"Next top" mouse models advancing CTCL research.

This review systematically describes the application of in vivo mouse models in studying cutaneous T-cell lymphoma (CTCL), a complex hematological neoplasm. It highlights the diverse research approaches essential for understanding CTCL's intricate pathogenesis and evaluating potential treatments. The review categorizes various mouse models, including xenograft, syngeneic transplantation, and genetically engineered mouse models (GEMMs), emphasizing their contributions to understanding tumor-host interactions, gene functions, and studies on drug efficacy in CTCL. It acknowledges the limitations of these models, particularly in fully replicating human immune responses and early stages of CTCL. The review also highlights novel developments focusing on the potential of skin-targeted GEMMs in studying natural skin lymphoma progression and interactions with the immune system from onset. In conclusion, a balanced understanding of these models' strengths and weaknesses are essential for accelerating the deciphering of CTCL pathogenesis and developing treatment methods. The GEMMs engineered to target specifically skin-homing CD4+ T cells can be the next top mouse models that pave the way for exploring the effects of CTCL-related genes.

Reassessing human MHC-I genetic diversity in T cell studies.

The Major Histocompatibility Complex class I (MHC-I) system plays a vital role in immune responses by presenting antigens to T cells. Allele specific technologies, including recombinant MHC-I technologies, have been extensively used in T cell analyses for COVID-19 patients and are currently used in the development of immunotherapies for cancer. However, the immense diversity of MHC-I alleles presents challenges. The genetic diversity serves as the foundation of personalized medicine, yet it also poses a potential risk of exacerbating healthcare disparities based on MHC-I alleles. To assess potential biases, we analysed (pre)clinical publications focusing on COVID-19 studies and T cell receptor (TCR)-based clinical trials. Our findings reveal an underrepresentation of MHC-I alleles associated with Asian, Australian, and African descent. Ensuring diverse representation is vital for advancing personalized medicine and global healthcare equity, transcending genetic diversity. Addressing this disparity is essential to unlock the full potential of T cells for enhancing diagnosis and treatment across all individuals.

Paediatric onset lymphomatoid papulosis: results of a multicentre retrospective cohort study, on behalf of the EORTC Cutaneous Lymphoma Tumours Group (CLTG).

BACKGROUND: Lymphomatoid Papulosis (LyP) is a rare cutaneous T-cell lymphoproliferative disorder. Comprehensive data on LyP in the paediatric population is scarce. OBJECTIVES: To characterize epidemiological, clinical, histopathological, and prognostic features of paediatric LyP. METHODS: This was a retrospective, multicentre international cohort study including 87 cases of children and adolescents with LyP diagnosed between 1998 and 2022. Patients aged ≤ 18 years old at disease onset were included. Diagnosis was made in each centre based on clinical-pathological correlation. RESULTS: Eighty-seven patients from 12 centres were included. The mean age at onset was 7.0 years (range 3 months-18 years) with a male to female ratio of 2:1. The mean time between onset of first cutaneous lesions and diagnosis was 1.3 years (range 0-14 years). Initial misdiagnosis concerned 26.4% of patients. Initially, LyP was most often misdiagnosed as Pityriasis lichenoides et varioliformis acuta (PLEVA), insect bites, or mollusca contagiosa. Erythematous papules or papulonodules were the most frequent clinical presentation. Pruritus was specifically mentioned for 20.7% of patients. The main histological subtype was type A in 55.1% of the cases. If analysed, monoclonal TCR rearrangement was found in 76.5% of the skin biopsies. The overall survival rate was 100% with follow up at 5 years available for 33 patients and at 15 years for 8 patients. A development of associated haematological malignancy (HM) occurred in 9.6% of the cases (7/73), including four mycosis fungoides (MF) cases, one primary cutaneous anaplastic large cell lymphoma (pc-ALCL), one systemic ALCL and one case of acute myeloid leukaemia. If we compare incidence rates of cancer with the world 0-19 years old population from 2001-2010, we estimate a significantly higher risk of associated malignancy in general, occurring before the age of 19 years old with incidence rate ratio of 87.49 (CI 86.01-88.99). CONCLUSIONS: We report epidemiological data from a large international cohort of children and adolescents with LyP. Overall the prognosis of the disease is good, with excellent survival rates for all patients. Due to increased risk of associated HM, a long-term follow-up should be recommended for LyP patients.

