Expression patterns of the immunosuppressive proteins PD-1/CD279 and PD-L1/CD274 at different stages of cutaneous T-cell lymphoma/mycosis fungoides

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

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

Pneumocystis jirovecii Pneumonia in a Patient With Localized Mycosis Fungoides Not Receiving Immunosuppressive Treatment

Pneumocystis jirovecii pneumonia (PCP) is the most common opportunistic infection in patients with human immunodeficiency virus (HIV), but it may develop in patients without HIV, whose immune system is suppressed by anticancer or immunosuppressive agents even when indicating normal counts of CD4+ T cells. Mycosis fungoides (MF) is a primary cutaneous T-cell lymphoma, which is believed not to cause immunosuppressive conditions unless it develops leukosis or metastasis or is treated with anticancer drugs or systemic immunosuppressants. Here, we report a case of PCP in a patient with localized MF not receiving immunosuppressive treatment. The patient, a woman in her 70s, presented with persistent dyspnea. High-resolution computed tomography (HRCT) showed diffuse ground-glass opacities in both lungs. Bronchoalveolar lavage fluid was positive for P. jirovecii. Moreover, the cytomegalovirus antigenemia test was positive, whereas tests for anti-HIV and antihuman T-cell lymphotropic virus antibodies were negative. The patient was treated with trimethoprim-sulfamethoxazole, prednisolone, and ganciclovir, which gradually improved the symptoms and diminished diffuse ground-glass opacities on HRCT. This case exemplifies a rare presentation of PCP with mild MF that was not treated with chemotherapy or immunosuppressants. The possible mechanisms for the development of PCP are discussed.

Folliculotropic Mycosis Fungoides Is Associated with Decreased PD1 Staining Compared with Classic Mycosis Fungoides

Programmed cell death protein 1 (PD-1) plays a pivotal role in immune system regulation, with its expression levels linked to malignancy prognosis. However, existing reports on PD-1 staining in mycosis fungoides (MF) present conflicting findings, and little attention has been given to PD-1 staining in different MF variants. To address this, we conducted a retrospective study, employing immunohistochemistry to examine PD-1 expression in cases of folliculotropic MF and non-folliculotropic MF. We analyzed 24 cases of folliculotropic MF and 18 cases of non-folliculotropic MF, and recorded both the percentage of PD-1-labeled tumor cells and the intensity score (negative, weak, medium, or strong). Our results revealed significant disparity in PD-1 labeling between patch/plaque MF and folliculotropic MF (p = 0.028). Non-folliculotropic MF exhibited higher PD-1 labeling in tumor cells (58.3%) compared to folliculotropic MF (40.2%). Notably, there was no significant difference in PD-1 staining between folliculotropic MF and non-folliculotropic MF when both were in the early stage/indolent disease category. However, when considering the tumor stage, folliculotropic MF exhibited PD-1 staining in tumor cells at a rate of 21.1%, while non-folliculotropic MF showed PD-1 staining in tumor cells at a rate of 46.6% (p = 0.005). Additionally, among folliculotropic MF cases, 13 out of 24 cases displayed differing PD-1 expression patterns between epidermal and dermal components, with preserved PD-1 staining in the epidermal component and loss of staining in the dermal component. Furthermore, consistent with the prior literature, tumor cells with large cell transformations exhibited significantly lower PD-1 labeling (p = 0.017). Our findings showcase the unique PD-1 staining patterns in MF.

Mycosis Fungoides and Sézary Syndrome: Microenvironment and Cancer Progression

Mycosis fungoides and Sézary syndrome are epidermotropic cutaneous lymphomas, and both of them are rare diseases. Mycosis fungoides is the most frequent primary cutaneous lymphoma. In about 25% of patients with mycosis fungoides, the disease may progress to higher stages. The pathogenesis and risk factors of progression in mycosis fungoides and Sézary syndrome are not yet fully understood. Previous works have investigated inter- and intrapatient tumor cell heterogeneity. Here, we overview the role of the tumor microenvironment of mycosis fungoides and Sézary syndrome by describing its key components and functions. Emphasis is put on the role of the microenvironment in promoting tumor growth or antitumor immune response, as well as possible therapeutic targets. We focus on recent advances in the field and point out treatment-related alterations of the microenvironment. Deciphering the tumor microenvironment may help to develop strategies that lead to long-term disease control and cure.

Harnessing the immune system in the treatment of cutaneous T cell lymphomas

Cutaneous T cell lymphomas are a rare subset of non-Hodgkin's lymphomas with predilection for the skin with immunosuppressive effects that drive morbidity and mortality. We are now appreciating that suppression of the immune system is an important step in the progression of disease. It should come as no surprise that therapies historically and currently being used to treat these cancers have immune modulating functions that impact disease outcomes. By understanding the immune effects of our therapies, we may better develop new agents that target the immune system and improve combinatorial treatment strategies to limit morbidity and mortality of these cancers. The immune modulating effect of therapeutic drugs in use and under development for cutaneous T cell lymphomas will be reviewed.

Primary cutaneous peripheral T-cell lymphomas with a T-follicular helper phenotype: an integrative clinical, pathological and molecular case series study

BACKGROUND

Primary cutaneous peripheral T-cell lymphomas with a T-follicular helper phenotype (pcTFH-PTCL) are poorly characterized, and often compared to, but not corresponding with, mycosis fungoides (MF), Sézary syndrome, primary cutaneous CD4⁺ lymphoproliferative disorder, and skin manifestations of angioimmunoblastic T-cell lymphomas (AITL).

OBJECTIVES

We describe the clinicopathological features of pcTFH-PTCL in this original series of 23 patients, and also characterize these cases molecularly.

METHODS

Clinical and histopathological data of the selected patients were reviewed. Patient biopsy samples were also analysed by targeted next-generation sequencing.

RESULTS

All patients (15 men, eight women; median age 66 years) presented with skin lesions, without systemic disease. Most were stage T3b, with nodular (n = 16), papular (n = 6) or plaque (atypical for MF, n = 1) lesions. Three (13%) developed systemic disease and died of lymphoma. Nine (39%) patients received more than one line of chemotherapy. Histologically, the lymphomas were CD4⁺ T-cell proliferations, usually dense and located in the deep dermis (n = 14, 61%), with the expression of at least two TFH markers (CD10, CXCL13, PD1, ICOS, BCL6), including three markers in 16 cases (70%). They were associated with a variable proportion of B cells. Eight patients were diagnosed with an associated B-cell lymphoproliferative disorder (LPD) on biopsy, including Epstein-Barr virus (EBV)-positive diffuse large B-cell lymphoma (n = 3), EBV⁺ LPD (n = 1) and monotypic plasma cell LPD (n = 4). Targeted sequencing showed four patients to have a mutated TET2-RHOAG17V association (as frequently seen in AITL) and another a TET2/DNMT3A/PLCG1/SETD2 mutational profile. The latter patient, one with a TET2-RHOA association, and one with no detected mutations, developed systemic disease and died. Five other patients showed isolated mutations in TET2 (n = 1), PLCG1 (n = 2), SETD2 (n = 1) or STAT5B (n = 1).

