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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., Competing Interests: Declaration of competing interest Caroline Ram-Wolff : Innate Pharma Adele de Masson, Martine Bagot, Maxime Battistella: Innate Pharma, Takeda, Recordati, Kyowa Kirin Helene Moins-Teisserenc, Armand Bensussan, Jerome Giustiniani, Ingrid Lazaridou: none, (Copyright © 2024 European Federation of Immunological Societies. Published by Elsevier B.V. All rights reserved.)

Background: Vorinostat (SAHA) is a histone deacetylase inhibitor that has shown clinical efficacy against advanced cutaneous T-cell lymphoma (CTCL). However, only a subset of patients with CTCL (30-35%) respond to SAHA and the response is not always sustainable. Thus, understanding the mechanisms underlying evasive resistance in this cancer is an unmet medical need to improve the efficacy of current therapies., Purpose: This study aims to identify factors contributing to resistance against SAHA in CTCL and ways to mitigate it., Methods and Results: In this study, we demonstrated that attenuated reactive oxygen species (ROS) induces the expression of interleukin (IL)-2Rα, one of the IL-2 receptors, which drives resistance to SAHA in CTCL. We also determined that cantharidin could overcome SAHA resistance to CTCL by blocking IL-2Rα-related signaling via ROS-dependent manner. Mechanistically, accelerated translation of IL-2Rα contributes to excessive IL-2Rα protein formation as a result of reduced ROS levels in SAHA-resistant CTCL. At the same time, amplified IL-2R signals are evidenced by strengthened interaction of IL-2Rβ with IL-2Rγ and Janus kinase/signal transducer and activator of transcription molecules, and by increased expression of protein kinase B (AKT)/mTOR and mitogen-activated protein kinase signaling. Moreover, cantharidin, an active constituent of Mylabris used in traditional Chinese medicine, markedly increased ROS levels, and thereby restrained IL-2Rα translation, resulting in suppression of downstream pathways in SAHA-resistant cells. Cantharidin is also found to synergize with SAHA and triggers SAHA-resistant cell death via IL-2R signaling both in vitro and in vivo., Conclusion: Our study uncovers a novel molecular mechanism of acquired SAHA resistance and also suggests that using cantharidin is a potential approach to overcome CTCL therapy resistance. Our findings underlie the therapeutic potential of cantharidin in treating CTCL., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Dysregulated nuclear-cytoplasmic trafficking has been shown to play a role in oncogenesis in several types of solid tumors and hematological malignancies. Exportin 1 (XPO1) is responsible for the nuclear export of several proteins and RNA species, mainly tumor suppressors. KPT-330, a small molecule inhibitor of XPO1, is approved for treating relapsed multiple myeloma and diffuse large B-cell lymphoma. Cutaneous T-cell lymphoma (CTCL) is an extranodal non-Hodgkin lymphoma with an adverse prognosis and limited treatment options in advanced stages. The effect of therapeutically targeting XPO1 with KPT-330 in CTCL has not been established. We report that XPO1 expression is upregulated in CTCL cells. KPT-330 reduces cell proliferation, induces G1 cell cycle arrest and apoptosis. RNA-sequencing was used to explore the underlying mechanisms. Genes associated with the cell cycle and the p53 pathway were significantly enriched with KPT-330 treatment. KPT-330 suppressed XPO1 expression, upregulated p53, p21 WAF1/Cip1 , and p27 Kip1 and their nuclear localization, and downregulated anti-apoptotic protein (Survivin). The in vivo efficacy of KPT-330 was investigated using a bioluminescent xenograft mouse model of CTCL. KPT-330 blocked tumor growth and prolonged survival (p < 0.0002) compared to controls. These findings support investigating the use of KPT-330 and next-generation XPO1 inhibitors in CTCL., (© 2024. The Author(s).)