Evaluation of Quality of Life and Treatment Satisfaction in Newly Diagnosed Cutaneous T-Cell Lymphoma Patients.

BACKGROUND: Little is known about the impact of MF on quality of life (QoL) in newly diagnosed patients. OBJECTIVES: To describe the impact of the MF diagnosis on QoL, patient expectations, and treatment satisfaction over the first 6 months after diagnosis. METHODS: Outcomes of this prospective cohort study of newly diagnosed MF patients conducted between 2020 and 2022 at the Leiden University Medical Center included the Skindex-29, RAND-12 Health Survey, degree of itch, pain, and fatigue (Visual Analogue Scale (VAS)), patient expectations, and Client Satisfaction Questionnaire-8 (CSQ-8), measured at baseline and after six months. RESULTS: A total of 28 patients with MF were included. At baseline, 66% (n = 18) "strongly-totally" expected positive effects of the treatment. At the time of diagnosis, 28% of the patients (n = 8) were moderately to severely affected. There was no statistical change in the Skindex-29 score sum score (20 [10-34] vs. 20 [9-36]; p = 0.81) or in the other three subdomains, the RAND-12 scores, and the VAS itch, pain, and fatigue over time. Treatment satisfaction was high overall. CONCLUSION: Despite that the newly diagnosed MF patients anticipate a positive treatment effect, few improvements in QoL and symptom reduction were found. These data can be used for adequate expectation management and provide a rationale for further evaluation of treatment regimens in these patients.

The development of in vitro organotypic 3D vulvar models to study tumor-stroma interaction and drug efficacy.

BACKGROUND: Vulvar squamous cell carcinoma (VSCC) is a rare disease with a poor prognosis. To date, there's no proper in vitro modeling system for VSCC to study its pathogenesis or for drug evaluation. METHODS: We established healthy vulvar (HV)- and VSCC-like 3D full thickness models (FTMs) to observe the tumor-stroma interaction and their applicability for chemotherapeutic efficacy examination. VSCC-FTMs were developed by seeding VSCC tumor cell lines (A431 and HTB117) onto dermal matrices harboring two NF subtypes namely papillary fibroblasts (PFs) and reticular fibroblasts (RFs), or cancer-associated fibroblasts (CAFs) while HV-FTMs were constructed with primary keratinocytes and fibroblasts isolated from HV tissues. RESULTS: HV-FTMs highly resembled HV tissues in terms of epidermal morphogenesis, basement membrane formation and collagen deposition. When the dermal compartment shifted from PFs to RFs or CAFs in VSCC-FTMs, tumor cells demonstrated more proliferation, EMT induction and stemness. In contrast to PFs, RFs started to lose their phenotype and express robust CAF-markers α-SMA and COL11A1 under tumor cell signaling induction, indicating a favored 'RF-to-CAF' transition in VSCC tumor microenvironment (TME). Additionally, chemotherapeutic treatment with carboplatin and paclitaxel resulted in a significant reduction in tumor-load and invasion in VSCC-FTMs. CONCLUSION: We successfully developed in vitro 3D vulvar models mimicking both healthy and tumorous conditions which serve as a promising tool for vulvar drug screening programs. Moreover, healthy fibroblasts demonstrate heterogeneity in terms of CAF-activation in VSCC TME which brings insights in the future development of novel CAF-based therapeutic strategies in VSCC.

Unveiling the hidden struggles: Exploring the profound impact of advanced stage cutaneous T-cell lymphoma on quality of life.

