymphomas (CTCL) are rare non-Hodgkin lymphomas with a generally indolent course managed with topical, skin-directed therapies. A small subset, however, will progress to advanced stage disease necessitating systemic therapy for disease control. Currently approved therapies have low response rates and generally short durations of response. Novel therapies, therefore, are urgently needed to address this unmet need. In this review, the mechanisms of CTCL pathogenesis and progression, including the role of the tumor microenvironment and molecular alterations, are summarized. Based on these biologic insights, novel therapies currently under investigation and those with a strong preclinical biologic rationale including T cell and macrophage checkpoint inhibitors, epigenetic regulators, targeted antibodies, tyrosine kinase inhibitors, and apoptosis modulating therapies are discussed.

Management of primary cutaneous lymphomas during the COVID-19 pandemic

Primary cutaneous lymphomas are defined as a heterogenic group of T- and B-cell non-Hodgkin lymphomas that present initially in the skin. Patients with primary cutaneous lymphomas are at a higher risk for developing complications in case of infection with the novel coronavirus severe acute respiratory syndrome coronavirus 2.

The coronavirus disease 2019 (COVID-19) pandemic has affected the established diagnostic approach, staging, and therapeutic guidelines in patients with primary cutaneous lymphomas. In the light of the current global health crisis, management of primary cutaneous lymphomas needs to be adjusted. The key to achieving this is to balance the optimal control of the lymphoma, with a minimal increase of the personal risk for COVID-19 exposure and complications.

FYN-TRAF3IP2 induces NF-κB signaling-driven peripheral T cell lymphoma

Angioimmunoblastic T cell lymphoma (AITL) and peripheral T cell lymphoma not-otherwise-specified (PTCL, NOS) have poor prognosis and lack driver actionable targets for directed therapies in most cases. Here we identify FYN-TRAF3IP2 as a recurrent oncogenic gene fusion in AITL and PTCL, NOS tumors. Mechanistically, we show that FYN-TRAF3IP2 leads to aberrant NF-κB signaling downstream of T cell receptor activation. Consistent with a driver oncogenic role, FYN-TRAF3IP2 expression in hematopoietic progenitors induces NF-κB-driven T cell transformation in mice and cooperates with loss of the Tet2 tumor suppressor in PTCL development. Moreover, abrogation of NF-κB signaling in FYN-TRAF3IP2-induced tumors with IκB kinase inhibitors delivers strong anti-lymphoma effects in vitro and in vivo. These results demonstrate an oncogenic and pharmacologically targetable role for FYN-TRAF3IP2 in PTCLs and call for the clinical testing of anti-NF-κB targeted therapies in these diseases.

ICOS is widely expressed in cutaneous T-cell lymphoma, and its targeting promotes potent killing of malignant cells

The treatment of advanced-stage cutaneous T-cell lymphoma (CTCL) remains an unmet medical need. Mogamulizumab, anti-KIR3DL2, and brentuximab vedotin (BV), an anti-CD30 antibody-drug conjugate (ADC) coupled with monomethyl-auristatin-E (MMAE), provided encouraging results, but new targeted therapies are needed. Inducible T-cell costimulator (ICOS), a T-cell costimulatory receptor, is a promising therapeutic target, not only because it is expressed by malignant T cells in CTCL but also because of its connection with the suppressive activity of regulatory T (Treg) cells. Immunohistochemical analysis revealed that ICOS was widely expressed by malignant cells in skin biopsy specimens from 52 patients with mycosis fungoides and Sézary syndrome (SS), as well as in involved node biopsy specimens from patients with SS. Furthermore, flow cytometry demonstrated its strong expression by circulating tumor cells in all our patients with SS. Percentages of ICOS+ Treg cells were significantly higher in patients with SS than in healthy donors. We then investigated the preclinical efficacy of anti-ICOS ADCs generated by coupling murine anti-ICOS monoclonal antibodies with MMAE and pyrrolobenzodiazepine. In 3 CTCL cell lines (Myla, MJ, and HUT78), we observed a significant dose-dependent decrease in cell viability in the presence of anti-ICOS ADCs. In addition, anti-ICOS-MMAE ADCs had an in vitro and in vivo efficacy superior to BV in a mouse xenograft model (MyLa). Finally, we assessed the efficacy of anti-ICOS ADCs in ICOS+ patient-derived xenografts from patients with SS and angioimmunoblastic T-cell lymphoma. Collectively, our findings provide the preliminary basis for a therapeutic trial.

