Long-term efficacy and safety of alemtuzumab in advanced primary cutaneous T-cell lymphomas

Pathophysiology of cutaneous T-cell lymphomas: Perspective from a French referral centre

Cutaneous T-cell lymphomas (CTCL) are a diverse group of malignant blood disorders characterized by initial skin infiltration, and sometimes, tumor spreading to lymph nodes, blood, and viscera. Mycosis fungoides is the most common form. Sézary syndrome is a distinctive form of CTCL marked by a significant presence of circulating tumor cells in peripheral blood. These diseases are characterized by the plasticity and heterogeneity of the tumor cells in the different tissue compartments, and a difficulty in identifying these tumor cells for diagnostic purposes and therapeutic monitoring. Progress has been made in the understanding of the pathophysiology of these diseases in recent years, and we provide here a review of these advancements.

MHC-I upregulation safeguards neoplastic T cells in the skin against NK cell-mediated eradication in mycosis fungoides

Cancer-associated immune dysfunction is a major challenge for effective therapies. The emergence of antibodies targeting tumor cell-surface antigens led to advancements in the treatment of hematopoietic malignancies, particularly blood cancers. Yet their impact is constrained against tumors of hematopoietic origin manifesting in the skin. In this study, we employ a clonality-supervised deep learning methodology to dissect key pathological features implicated in mycosis fungoides, the most common cutaneous T-cell lymphoma. Our investigations unveil the prominence of the IL-32β-major histocompatibility complex (MHC)-I axis as a critical determinant in tumor T-cell immune evasion within the skin microenvironment. In patients' skin, we find MHC-I to detrimentally impact the functionality of natural killer (NK) cells, diminishing antibody-dependent cellular cytotoxicity and promoting resistance of tumor skin T-cells to cell-surface targeting therapies. Through murine experiments in female mice, we demonstrate that disruption of the MHC-I interaction with NK cell inhibitory Ly49 receptors restores NK cell anti-tumor activity and targeted T-cell lymphoma elimination in vivo. These findings underscore the significance of attenuating the MHC-I-dependent immunosuppressive networks within skin tumors. Overall, our study introduces a strategy to reinvigorate NK cell-mediated anti-tumor responses to overcome treatment resistance to existing cell-surface targeted therapies for skin lymphoma.

What's New in Cutaneous T-Cell Lymphoma-Associated Pruritus

Cutaneous T-cell lymphomas are a heterogenous group of lymphomas that cause various skin manifestations. Severe pruritus occurs frequently in cutaneous T-cell lymphoma and negatively impacts patients' quality of life. The pathophysiology of cutaneous T-cell lymphoma-associated itch is complex and involves various immune cells, inflammatory cytokines, and neuroimmune interactions. Treating cutaneous T-cell lymphoma pruritus can be challenging, and there have been few randomized controlled studies evaluating the use of antipruritic treatments in these patients. Systemic therapies targeting the disease have also been shown to have some antipruritic effects. Furthermore, although biologic therapy has revolutionized the treatment of other pruritic skin conditions, the use of biologics in cutaneous T-cell lymphoma remains controversial.

Allogeneic transplantation and cellular therapies in cutaneous T-cell lymphoma

INTRODUCTION

Mycosis fungoides (MF) and Sezary syndrome (SS) are the most common types of cutaneous T-cell lymphoma. Although many available treatments offer temporary disease control, allogeneic hematopoietic stem cell transplant (allo-HSCT) is the only curative treatment option for advanced stage MF and SS. CAR T-cell therapy is a promising new avenue for treatment.

AREAS COVERED

In this review, we discuss the evidence supporting the use of allo-HSCT for the treatment of MF/SS, including disease status at the time of transplant, conditioning regimen, total body irradiation (TBI), and donor lymphocyte infusion (DLI). We also address the potential role for CAR T-cell therapy in CTCL.

EXPERT OPINION

Allo-HSCT is an effective treatment for patients with advanced MF and SS. However, significant research is required to determine optimal treatment protocols. Data support the use of reduced-intensity conditioning regimens and suggests that the use of TBI for debulking of skin disease may result in more durable remissions. Donor lymphocyte infusions (DLI) appear to be particularly effective in inducing complete remission in MF/SS patients with relapsed or residual disease. Challenges with CAR-T therapies in T-cell lymphoma include T-cell fratricide due to shared antigens on malignant and nonmalignant T-cells, penetrance into the skin compartment, and CAR-T cell persistence.