CONCLUSIONS

Patients with pcTFH-PTCL have pathological and genetic features that overlap with those of systemic lymphoma of TFH derivation. Clinically, most remained confined to the skin, with only three patients showing systemic spread and death. Whether pcTFH-PTCL should be integrated as a new subgroup of TFH lymphomas in future classifications is still a matter of debate. What is already known about this topic? There is a group of cutaneous lymphomas that express T-follicular helper (TFH) markers that do not appear to correspond to existing World Health Organization diagnostic entities. These include mycosis fungoides, Sézary syndrome, or primary cutaneous CD4⁺ small/medium-sized T-cell lymphoproliferative disorder or cutaneous extensions of systemic peripheral T-cell lymphomas (PTCL) with TFH phenotype. What does this study add? This is the first large original series of patients with a diagnosis of primary cutaneous PTCL with a TFH phenotype (pcTFH-PTCL) to be molecularly characterized. pcTFH-PTCL may be a standalone group of cutaneous lymphomas with clinicopathological and molecular characteristics that overlap with those of systemic TFH lymphomas, such as angioimmunoblastic T-cell lymphoma, and does not belong to known diagnostic groups of cutaneous lymphoma. This has an impact on the treatment and follow-up of patients; the clinical behaviour needs to be better clarified in further studies to tailor patient management.

A High Programmed Cell Death Protein 1 Hormone Receptor Score on Skin Biopsy is Associated with Sézary Syndrome Diagnosis: A Study of 91 Patients with Erythroderma

Erythroderma is challenging to diagnose. The aim of this single-centre retrospective study was to identify factors that can be used to improve the diagnosis of erythroderma. Among 91 patients with erythroderma, 21 were diagnosed with eczema, 17 with psoriasis, 20 with drug-induced erythroderma, 13 with erythrodermic mycosis fungoides and 20 with Sézary syndrome. Nail alterations, ear involvement, and severe scaling were significantly associated with psoriasis (p = 0.044). Fever and hypereosinophilia were associated with drug-induced erythroderma. Expression of programmed cell death protein 1 was observed in all skin biopsies. However, with Sézary syndrome, programmed cell death protein 1 expression was significantly higher than with other aetiologies. A programmed cell death protein 1 hormone receptor score (H-score) >50 was associated with Sézary syndrome (p < 0.001, sensitivity 75%, specificity 92%) as well as CXCL13 expression (p < 0.044). CD7 loss was more frequent with erythrodermic mycosis fungoides and Sézary syndrome (p = 0.022). This study reports the importance of programmed cell death protein 1 expression for the differential diagnosis of Sézary syndrome and other aetiologies, including erythrodermic mycosis fungoides.

The role of immune checkpoint receptors in the malignant phenotype of cutaneous T cell lymphoma

Immune checkpoint receptors (ICR) modulate the immune response and are critical hubs for immunotherapy. However, data on their role in T lymphoid malignancies, such as cutaneous T cell lymphoma (CTCL), is sparse. We aimed to explore the role of ICR in the malignant features of transformed T lymphocytes and evaluate the effect of ICR-targeting monoclonal antibodies, often used as immunotherapy for solid tumors. We used the CTCL cell line HH and the Sézary cell line Hut78 to examine ICR expression and the effects of ICR inhibition on cell viability and proliferation. Despite their shared T cell progeny, the different CTCL cell lines exhibit markedly different ICR expression profiles. Programmed cell death-ligand 1 (PD-L1) was expressed by both cell lines, while programmed death-1 (PD-1) was expressed only by the HH cell line. Common to all malignant T cells was an autonomous hyper-proliferative state that did not require T cell receptor stimulation. A monoclonal antibody blocking PD-1 had a small but statistically significant augmenting effect on T cell proliferation. Of note, when the cells were exposed to ionizing radiation, healthy lymphocytes and those derived from the HH cell line were salvaged by anti-PD-L1. We show a regulatory role of ICR, mainly PD-1 and its ligand PD-L1, on cutaneous T cell malignancy.

PD-1 improves accurate detection of Sezary cells by flow cytometry in peripheral blood in mycosis fungoides/Sezary syndrome

BACKGROUND

Accurate Sezary cell detection in peripheral blood of mycosis fungoides/Sezary syndrome (MF/SS) patients by flow cytometry can be difficult due to overlapping immunophenotypes with normal T cells using standard markers. We assessed the utility of programmed death-1 (PD-1/CD279), a transmembrane protein expressed in some hematopoietic cells, for identification and quantitation of circulating Sezary cells among established markers using flow cytometry.

METHODS

50 MF/SS and 20 control blood samples were immunophenotyped by flow cytometry. Principal component analysis (PCA) assessed contributions of antigens to separation of abnormal from normal T cell populations. PD-1 was assessed over time in blood and bone marrow of available MF/SS cases.

RESULTS

Normal CD4+ T cells showed dim/intermediate to absent PD-1 expression. PD-1 in Sezary cells was informatively brighter (≥1/3 log) than internal normal CD4+ T cells in 39/50 (78%) cases. By PCA, PD-1 ranked 3rd behind CD7 and CD26 in population separation as a whole; it ranked in the top 3 markers in 32/50 (64%) cases and 1st in 4/50 (8%) cases when individual abnormal populations were compared to total normal CD4+ T cells. PD-1 clearly separated Sezary from normal CD4+ T cells in 15/26 (58%, 30% of total) cases with few and subtle alterations of pan-T cell antigens/CD26 and was critical in 6 (12% of total), without which identification and quantification were significantly affected or nearly impossible. PD-1 remained informative in blood/bone marrow over time in most patients.

CONCLUSIONS

PD-1 significantly contributes to accurate flow cytometric Sezary cell assessment in a routine Sezary panel.

Case Report: Outcome and Adverse Events of Anti-PD-1 Antibody Plus Chidamide for Relapsed/Refractory Sézary Syndrome: Case Series and A Literature Review

Sézary syndrome (SS) is an aggressive leukemic variant of cutaneous T-cell lymphoma with a poor prognosis and survival rate. Existing therapies for relapsed/refractory (R/R) SS have a low response rate with a short duration time. Herein, we presented three cases of R/R SS treated with the anti-PD-1 antibody and chidamide. Case 1 and case 2 showed the potential efficacy of this combination therapy with a long duration time. Case 2 and case 3 both showed that the patients developed acute and transient worsening of erythroderma and pruritus after anti-PD-1 antibody infusion, and this flare reaction was associated with transient decreased leukocytes and lymphocytes in peripheral blood. To the best of our knowledge, this is the first report of the anti-PD-1 antibody combined with chidamide for treatment of R/R SS. This report suggests that the combination therapy may be a new and effective treatment and that further clinical trials are needed to prove it and elucidate the mechanism of this combination therapy and its flare reaction.

