Primary Cutaneous T-Cell Lymphomas: Mycosis Fungoides and Sezary Syndrome

Determination of T-cell clonality and expression profiles of Toll-like receptors signaling pathway genes and related miRNAs in patients with mycosis fungoides

Cutaneous T-cell lymphomas (CTCL) encompass a group of diseases characterized by the presence of malignant clonal CD4+ T lymphocytes in the skin. Mycosis fungoides (MF) is the most prevalent form of CTCL, accounting for approximately 60 % of cutaneous T-cell lymphomas and 50 % of all primary cutaneous lymphomas. Despite ongoing research, the precise pathogenesis of MF remains incompletely understood. Toll-like receptors (TLRs) have the ability to specifically recognize ligands, subsequently induce the expression of diverse genes and activate innate immunity within the cell. Furthermore, miRNAs play a crucial role in regulating various aspects of immune cell function. The aim of our study was to explore the potential roles of TLRs and the genes implicated in their signal transduction, along with the expression status of miRNAs in the mechanisms underlying MF. Additionally, we assessed the clonal status and compared it with clinicopathological data using a T-cell clonality assay. To determine the expression status of TLR pathway genes and miRNAs, we conducted RT-PCR analysis on 52 MF samples and 50 control paraffin block materials. Pathway analysis were conducted using the KEGG database. T-cell receptor (TCR) gamma clonality changes were evaluated. Results from the study revealed increased expressions of TLR-1, -4, -8, IRF7, TRAF3, MEK1, MEK2, Elk1, NFkB, hsa-miR-21-5p, and hsa-miR-155-5p, as well as decreased expressions of hsa-miR-130a-3p, hsa-miR-210-3p, and hsa-let-7e-5p in the MF group. TCR gamma clonal change analysis demonstrated that 55.5 % of the analysed DNAs exhibited monoclonal and biallelic patterns, while 45.5 % displayed polyclonality. These findings collectively suggest the potential influence and therapeutic possibilities of the TLR signalling pathway in the molecular pathogenesis of MF.

Identification of Skin Lesions by Snapshot Hyperspectral Imaging

This study pioneers the application of artificial intelligence (AI) and hyperspectral imaging (HSI) in the diagnosis of skin cancer lesions, particularly focusing on Mycosis fungoides (MF) and its differentiation from psoriasis (PsO) and atopic dermatitis (AD). By utilizing a comprehensive dataset of 1659 skin images, including cases of MF, PsO, AD, and normal skin, a novel multi-frame AI algorithm was used for computer-aided diagnosis. The automatic segmentation and classification of skin lesions were further explored using advanced techniques, such as U-Net Attention models and XGBoost algorithms, transforming images from the color space to the spectral domain. The potential of AI and HSI in dermatological diagnostics was underscored, offering a noninvasive, efficient, and accurate alternative to traditional methods. The findings are particularly crucial for early-stage invasive lesion detection in MF, showcasing the model's robust performance in segmenting and classifying lesions and its superior predictive accuracy validated through k-fold cross-validation. The model attained its optimal performance with a k-fold cross-validation value of 7, achieving a sensitivity of 90.72%, a specificity of 96.76%, an F1-score of 90.08%, and an ROC-AUC of 0.9351. This study marks a substantial advancement in dermatological diagnostics, thereby contributing significantly to the early and precise identification of skin malignancies and inflammatory conditions.

Malignant T cells induce skin barrier defects through cytokine-mediated JAK/STAT signaling in cutaneous T-cell lymphoma

Cutaneous T-cell lymphoma (CTCL) is a devastating lymphoid malignancy characterized by the accumulation of malignant T cells in the dermis and epidermis. Skin lesions cause serious symptoms that hamper quality of life and are entry sites for bacterial infection, a major cause of morbidity and mortality in advanced diseases. The mechanism driving the pathological processes that compromise the skin barrier remains unknown. Here, we report increased transepidermal water loss and compromised expression of the skin barrier proteins filaggrin and filaggrin-2 in areas adjacent to TOX-positive T cells in CTCL skin lesions. Malignant T cells secrete mediators (including cytokines such as interleukin 13 [IL-13], IL-22, and oncostatin M) that activate STAT3 signaling and downregulate filaggrin and filaggrin-2 expression in human keratinocytes and reconstructed human epithelium. Consequently, the repression of filaggrins can be counteracted by a cocktail of antibodies targeting these cytokines/receptors, small interfering RNA-mediated knockdown of JAK1/STAT3, and JAK1 inhibitors. Notably, we show that treatment with a clinically approved JAK inhibitor, tofacitinib, increases filaggrin expression in lesional skin from patients with mycosis fungoides. Taken together, these findings indicate that malignant T cells secrete cytokines that induce skin barrier defects via a JAK1/STAT3-dependent mechanism. As clinical grade JAK inhibitors largely abrogate the negative effect of malignant T cells on skin barrier proteins, our findings suggest that such inhibitors provide novel treatment options for patients with CTCL with advanced disease and a compromised skin barrier.

Emerging drugs for the treatment of cutaneous T-cell lymphoma

INTRODUCTION

Cutaneous T cell lymphoma (CTCL) is a rare and incurable group of non-Hodgkin lymphomas that manifests as patches, plaques, tumors, and/or erythroderma in the skin. Standard skin-directed therapies for CTCL are effective in patients with indolent early-stage disease but more advanced/refractory stage patients require systemic therapies. However, none of the treatments are considered curative and most patients suffer from relapses. Biologic therapies and immunotherapy provide novel treatment options for patients with advanced or refractory disease.