Early intervention of extracorporeal photopheresis for advancing/progressing cutaneous T-cell lymphoma

Patients with cutaneous T-cell lymphoma with progressive disease typically undergo a series of skin-directed and systemic therapy regimens during cycles of response and relapse. Extracorporeal photopheresis (ECP) is an effective and safe systemic treatment option, often reserved for later stages of disease and typically employed after failure of several other therapies. ECP has benefits in response rate, time to next treatment, and tolerability that may support its use earlier in the treatment cycle for advancing/progressing disease.

Histopathological Markers for Target Therapies in Primary Cutaneous Lymphomas

In recent years, targeted (biological) therapies have become available also for primary cutaneous T-cell lymphomas (PCTCLs) including anti-CD30 (brentuximab vedotin) in mycosis fungoides, primary cutaneous anaplastic large T-cell lymphoma, lymphomatoid papulosis; anti-CCR4 (mogamulizumab) in Sezary syndrome; anti-CD123 (tagraxofusp) in blastic plasmocytoid cell neoplasm. Moreover, anti-PD1 (nivolumab), anti-PDL1 (pembrolizumab, atezolizumab), anti-CD52 (alemtuzumab), anti-KIR3DL2-CD158k (lacutamab), and anti-CD70 (cusatuzumab) have been tested or are under investigations in phase II trials. The expression of these epitopes on neoplastic cells in skin biopsies or blood samples plays a central role in the management of PCTCL patients. This narrative review aims to provide readers with an update on the latest advances in the newest therapeutic options for PCTCLs.

Advancements in the treatment of mycosis fungoides and Sézary syndrome: monoclonal antibodies, immunotherapies, and Janus kinase inhibitors

Mycosis fungoides (MF) and Sézary syndrome (SS) are forms of cutaneous T cell lymphoma (CTCL) that pose significant challenges in their clinical management, particularly in refractory and advanced-stage disease. With the emergence of novel therapeutic modalities however, there are increasing opportunities to exploit the current understanding of pathophysiologic mechanisms of MF/SS for treatment. This review summarizes recent advances in the treatment of MF/SS, with a focus on monoclonal antibodies, immunotherapies, and Janus kinase (JAK) inhibitors, including ongoing clinical trials.

Advances in Immunotherapy for the Treatment of Cutaneous T-Cell Lymphoma

Cutaneous T-Cell Lymphoma (CTCL) is a heterogenous disease that consists of distinct clinicopathologic entities and presentations requiring a unique and expert approach to management. The most common subtype is mycosis fungoides, in which local disease has an excellent prognosis and is often managed with topical therapy alone. More extensive cutaneous involvement as well as involvement of lymph nodes and the peripheral blood (Sezary syndrome) require systemic therapies. Recent years have brought an expansion of therapeutic options, specifically with immune-based approaches that were developed using the knowledge gained regarding the biology and molecular pathology of CTCL. Previous systemic therapies such as retinoids, histone deacetylase inhibitors, and chemotherapeutic agents come with significant toxicity and only short-term response. Newer agents such as mogamulizumab and brentuximab vedotin use a targeted immune-based approach leading to longer periods of response with less systemic toxicity. While still in its infancy, the use of immune checkpoint inhibitors such as nivolumab and pembrolizumab appears promising, and while their current clinical application is limited, early data suggest possible future areas for research of immune manipulation to treat CTCL. Herein, we review these novel immune-based treatment strategies, their superiority over prior systemic options, and the ongoing need for further research and clinical trial enrollment.

Education and Empowering Special Forces to Eradicate Secret Defectors: Immune System-Based Treatment Approaches for Mature T- and NK-Cell Malignancies

Mature T- and NK-cell leukemia/lymphoma (MTCL/L) constitute a heterogeneous group of, currently, 30 distinct neoplastic entities that are overall rare, and all present with a challenging molecular markup. Thus, so far, the use of first-line cancer treatment modalities, including chemotherapies, achieve only limited clinical responses associated with discouraging prognoses. Recently, cancer immunotherapy has evolved rapidly, allowing us to help patients with, e.g., solid tumors and also relapsed/refractory B-cell malignancies to achieve durable clinical responses. In this review, we systematically unveiled the distinct immunotherapeutic approaches available, emphasizing the special impediments faced when trying to employ immune system defense mechanisms to target 'one of their own-gone mad'. We summarized the preclinical and clinical efforts made to employ the various platforms of cancer immunotherapies including antibody-drug conjugates, monoclonal as well as bispecific antibodies, immune-checkpoint blockades, and CAR T cell therapies. We emphasized the challenges to, but also the goals of, what needs to be done to achieve similar successes as seen for B-cell entities.