Erythrodermic mycosis fungoides and Sézary syndrome are chronic, relapsing-remitting diseases that greatly impacts patients' quality of life (QoL). Mogamulizumab-kpkc (Mogamulizumab) is a novel therapeutic agent for cutaneous T-cell lymphomas with a notable impact on progression-free survival. Qualitative assessment methods allow a broader exploration and greater insight in individual patient experience than quantitative studies. However, there is limited data on the impact of mogamulizumab on health-related QoL. To investigate the impact of erythrodermic cutaneous T-cell lymphoma (E-CTCL) on QoL and the effect of mogamulizumab on the QoL. Semi-structured interview were conducted with seven patients with E-CTCL that were receiving mogamulizumab treatment. Five major themes arose: Diagnosis and the diagnostic delay and uncertainty experienced by participants; Physical functioning due to the high symptom burden; Psychological and social functioning considering the significant impact on daily life; Treatment and the effect of mogamulizumab; and Support by family, friends and health professionals. Mogamulizumab therapy resulted in a significant decrease of symptoms. The small sample size should also be taken into account although data saturation was reached. This study gives a broad insight into the large impact of E-CTCL and the major consequences on the physical functioning as well as on the emotional/psychological and social well-being. Mogamulizumab appears to have a positive effect on symptoms.

Autoantibody subclass predominance is not driven by aberrant class switching or impaired B cell development.

A subset of autoimmune diseases is characterized by predominant pathogenic IgG4 autoantibodies (IgG4-AID). Why IgG4 predominates in these disorders is unknown. We hypothesized that dysregulated B cell maturation or aberrant class switching causes overrepresentation of IgG4+ B cells and plasma cells. Therefore, we compared the B cell compartment of patients from four different IgG4-AID with two IgG1-3-AID and healthy donors, using flow cytometry. Relative subset abundance at all maturation stages was normal, except for a, possibly treatment-related, reduction in immature and naïve CD5+ cells. IgG4+ B cell and plasma cell numbers were normal in IgG4-AID patients, however they had a (sub)class-independent 8-fold increase in circulating CD20-CD138+ cells. No autoreactivity was found in this subset. These results argue against aberrant B cell development and rather suggest the autoantibody subclass predominance to be antigen-driven. The similarities between IgG4-AID suggest that, despite displaying variable clinical phenotypes, they share a similar underlying immune profile.

Use of Pegylated Interferon Alpha-2a in Cutaneous T-cell Lymphoma: A Retrospective Case Collection.

Mycosis fungoides and Sézary syndrome are rare and largely incurable types of cutaneous T-cell lymphoma with limited therapeutic options. In 1984 Bunn et al. reported that interferon alpha is an efficient monotherapy in cutaneous T-cell lymphoma and 14 years later it was shown in a prospective, randomized trial that a combination of interferon alpha and psoralen plus ultraviolet A therapy (PUVA) is most efficient in the treatment of cutaneous T-cell lymphoma. Since then interferon alpha as single agent or, most often, in combination with phototherapy and/or retinoids has been integrated as standard of care in cutaneous T-cell lymphoma guidelines worldwide. However, production of interferon alpha was discontinued recently worldwide and pegylated interferon alpha-2a (PEG-IFNα) has been used as an alternative therapy. In contrast to numerous interferon alpha studies, only a few studies focusing on PEG-IFNα are available. Therefore, the aim of this study was to conduct a retrospective data collection to report on the efficacy, adverse events and therapy regimens of PEG-IFNα in cutaneous T-cell lymphoma. In 28 patients with cutaneous T-cell lymphoma treated in Germany and in the Netherlands, 36% of patients achieved complete remission, 36% partial remission and 29% stable disease. Eighteen percent of patients developed adverse events during therapy, which led to the discontinuation of PEG-IFNα therapy in 2 patients. The most common concomittant therapies were oral PUVA phototherapy and local radiotherapy. In conclusion, PEG-IFNα, especially in combination with skin-directed therapies, is an effective treatment option for cutaneous T-cell lymphoma in clinical practice.

EORTC consensus recommendations for the treatment of mycosis fungoides/Sézary syndrome - Update 2023.