Cutaneous T cell lymphoma (CTCL) is a varied group of neoplasms that affects the skin. Acquired resistance against chemotherapeutic drugs and associated toxic side effects are limitations that warrant search for novel drugs against CTCL. Embelin (EMB) is a naturally occurring benzoquinone derivative that has gained attention owing to its anticancer pharmacological actions and nontoxic nature. We assessed the anticancer activity of EMB against CTCL cell lines, HuT78, and H9. EMB inhibited viability of CTCL cells in a dose-dependent manner. EMB activated extrinsic and intrinsic pathways of apoptosis as shown by the activation of initiator and executioner caspases. EMB-induced apoptosis also involved suppression of inhibitors of apoptosis, XIAP, cIAP1, and cIAP2. PARP cleavage and upregulation of pH2AX indicated DNA damage induced by EMB. In conclusion, we characterized a novel apoptosis-inducing activity of EMB against CTCL cells, implicating EMB as a potential therapeutic agent against CTCL.

Bexarotene, a drug approved for treatment of cutaneous T-cell lymphoma (CTCL), is classified as a rexinoid by its ability to act as a retinoid X receptor (RXR) agonist with high specificity. Rexinoids are capable of inducing RXR homodimerization leading to the induction of apoptosis and inhibition of proliferation in human cancers. Numerous studies have shown that bexarotene is effective in reducing viability and proliferation in CTCL cell lines. However, many treated patients present with cutaneous toxicity, hypothyroidism, and hyperlipidemia due to crossover activity with retinoic acid receptor (RAR), thyroid hormone receptor (TR), and liver X receptor (LXR) signaling, respectively. In this study, 10 novel analogs and three standard compounds were evaluated side-by-side with bexarotene for their ability to drive RXR homodimerization and subsequent binding to the RXR response element (RXRE). In addition, these analogs were assessed for proliferation inhibition of CTCL cells, cytotoxicity, and mutagenicity. Furthermore, the most effective analogs were analyzed via qPCR to determine efficacy in modulating expression of two critical tumor suppressor genes, ATF3 and EGR3. Our results suggest that these new compounds may possess similar or enhanced therapeutic potential since they display enhanced RXR activation with equivalent or greater reduction in CTCL cell proliferation, as well as the ability to induce ATF3 and EGR3. This work broadens our understanding of RXR-ligand relationships and permits development of possibly more efficacious pharmaceutical drugs. Modifications of RXR agonists can yield agents with enhanced biological selectivity and potency when compared to the parent compound, potentially leading to improved patient outcomes.

Constitutively activated tyrosine kinase JAK3 is implicated in the pathogenesis of cutaneous T-cell lymphomas (CTCL). The mechanisms of constitutive JAK3 activation are unknown although a JAK3 mutation was reported in a small portion of CTCL patients. In this study, we assessed the oncogenic roles of a newly identified JAK3-INSL3 fusion transcript in CTCL. Total RNA from malignant T-cells in 33 patients with Sézary syndrome (SS), a leukemic form of CTCL, was examined for the new JAK3-INSL3 fusion transcript by RT-PCR followed by Sanger sequencing. The expression levels were assessed by qPCR and correlated with patient survivals. Knockdown and/or knockout assays were conducted in two CTCL cell lines (MJ cells and HH cells) by RNA interference and/or CRISPR/Cas9 gene editing. SS patients expressed heterogeneous levels of a new JAK3-INSL3 fusion transcript. Patients with high-level expression of JAK3-INSL3 showed poorer 5-year survival (n = 19, 42.1%) than patients with low-level expression (n = 14, 78.6%). CTCL cells transduced with specific shRNAs or sgRNAs had decreased new JAK3-INSL3 fusion transcript expression, reduced cell proliferation, and decreased colony formation. In NSG xenograft mice, smaller tumor sizes were observed in MJ cells transduced with specific shRNAs than cells transduced with controls. Our results suggest that the newly identified JAK3-INSL3 fusion transcript confers an oncogenic event in CTCL.