Single-cell analyses reveal novel molecular signatures and pathogenesis in cutaneous T cell lymphoma

Sézary syndrome (SS) is a rare and aggressive type of cutaneous T cell lymphoma (CTCL) with a poor prognosis. Intra-tumoral heterogeneity caused by different disease compartments (e.g., skin, blood) and poor understanding of the pathogenesis has created obstacles to the precise diagnosis and targeted treatment of the disease. Here we performed a comprehensive analysis by integrating single-cell transcriptomic data of 40,333 peripheral blood mononuclear cells (PBMCs) and 41,580 skin cells, as well as single-cell chromatin accessibility data of 11,058 PBMCs from an SS patient and matched healthy controls (HCs). Validation and functional investigation were carried out in an independent cohort consisting of SS patients, mycosis fungoides (MF) patients, psoriatic erythroderma patients, and HCs, as well as multiple cell lines. The analysis revealed that skin-derived Sézary cells (SCs) had a shifting trend to more advanced mature phenotypes compared to blood-derived SCs. A series of specific marker genes (TOX, DNM3, KLHL42, PGM2L1, and SESN3) shared in blood- and skin-derived SCs were identified, facilitating the diagnosis and prognosis of MF/SS. Moreover, luciferase reporter assays and gene knockdown assays were used to verify that KLHL42 was transcriptionally activated by GATA3 in SS. Functional assays indicated that KLHL42 silencing significantly inhibited aggressive CTCL cell proliferation and promoted its apoptosis. Therefore, targeting inhibition KLHL42 might serve as a promising therapeutic approach in CTCL.

Folliculotropic Mycosis Fungoides: Current Guidance and Experience from Clinical Practice

Introduction

Folliculotropic mycosis fungoides (FMF) is the most frequent variant of mycosis fungoides (MF), with clinical features which differ from the classic form. As for therapeutic options, the latest guidelines on MF agree on a stage-driven strategy, in consideration of clinical presentation, symptom burden and patient’s comorbidities.

Materials and Methods

A search on MEDLINE, PubMed, Scopus and Cochrane Library was conducted to gather the latest evidence on FMF clinical management. Manuscripts published in the last five years (January 2017–April 2022) were included. Our single-center experience was also described.

Results

A total of 15 articles were analyzed, with a total of 432 patients (disease stage from IA to IVA2). The most widely-used treatment was psoralen ultra-violet A (PUVA) in monotherapy or in association with other drugs. Oral retinoid-based therapy was also described as a therapeutic option alone or in combination. Other therapy reported were based on Brentuximab Vedotin, Mogamulizumab, Carmustine, topical steroids, tazarotene and excimer laser, interferon, nitrogen mustard, imiquimod, systemic chemotherapy, extracorporeal photopheresis and stem cell transplantation.

Discussion

FMF is characterized by specific clinical-pathologic features. Advanced forms assume characteristics more similar to classic MF (infiltrated plaques and nodules), whilst early stages can present in a wide range of clinical forms (acneiform lesions, follicular-like keratoses, erythematous patches). As for therapeutic options, in absence of specific guidelines, a high number of treatments are described in clinical practice, with variable results. Phototherapy in all its forms, especially as PUVA, appears to have the greatest initial therapeutic success. Retinoids, although widely used, appear to be poorly effective in monotherapy, particularly acitretin. Combination treatment with phototherapy seems to be advisable. Ionizing treatments, such as radiotherapy and TSEBT, appear effective, at least in the short term. Overall, an integrated approach is mandatory for the inconstant course of the disease and its multidisciplinary nature.

[Current therapeutic options in Mycosis fungoides and Sézary syndrome]

Driven by the approval of new targeted therapies, significant progress has been made in recent years in the clinical management of cutaneous T‑cell lymphomas. Although there are no curative treatment options for cutaneous T‑cell lymphomas, response rates are often encouraging, in particular when using combination therapies. The decision for the appropriate form of treatment depends on the specific diagnosis, disease stage, and the history of prior therapies. This article provides a comprehensive overview of current treatment options in mycosis fungoides and Sézary syndrome, based on the recently published, revised German S2k guidelines on cutaneous lymphomas (update 2021). In addition, we present promising, yet-to-be-approved therapies that at least in part can be already used off-label in clinical practice today.

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.