On behalf of the EORTC Cutaneous Lymphoma Tumours Group (EORTC-CLTG) and following up on earlier versions published in 2006 and 2017 this document provides an updated standard for the treatment of mycosis fungoides and Sézary syndrome (MF/SS). It considers recent relevant publications and treatment options introduced into clinical practice after 2017. Consensus was established among the authors through a series of consecutive consultations in writing and a round of discussion. Treatment options are assigned to each disease stage and, whenever possible and clinically useful, separated into first- and second line options annotated with levels of evidence. Major changes to the previous version include the incorporation of chlormethine, brentuximab vedotin, and mogamulizumab, recommendations on the use of pegylated interferon α (after withdrawal of recombinant unpegylated interferons), and the addition of paragraphs on supportive therapy and on the care of older patients. Still, skin-directed therapies are the most appropriate option for early-stage MF and most patients have a normal life expectancy but may suffer morbidity and impaired quality of life. In advanced disease treatment options have expanded recently. Most patients receive multiple consecutive therapies with treatments often having a relatively short duration of response. For those patients prognosis is still poor and only for a highly selected subset long term remission can be achieved with allogeneic stem cell transplantation. Understanding of the disease, its epidemiology and clinical course, and its most appropriate management are gradually advancing, and there is well-founded hope that this will lead to further improvements in the care of patients with MF/SS.

Socs1-knockout in skin-resident CD4+ T cells in a protracted contact-allergic reaction results in an autonomous skin inflammation with features of early-stage mycosis fungoides.

Recent detailed genomic analysis of mycosis fungoides (MF) identified suppressor of cytokine signaling 1 (SOCS1), an inhibitor of JAK/STAT signaling, as one of the frequently deleted tumor suppressors in MF, and one-copy deletion of SOCS1 was confirmed in early-stage MF lesions. To better understand the functional role of SOCS1 in the genesis of MF, we used a genetically engineered mouse model emulating heterozygous SOCS1 loss in skin resident CD4+ T cells. In these mice an experimentally induced contact-allergic reaction was maintained for 20 weeks. Ten weeks after discontinuing contact-allergic challenges, only the skin with locally one-copy deletion of Socs1 in CD4+ T cells still showed high numbers of CD3+/CD4+ Socs1 k.o. cells in the dermis (p ＜ 0.0001) with prevalent Stat3 activation (p ＜0.001). And in one out of 9 mice, this had progressed to far more dramatic increases, including the thickened epidermis, and with an explosive growth of Socs1 k.o. T cells in circulation; indicative of cutaneous lymphoma. Hence, we show that Socs1 mono-allelic loss in CD4+ T cells locally in protractedly inflamed skin results in autonomous skin inflammation with features of early-stage MF.

Artificial intelligence in digital pathology of cutaneous lymphomas: A review of the current state and future perspectives.

Primary cutaneous lymphomas (CLs) represent a heterogeneous group of T-cell lymphomas and B-cell lymphomas that present in the skin without evidence of extracutaneous involvement at time of diagnosis. CLs are largely distinct from their systemic counterparts in clinical presentation, histopathology, and biological behavior and, therefore, require different therapeutic management. Additional diagnostic burden is added by the fact that several benign inflammatory dermatoses mimic CL subtypes, requiring clinicopathological correlation for definitive diagnosis. Due to the heterogeneity and rarity of CL, adjunct diagnostic tools are welcomed, especially by pathologists without expertise in this field or with limited access to a centralized specialist panel. The transition into digital pathology workflows enables artificial intelligence (AI)-based analysis of patients' whole-slide pathology images (WSIs). AI can be used to automate manual processes in histopathology but, more importantly, can be applied to complex diagnostic tasks, especially suitable for rare disease like CL. To date, AI-based applications for CL have been minimally explored in literature. However, in other skin cancers and systemic lymphomas, disciplines that are recognized here as the building blocks for CLs, several studies demonstrated promising results using AI for disease diagnosis and subclassification, cancer detection, specimen triaging, and outcome prediction. Additionally, AI allows discovery of novel biomarkers or may help to quantify established biomarkers. This review summarizes and blends applications of AI in pathology of skin cancer and lymphoma and proposes how these findings can be applied to diagnostics of CL.

Correction: Wind et al. Topical Bimiralisib Shows Meaningful Cutaneous Drug Levels in Healthy Volunteers and Mycosis Fungoides Patients but No Clinical Activity in a First-in-Human, Randomized Controlled Trial. Cancers 2022, 14, 1510.

The authors wish to make the following corrections to this paper [...].

Identifying unmet needs and challenges in the definition of a plaque in mycosis fungoides: An EORTC-CLTG/ISCL survey.