Cutaneous T cell lymphoma (CTCL) is a disfiguring and incurable disease characterized by skin-homing malignant T cells surrounded by immune cells that promote CTCL growth through an immunosuppressive tumor microenvironment (TME). Preliminary data from our phase I clinical trial of anti-programmed cell death ligand 1 (anti-PD-L1) combined with lenalidomide in patients with relapsed/refractory CTCL demonstrated promising clinical efficacy. In the current study, we analyzed the CTCL TME, which revealed a predominant PD-1+ M2-like tumor-associated macrophage (TAM) subtype with upregulated NF-κB and JAK/STAT signaling pathways and an aberrant cytokine and chemokine profile. Our in vitro studies investigated the effects of anti-PD-L1 and lenalidomide on PD-1+ M2-like TAMs. The combinatorial treatment synergistically induced functional transformation of PD-1+ M2-like TAMs toward a proinflammatory M1-like phenotype that gained phagocytic activity upon NF-κB and JAK/STAT inhibition, altered their migration through chemokine receptor alterations, and stimulated effector T cell proliferation. Lenalidomide was more effective than anti-PD-L1 in downregulation of the immunosuppressive IL-10, leading to decreased expression of both PD-1 and PD-L1. Overall, PD-1+ M2-like TAMs play an immunosuppressive role in CTCL. Anti-PD-L1 combined with lenalidomide provides a therapeutic strategy to enhance antitumor immunity by targeting PD-1+ M2-like TAMs in the CTCL TME.

Background: Mycosis Fungoides (MF) is a common cutaneous T-cell lymphoma. It can sometimes be challenging to diagnose MF using current clinico-histopathological criteria. Non-invasive molecular profiling analysis has the potential to aid the diagnosis and understanding of MF., Method: Lesional and body site matched normal stratum corneum samples were obtained from the same MF patients (n = 28) using adhesive discs, followed by proteomic analyses using data-independent acquisition mass spectrometry (DIA-MS). Differential abundance analyses and bioinformatic analyses were performed to identify differentially abundant proteins and altered biofunctions between the MF and normal stratum corneum samples., Results: In total, 1303 proteins were identified, of which 290 proteins were significantly changed in the MF cohort compared to the normal stratum corneum. Ingenuity pathway analysis (IPA) predicted the significant inhibition of cell death of cancer cells and significant activation of immune-related activities and viral infection in the MF lesions. MF lesions were also associated with upstream regulators relating to immuno-oncologic dysfunctions. The top-250 variating proteins efficiently separated normal stratum corneum from matched MF samples., Conclusion: Non-invasive proteomic analysis could transform the diagnosis of MF by reducing the need for invasive biopsy. The identification of altered biological functions may serve as useful biomarkers to predict MF progression., (© 2023 The Authors. Proteomics - Clinical Applications published by Wiley-VCH GmbH.)

Aims: The aim was to gain insight into the biology of primary cutaneous CD4 + small/medium T-cell lymphoproliferative disorder (PCSM-LPD)., Methods: We describe the histopathological and clinical characteristics of 177 PCSM-LPD diagnosed at our consultation centre. We performed immunohistochemical multistaining in a subset of cases (n = 46) including PD1, Cyclin D1, and multiple markers of proliferation. We evaluated clonal T-cell-receptor-(TCR) rearrangements and used tissue microdissection to analyse TCR-clonality of PD1(+) cells., Results: The cohort of n = 177 PCSM-LPD included 84 males and 93 females (median age 57, range 13-85). Clinical presentation was as a solitary nodule or plaque (head and neck > trunk > extremities). Most patients were treated by local excision or steroids (96%, 69/72); relapses occurred in 12/65 (18%) of patients with follow up. Histopathology revealed the predominance of a nodular pattern (75%, 134/177) and frequent clustering of PD1(+) large cells (70%, 103/147). We detected Cyclin D1 and PD1 coexpression (>10% of PD1(+)-cells) in 26/46 (57%), which was not associated with CCND1 breaks or amplifications. PD1(+)-cells in PCSM-LPDs showed a significantly higher expression of proliferation-associated proteins compared to PD1(-)-cells. A clonal TCR-rearrangement was present in 176/177 (99%), with a clonal persistence in 7/8 patients at relapse including distant sites. Tissue-microdissection revealed PD1(+)-cells as the source of clonality, whilst PD1(-)-cells remained polyclonal., Conclusion: PCSM-LPD is a clinically indolent, albeit neoplastic, disease driven by clonal expansion of PD1(+)-cells. We demonstrate Cyclin D1-expression associated with accelerated proliferation as a surprising new biological feature of the disease., (© 2022 The Authors. Histopathology published by John Wiley & Sons Ltd.)