NCCN Guidelines Insights: Primary Cutaneous Lymphomas, Version 2.2020

Mycosis fungoides (MF) is the most common subtype of cutaneous T-cell lymphoma (CTCL), and Sézary syndrome (SS) is a rare erythrodermic and leukemic subtype of CTCL characterized by significant blood involvement. Although early-stage disease can be effectively treated predominantly with skin-directed therapies, systemic therapy is often necessary for the treatment of advanced-stage disease. Systemic therapy options have evolved in recent years with the approval of novel agents such as romidepsin, brentuximab vedotin, and mogamulizumab. These NCCN Guidelines Insights discuss the diagnosis and management of MF and SS (with a focus on systemic therapy).

Mycosis fungoides and Sézary syndrome: focus on the current treatment scenario

Cutaneous T-cell lymphomas are a heterogeneous group of lymphoproliferative disorders, characterized by infiltration of the skin by mature malignant T cells. Mycosis fungoides is the most common form of cutaneous T-cell lymphoma, accounting for more than 60% of cases. Mycosis fungoides in the early-stage is generally an indolent disease, progressing slowly from some patches or plaques to more widespread skin involvement. However, 20% to 25% of patients progress to advanced stages, with the development of skin tumors, extracutaneous spread and poor prognosis. Treatment modalities can be divided into two groups: skin-directed therapies and systemic therapies. Therapies targeting the skin include topical agents, phototherapy and radiotherapy. Systemic therapies include biological response modifiers, immunotherapies and chemotherapeutic agents. For early-stage mycosis fungoides, skin-directed therapies are preferred, to control the disease, improve symptoms and quality of life. When refractory or in advanced-stage disease, systemic treatment is necessary. In this article, the authors present a compilation of current treatment options for mycosis fungoides and Sézary syndrome.

Targeted Approaches to T-Cell Lymphoma

The T-cell lymphomas are a rare group of Non-Hodgkin's lymphomas derived from mature T-lymphocytes. They are divided broadly into the Peripheral T-cell lymphomas and the Cutaneous T-cell lymphomas. Clinical outcomes vary widely but are generally unsatisfactory with current treatments. The development of an understanding of the various critical pathways in T-cell lymphogenesis and subsequent identification of therapeutic targets has led to a rapid expansion of the previously underwhelming T-cell lymphoma armament. This review aims to provide an up-to-date overview of the current state of targeted therapies in the T-cell lymphomas, including novel antibody-based treatments, small molecule inhibitors and immune-based therapies.

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.

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.

Topical and Systemic Formulation Options for Cutaneous T Cell Lymphomas

Although various anti-cutaneous T-cell lymphoma (CTCL) therapies are available for clinical use, appropriate chemotherapy lines for the treatment of CTCLs have yet to be established. Therefore, to date, various clinical trials for the treatment of advanced CTCLs are ongoing. In this review, we evaluate the therapeutic options that are available in clinical practice for treatment of early- and advanced-stage CTCLs (targeted therapies, histone deacetylase (HDAC) inhibitors, retinoids, interferons, cytotoxic drugs, etc.). We also examine clinical trials of novel regimens for the treatment of CTCLs.

Outlines of the Japanese guidelines for the management of primary cutaneous lymphomas 2020

Since the publication of the Japanese "Guidelines for the management of cutaneous lymphomas" in 2011, the World Health Organization (WHO) classification of hematolymphoid neoplasms and the WHO-European Organisation for Research and Treatment of Cancer classification for primary cutaneous lymphomas were updated and a number of novel systemic drugs for cutaneous T-cell lymphoma had been approved in Japan. In 2020, we revised the Japanese guidelines for the management of cutaneous lymphomas with consideration of the recent advances in the understanding of the pathophysiology and classification of cutaneous lymphomas together with the update of treatment strategies reflecting the advent of novel drugs. In addition to a brief explanation of epidemiology, diagnosis, staging system, prognosis and management of each subtype of cutaneous lymphomas, the recommendations for nine clinical questions regarding treatment options that can vary even among experts are also described. A systematic review process and determination of recommendations in answer to each clinical question have been performed in accordance with the Grading of Recommendations, Assessment, Development and Evaluation scheme by a multidisciplinary expert panel consisting of dermatologists, a hematologist and a radiation oncologist. In this article, we present the outlines of the revised Japanese "Guidelines for the management of cutaneous lymphomas".

Allogeneic Hematopoietic Stem Cell Transplantation in Cutaneous T-Cell Lymphomas

Simple Summary

Advanced-stage cutaneous T-cell lymphomas are aggressive diseases with frequent disease relapses and a reduced overall survival. Most treatment regimens fail to induce long-term remissions. Allogeneic hematopoietic stem cell transplantation has been associated with treatment-free long-term remissions and holds a potential for cure in this disease but is associated with frequent complications, mostly linked to the development of graft-versus-host disease and infections. Herein, we review the current evidence supporting the use of allogeneic stem cell transplantation in advanced-stage cutaneous T-cell lymphomas.