BACKGROUND: Consensus about the definition and classification of 'plaque' in mycosis fungoides is lacking. OBJECTIVES: To delineate a comprehensive view on how the 'plaque' entity is defined and managed in clinical practice; to evaluate whether the current positioning of plaques in the TNMB classification is adequate. METHODS: A 12-item survey was circulated within a selected panel of 22 experts (pathologists, dermatologists, haematologists and oncologists), members of the EORTC and International Society for Cutaneous Lymphoma. The questionnaire discussed clinical and histopathological definitions of plaques and its relationship with staging and treatment. RESULTS: Total consensus and very high agreement rates were reached in 33.3% of questions, as all panellists regularly check for the presence of plaques, agree to evaluate the presence of plaques as a potential separate T class, and concur on the important distinction between plaque and patch for the management of early-stage MF. High agreement was reached in 41.7% of questions, since more than 50% of the responders use Olsen's definition of plaque, recommend the distinction between thin/thick plaques, and agree on performing a biopsy on the most infiltrated/indurated lesion. High divergence rates (25%) were reported regarding the possibility of a clinically based distinction between thin and thick plaques and the role of histopathology to plaque definition. CONCLUSIONS: The definition of 'plaque' is commonly perceived as a clinical entity and its integration with histopathological features is generally reserved to specific cases. To date, no consensus is achieved as for the exact definition of thin and thick plaques and current positioning of plaques within the TNMB system is considered clinically inadequate. Prospective studies evaluating the role of histopathological parameters and other biomarkers, as well as promising diagnostic tools, such as US/RM imaging and high-throughput blood sequencing, are much needed to fully integrate current clinical definitions with more objective parameters.

HLA expression as a risk factor for metastases of cutaneous squamous-cell carcinoma in organ- transplant recipients.

BACKGROUND: Solid organ-transplant recipients (SOTR) have an increased risk of cutaneous squamous-cell carcinoma (cSCC), metastasis and death from cSCC. In immunocompetent patients with mucosal SCC, downregulation of HLA class I is associated with poor prognosis. Since the degree of HLA expression on tumor cells could play a role in immunogenicity and pathophysiology of cSCC metastasis, we hypothesized that decreased HLA expression is associated with an increased risk of metastasis. METHODS: We compared HLA expression between primary metastasized cSCCs, their metastases, and non-metastasized cSCCs from the same patients. Samples were stained for HLA-A, HLA-B/-C and quantified by calculating the difference in immunoreactivity score (IRS) of the primary cSCC compared with all non-metastasized cSCCs. RESULTS: The mean IRS score for HLA-B/C expression was 2.07 point higher in metastasized compared to non-metastasized cSCCs (p = 0.065, 95 % CI -0.18-4.32). 83.3 % of the primary metastasized cSCCs had an IRS score of 4 or higher, compared to 42.9 % in non-metastasized cSCCs. Moderately to poorly differentiated cSCCs had more HLA class I expression compared to well-differentiated cSCCs. CONCLUSION: Contrary to immunocompetent patients, HLA-B/C expression tends to be upregulated in metastasized cSCC compared to non-metastasized cSCC in SOTR, suggesting that different tumor escape mechanisms play a role in SOTR compared to immunocompetent patients.

In vivo modelling of cutaneous T-cell lymphoma: The role of SOCS1.