PD-1 and PD-L1 expression in mycosis fungoides and Sézary Syndrome

BACKGROUND

The mechanisms involved in mycosis fungoides and Sezary Syndrome progression are largely unknown. Over the last decade the interest in immune system contrast of neoplasm has grown owing to the introduction of immunotherapy. PD-1 and its ligand (PD-L1) are the target of several immunotherapy treatment. In the literature reports on the expression of PD-1 and PD-L1 have provided contrasting results.

METHODS

In our analysis we investigated PD-1 expression in neoplastic cells and in tumour infiltrating lymphocytes (TILs) as well as PD-L1 expression in tumour cells and in tumour associated macrophages (TAMs). PD-L1 and PD-1 positive cells were counted in 5 high-power fields (HPF) and scored as the average number of positive neoplastic cells/TILs/TAMs per HPF.

RESULTS

From databases of two institutions (Bologna and Florence) thirty-five patients corresponding to 43 biopsies were retrieved. In seven instances sequential biopsies were present. No statistically significant expression was observed comparing early to advanced stages by analysing PD-1 by tumour cells and TILs and of PD-L1 by tumour cells and TAMs.

CONCLUSIONS

Our results corroborate that PD-1 and PD-L1 expression is not stage-dependent in mycosis fungoides and Sezary syndrome. However, PD-1 and PD-L1 expression in affected patients provides a rationale to schedule anti PD-1/PD-L1 drugs.

Expression of Immune Checkpoint Molecules PD1, PD-L1 and ICOS in Mycosis Fungoides and Sézary Syndrome: Association with Disease Stage and Clinical Outcome

Background

The relationship between immune checkpoint status and disease outcome is a major focus of research in cutaneous T‐cell lymphoma (CTCL), a disfiguring neoplastic dermatological disorder. Mycosis fungoides (MF) and Sézary syndrome (SS) are the two most common types of CTCL.

Objectives

The aim was to evaluate the immune checkpoint markers programmed death protein 1 (PD1), inducible T‐cell co‐stimulator (ICOS) and programmed death‐ligand 1 (PD‐L1) in skin biopsies from patients with CTCL relative to disease stage and overall survival.

Methods

This consecutive case series enrolled 47 patients: 57% had stage IA–IIA disease and 43% had stage IIB–IVA2 disease (including seven with SS).

Results

PD1, PD‐L1 and ICOS expression was seen in all biopsies. Notably, PD‐L1 was predominantly expressed on histiocytes/macrophages, but focal expression on CTCL cells was seen. High expression of either ICOS or PD‐L1 was associated with advanced‐stage disease (P = 0·007 for both) and with the appearance of large‐cell transformation (LCT), a histopathological feature associated with a poor prognosis (ICOS: P = 0·02; PD‐L1: P = 0·002). PD1 expression was not significantly associated with disease stage (P = 0·12) or LCT (P = 0·49), but expression was high in SS biopsies. A high combined checkpoint marker score (PD1, PD‐L1 and ICOS) was associated with advanced‐stage disease (P = 0·001), LCT (P = 0·021) and lower overall survival (P = 0·014).

Conclusions

These findings demonstrate the existence of a complex immunoregulatory microenvironment in CTCL and support the development of immunotherapies targeting ICOS and PD‐L1 in advanced disease.

The Role of Tumor Microenvironment in Mycosis Fungoides and Sézary Syndrome

Mycosis fungoides (MF) and Sézary syndrome (SS) are the most common subtypes of cutaneous T-cell lymphomas (CTCLs). Most cases of MF display an indolent course during its early stage. However, in some patients, it can progress to the tumor stage with potential systematic involvement and a poor prognosis. SS is defined as an erythrodermic CTCL with leukemic involvements. The pathogenesis of MF and SS is still not fully understood, but recent data have found that the development of MF and SS is related to genetic alterations and possibly to environmental influences. In CTCL, many components interacting with tumor cells, such as tumor-associated macrophages, fibroblasts, dendritic cells, mast cells, and myeloid-derived suppressor cells, as well as with chemokines, cytokines and other key players, establish the tumor microenvironment (TME). In turn, the TME regulates tumor cell migration and proliferation directly and indirectly and may play a critical role in the progression of MF and SS. The TME of MF and SS appear to show features of a Th2 phenotype, thus dampening tumor-related immune responses. Recently, several studies have been published on the immunological characteristics of MF and SS, but a full understanding of the CTCL-related TME remains to be determined. This review focuses on the role of the TME in MF and SS, aiming to further demonstrate the pathogenesis of the disease and to provide new ideas for potential treatments targeted at the microenvironment components of the tumor.

Immune cell topography predicts response to PD-1 blockade in cutaneous T cell lymphoma

Cutaneous T cell lymphomas (CTCL) are rare but aggressive cancers without effective treatments. While a subset of patients derive benefit from PD-1 blockade, there is a critically unmet need for predictive biomarkers of response. Herein, we perform CODEX multiplexed tissue imaging and RNA sequencing on 70 tumor regions from 14 advanced CTCL patients enrolled in a pembrolizumab clinical trial (NCT02243579). We find no differences in the frequencies of immune or tumor cells between responders and non-responders. Instead, we identify topographical differences between effector PD-1⁺ CD4⁺ T cells, tumor cells, and immunosuppressive Tregs, from which we derive a spatial biomarker, termed the SpatialScore, that correlates strongly with pembrolizumab response in CTCL. The SpatialScore coincides with differences in the functional immune state of the tumor microenvironment, T cell function, and tumor cell-specific chemokine recruitment and is validated using a simplified, clinically accessible tissue imaging platform. Collectively, these results provide a paradigm for investigating the spatial balance of effector and suppressive T cell activity and broadly leveraging this biomarker approach to inform the clinical use of immunotherapies.

Clinical Response in Heavily Pretreated Mycosis Fungoides with Pembrolizumab: A Case Report

Mycosis fungoides (MF) is a disease almost impossible to cure. In the context of heavily pretreated patients, the anti-programmed cell death protein 1 (anti-PD-1) pembrolizumab is a valid therapeutic option. The alteration of the PD-1-PD ligand 1 (PD-L1) axis is often present in MF, and this aspect explains the feasibility of this therapy. We report the case of a 60-year-old woman diagnosed with MF in 2003, Olsen stage IA (T1M0NXBO). Since the moment of the diagnosis, she received 10 lines of therapy, with a short duration of response after each one of them. In April 2020, our patient started pembrolizumab 2 mg/kg every 3 weeks, and she achieved a partial response after the 4th cycle, consistent with the modified severity assessment tool (mSWAT) 1, which she is still maintaining after 10 cycles. No grade ≥3 adverse events were recorded. We conclude that pembrolizumab can induce extremely rapid responses in MF, with very low toxicity.