Engagement of lymphoma T cell receptors causes accelerated growth and the secretion of an NK cell-inhibitory factor

The development of T cell lymphomas in mice that constitutively express a single T cell receptor is surveilled by the action of NK cells. We investigated the effects of engaging the lymphoma TCR in this mouse model. We stimulated lymphoma cells expressing an ovalbumin-specific TCR in vivo using listeria monocytogenes as a vehicle. Infections with listeria expressing ovalbumin but not with control bacteria caused a stable change in lymphoma cells that allowed its growth in mice with normal NK cells. TCR engagement furthermore enhanced lymphoma growth in NK-cell-depleted mice suggesting a lymphoma-intrinsic change that lead to accelerated growth. The ability to grow in mice without prior NK cell depletion did not appear to be accompanied by changes in the recognition of lymphoma by NK cells. Rather, lymphoma immunization was associated with a decrease in NK cell numbers: Leukemic phases were observed for all mice starting three to eight weeks after immunizations, and leukemias were succeeded by the disappearance of NK cells from blood. We also observed strong decreases of NK cell numbers in spleens at the time of death. Co-culture experiments showed decreases in the ability of NK cells to proliferate in response to IL-15 when post-immunization lymphoma cells were present in a mechanism that did not require direct cell contact. Together these data suggest that TCR engagement caused intrinsic changes in T cell lymphoma cells resulting in both accelerated in vivo growth and in the secretion of a factor that caused NK cell disappearance.

Peripheral T cell lymphomas: from the bench to the clinic

Peripheral T cell lymphomas (PTCLs) are a heterogeneous group of orphan neoplasms. Despite the introduction of anthracycline-based chemotherapy protocols, with or without autologous haematopoietic transplantation and a plethora of new agents, the progression-free survival of patients with PTCLs needs to be improved. The rarity of these neoplasms, the limited knowledge of their driving defects and the lack of experimental models have impaired clinical successes. This scenario is now rapidly changing with the discovery of a spectrum of genomic defects that hijack essential signalling pathways and foster T cell transformation. This knowledge has led to new genomic-based stratifications, which are being used to establish objective diagnostic criteria, more effective risk assessment and target-based interventions. The integration of genomic and functional data has provided the basis for targeted therapies and immunological approaches that underlie individual tumour vulnerabilities. Fortunately, novel therapeutic strategies can now be rapidly tested in preclinical models and effectively translated to the clinic by means of well-designed clinical trials. We believe that by combining new targeted agents with immune regulators and chimeric antigen receptor-expressing natural killer and T cells, the overall survival of patients with PTCLs will dramatically increase.

Expression of the checkpoint receptors LAG-3, TIM-3 and VISTA in peripheral T cell lymphomas

AIMS

Peripheral T cell lymphomas represent approximately 10%-15% of non-Hodgkin lymphomas and are characterised by an aggressive clinical courses and poor outcomes. Ligands provided by constituents of the tumour microenvironment engage receptors expressed by malignant T cells, promoting tumour growth and chemotherapy resistance. In addition to stimulatory receptors that promote the growth and survival of malignant T cells, recent studies suggest that homologous inhibitory receptors may have an opposing effect and function as tumour suppressors. For example, recent data suggest that programmed cell death 1 blockade may lead to increased lymphoma growth. Therefore, the identification of alternative checkpoint receptors in T cell lymphoproliferative neoplasms is an important and clinically relevant question.

METHODS

The checkpoint receptors T cell immunoglobulin-3 (TIM-3), V-domain Ig-containing suppressor of T cell activation (VISTA) and lymphocyte-activation gene 3 (LAG-3) play fundamental roles in peripheral tolerance, and their ligands are exploited by many solid tumours to evade host immunity. However, their expression in T cell lymphoproliferative neoplasms has not been evaluated. In this study, we evaluated the expression of TIM-3, VISTA and LAG-3 in a cohort of peripheral T cell lymphomas cases by immunohistochemistry and flow cytometric analysis.