Introduction: Mycosis fungoides (MF), the most common type of Cutaneous T cell Lymphoma (CTCL), is characterized by an inflamed skin intermixed with proliferating malignant mature skin-homing CD4+ T cells. Detailed genomic analyses of MF skin biopsies revealed several candidate genes possibly involved in genesis of these tumors and/or potential targets for therapy. These studies showed, in addition to common loss of cell cycle regulator CDKN2A, activation of several oncogenic pathways, most prominently and consistently involving JAK/STAT signaling. SOCS1, an endogenous inhibitor of the JAK/STAT signaling pathway, was identified as a recurrently deleted gene in MF, already occurring in the earliest stages of the disease. Methods: To explore the mechanisms of MF, we create in vivo mouse models of autochthonous CTCLs and these genetically engineered mouse models (GEMMS) can also serve as valid experimental models for targeted therapy. We describe the impact of allelic deletion of Socs1 in CD4 T cells of the skin. To achieve this, we crossed inducible Cre-transgenic mice in the CD4 lineage with transgenic mice carrying floxed genes of Socs1. We first determined optimal conditions for Socs1 ablation with limited effects on circulating CD4 T-cells in blood. Next, we started time-course experiments mimicking sustained inflammation, typical in CTCL. FACS analysis of the blood was done every week. Skin biopsies were analyzed by immunocytochemical staining at the end of the experiment. Results: We found that the Socs1 knockout transgenic group had thicker epidermis of treated skin compared with the control group and had more CD3 and CD4 in the skin of the transgenic group compared to the control group. We also noted more activation of Stat3 by staining for P-Stat3 in Socs1 knockout compared to wt CD4+T cells in the skin. The results also indicated that single copy loss of Socs1 in combination with sustained inflammation is insufficient to start a phenotype resembling early stage mycosis fungoides within eight weeks in these mice. Conclusion: In sum, we developed and optimized an autochthonous murine model permitting selective knockout of Socs1 in skin infiltrating CD4 T-cells. This paves the way for more elaborate experiments to gain insight in the oncogenesis of CTCL.

DOT1L inhibition does not modify the sensitivity of cutaneous T cell lymphoma to pan-HDAC inhibitors in vitro.

Cutaneous T-cell lymphomas (CTCLs) are a subset of T-cell malignancies presenting in the skin. The treatment options for CTCL, in particular in advanced stages, are limited. One of the emerging therapies for CTCL is treatment with histone deacetylase (HDAC) inhibitors. We recently discovered an evolutionarily conserved crosstalk between HDAC1, one of the targets of HDAC inhibitors, and the histone methyltransferase DOT1L. HDAC1 negatively regulates DOT1L activity in yeast, mouse thymocytes, and mouse thymic lymphoma. Here we studied the functional relationship between HDAC inhibitors and DOT1L in two human CTCL cell lines, specifically addressing the question whether the crosstalk between DOT1L and HDAC1 observed in mouse T cells plays a role in the therapeutic effect of clinically relevant broad-acting HDAC inhibitors in the treatment of human CTCL. We confirmed that human CTCL cell lines were sensitive to treatment with pan-HDAC inhibitors. In contrast, the cell lines were not sensitive to DOT1L inhibitors. Combining both types of inhibitors did neither enhance nor suppress the inhibitory effect of HDAC inhibitors on CTCL cells. Thus our in vitro studies suggest that the effect of commonly used pan-HDAC inhibitors in CTCL cells relies on downstream effects other than DOT1L misregulation.

Genetic Stability of Driver Alterations in Primary Cutaneous Diffuse Large B-Cell Lymphoma, Leg Type and Their Relapses: A Rationale for the Use of Molecular-Based Methods for More Effective Disease Monitoring.

Primary cutaneous diffuse large B-cell lymphoma, leg type (PCDLBCL-LT) is a rare, aggressive cutaneous lymphoma with a 5-year disease-specific survival of only ~55%. Despite high response rates to initial immune-polychemotherapy, most patients experience a disease relapse. The genetic evolution of primary and relapsed/refractory disease has only scarcely been studied in PCDLBCL-LT patients. Therefore, in this retrospective cohort study, 73 primary/pre-treatment and relapsed/refractory biopsies of 57 patients with PCDLBCL-LT were molecularly characterized with triple FISH and targeted next-generation sequencing for 52 B-cell-lymphoma-relevant genes, including paired analysis in 16 patients. In this cohort, 95% of patients harboured at least one of the three main driver alterations (mutations in MYD88/CD79B and/or CDKN2A-loss). In relapsed/refractory PCDLBCL-LT, these oncogenic aberrations were persistently present, demonstrating genetic stability over time. Novel alterations in relapsed disease affected mostly CDKN2A, MYC, and PIM1. Regarding survival, only MYC rearrangements and HIST1H1E mutations were statistically significantly associated with an inferior outcome. The stable presence of one or more of the three main driver alterations (mutated MYD88/CD79B and/or CDKN2A-loss) is promising for targeted therapies addressing these alterations and serves as a rationale for molecular-based disease monitoring, improving response evaluation and early identification and intervention of disease relapses in these poor-prognostic PCDLBCL-LT patients.