The pivotal role of cytotoxic NK cells in mediating the therapeutic effect of anti-CD47 therapy in mycosis fungoides

CD47 is frequently overexpressed on tumor cells and is an attractive therapeutic target. The mechanism by which anti-CD47 immunotherapy eliminates cutaneous lymphoma has not been explored. We utilized CRISPR/Cas-9 CD47 knock-out, depletion of NK cells, and mice genetically deficient in IFN-γ to elucidate the mechanism of anti-CD47 therapy in a murine model of cutaneous T cell lymphoma (CTCL). CD47 was found to be a crucial factor for tumor progression since CD47 KO CTCL exhibited a delay in tumor growth. The treatment of CD47 WT murine CTCL with anti-CD47 antibodies led to a significant reduction in tumor burden as early as four days after the first treatment and accompanied by an increased percentage of cytotoxic NK cells at the tumor site. The depletion of NK cells resulted in marked attenuation of the anti-tumor effect of anti-CD47. Notably, the treatment of CD47 WT tumors in IFN-γ KO mice with anti-CD47 antibodies was efficient, demonstrating that IFN-γ was not required to mediate anti-CD47 therapy. We were able to potentiate the therapeutic effect of anti-CD47 therapy by IFN-α. That combination resulted in an increased number of cytotoxic CD107a + IFN-γ-NK1.1 cells and intermediate CD62L + NKG2a-NK1.1. Correlative data from a clinical trial (clinicaltrials.gov, NCT02890368) in patients with CTCL utilizing SIRPαFc to block CD47 confirmed our in vivo observations.

Immune Check Point Inhibitors in Primary Cutaneous T-Cell Lymphomas: Biologic Rationale, Clinical Results and Future Perspectives

Primary cutaneous T-cell lymphomas (PCTCL) are the most common types of cutaneous lymphomas, with Mycosis fungoides as the most frequent subtype. Besides early stages which usually have a good prognosis, advanced stages remain a great therapeutic challenge with low survival rates. To date, none of the currently available therapeutic options have significantly improved the outcomes of advanced cutaneous lymphomas. Recent studies have demonstrated that immune-checkpoint molecules, such as PD-1 and CTLA-4, play part in the proliferation pathways of neoplastic T-cells, as well as in other tumors. Hence, the potential role of immune-checkpoint-inhibitors in treating cutaneous lymphomas has been investigated in the last years. Herein, we outline the current knowledge regarding the role of immune-checkpoint molecules in PCTCL, their signaling pathways, microenvironment and therapeutic inhibition rationale. Moreover, we review the published data on immunotherapies in PCTCL and summarize the currently ongoing clinical trials in this field.

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.

Mycosis fungoides development after combined immune checkpoint blockade therapy in a patient with malignant melanoma: a case report

Immune checkpoint blockade therapy can induce immune-related toxicity, but cutaneous lymphoma development has not been reported. A 56-year-old woman presented with two well-demarcated erythematous macules on the right sole and vitiligo on her extremities. Her facial melanoma had been treated with combination therapy (ipilimumab and pembrolizumab), followed by pembrolizumab monotherapy, a year prior. Microscopy revealed small-to-medium-sized lymphocytes permeating along with the basal epidermal layer. These were immuno-positive for CD2, CD3, and CD5, and showed complete CD7 loss; CD30, TCR-beta F1, and PD-1 were also detected. They exclusively expressed CD8, not CD4, and had a Ki-67 labeling index of 30-40%. Epstein-Barr virus in-situ hybridization was negative. Clonal T-cell receptor beta and gamma chain gene rearrangements were detected. Hence, the lesions were diagnosed as mycosis fungoides. This is the first report of mycosis fungoides development after anti-melanoma immunotherapy. The patient is currently on steroid ointments and phototherapy.

Patterns of Gene Expression in Cutaneous T-Cell Lymphoma: Systematic Review of Transcriptomic Studies in Mycosis Fungoides

Mycosis fungoides (MF) is the most prevalent type of skin lymphoma. In its early stages, it has a favorable prognosis. However, in its late stages, it is associated with an increased risk of mortality. This systematic review aimed to identify the transcriptomic changes involved in MF pathogenesis and progression. A literature search was conducted using the database PubMed, followed by the extraction of 2245 genes which were further filtered to 150 recurrent genes that appeared in two or more publications. Categorization of these genes identified activated pathways involved in pathways such as cell cycle and proliferation, chromosomal instability, and DNA repair. We identified 15 genes implicated in MF progression, which were involved in cell proliferation, immune checkpoints, resistance to apoptosis, and immune response. In highlighting the discrepancies in the way MF transcriptomic data is obtained, further research can focus on not only unifying their approach but also focus on the 150 pertinent genes identified in this review.

Cell signaling in cutaneous T-cell lymphoma microenvironment: promising targets for molecular-specific treatment

Cutaneous T-cell lymphomas (CTCL) result from the infiltration and proliferation of a population of T cells in the skin, inducing changes in the activity of both T cells and surrounding skin cells. In the CTCL microenvironment, cell interactions mediated by cell signaling pathways are altered. Defining changes in cell signaling enables to understand T-cell deregulations in the CTCL microenvironment and thus the progression of the disease. Moreover, characterizing signaling networks activated in CTCL stages can lead to consider new molecular biomarkers and therapeutic targets. Focusing on mycosis fungoides (MF), the most frequent variant of CTCL, and Sézary syndrome (SS), its leukemic variant, this review highlights recent molecular and genetic findings revealing modifications of key signaling pathways involved in (1) cell proliferation, cell growth, and cell survival such as MAP kinases and PI3K/Akt; (2) immune responses derived from TCR, TLR, JAK/STAT, and NF-kB; and (3) changes in tissue conditions such as extracellular matrix remodeling, hypoxia, and angiogenesis. Alterations in these signaling networks promote malignant T-cell proliferation and survival, T-cell migration, inflammation, and suppression of immune regulation of malignant T cells, making a skin microenvironment that allows disease progression. Targeting key proteins of these signaling pathways, using molecules already available and used in research, in clinical trials, and with other disease indications, can open the way to different therapeutic options in CTCL treatment.

Engaging the Innate and Adaptive Antitumor Immune Response in Lymphoma

Immunotherapy has emerged as a powerful therapeutic strategy for many malignancies, including lymphoma. As in solid tumors, early clinical trials have revealed that immunotherapy is not equally efficacious across all lymphoma subtypes. For example, immune checkpoint inhibition has a higher overall response rate and leads to more durable outcomes in Hodgkin lymphomas compared to non-Hodgkin lymphomas. These observations, combined with a growing understanding of tumor biology, have implicated the tumor microenvironment as a major determinant of treatment response and prognosis. Interactions between lymphoma cells and their microenvironment facilitate several mechanisms that impair the antitumor immune response, including loss of major histocompatibility complexes, expression of immunosuppressive ligands, secretion of immunosuppressive cytokines, and the recruitment, expansion, and skewing of suppressive cell populations. Accordingly, treatments to overcome these barriers are being rapidly developed and translated into clinical trials. This review will discuss the mechanisms of immune evasion, current avenues for optimizing the antitumor immune response, clinical successes and failures of lymphoma immunotherapy, and outstanding hurdles that remain to be addressed.