Abstract

Cutaneous T-cell lymphomas (CTCLs) are non-Hodgkin lymphomas that develop primarily in the skin. They account for almost 80% of primary cutaneous lymphomas. Epidermotropic CTCLs (mycosis fungoides (MF) and Sézary syndrome (SS)) are the most common form of CTCL. The course of the disease ranges from an indolent clinical behavior in early-stage disease to an aggressive evolution in the advanced stages. Advanced-stage disease is defined by the presence of tumors, erythroderma, or significant blood, nodal or visceral involvement. Advanced-stage disease is characterized by frequent disease relapses, refractory disease, a severely impaired quality of life and reduced overall survival. In the last twenty-five years, allogeneic hematopoietic stem cell transplantation (HSCT) has led to prolonged remissions in advanced CTCL, presumably linked to a graft-versus-lymphoma effect and is thus emerging as a potential cure of the disease. However, the high post-transplant relapse rate and severe morbidity and mortality associated with graft-versus-host disease and infections are important issues. Allogeneic HSCT is thus mostly considered in young patients with no comorbidities and an aggressive, advanced-stage CTCL. Allogeneic HSCT gives the best results in patients with a pre-transplant complete remission of the lymphoma. For this reason, one of the challenges is to define the best time to consider allogeneic HSCT in the disease course. Early identification of patients at high risk for progression is important to identify candidates who may benefit from allogeneic HSCT before their disease becomes treatment-refractory. This review describes the role of allogeneic HSCT in CTCL, summarizes the published data and future perspectives in this area.

Eosinophilia Associated With CD3-CD4+ T Cells: Characterization and Outcome of a Single-Center Cohort of 26 Patients

Background: Lymphocytic variant hypereosinophilic syndrome is characterized by marked over-production of eosinophilopoietic factor(s) by dysregulated T cells leading to eosinophil expansion. In most cases, these T cells are clonal and express a CD3^-CD4⁺ phenotype. As this is a rare disorder, presenting manifestations, disease course, treatment responses, and outcome are not well-characterized. Materials and Methods: In this retrospective single-center observational study, we reviewed medical files of all patients with persistent hypereosinophilia seen between 1994 and 2019 in whom CD3^-CD4⁺ T cells were detected. Data collection included clinical and biological findings at presentation, treatment responses, disease course, and serial CD3^-CD4⁺ T cell counts. Results: Our cohort comprises 26 patients, including 2 with hypereosinophilia of undetermined significance. All 24 symptomatic patients had cutaneous lesions and/or angioedema, and fasciitis was present in several cases. The aberrant T cell subset represented 2% or less total lymphocytes in 11 subjects. TCR gene rearrangement patterns on whole blood were polyclonal in these cases, while they all had serum CCL17/TARC levels above 1,500 pg/ml. Disease manifestations were mild and did not require maintenance therapy in roughly one third of the cohort, while two thirds required long-term oral corticosteroids and/or second-line agents. Among these, interferon-alpha was the most effective treatment option with a response observed in 8/8 patients, one of whom was cured of disease. Treatment had to be interrupted in most cases however due to poor tolerance and/or development of secondary resistance. Anti-interleukin-5 antibodies reduced blood eosinophilia in 5/5 patients, but clinical responses were disappointing. A sub-group of 5 patients had severe treatment-refractory disease, and experienced significant disease- and treatment-related morbidity and mortality, including progression to T cell lymphoma in three. Conclusions: This retrospective longitudinal analysis of the largest monocentric cohort of CD3^-CD4⁺ T cell associated lymphocytic variant hypereosinophilic syndrome published so far provides clinicians confronted with this rare disorder with relevant new data on patient presentation and outcome that should help tailor therapy and follow-up to different levels of disease severity. It highlights the need for novel therapeutic options, especially for the subset of patients with severe treatment-refractory disease. Future research efforts should be made toward understanding CD3^-CD4⁺ T cell biology in order to develop new treatments that target primary pathogenic mechanisms.

Pathogenesis and Therapy of Primary Cutaneous T-Cell Lymphoma: Collegium Internationale Allergologicum (CIA) Update 2020

Cutaneous T-cell lymphoma (CTCL) is a heterogeneous disease group of unknown etiology with a complex immunological background. As CTCL arises from T cells that have a vital role in the antitumor response, their therapy is largely aimed at reversing the immunological mechanisms leading to or manifesting during this malignancy. Early disease stages can be controlled with skin-directed therapy in most CTCL cases. Still, advanced CTCL has a dismal prognosis and warrants systemic therapy. Despite considerable progress in understanding the pathophysiology of the disease and the numerous systemic treatment options available, long-term remission rates with conventional treatments alone are still low. Allogeneic hematopoietic stem cell transplantation is currently the only curative option for advanced CTCL, including mycosis fungoides and Sézary syndrome. The aims of this review is to summarize the recent findings on the immunology of this heterogeneous disease and to present the advances in its clinical management.