RESULTS

Our results demonstrate that TIM-3, VISTA and LAG-3 expression is rarely identified within a large cohort of T cell lymphomas and its tumour microenvironment.

CONCLUSIONS

Our data suggest that immune-regulatory roles for TIM-3, VISTA and LAG-3 may be predominant in lymphomas subsets different than the ones analysed in the current study. However, a potential role for these checkpoint receptors as tumour suppressors in T cell lymphomas remains to be elucidated.

Clinicopathological features of programmed cell death-1 and programmed cell death-ligand-1 expression in the tumor cells and tumor microenvironment of angioimmunoblastic T cell lymphoma and peripheral T cell lymphoma not otherwise specified

The expression patterns of programmed cell death-1 (PD-1) and programmed cell death-ligand-1 (PD-L1) and their clinicopathological implications were investigated in peripheral T cell lymphoma (PTCL) including angioimmunoblastic T cell lymphoma (AITL) and PTCL-not otherwise specified (PTCL-NOS). PTCL-NOS was further classified into nodal PTCL with follicular helper T cell (Tfh) phenotype ("PTCL-Tfh_new") and "PTCL-NOS_new". PD-1 and PD-L1 expression on tumor cells and reactive immune cells was evaluated using immunohistochemistry. PD-1 and PD-L1 expression on tumor cells (PD-1^T and PD-L1^T, respectively) was interpreted as positive when more than 5% of tumor cells expressed PD-1 or PD-L1. For PD-1 and PD-L1 on tumor cells and/or reactive immune cells (PD-1^T + IC and PD-L1^T + IC, respectively), a cutoff of 10% of cells was used. PD-1^T, PD-L1^T, and PD-L1^T + IC expressions tended to be higher in AITLs than in PTCLs-NOS. PD-1^T, PD-1^T + IC, PD-L1^T, and PD-L1^T + IC expressions tended to be higher in PTCLs with Tfh phenotype including AITLs and "PTCL-Tfh_new" than in PTCLs without Tfh phenotype. The serum LDH level was significantly elevated in patients with PTCL positive for PD-L1^T (P = 0.006) and PD-L1^T + IC (P < 0.001). Patients with PTCL who were positive for combined expression of PD-1^T/PD-L1^T + IC presented at older ages (P = 0.010), nodal diseases (P = 0.001), higher IPI (P = 0.060), and elevated LDH (P = 0.030). Combined PD-1^T/PD-L1^T + IC positivity was related to shorter overall survival in patients with AITL (P = 0.051). Combined PD-1^T/PD-L1^T + IC positivity was a significant poor prognostic factor in patients with stage IV AITL, independent of B symptoms and performance status (HR = 6.282 [CI, 1.655-23.844], P = 0.007). In summary, the PD-1/PD-L1 pathway could be a potential prognostic and therapeutic biomarker for PTCL.

The new biology of PTCL-NOS and AITL: current status and future clinical impact

Peripheral T-cell lymphomas (PTCL) comprise a heterogeneous group of aggressive lymphoproliferative disorders almost all of which are associated with poor clinical outcomes. Angioimmunoblastic T-cell lymphoma (AITL) and some peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS) have similarities to normal CD4⁺ T-cell subsets in their gene expression profiles. A cell of origin model is, therefore, emerging and is likely to be refined in the future. Follicular helper (Tfh) T cells are now established as the cell of origin of AITL and about 20% of PTCL-NOS. Sequencing studies have identified recurrent genetic alterations in epigenetic modifiers, T-cell receptor signalling pathway intermediates or RHOA, most commonly a specific mutation leading to RHOA G17V. While PTCL-NOS remains a diagnosis of exclusion, advances in genomics have identified subgroups expressing transcription factors TBX 21 (Th1-like origin) and GATA3 (Th2-like origin). These findings suggest new biomarkers and new therapeutic avenues including the hypomethylating agent azacytidine, or inhibitors of proximal T-cell receptor (TCR) signalling and potentially certain monoclonal antibodies. The advances over the past few years, therefore, prompt stratified medicine approaches to test biologically based treatments and determine the clinical utility of the new disease classifications.