The immunopathogenesis and immunotherapy of cutaneous T cell lymphoma: Pathways and targets for immune restoration and tumor eradication

Cutaneous T cell lymphomas (CTCLs) are malignancies of skin-trafficking T cells. Patients with advanced CTCL manifest immune dysfunction that predisposes to infection and suppresses the antitumor immune response. Therapies that stimulate immunity have produced superior progression-free survival compared with conventional chemotherapy, reinforcing the importance of addressing the immune deficient state in the care of patients with CTCL. Recent research has better defined the pathogenesis of these immune deficits, explaining the mechanisms of disease progression and revealing potential therapeutic targets. The features of the malignant cell in mycosis fungoides and Sézary syndrome are now significantly better understood, including the T helper 2 cell phenotype, regulatory T cell cytokine production, immune checkpoint molecule expression, chemokine receptors, and interactions with the microenvironment. The updated model of CTCL immunopathogenesis provides understanding into clinical progression and therapeutic response.

PD-L1 expression in peripheral T-cell lymphomas is not related to either PD-L1 gene amplification or rearrangements

Nodal peripheral T-cell lymphomas (n-PTCL) are aggressive lymphomas with no specific treatment. Programmed death 1 (PD-1) inhibits T-cell activation and proliferation, and the expression of its ligand PD-L1 has been associated with worse prognosis in some tumors. We performed immunohistochemistry for PD-1, p-STAT3, and PD-L1 (Clones SP142/263/22C3/28.8) and FISH studies for PD-L1/2 genes in chromosome 9p in a series of 168 formalin-fixed, paraffin-embedded n-PTCL samples. PD-L1 (clone 263) was the most frequently detected in both tumor cells (especially in the ALCL subgroup) and the microenvironment (especially in the AITL subgroup). In five ALCL cases, 3-4 copies of the two loci of chromosome 9 were found, suggestive of polyploidy. PD-L1 correlated with p-STAT3 on tumor cells. PD-1 expression in tumor cells was related to expression of PD-L1 in microenvironment. The expression of PD-L1 on tumor cells or microenvironment suggests that some n-PTCL cases might benefit from immune check-point modulation therapy.

Clinicopathological and prognostic significance of programmed death ligant-1 expression in gastric cancer: a meta-analysis

Background

Gastric cancer (GC) is a common malignant tumor with a high incidence in China. The use of immune checkpoint inhibitors has become the focus of tumor immunotherapy in recent years. This study was to investigate the clinicopathological and prognostic significance of programmed death ligant-1 (PD-L1) expression in GC.

Methods

We searched the PubMed, ScienceNet, EMbase, CNKI, and Wanfang databases for retrospective cohort studies on the clinicopathology and prognosis of PD-L1 expression in GC published between January 2010 and April 2020. The literature was first selected to extract data according to the inclusion and exclusion criteria, then a meta-analysis performed using Stata15.0 software. Publication bias and sensitivity analysis were carried out for the included studies.

Results

A total of 3,218 patients in 15 studies were included in the meta-analysis. The positive expression of PD-L1 was related to a decrease in the 3-year survival rate (HR =1.32, 95% CI: 1.02-1.49, P=0.028) and 5-year survival rate (HR =1.39, 95% CI: 1.14-1.69, P=0.001). The difference in PD-L1 expression was related to lymph node metastasis (OR =1.73, 95% CI: 1.18-2.54, P<0.001), but not to tumor stage (OR =1.28, 95% CI: 0.81-2.02, P=0.292).

Conclusions

The results show that PD-L1 is related to the prognosis of GC. Its high expression decreases the 3- and 5-year survival rates and promotes lymph node metastasis, but does not reflect tumor stage. The results may provide a theoretical basis for the choice of clinical immunotherapy in GC patients.

Phenotypical Markers, Molecular Mutations, and Immune Microenvironment as Targets for New Treatments in Patients with Mycosis Fungoides and/or Sézary Syndrome

Primary cutaneous lymphomas encompass a wide spectrum of rare lymphoproliferative disorders originating in the skin, among which, mycosis fungoides (MF) is the most common subtype. The treatment of this disease is based on skin-directed therapies eventually in association with biologic response modifiers in the early phases, whereas in patients with the advanced stages, several therapeutic strategies can be used including mono and/or polychemotherapy and bone marrow transplantation. In recent years, the identification of specific markers (phenotypical, immunological, and molecular) has led to the development of several studies (including two randomized phase III trials). The results of these studies are modifying our therapeutic strategy toward a personalized treatment approach in which the clinical characteristics of the patients and tumor-node-metastasis-blood stage are considered together with the expression of specific markers (i.e., a CD30-positive expression for the use of brentuximab vedotin). This review will provide a comprehensive scenario of the main phenotypical, molecular, and immunological markers related to MF pathogenesis and disease evolution, which could represent the target for the development of innovative effective treatments in this disease.

Current Clinical Applications and Future Perspectives of Immune Checkpoint Inhibitors in Non-Hodgkin Lymphoma

Cancer cells escape immune recognition by exploiting the programmed cell-death protein 1 (PD-1)/programmed cell-death 1 ligand 1 (PD-L1) immune checkpoint axis. Immune checkpoint inhibitors that target PD-1/PD-L1 unleash the properties of effector T cells that are licensed to kill cancer cells. Immune checkpoint blockade has dramatically changed the treatment landscape of many cancers. Following the cancer paradigm, preliminary results of clinical trials in lymphoma have demonstrated that immune checkpoint inhibitors induce remarkable responses in specific subtypes, most notably classical Hodgkin lymphoma and primary mediastinal B-cell lymphoma, while in other subtypes, the results vary considerably, from promising to disappointing. Lymphomas that respond to immune checkpoint inhibitors tend to exhibit tumor cells that reside in a T-cell-rich immune microenvironment and display constitutive transcriptional upregulation of genes that facilitate innate immune resistance, such as structural variations of the PD-L1 locus, collectively referred to as T-cell-inflamed lymphomas, while those lacking such characteristics are referred to as noninflamed lymphomas. This distinction is not necessarily a sine qua non of response to immune checkpoint inhibitors, but rather a framework to move the field forward with a more rational approach. In this article, we provide insights on our current understanding of the biological mechanisms of immune checkpoint evasion in specific subtypes of B-cell and T-cell non-Hodgkin lymphomas and summarize the clinical experience of using inhibitors that target immune checkpoints in these subtypes. We also discuss the phenomenon of hyperprogression in T-cell lymphomas, related to the use of such inhibitors when T cells themselves are the target cells, and consider future approaches to refine clinical trials with immune checkpoint inhibitors in non-Hodgkin lymphomas.