AREAS COVERED

This review provides a discussion of recently approved biological and novel therapeutics that are actively developed for the management of the heterogenous group of CTCL.

EXPERT OPINION

Mogamulizumab and brentuximab vedotin have reached the market and are approved for the treatment of CTCL, providing valuable options. Additionally, therapies utilizing immune checkpoint inhibitors, miRNA inhibitors, and peptide inhibitors show promising results in clinical trials. Durvalumab, pembrolizumab, TTI-621, BNZ-1, and MRG-106 are several of the emerging treatments still in trials. Further combinatorial studies are needed as none of the treatments have demonstrated long term remissions.

The role of Dipeptidyl Peptidase-4 in cutaneous disease

Dipeptidyl peptidase-4 (DPP4) is a multifunctional, transmembrane glycoprotein present on the cell surface of various tissues. It is present in multiple molecular forms including cell surface and soluble. The role of DPP4 and its inhibition in cutaneous dermatoses have been a recent point of investigation. DPP4 exerts a notable influence on T-cell biology, the induction of skin-specific lymphocytes, and the homeostasis between regulatory and effector T cells. Moreover, DPP4 interacts with a broad range of molecules, including adenosine deaminase, caveolin-1, CXCR4 receptor, M6P/insulin-like growth factor II-receptor and fibroblast activation protein-α, triggering downstream effects that modulate the immune response, cell adhesion and chemokine activity. DPP4 expression on melanocytes, keratinocytes and fibroblasts further alters cell function and, thus, has crucial implications in cutaneous pathology. As a result, DPP4 plays a significant role in bullous pemphigoid, T helper type 1-like reactions, cutaneous lymphoma, melanoma, wound healing and fibrotic disorders. This review illustrates the multifactorial role of DPP4 expression, regulation, and inhibition in cutaneous diseases.

Hypopigmented Mycosis Fungoides: Loss of Pigmentation Reflects Antitumor Immune Response in Young Patients

Hypopigmented mycosis fungoides (HMF) is a form of cutaneous T-cell lymphoma (CTCL), a heterogeneous group of extranodal non-Hodgkin's lymphomas. HMF has a unique set of defining features that include light colored to achromic lesions, a predilection for darker skin phototypes, an early onset of disease, and predominance of CD8⁺ T-cells, among others. In the current review, we detail the known pathways of molecular pathogenesis for this lymphoma and posit that an active Th1/cytotoxic antitumor immune response in part explains why this variant is primarily seen in children/adolescents and young adults, who do not exhibit signs of immunosenescence. As a result of this potent cytotoxic response, HMF patients experience mostly favorable overall prognosis, while hypopigmentation may in fact represent a useful surrogate marker of cytotoxic immunity targeting the malignant cells. Understanding the molecular processes behind the specific features that define HMF may lead to improved diagnostic accuracy, personalized prognosis by risk stratification, and improved management of HMF. Moreover, improving our knowledge of HMF may aid our further understanding of other cutaneous lymphomas.

How It Works: The Immunology Underlying Phototherapy

Phototherapeutic modalities induce apoptosis of keratinocytes and immune cells, impact cytokine production, downregulate the IL-23/Th17 axis, and induce regulatory T cells. As in anti-IL-17 or anti-IL-23 antibody treatment, the dual action of phototherapy on skin and the immune system is likely responsible for sustained resolution of lesions in diseases such as psoriasis. In cutaneous T cell lymphoma, phototherapy may function by causing tumor cell apoptosis and eliminating the neoplastic and inflammatory infiltrate. Further research on phototherapeutic mechanisms will help advance, optimize, and refine dermatologic treatments and may open up novel avenues for treatment strategies in dermatology and beyond.

Cytotoxic impact of a perillyl alcohol-temozolomide conjugate, NEO212, on cutaneous T-cell lymphoma in vitro

Background:

Mycosis fungoides (MF) and Sézary syndrome (SS) are subtypes of primary cutaneous lymphomas and represent complex diseases regarding their physiopathology and management. Depending on the stage of the disease, different treatment regimens are applied, but there is no consensus on an optimal approach. Prognosis for patients with early stage MF is favorable, but significantly worsens in advanced disease and in SS, where patients frequently relapse and require multiple therapies.

Methods:

We investigated the potential anticancer effects of NEO212, a novel compound generated by covalently conjugating perillyl alcohol (a natural monoterpene) to temozolomide (an alkylating agent), on MF and SS cell lines in vitro. HUT-78, HUT-102, and MyLa cells were treated with NEO212 under different conditions, and drug effects on proliferation, viability, and apoptosis were characterized.

Results:

NEO212 inhibited proliferation, diminished viability, and stimulated apoptosis in all cell lines, although with varying degrees of potency in the different cell lines. It down-regulated c-myc and cyclin D1 proteins, which are required for cell proliferation, but triggered endoplasmic reticulum stress and activation of caspases. Pretreatment of cells with antioxidants ascorbic acid and beta-mercaptoethanol prevented these NEO212-induced effects.

Conclusions:

NEO212 exerted promising anticancer effects on SS and MF cell lines. The generation of reactive oxygen species (ROS) appears to play a key role in the NEO212-induced cell death process, because the blockage of ROS with antioxidants prevented caspase activation. We propose that NEO212 should be investigated further toward clinical testing in these tumor types.