Cutaneous T Cell Lymphoma: A Difficult Diagnosis Demystified

Cutaneous T cell lymphoma (CTCL) represents a heterogeneous group of extranodal non-Hodgkin lymphomas in which monoclonal T lymphocytes infiltrate the skin. The mechanism of CTCL development is not fully understood, but likely involves dysregulation of various genes and signaling pathways. A variety of treatment modalities are available, and although they can induce remission in most patients, the disease may recur after treatment cessation. Owing to relatively low incidence and significant chronicity of disease, and the high morbidity of some therapeutic regimens, further clinical trials are warranted to better define the ideal treatment option for each subtype of CTCL.

Leukaemic variants of cutaneous T-cell lymphoma: Erythrodermic mycosis fungoides and Sézary syndrome

Mycosis fungoides (MF) and Sézary syndrome (SS) are the most common types of cutaneous lymphoma, accounting for approximately 60% of cutaneous T-cell lymphomas. Diagnosis requires correlation of clinical, histologic, and molecular features. A multitude of factors have been linked to the aetiopathogenesis, however, none have been definitively proven. Erythrodermic MF (E-MF) and SS share overlapping clinical features, such as erythroderma, but are differentiated on the degree of malignant blood involvement. While related, they are considered to be two distinct entities originating from different memory T cell subsets. Differential expression of PD-1 and KIR3DL2 may represent a tool for distinguishing MF and SS, as well as a means of monitoring treatment response. Treatment of E-MF/SS is guided by disease burden, patients' ages and comorbidities, and effect on quality of life. Current treatment options include biologic, targeted, immunologic, and investigational therapies that can provide long term response with minimal side effects. Currently, allogeneic stem cell transplantation is the only potential curative treatment.

Expression and function of Kv1.3 channel in malignant T cells in Sézary syndrome

The voltage-gated potassium channel Kv1.3 (KCNA3) is expressed by a subset of chronically activated memory T cells and plays an important role in their activation and proliferation. Here, we show that primary malignant T cells isolated from patients with Sézary syndrome (SS) express Kv1.3 and are sensitive to potent Kv1.3 inhibitors ShK and Vm24, but not sensitive to a less potent inhibitor [N17A/F32T]-AnTx. Kv1.3 blockade inhibits CD3/CD28-induced proliferation and IL-9 expression by SS cells in a concentration-dependent manner. In parallel, CD3/CD28-mediated CD25 induction is inhibited, whereas Kv1.3 blockade has no effect on apoptosis or cell death as judged by Annexin V and PI staining. In conclusion, we provide the first evidence that malignant T cells in SS express functional Kv1.3 channels and that Kv1.3 blockade inhibits activation-induced proliferation as well as cytokine and cytokine receptor expression in malignant T cells, suggesting that Kv1.3 is a potential target for therapy in SS.

Antibody-Directed Therapies: Toward a Durable and Tolerable Treatment Platform for CTCL

Cutaneous T-cell lymphomas (CTCL) are a rare group of heterogeneous disorders characterized by cutaneous involvement of monoclonal T-lymphocytes. Although indolent at early stages, CTCL can confer significant morbidity, and mortality when advanced. There is an unmet need for tolerable and durable treatments with antibodies recently gaining promise. Here we review approved systemic therapies and discuss select antibodies in development.

Existing and Emerging Therapies for Cutaneous T-Cell Lymphoma

Cutaneous T-cell lymphomas (CTCL) are a heterogeneous group of non-Hodgkin lymphomas characterized by an infiltration of malignant monoclonal T lymphocytes into the skin. Mycosis fungoides (MF), the most common subtype, and the rarer Sézary syndrome (SS), are considered the classical forms of CTCL, which, because of a varying presentation and lack of genetic and immunophenotypical markers, can often have a delayed diagnosis. With skin-directed topical treatment being the mainstay of therapy in the early stages, there is an absence of long-term curative therapies for advanced disease. Recent insight into the pathogenesis of CTCL has identified new potential therapeutic targets including the monoclonal antibody therapies, brentuximab vedotin and mogamulizumab. Brentuximab vedotin, an anti-CD30 antibody-drug conjugate, received extended approval by the US FDA in 2017 to include primary cutaneous anaplastic large-cell lymphoma and CD30-expressing MF. Mogamulizumab, an anti-CCR4 antibody, received FDA approval in 2018 for relapsed or refractory MF and SS. Further targets and therapies continue to be investigated, including the monoclonal antibody therapy alemtuzumab, an anti-CD52 antibody, and the immune checkpoint blockade therapies, pembrolizumab and nivolumab. These new and emerging targets and therapies may lead to a promising broadening of CTCL treatment options in the future.