Primary Cutaneous CD4+ Small/Medium T-Cell Lymphoproliferative Disorders: A Clinical, Pathologic, and Molecular Study of 60 Cases Presenting With a Single Lesion: A Multicenter Study of the French Cutaneous Lymphoma Study Group

Primary cutaneous CD4 small/medium T-cell lymphoproliferative disorder (PCSMLPD) is a recently recognized entity in the 2017 World Health Organization (WHO) classification. It belongs to the T-follicular helper (TFH) lymphoproliferations. The clinical, pathologic, and molecular features of this localized disease are underresearched. We conducted a retrospective multicentric study of 60 patients with a PCSMLPD that presented as a single cutaneous lesion. Clinical, pathologic, and targeted molecular analyses were performed. PCSMLPD presented mostly as a nodule (45%), located on the head and neck area (50%) in adults (mean age: 59 y [43.3 to 75.2]). All patients had an indolent disease course, either at initial staging or during follow-up (mean: 16.6 mo [1.3 to 31.9]). Spontaneous regression was reported in 31.9% of cases. The infiltrates were most often nodular and/or diffuse, expanding in the whole dermis (78%, Pattern 1), rather than subepidermal band-like in the superficial dermis (22%, Pattern 2). Epidermotropism, folliculotropism, and capillary hyperplasia were common. The expression of TFH lineage markers was more extensive in lesions with Pattern 2, but a substantial B-cell infiltrate was seen in both types of lesions. A clonal rearrangement of the TCR genes was identified in 68% of cases. One sample of the 13 tested revealed a mutation in the DNMT3A gene among the 9 genes studied (TET2, DNMT3A, IDH2, RHOA, SETD2, PLCG1, STAT3, STAT5B, and CD28). PCSMLPD follows a benign clinical course and can spontaneously regress after biopsy. Although PCSMLPD expresses TFH lineage markers, mutations usually found in angioimmunoblastic T-cell lymphomas are uncommon.

Enhancing antitumor immunity through checkpoint blockade as a therapeutic strategy in T-cell lymphomas

The majority of historical therapies for managing T-cell lymphomas (TCLs) have consisted of T-cell-depleting strategies. Unfortunately, these forms of therapies can hamper the ability to mount effective antitumor immune responses. Recently, the use of checkpoint inhibitors has revolutionized the therapy of solid and hematologic malignancies. The development of immunotherapies for the management of TCL has lagged behind other malignancies given 2 central reasons: (1) the competing balance of depleting malignant T cells while simultaneously enhancing an antitumor T-cell response and (2) concern for tumor hyperprogression by blocking inhibitory signals on the surface of the malignant T cell, thereby leading to further proliferation of the malignant cells. These challenges were highlighted with the discovery that programmed cell death protein 1 (PD-1) functions paradoxically as a haploinsufficient tumor suppressor in preclinical TCL models. In contrast, some preclinical and clinical evidence suggests that PD-1/programmed death ligand 1 may become an important therapeutic tool in the management of patients with TCL. Improved understanding of the immune landscape of TCL is necessary in order to identify subsets of patients most likely to benefit from checkpoint-inhibitor therapy. With increased preclinical research focus on the tumor microenvironment, substantial strides are being made in understanding how to harness the power of the immune system to treat TCLs. In this review, designed to be a "call to action," we discuss the challenges and opportunities of using immune-modulating therapies, with a focus on checkpoint inhibitors, for the treatment of patients with TCL.

Enhanced PD-L1 expression on tumor cells in primary cutaneous large T-cell lymphoma with CD30 expression as classic Hodgkin lymphoma mimics: A report of lymph node lesions of two cases

Neoplastic PD-L1 (nPD-L1, clone SP142) expression remains unclear in cutaneous T-cell lymphoma (CTCL), although it is well-documented in classic Hodgkin lymphoma (CHL). Here, we report two cases of primary cutaneous large T-cell lymphoma (PCLTCL) with CD30 expression that developed secondary nodal lesions morphologically mimicking CHL, and describe their PD-L1 expression. Our two cases (52- and 60-year-old males) had long-standing clinical courses of CTCL. Their PCLTCL with CD30 expression developed nodal lesions, having a nodular growth pattern containing scattered CD30+ Hodgkin and Reed-Sternberg-like and/or lacunar cells that expressed CD15 but did not harbor Epstein-Barr virus. Their differential diagnosis from CHL was challenging. A diagnosis of PCLTCL with secondary nodal involvement featuring CHL mimicry was based on comparison of the primary and secondary lesions. In one case, shared expression of the same T-cell antigen was revealed by immunohistochemistry, and in the other, identical clonal TCR rearrangement was demonstrated by polymerase chain reaction (PCR). Interestingly, nPD-L1 was expressed on more than 50% of the tumor cells in the secondary nodal lesions, but on very few in the primary cutaneous lesions, in both cases. This is the first report of nPD-L1 expression greatly increasing with PCLTCL tumor progression to nodal involvement.

Immune Checkpoint Molecules in Primary Diffuse Large B-Cell Lymphoma of the Central Nervous System

Introduction:

Primary Diffuse Large B Cell Lymphoma of CNS (PCNSL) is a rare variant of Diffuse Large B Cell Lymphoma (DLBCL) and presents with an aggressive clinical course and usually resistant to commonly used therapy regimens. Recently, role of immune checkpoint molecules including PD-1 and PD-L1 confirmed in some solid tumors and lymphoma resulting tumor cells escape the immune system and help to survive and to spread. Inhibitors of PD-1 and PD-L1 have shown lasting responses in several solid and some hematological tumors, while limited studies evaluate checkpoint molecules on PCNSL.

Method:

In this study, we investigated PD-1 and PD-L1 expression by immunostaining on 71 patients with PCNSL and correlation with demographic data, location of the tumor, proliferation rate, cell of origin, and CD8 positive T cell infiltration in tumor microenvironment.

Results:

16 from71 showed PD-1 expression, while PD-L1 expression were 42/71. No association was determined between PD-1/PD-L1 expression and gender, cell of origin, and proliferation rate, but a highly significant difference was determined between the infiltration of CD8 positive T cells in two groups of PD-1/PD-L1 positive and negative.

Conclusion:

This study revealed expression of check point molecules in remarkable number of PCNSL which may open new therapeutic recommendations in this aggressive lymphoma type.

Staphylococcus aureus alpha-toxin inhibits CD8+ T cell-mediated killing of cancer cells in cutaneous T-cell lymphoma

Staphylococcus aureus and its toxins have been linked to disease progression and mortality in advanced stages of cutaneous T-cell lymphoma (CTCL). CD8+ T cells play a crucial role in anti-cancer responses and high CD8+ T cell numbers in tumor lesions are associated with a favorable prognosis in CTCL. Here, we show that CD8+ T cells from both healthy donors and Sézary syndrome patients are highly susceptible to cell death induced by Staphylococcal alpha-toxin, whereas malignant T cells are not. Importantly, alpha-toxin almost completely blocks cytotoxic killing of CTCL tumor cells by peptide-specific CD8+ T cells, leading to their escape from induced cell death and continued proliferation. These findings suggest that alpha-toxin may favor the persistence of malignant CTCL cells in vivo by inhibiting CD8+ T cell cytotoxicity. Thus, we propose a novel mechanism by which colonization with Staphylococcus aureus may contribute to cancer immune evasion and disease progression in CTCL.