High activation of STAT5A drives peripheral T-cell lymphoma and leukemia

Recurrent gain-of-function mutations in the transcription factors STAT5A and much more in STAT5B were found in hematopoietic malignancies with the highest proportion in mature T- and natural killer-cell neoplasms (peripheral T-cell lymphoma, PTCL). No targeted therapy exists for these heterogeneous and often aggressive diseases. Given the shortage of models for PTCL, we mimicked graded STAT5A or STAT5B activity by expressing hyperactive Stat5a or STAT5B variants at low or high levels in the hematopoietic system of transgenic mice. Only mice with high activity levels developed a lethal disease resembling human PTCL. Neoplasia displayed massive expansion of CD8⁺ T cells and destructive organ infiltration. T cells were cytokine-hypersensitive with activated memory CD8⁺ T-lymphocyte characteristics. Histopathology and mRNA expression profiles revealed close correlation with distinct subtypes of PTCL. Pronounced STAT5 expression and activity in samples from patients with different subsets underline the relevance of JAK/STAT as a therapeutic target. JAK inhibitors or a selective STAT5 SH₂ domain inhibitor induced cell death and ruxolitinib blocked T-cell neoplasia in vivo. We conclude that enhanced STAT5A or STAT5B action both drive PTCL development, defining both STAT5 molecules as targets for therapeutic intervention.

Role of Inducible Co-Stimulator (ICOS) in cancer immunotherapy

Introduction: The promotion of antitumor response by targeting co-stimulatory B7 superfamily members has become evident to create a new wave of cancer immunotherapy. Inducible Co-Stimulator (ICOS), which is expressed on activated T cells, gained interest in the translational medicine community.Areas covered: We performed an extensive literature review using the keywords 'ICOS' and 'cancer', and the Clinicaltrials.gov database for early phase clinical trials targeting ICOS. In this review, we highlight the dual role of ICOS in oncogenesis in different malignancies. We summarize the current state of knowledge about ICOS/ICOSL pathway targeting by immunotherapies.Expert opinion: Due to its multifaceted link with anti-tumor immunity, both antagonist and agonist antibodies might be of interest to target the ICOS/ICOSL pathway for tumor treatment. Indeed, ICOS activation might potentiate the effect of an inhibitory checkpoint blockade, while its neutralization could decrease the function of immunosuppressive Tregs and inhibit lymphoid tumor cells expressing Tfh markers.

Colony-Stimulating Factor 1 Receptor (CSF1R) Activates AKT/mTOR Signaling and Promotes T-Cell Lymphoma Viability

PURPOSE

Peripheral T-cell lymphomas are clinically aggressive and usually fatal, as few complete or durable remissions are achieved with currently available therapies. Recent evidence supports a critical role for lymphoma-associated macrophages during T-cell lymphoma progression, but the specific signals involved in the cross-talk between malignant T cells and their microenvironment are poorly understood. Colony-stimulator factor 1 receptor (CSF1R, CD115) is required for the homeostatic survival of tissue-resident macrophages. Interestingly, its aberrant expression has been reported in a subset of tumors. In this article, we evaluated its expression and oncogenic role in T-cell lymphomas.

EXPERIMENTAL DESIGN

Loss-of-function studies, including pharmacologic inhibition with a clinically available tyrosine kinase inhibitor, pexidartinib, were performed in multiple in vitro and in vivo models. In addition, proteomic and genomic screenings were performed to discover signaling pathways that are activated downstream of CSF1R signaling.

RESULTS

We observed that CSF1R is aberrantly expressed in many T-cell lymphomas, including a significant number of peripheral and cutaneous T-cell lymphomas. Colony-stimulating factor 1 (CSF1), in an autocrine or paracrine-dependent manner, leads to CSF1R autophosphorylation and activation in malignant T cells. Furthermore, CSF1R signaling was associated with significant changes in gene expression and in the phosphoproteome, implicating PI3K/AKT/mTOR in CSF1R-mediated T-cell lymphoma growth. We also demonstrated that inhibition of CSF1R in vivo and in vitro models is associated with decreased T-cell lymphoma growth.