Primary cutaneous T-cell lymphomas (CTCLs) constitute a heterogeneous group of non-Hodgkin T-cell lymphomas that present in the skin. In recent years, significant progress has been made in the understanding of the pathogenesis of CTCLs. Progress in CTCL classifications combined with technical advances, in particular next-generation sequencing, enabled a more detailed analysis of the genetic and epigenetic landscape and transcriptional changes in clearly defined diagnostic entities. These studies not only demonstrated extensive heterogeneity between different CTCL subtypes but also identified recurrent alterations that are highly characteristic for diagnostic subgroups of CTCLs. The identified alterations, in particular, involve epigenetic remodeling, cell cycle regulation, and the constitutive activation of targetable oncogenic pathways. In this respect, aberrant JAK-STAT signaling is a recurrent theme; however, it is not universal for all CTCLs and has seemingly different underlaying causes in different entities. A number of the mutated genes identified are potentially actionable targets for the development of novel therapeutic strategies. Moreover, these studies have produced an enormous amount of information that will be critically important for the further development of improved diagnostic and prognostic biomarkers that can assist in the clinical management of patients with CTCL. In the present review, the main findings of these studies in relation to their functional impact on the malignant transformation process are discussed for different subtypes of CTCLs., (© 2022 by The American Society of Hematology.)

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., (© 2021. The Author(s).)

We describe here for the first time a lipid-binding-domain (LBD) in p38γ mitogen-activated protein kinase (MAPK) involved in the response of T cells to a newly identified inhibitor, CSH71. We describe how CSH71, which binds to both the LBD and the ATP-binding pocket of p38γ, is selectively cytotoxic to CTCL Hut78 cells but spares normal healthy peripheral blood mononuclear (PBMC) cells, and propose possible molecular mechanisms for its action. p38γ is a key player in CTCL development, and we expect that the ability to regulate its expression by specifically targeting the lipid-binding domain will have important clinical relevance. Our findings characterize novel mechanisms of gene regulation in T lymphoma cells and validate the use of computational screening techniques to identify inhibitors for therapeutic development., (© 2021 The Authors. FEBS Letters published by John Wiley & Sons Ltd on behalf of Federation of European Biochemical Societies.)

CD147, a transmembrane glycoprotein that belongs to the immunoglobulin superfamily, and cyclophilin A (CypA), one of the binding partners of CD147, are overexpressed in tumor cells and associated with the progression of several malignancies, including both solid and hematological malignancies. However, CD147 and CypA involvement in cutaneous T-cell lymphoma (CTCL) has not been reported. In this study, we examined CD147 and CypA expression and function using clinical samples of mycosis fungoides (MF) and Sézary syndrome (SS) and CTCL cell lines. CD147 and CypA were overexpressed by tumor cells of MF/SS, and CypA was also expressed by epidermal keratinocytes in MF/SS lesional skin. Serum CypA levels were increased and correlated with disease severity markers in MF/SS patients. Anti-CD147 antibody and/or anti-CypA antibody suppressed the proliferation of CTCL cell lines, both in vitro and in vivo, via downregulation of phosphorylated extracellular-regulated kinase 1/2 and Akt. These results suggest that CD147-CypA interactions can contribute to the proliferation of MF/SS tumor cells in both a autocrine and paracrine manner, and that the disruption of CD147-CypA interactions could be a new therapeutic strategy for the treatment of MF/SS.

New treatments are needed for patients with cutaneous T-cell lymphoma (CTCL), particularly for advanced mycosis fungoides (MF) and Sezary syndrome (SS). The immunopathology of MF and SS is complex, but recent advances in tumor microenvironment understanding have identified CCR4 as a promising therapeutic target. CCR4 is widely expressed on malignant T cells and Tregs in the skin and peripheral blood of patients with MF and SS. The interaction of CCR4 with its dominant ligands CCL17 and CCL22 plays a critical role in the development and progression of CTCL, facilitating the movement into, and accumulation of, CCR4-expressing T cells in the skin, and recruiting CCR4-expressing Tregs into the tumor microenvironment. Expression of CCR4 is upregulated at all stages of MF and in SS, increasing with advancing disease. Several CCR4-targeted therapies are being evaluated, including "chemotoxins" targeting CCR4 via CCL17, CCR4-directed chimeric antigen receptor-modified T-cell therapies, small-molecule CCR4 antagonists, and anti-CCR4 monoclonal antibodies. Only one is currently approved: mogamulizumab, a defucosylated, fully humanized, anti-CCR4, monoclonal antibody for the treatment of relapsed/refractory MF and SS. Clinical trial da1ta confirm that mogamulizumab is an effective and well-tolerated treatment for relapsed/refractory MF or SS, demonstrating the clinical value of targeting CCR4., (© 2021 The Authors. European Journal of Immunology published by Wiley-VCH GmbH.)