Management of mycosis fungoides-type cutaneous T-cell lymphoma (MF-CTCL): focus on chlormethine gel

Mycosis fungoides (MF) is a low-grade cutaneous lymphoma accounting for more than half of primary cutaneous T-cell lymphomas (CTCLs). Due to the rarity of CTCL, randomized studies are lacking, and treatment is based mainly on the recent published European Organisation for Research and Treatment of Cancer guidelines. Basically, early-stage MF is treated with skin-directed treatments, whereas advanced-stage MF requires more aggressive therapies. Among the skin-directed therapies, nitrogen mustard has been used for more than 50 years. A gel formulation was developed recently, showing a slight decrease in efficacy, counterbalanced by better tolerance (essentially due to a decrease in delayed hypersensitivity reactions). This review aims to summarize the current management of MF and the role of chlormethine gel in the treatment of the disease.

[Primary skin lymphomas: Current therapy]

Therapeutic progress in primary cutaneous lymphomas continues to be largely dominated by the T-cell lymphomas, towards which the great majority of recent therapeutic innovations have been directed. The latter include local treatments consisting either of relatively classical but "revamped" approaches involving different pharmaceutical forms (example: chlormethine gel) or else lower but seemingly equally effective dosages (electron therapy), or of more innovative approaches (example: UVA-1, dynamic phototherapy, imiquimod, resimiquimod). However, significant progress has been made chiefly in terms of systemic treatments with the emergence of "targeted" drugs that directly and specifically target tumour cells (monoclonal antibodies directed against CD30, CCR4 or CD158k) and the further development of "small" molecules such as histone deacetylase inhibitors and new cytostatics. Immunotherapies, which have proven so effective in other areas of oncodermatology, are also of great interest, while allogeneic haematopoietic stem-cell transplantation has clearly shown its superiority over autologous transplantation and now constitutes a significant component of the therapeutic arsenal in advanced disease. While the innovations in terms of B-cell lymphomas are certainly less significant, mention must also be made of the value of rituximab combined with polychemotherapy (CHOP) and of lenalidomide (as second-line therapy) in primary cutaneous diffuse large B-cell lymphoma, leg type, along with the development of localized (very) low-dose radiotherapy in unilesional or paucilesional indolent forms.

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.

[Treatment of mycosis fungoides and Sézary syndrome]

Adequate therapeutic management of cutaneous T-cell lymphoma (CTCL) requires the identification of the exact CTCL stage and entity within the current WHO classification. There is no curative therapy for CTCL yet, so that treatment currently aims at improving symptoms and quality of life as well as reducing relapse rates. The treatment has to be stage-adapted. Therapeutic options comprise skin-directed as well as systemic treatment. In early stages, phototherapy and local steroids are the first-line therapeutic options. For the therapy of higher stages, interferon alpha and the RXR-specific retinoid bexarotene are used as first-line medications. Second-line treatment comprises monochemotherapy with agents like gemcitabine or liposomal doxorubicine. Nevertheless, the high relapse rates in higher stages make novel alternative treatment options necessary. As future therapy, especially the fusion protein brentuximab-vedotin directed against CD30 shows promising potential in clinical studies.

Kutane Lymphome

Kutane Lymphome (cutaneous lymphomas: CL) umfassen die Gruppe der kutanen T-Zell-Lymphome (cutaneous T-cell lymphomas: CTCL), kutanen B-Zell-Lymphome (cutaneous B-cell lymphomas: CBCL) und die sog. hämatodermischen Neoplasien (HN). CL gehören zur Gruppe der Non-Hodgkin-Lymphome (NHL) und stellen in der Subgruppe der extranodalen NHL die zweithäufigste Gruppe hinter den gastrointestinalen Lymphomen dar (Jaffe et al. 2009). Man unterscheidet zwischen primären und sekundären CL. Primäre CL haben ihren Ursprung in der Haut und bleiben in der Regel darauf auch längere Zeit beschränkt, während sekundäre CL kutane Manifestationen von primär nodalen oder extranodalen Lymphomen darstellen (Willemze 2005). Die primären CL unterscheiden sich hinsichtlich klinischem Verlauf, Therapieoptionen und Prognose erheblich von nodalen und extrakutanen Lymphomen. So zeigen z. B. die primär kutanen CD30+-T-Zell-Lymphome einen gutartigen Verlauf, wogegen die nodalen Varianten als aggressiv eingestuft werden. Da die CL zumeist weniger aggressiv sind, werden sie auch weniger aggressiv behandelt.