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.

Blockade of programmed cell death protein 1 (PD-1) in Sézary syndrome reduces Th2 phenotype of non-tumoral T lymphocytes but may enhance tumor proliferation

Sézary syndrome (SS) is an aggressive leukemic variant of cutaneous T-cell lymphoma (L-CTCL) that arises from malignant clonally derived skin-homing CD4⁺ T cells. Based on advancements in our understanding of the mechanisms underlying L-CTCL, boosting the suppressed immune response emerges as a promising strategy in SS management. Immune checkpoint inhibitory molecules have already demonstrated efficacy in a wide spectrum of malignancies. Currently, agents targeting the programmed death-1 (PD-1) axis are under evaluation in L-CTCL. Here we investigated the expression of PD-1 and its ligands, PD-L1 and PD-L2 in blood and skin from patients with L-CTCL. We demonstrate that PD-1 expression is markedly increased on tumor T cells compared to non-tumor CD4⁺ T cells from SS patients and to CD4⁺ cells from healthy individuals. In contrast, PD-L1 shows decreased expression on tumor T cells, while PD-L2 expression is low without significant differences between these groups. Functional PD-1 blockade in vitro resulted in reduced Th2 phenotype of non-tumor T lymphocytes, but enhanced the proliferation of tumor T cells from SS patients. Our study sheds some light on the PD-1 axis in both peripheral blood and skin compartments in SS patients, which may be relevant for the treatment of L-CTCL with immune checkpoint inhibitor.

Progression of mycosis fungoides occurs through divergence of tumor immunophenotype by differential expression of HLA-DR

Immunotherapy is a valuable treatment for many cancer patients, and there is considerable interest in understanding the mechanisms of immune evasion to guide appropriate management. Mycosis fungoides (MF) is a malignant disorder of skin-homing CD4⁺ T cells, and it exhibits a highly variable clinical course during which the tumor-specific immune response may be an important determinant. An unusual feature of MF is that tumor-infiltrating lymphocytes (TILs) must attempt to control a malignant cell from within their own lineage. We obtained skin biopsies and blood from 43 patients with CD4⁺ MF and undertook a detailed phenotypic and functional analysis of CD4⁺ and CD8⁺ T cells. Clonotypic TCRBV staining allowed delineation of malignant and reactive CD4⁺ subsets. CD4⁺ and CD8⁺ TILs displayed a comparable "exhausted" phenotype that was characterized by expression of PD-1 and TIGIT but retained cytotoxic activity and production of interferon-γ and interleukin-17 in early-stage disease. In contrast, tumor cells were much more heterogeneous and were divided into 3 discrete subsets based on differential expression of HLA-DR: "cold" (DR^-), "exhausted" (DR⁺ PD-1⁺), and "evasive" (DR⁺⁺ PD-L1⁺) phenotypes. Disease progression was associated with increasing divergence of the tumor phenotype away from that of TILs and reduced functional activity within TILs. These observations reveal that the phenotype and function of TIL populations are constrained at all stages of disease, whereas the tumor evolves discrete phenotypic profiles of escape during clinical progression. The findings should help to direct appropriate immunotherapeutic interventions for individual patients.

Pembrolizumab in Relapsed and Refractory Mycosis Fungoides and Sézary Syndrome: A Multicenter Phase II Study

PURPOSE

To assess the efficacy of pembrolizumab in patients with advanced relapsed or refractory mycosis fungoides (MF) or Sézary syndrome (SS).

PATIENTS AND METHODS

CITN-10 is a single-arm, multicenter phase II trial of 24 patients with advanced MF or SS. Patients were treated with pembrolizumab 2 mg/kg every 3 weeks for up to 24 months. The primary end point was overall response rate by consensus global response criteria.

RESULTS

Patients had advanced-stage disease (23 of 24 with stage IIB to IV MF/SS) and were heavily pretreated with a median of four prior systemic therapies. The overall response rate was 38% with two complete responses and seven partial responses. Of the nine responding patients, six had 90% or more improvement in skin disease by modified Severity Weighted Assessment Tool, and eight had ongoing responses at last follow-up. The median duration of response was not reached, with a median response follow-up time of 58 weeks. Immune-related adverse events led to treatment discontinuation in four patients. A transient worsening of erythroderma and pruritus occurred in 53% of patients with SS. This cutaneous flare reaction did not result in treatment discontinuation for any patient. The flare reaction correlated with high PD-1 expression on Sézary cells but did not associate with subsequent clinical responses or lack of response. Treatment responses did not correlate with expression of PD-L1, total mutation burden, or an interferon-γ gene expression signature.

CONCLUSION

Pembrolizumab demonstrated significant antitumor activity with durable responses and a favorable safety profile in patients with advanced MF/SS.

Novel and Future Therapeutic Drugs for Advanced Mycosis Fungoides and Sézary Syndrome

Mycosis fungoides (MF) and Sézary syndrome (SS) are the most common subtypes of cutaneous T-cell lymphoma. The majority of MF cases present with only patches and plaques and the lesions are usually limited to the skin. On the other hand, in some cases, patients show skin tumors or erythroderma followed by lymph node involvement and rarely visceral organ involvement. SS is a rare, aggressive cutaneous T-cell lymphoma marked by exfoliative erythroderma, lymphadenopathy, and leukemic blood involvement. Because patients with relapsed or refractory MF/SS display a poor prognosis and the current treatment options are characterized by high rates of relapse, there is unmet need for the efficient treatment. This review provides a discussion of the recent and future promising therapeutic approaches in the management of advanced MF/SS. These include mogamulizumab, brentuximab vedotin, alemtuzumab, immune checkpoint inhibitors, IPH4102 (anti-KIR3DL2 antibody), histone deacetylase inhibitors (vorinostat, romidepsin, panobinostat, belinostat, and resminostat), pralatrexate, forodesine, denileukin diftitox, duvelisib, lenalidomide, and everolimus.

PD-1 Tumor Suppressor Signaling in T Cell Lymphomas

The inhibitory receptor PD-1 is critical to balancing antigen-induced T cell activation; its inhibition is currently being explored to enhance antitumor T cell immunity with certain successful outcomes. However, PD-1 has also emerged as a central tumor suppressor in T cell lymphomas, where the tumor cell originates from a T cell itself. These aggressive cancers are frequently characterized by oncogenic mutations in T cell receptor (TCR) signaling pathways. PD-1 activity within malignant T cells can negatively regulate the PI3K/AKT and PKCθ/NF-κB tumor survival pathways and PD-1 is frequently inactivated in this human malignancy. This review summarizes current insights into oncogenic T cell signaling, discusses tumor-suppressive functions and mechanisms of PD-1 in T cell lymphomagenesis, and addresses potential unwanted effects caused by PD-1 checkpoint inhibition.