In cutaneous T cell lymphoma (CTCL), a dominant Th2 profile associated with disease progression has been proposed. Moreover, although the production and regulation of IL-4 expression during the early stages of the disease may have important implications in later stages, these processes are poorly understood. Here, we demonstrate the presence of TOX + CD4 + T cells that produce IL-4 + in early-stage skin lesions of CTCL patients and reveal a complex mechanism by which the NLRP3 receptor promotes a Th2 response by controlling IL-4 production. Unassembled NLRP3 is able to translocate to the nucleus of malignant CD4 + T cells, where it binds to the human il-4 promoter. Accordingly, IL-4 expression is decreased by knocking down and increased by promoting the nuclear localization of NLRP3. We describe a positive feedback loop in which IL-4 inhibits NLRP3 inflammasome assembly, thereby further increasing its production. IL-4 induced a potentially malignant phenotype measured based on TOX expression and proliferation. This mechanism of IL-4 regulation mediated by NLRP3 is amplified in late-stage CTCL associated with disease progression. These results indicate that NLRP3 might be a key regulator of IL-4 expression in TOX + CD4 + T cells of CTCL patients and that this mechanism might have important implications in the progression of the disease., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Huanosta-Murillo, Alcántara-Hernández, Hernández-Rico, Victoria-Acosta, Miranda-Cruz, Domínguez-Gómez, Jurado-Santacruz, Patiño-López, Pérez-Koldenkova, Palma-Guzmán, Licona-Limón, Fuentes-Pananá, Lemini-López and Bonifaz.)

Background: Mycosis fungoides (MF) is a primary cutaneous T-cell lymphoma (CTCL) that transforms from mature, skin-homing T cells and progresses during the early stages in the skin. The role of the skin microenvironment in MF development is unclear, but recent findings in a variety of cancers have highlighted the role of stromal fibroblasts in promoting or inhibiting tumorigenesis. Stromal fibroblasts are an important part of the cutaneous tumor microenvironment (TME) in MF. Here we describe studies into the interaction of TME-fibroblasts and malignant T cells to gain insight into their role in CTCL., Methods: Skin from normal (n = 3) and MF patients (n = 3) were analyzed for FAPα by immunohistochemistry. MyLa is a CTCL cell line that retains expression of biomarkers TWIST1 and TOX that are frequently detected in CTCL patients. MyLa cells were cultured in the presence or absence of normal or MF skin derived fibroblasts for 5 days, trypsinized to detached MyL a cells, and gene expression analyzed by RT-PCR for MF biomarkers (TWIST1 and TOX), Th1 markers (IFNG, TBX21), Th2 markers (GATA3, IL16), and proliferation marker (MKI67). Purified fibroblasts were assayed for VIM and ACTA2 gene expression. Cellular senescence assay was performed to assess senescence., Results: MF skin fibroblast showed increased expression of FAP-α with increasing stage compared to normal. Normal fibroblasts co-cultured with MyLa cells suppressed expression of TWIST1 (p < 0.0006), and TOX (p < 0.03), GATA3 (p < 0.02) and IL16 (p < 0.03), and increased expression of IFNG (p < 0.03) and TBX21 (p < 0.03) in MyLa cells. In contrast, MyLa cells cultured with MF fibroblasts retained high expression of TWIST1, TOX and GATA3. MF fibroblasts co-culture with MyLa cells increased expression of IL16 (p < 0.01) and IL4 (p < 0.02), and suppressed IFNG and TBX21 in MyLa cells. Furthermore, expression of MKI67 in MyLa cells was suppressed by normal fibroblasts compared to MF fibroblasts., Conclusion: Skin fibroblasts represent important components of the TME in MF. In co-culture model, normal and MF fibroblasts have differential influence on T-cell phenotype in modulating expression of Th1 cytokine and CTCL biomarker genes to reveal distinct roles with implications in MF progression.