CONCLUSIONS

Collectively, these findings implicate CSF1R in T-cell lymphomagenesis and have significant therapeutic implications.

Tyrosine kinase inhibition to improve anthracycline-based chemotherapy efficacy in T-cell lymphoma

Background

Anthracycline-containing regimens, namely cyclophosphamide, doxorubicin, vincristine and prednisone (CHOP) or CHOEP (CHOP + etoposide), represent the current standard of care for patients with newly diagnosed peripheral T-cell lymphomas (PTCLs), although responses are unsatisfactory. In this study, we investigated the pathways able to mitigate the sensitivity to CHOP-based regimens in preclinical models of T-cell lymphoma (TCL) to select agents for the development of CHOP-based drug combinations.

Methods

We performed gene expression profiling of malignant T-cell lines exposed to CHOEP; flow cytometry was employed to study the effects of drug combinations on cell viability, cell cycle distribution, apoptosis and mitochondrial membrane depolarisation. Western blot analyses were performed to study cell signalling downstream of the T-cell receptor and apoptosis. The in vivo effect of the drug combination was tested in xenograft models.

Results

We highlighted a modulation of tyrosine kinases belonging to the T-cell receptor pathway upon chemotherapy that provided the rationale for combining the tyrosine kinase inhibitor dasatinib with CHOEP. Dasatinib improves CHOEP activity and reduces viability in vitro. Furthermore, combination treatment results in tumour growth inhibition in in vivo xenograft mouse models.

Conclusions

Our data provide the rationale for clinical testing of the dasatinib–CHOEP combination in patients with T-cell lymphoma.

Mycosis fungoides and Sézary syndrome: 2019 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Cutaneous T-cell lymphomas (CTCL) are a heterogenous group of T-cell neoplasms involving the skin, the majority of which may be classified as Mycosis fungoides (MF) or Sézary syndrome (SS).

DIAGNOSIS

The diagnosis of MF or SS requires the integration of clinical and histopathologic data.

RISK-ADAPTED THERAPY

TNMB (tumor, node, metastasis, blood) staging remains the most important prognostic factor in MF/SS and forms the basis for a "risk-adapted," multi-disciplinary approach to treatment. For patients with disease limited to the skin, skin-directed therapies are preferred, as both disease-specific and overall survival for these patients is favorable. In contrast, patients with advanced-stage disease with significant nodal, visceral or blood involvement are generally approached with systemic therapies. These include biologic-response modifiers, histone deacetylase (HDAC) inhibitors, or antibody-based strategies, in an escalating fashion. In highly-selected patients, allogeneic stem-cell transplantation may be considered, as this may be curative in some patients.

GATA-3 in T-cell lymphoproliferative disorders

GATA-3 regulates the differentiation, proliferation, survival, and function of peripheral T cells and their thymic progenitors. Recent findings, reviewed here, not only implicate GATA-3 in the pathogenesis of molecularly, genetically, and clinically distinct T-cell lymphoproliferative disorders, but also have significant diagnostic, prognostic, and therapeutic implications.

High-Throughput Sequence Analysis of Peripheral T-Cell Lymphomas Indicates Subtype-Specific Viral Gene Expression Patterns and Immune Cell Microenvironments