Antibody-Based Therapies for Cutaneous T-Cell Lymphoma

Cutaneous T-cell lymphomas (CTCLs) are a group of non-Hodgkin's lymphomas that present in the skin. In early-stage disease, the course is generally chronic and indolent; however, in advanced stages of disease, therapies rarely provide long-lasting responses, and the only potential curative therapy is allogeneic hematopoietic stem-cell transplantation. This has led to the search for novel targeted therapies to better treat more advanced stages of CTCLs that cannot be controlled by typical treatment regimens. One area of advancement has been the development of antibodies specifically targeted to cell types that are known to be involved in CTCL. At present, brentuximab vedotin, an antibody-drug conjugate composed of an anti-cluster of differentiation (CD)-30 antibody covalently linked to monomethyl auristatin E, is approved for the treatment of CD30+ lymphoproliferative disorders [lymphomatoid papulosis (LyP) and primary cutaneous-anaplastic large-cell lymphoma (pc-ALCL)] as well as transformed CD30+ mycosis fungoides (MF). Additionally, mogamulizumab, an anti-chemokine receptor 4 (CCR4) monoclonal antibody, is approved for patients with MF or Sézary syndrome (SS) for whom one prior systemic therapy has failed. Trials are underway looking into the use of immune checkpoint inhibitors in the treatment of CTCLs. As we continue to research CTCL, and as antibody-based therapies continue to advance, more antibody-specific targeted therapy could provide alternative treatment regimens for patients with advanced CTCL.

Programmed cell death protein receptor and ligands in haematological malignancies - Current status

The checkpoint inhibitors have been continuously present in haematology for 20 years. From the first description, several of them were enrolled to the list of the oncological drugs. The research on nivolumab, avelumab, durvolumab is still in progress. In the treatment of some diseases, for instance, Hodgkin lymphoma, the programmed death cell pathway has already an important role. During the last years, the guidelines were enriched by using these drugs, both in solid and haematological malignancies. In this review, we present a history of discovery, research and clinical use of this new class of drugs potentially providing a significant change in curability rates of some haematological malignancies.

Clinical and histopathological significance of PD-1 expression in cutaneous lesions of adult T-cell leukemia-lymphoma

BACKGROUND

Adult T-cell leukemia-lymphoma (ATL) is a mature T-cell malignancy caused by human T-cell leukemia virus type I infection and is known to exhibit cutaneous involvement in 50% or more patients. Few studies have evaluated the clinicopathological significance of programmed death-1 (PD-1) expression in the cutaneous lesions of ATL.

METHODS

Skin biopsy specimens from 29 ATL patients with cutaneous lesions were evaluated regarding the clinicopathological feature, survival outcome, and PD-1 expression level on infilitrated CD3+CD4 + CD25+ cells. The optimal cut-off point of PD-1 expression for clinicopathological feature and outcome was determined as the value of the maximum Youden index by receiver operating characteristic (ROC) analysis.

RESULTS

PD-1 was expressed broadly from zero to 90% on the skin biopsy specimens of the 29 patints, with the median value of 50%. The PD-1-expression level was significantly higher in the poorer-prognosis eruption group (nodulotumoral, erythrodermic and purpuric types) (P = 0.003), in the poorer histopathological infiltration patterns (diffuse and nodular) (P = 0.007), and in the poorer infiltrating cell-size group (large-sized cells) (P = 0.017) than in the corresponding group. ROC curve analyses showed that the optimal cut-off value for PD-1-expression level to predict the poorer-prognosis eruption, the poorer- histopathological infiltration pattern, the poorer infiltration cell size, and the poorer outcome (death) was 60%, 50%, 50%, and 80%, respectively. Patients with high PD-1 expression had a shorter median survival time than those with low PD-1 expression (18.2 months vs. 26.0 months), but the difference was not statistically significant.

CONCLUSIONS

ATL patients with cutaneous lesions in which PD-1 were highly expressed have more advanced dermatological and histopathological patterns and possibly worse survival than those with low PD-1 expression on cutaneous lesions. Further large-scale studies are warranted to verify these findings.

Current Immunotherapeutic Approaches in T Cell Non-Hodgkin Lymphomas

T cell non-Hodgkin lymphoma (T-NHL) is a rare and heterogeneous group of neoplasms of the lymphoid system. With the exception of a few relatively indolent entities, T-NHL is typically aggressive, treatment resistant, and associated with poor prognosis. Relatively few options with proven clinical benefit are available for patients with relapsed or refractory disease. Immunotherapy has emerged as a promising treatment for the management of patients with hematological malignancies. The identification of tumor antigens has provided a large number of potential targets. Therefore, several monoclonal antibodies (alemtuzumab, SGN-30, brentuximab vedotin, and mogamulizumab), directed against tumor antigens, have been investigated in different subtypes of T-NHL. In addition to targeting antigens involved in cancer cell physiology, antibodies can stimulate immune effector functions or counteract immunosuppressive mechanisms. Chimeric antigen receptor (CAR)-T cells directed against CD30 and immune checkpoint inhibitors are currently being investigated in clinical trials. In this review, we summarize the currently available clinical evidence for immunotherapy in T-NHL, focusing on the results of clinical trials using first generation monoclonal antibodies, new immunotherapeutic agents, immune checkpoint inhibitors, and CAR-T cell therapies.

Primary T Cells from Cutaneous T-cell Lymphoma Skin Explants Display an Exhausted Immune Checkpoint Profile

Cutaneous T-cell lymphoma (CTCL) develops from clonally expanded CD4+ T cells in a background of chronic inflammation. Although dendritic cells (DCs) stimulate T cells and are present in skin, cutaneous T cells in CTCL do not respond with effective antitumor immunity. We evaluated primary T-cell and DC émigrés from epidermal and dermal explant cultures of skin biopsies from CTCL patients (n = 37) and healthy donors (n = 5). Compared with healthy skin, CD4+ CTCL populations contained more T cells expressing PD-1, CTLA-4, and LAG-3. CD8+ CTCL populations contained more T cells expressing CTLA-4 and LAG-3. CTCL populations also contained more T cells expressing the inducible T-cell costimulator (ICOS), a marker of T-cell activation. DC émigrés from healthy or CTCL skin biopsies expressed PD-L1, indicating that maturation during migration resulted in PD-L1 expression irrespective of disease. Most T cells did not express PD-L1. Using skin samples from 49 additional CTCL patients for an unsupervised analysis of genome-wide mRNA expression profiles corroborated that advanced T3/T4-stage samples expressed more checkpoint inhibition mRNA compared with T1/T2 stage patients or healthy controls. Exhaustion of activated T cells is therefore a hallmark of both CD4+ and CD8+ T cells isolated from the lesional skin of patients with CTCL, with increasing expression as the disease progresses. These results justify identification of antigens driving T-cell exhaustion and the evaluation of immune checkpoint inhibition to reverse T-cell exhaustion earlier in the treatment of CTCL. Cancer Immunol Res; 6(8); 900-9. ©2018 AACR.