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.

Systemic Treatment Options for Advanced-Stage Mycosis Fungoides and Sézary Syndrome

PURPOSE OF REVIEW

Cutaneous T-cell lymphoma (CTCL) is a rare form of non-Hodgkin lymphoma. Globally, the most common subtypes of CTCL are mycosis fungoides and Sézary syndrome. CTCL can confer significant morbidity and even mortality in advanced disease. Here we review the current and potential future treatments for advanced-stage CTCL.

RECENT FINDINGS

Heterogeneity of treatment choice has been demonstrated both in US and non-US centers. Systemic treatment choice is currently guided by prognostic features, incorporating stage, immunophenotypic and molecular findings, and patient-specific factors such as age and comorbidities. Randomized controlled studies are uncommon, and the literature is composed predominantly of retrospective, cohort, and early-phase studies. International consensus guidelines are available; however, the lack of comparative trials means that there is no clear algorithmic approach to treatment. This review article reports on the systemic treatment options in current use for advanced CTCL, and on the possible future therapies, acknowledging that an algorithmic approach is not yet forthcoming to guide treatment prioritization.

Current systemic therapeutic options for advanced mycosis fungoides and Sézary syndrome

Mycosis fungoides (MF) and Sézary syndrome (SS) are the most common cutaneous T-cell lymphomas (CTCLs). Both lack curative options, and advanced-stage carries a poor prognosis. Whilst there are a number of treatments available, achieving and maintaining a durable remission remains challenging. We review current systemic treatment options as monotherapy for advanced-stage MF (IIB-IV), appraising their mechanism of action, analyzing their efficacy, and describing toxicities. Individually, reported overall response rates (ORR) vary widely in the literature and duration of responses are typically short, ranging from 7.5 to 22.4 months. Combined therapy is frequently used in an effort to boost responses, although prospective studies comparing combinations to single agent therapies are rarely conducted. While recent translational research has led to increased understanding of the immunopathogenesis of MF and SS and the development of new treatments, current standard of care therapies are not curative and have low ORR for advanced-stage disease.

Therapeutic Antibodies to KIR3DL2 and Other Target Antigens on Cutaneous T-Cell Lymphomas

KIR3DL2 is a member of the killer cell immunoglobulin-like receptor (KIR) family that was initially identified at the surface of natural killer (NK) cells. KIR3DL2, also known as CD158k, is expressed as a disulfide-linked homodimer. Each chain is composed of three immunoglobulin-like domains and a long cytoplasmic tail containing two immunoreceptor tyrosine-based inhibitory motifs. Beside its expression on NK cells, it is also found on rare circulating T lymphocytes, mainly CD8⁺. Although the KIR gene number varies between haplotype, KIR3DL2 is a framework gene present in all individuals. Together with the presence of genomic regulatory sequences unique to KIR3DL2, this suggests some particular functions for the derived protein in comparison with other KIR family members. Several ligands have been identified for KIR3DL2. As for other KIRs, binding to HLA class I molecules is essential for NK development by promoting phenomena such as licensing and driving NK cell maturation. For KIR3DL2, this includes binding to HLA-A3 and -A11 and to the free heavy chain form of HLA-B27. In addition, KIR3DL2 binds to CpG oligonucleotides (ODN) and ensures their transport to endosomal toll-like receptor 9 that promotes cell activation. These characteristics have implicated KIR3DL2 in several pathologies: ankylosing spondylitis and cutaneous T-cell lymphomas such as Sézary syndrome, CD30⁺ cutaneous lymphoma, and transformed mycosis fungoides. Consequently, a new generation of humanized monoclonal antibodies (mAbs) directed against KIR3DL2 has been helpful in the diagnosis, follow-up, and treatment of these diseases. In addition, preliminary clinical studies of a novel targeted immunotherapy for cutaneous T-cell lymphomas using the anti-KIR3DL2 mAb IPH4102 are now underway. In this review, we discuss the various aspects of KIR3DL2 on the functions of CD4⁺ T cells and how targeting this receptor helps to develop innovative therapeutic strategies.