Certain peripheral T-cell lymphomas (PTCLs) have been associated with viral infection, particularly infection with Epstein-Barr virus (EBV). However, a comprehensive virome analysis across PTCLs has not previously been reported. Here we utilized published whole-transcriptome RNA sequencing (RNA-seq) data sets from seven different PTCL studies and new RNA-seq data from our laboratory to screen for virus association, to analyze viral gene expression, and to assess B- and T-cell receptor diversity paradigms across PTCL subtypes. In addition to identifying EBV in angioimmunoblastic T-cell lymphoma (AITL) and extranodal NK/T-cell lymphoma (ENKTL), two PTCL subtypes with well-established EBV associations, we also detected EBV in several cases of anaplastic large-cell lymphoma (ALCL), and we found evidence of infection by the oncogenic viruses Kaposi's sarcoma-associated herpesvirus and human T-cell leukemia virus type 1 in isolated PTCL cases. In AITLs, EBV gene expression analysis showed expression of immediate early, early, and late lytic genes, suggesting either low-level lytic gene expression or productive infection in a subset of EBV-infected B-lymphocyte stromal cells. Deconvolution of immune cell subpopulations demonstrated a greater B-cell signal in AITLs than in other PTCL subtypes, consistent with a larger role for B-cell support in the pathogenesis of AITL. Reconstructed T-cell receptor (TCR) and B-cell receptor (BCR) repertoires demonstrated increased BCR diversity in AITLs, consistent with a possible EBV-driven polyclonal response. These findings indicate potential alternative roles for EBV in PTCLs, in addition to the canonical oncogenic mechanisms associated with EBV latent infection. Our findings also suggest the involvement of other viruses in PTCL pathogenesis and demonstrate immunological alterations associated with these cancers.IMPORTANCE In this study, we utilized next-generation sequencing data from 7 different studies of peripheral T-cell lymphoma (PTCL) patient samples to globally assess viral associations, provide insights into the contributions of EBV gene expression to the tumor phenotype, and assess the unique roles of EBV in modulating the immune cell tumor microenvironment. These studies revealed potential roles for EBV replication genes in some PTCL subtypes, the possible role of additional human tumor viruses in rare cases of PTCLs, and a role for EBV in providing a unique immune microenvironmental niche in one subtype of PTCLs. Together, these studies provide new insights into the understudied role of tumor viruses in PTCLs.

Ontogeny, Genetics, Molecular Biology, and Classification of B- and T-Cell Non-Hodgkin Lymphoma

Mature B- and T-cell lymphomas are diverse in their biology, etiology, genetics, clinical behavior, and response to specific therapies. Here, we review the principles of diagnostic classification for non-Hodgkin lymphomas, summarize the characteristic features of major entities, and place recent biological and molecular findings in the context of principles that are applicable across the spectrum of mature lymphoid cancers.

Soluble immune checkpoint molecules: Serum markers for cancer diagnosis and prognosis

BACKGROUND

With the recent advances in the understanding of the interaction of the immune system with developing tumor, it has become imperative to consider the immunological parameters for both cancer diagnosis and disease prognosis. Additionally, in the era of emerging immunotherapeutic strategies in cancer, it is very important to follow the treatment outcome and also to predict the correct immunotherapeutic strategy in individual patients. There being enormous heterogeneity among tumors at different sites or between primary and metastatic tumors in the same individual, or interpatient heterogeneity, it is very important to study the tumor-immune interaction in the tumor microenvironment and beyond. Importantly, molecular tools and markers identified for such studies must be suitable for monitoring in a noninvasive manner.

RECENT FINDINGS

Recent studies have shown that the immune checkpoint molecules play a key role in the development and progression of tumors. In-depth studies of these molecules have led to the development of most of the cancer immunotherapeutic reagents that are currently either in clinical use or under different phases of clinical trials. Interestingly, many of these cell surface molecules undergo alternative splicing to produce soluble isoforms, which can be tracked in the serum of patients.

CONCLUSIONS

Several studies demonstrate that the serum levels of these soluble isoforms could be used as noninvasive markers for cancer diagnosis and disease prognosis or to predict patient response to specific therapeutic strategies.

Inducible Co-Stimulator (ICOS) as a potential therapeutic target for anti-cancer therapy

INTRODUCTION

The recent success of checkpoint-inhibitors in cancer treatment paved the way for the development of new strategies of agonist and antagonist agents against B7 superfamily members. Inducible Co-Stimulator (ICOS), a co-stimulatory receptor for T-cell enhancement, arouses interest. Areas covered: We performed an extensive literature search with PUBMED using the keywords 'ICOS' and 'cancer' to discuss its involvement in oncogenesis, its expression in different malignancies, and its targeting in relevant preclinical studies. We also searched the Clinicaltrials.gov database for recent updates on early phase clinical trials. Expert opinion: ICOS/ICOSL axis has a dual effect and might participate in anti-tumour T cell response as well as a pro-tumour response due to its connection with regulatory T-cells (Tregs) suppressive activity. Therefore, both antagonist and agonist antibodies might be of interest in the targeting ICOS/ICOSL pathway for cancer treatment. In preclinical studies, ICOS agonist monoclonal antibodies (mAbs) have shown to potentiate the effect of inhibitory checkpoint blockade. In contrast, antagonistic anti-ICOS mAbs could not only inhibit lymphoid tumour cells expressing ICOS, but also dampen immunosuppressive Tregs. Two agonist and one antagonist mAbs are evaluated in phase I/II trials. Efficacy, safety, and combination strategies with anti-ICOS agonist or antagonist have yet to be specified.

Survival following salvage therapy for primary refractory peripheral T-cell lymphomas (PTCL)

Optimal salvage therapy for primary refractory peripheral T-cell lymphomas (PTCL) and the role of hematopoietic stem cell transplant (SCT) remain poorly defined. We conducted a retrospective review of clinical outcomes and prognostic factors in a single-center cohort of 93 patients with primary refractory PTCL, defined as progression during first-line therapy or relapse within 6 months of its completion. Clinical outcomes were poor in this population, with median event-free survival (EFS) of 3.5 months, median overall survival (OS) of 9.1 months, and 34% 3-year survival. Outcomes were comparable in patients who progressed through first-line therapy and patients who achieved CR/PR and subsequently relapsed within 6 months. A majority exhibited high-risk features and had intermediate to high risk IPI, which correlated with inferior outcomes. There was no difference in outcomes between patients who received single-agent salvage regimens and patients who underwent traditional, multi-agent salvage regimens. Thus, participation in well-designed clinical trials should be encouraged in this population. Additionally, there may be a trend toward improved EFS and OS in patients who underwent autologous or allogeneic SCT compared to patients who achieved CR or PR but were not transplanted.

A single center phase II study of ixazomib in patients with relapsed or refractory cutaneous or peripheral T-cell lymphomas

The transcription factor GATA-3, highly expressed in many cutaneous T-cell lymphoma (CTCL) and peripheral T-cell lymphomas (PTCL), confers resistance to chemotherapy in a cell-autonomous manner. As GATA-3 is transcriptionally regulated by NF-κB, we sought to determine the extent to which proteasomal inhibition impairs NF-κB activation and GATA-3 expression and cell viability in malignant T cells. Proteasome inhibition, NF-κB activity, GATA-3 expression, and cell viability were examined in patient-derived cell lines and primary T-cell lymphoma specimens ex vivo treated with the oral proteasome inhibitor ixazomib. Significant reductions in cell viability, NF-κB activation, and GATA-3 expression were observed preclinically in ixazomib-treated cells. Therefore, an investigator-initiated, single-center, phase II study with this agent in patients with relapsed/refractory CTCL/PTCL was conducted. Concordant with our preclinical observations, a significant reduction in NF-κB activation and GATA-3 expression was observed in an exceptional responder following one month of treatment with ixazomib. While ixazomib had limited activity in this small and heterogeneous cohort of patients, inhibition of the NF-κB/GATA-3 axis in a single exceptional responder suggests that ixazomib may have utility in appropriately selected patients or in combination with other agents.

Emerging therapeutic targets in myeloproliferative neoplasms and peripheral T-cell leukemia and lymphomas

Introduction: Hematopoietic neoplasms are often driven by gain-of-function mutations of the JAK-STAT pathway together with mutations in chromatin remodeling and DNA damage control pathways. The interconnection between the JAK-STAT pathway, epigenetic regulation or DNA damage control is still poorly understood in cancer cell biology.

Areas covered: Here, we focus on a broader description of mutational insights into myeloproliferative neoplasms and peripheral T-cell leukemia and lymphomas, since sequencing efforts have identified similar combinations of driver mutations in these diseases covering different lineages. We summarize how these pathways might be interconnected in normal or cancer cells, which have lost differentiation capacity and drive oncogene transcription.

Expert opinion: Due to similarities in driver mutations including epigenetic enzymes, JAK-STAT pathway activation and mutated checkpoint control through TP53, we hypothesize that similar therapeutic approaches could be of benefit in these diseases. We give an overview of how driver mutations in these malignancies contribute to hematopoietic cancer initiation or progression, and how these pathways can be targeted with currently available tools.