New therapeutic strategies are needed for cutaneous T-cell lymphoma (CTCL), and the plant extract ingenol mebutate (PEP005) may be considered. PEP005 has been approved for actinic keratosis, and proapoptotic activities were described in different cancer cells. Here, we aimed to investigate its efficacy in four CTCL cell lines and its mode of action. While HuT-78 and HH responded with induced apoptosis as well as with loss of cell viability and cell proliferation, MyLa and SeAx remained resistant. Interestingly, both sensitive and resistant cells showed caspase-8 activation and enhanced levels of reactive oxygen species (ROS), while final caspase-3 activation was restricted to sensitive cells. Apoptosis induction was prevented by the caspase inhibitor QVD-Oph as well as by the antioxidant vitamin E. Caspase activation by PEP005 may be explained to some extent by the downregulation of the caspase antagonistic proteins c-FLIP and XIAP in sensitive cells, whereas both proteins were strongly expressed in resistant cells. Finally, PEP005 resulted in the activation of proapoptotic PKCδ, and the PKC inhibitor bisindolylmaleimide I reduced apoptosis, caspase-3 processing and ROS production, as well as restored cell viability. In conclusion, PKCδ appeared as a central player in apoptosis regulation in CTCL cells, also suggesting its therapeutic targeting.

Background: The surface protein CD30 is a therapeutic target of monoclonal antibody therapy. Knowledge of the frequency of CD30 expression and its prognostic relevance is therefore interesting, not only in lymphoproliferative disorders (LPD) but also in solid tumors of the skin., Methods: A review was completed in PubMed for all published reports of CD30 expression in cutaneous lymphomas, mastocytosis, epithelial tumors and sarcomas from 1982 to April 2019. Only accessible articles in English and German were considered. Entities with an expected CD30 expression, such as CD30-positive LPD, were not evaluated., Results: The electronic research identified 1091 articles and a further 34 articles were obtained from manual bibliographic reference. Overall 91 articles were included that examined CD30 expression in various entities of cutaneous neoplasms and matched the inclusion criteria., Conclusion: Apart from cutaneous CD30-positive LPD, the best-studied group for CD30 expression was mycosis fungoides (MF). CD30 positivity was found in 32% of classical (patch and plaque stage) and in 59.4% cases of transformed MF. CD30 was also frequently expressed in cutaneous mastocytosis (96.5%). In solid tumors, some single reports describe CD30 expression by tumor cells, but CD30-reactive lymphocytes were frequently observed in the tumor microenvironment (TME), especially in keratoacanthoma (KA)., (© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: The combination of JAK/STAT and HDAC inhibitors exerted beneficial effects in haematological malignancies, presenting promising therapeutic CTCL targets. We aim to investigate the efficacy of JAK1/2i ruxolitinib in combination with HDACi resminostat in CTCL in vitro., Material & Methods: Non-toxic concentrations of ruxolitinib and/or resminostat were administered to MyLa (MF) and SeAx (SS) cells for 24h. Cytotoxicity, cell proliferation and apoptosis were estimated through MTT, BrdU/7AAD and Annexin V/PI assay. Multi-pathway analysis was performed to investigate the effect of JAK1/2i and/or HDACi on JAK/STAT, Akt/mTOR and MAPK signalling pathways., Results: Both drugs and their combination were cytotoxic in MyLa (p<0.05) and in SeAx cell line (p<0.001), inhibited proliferation of MyLa (p<0.001) and SeAx (p<0.001) at 24h, compared to untreated cells. Moreover, combined drug treatment induced apoptosis after 24h (p<0.001) in MyLa, and SeAx (p<0.001). The combination of drugs had a strong synergistic effect with a CI<1. Importantly, the drugs' combination inhibited phosphorylation of STAT3 (p<0.001), Akt (p<0.05), ERK1/2 (p<0.001) and JNK (p<0.001) in MyLa, while it reduced activation of Akt (p<0.05) and JNK (p<0.001) in SeAx., Conclusion: The JAKi/HDACi combination exhibited substantial anti-tumor effects in CTCL cell lines, and may represent a promising novel therapeutic modality for CTCL patients., Competing Interests: The authors have declared that no competing interests exist.

The signal transducer and activator of transcription 6 (STAT6) is a critical up-stream mediator of interleukin-13 (IL-13) and IL-4 signaling and is constitutively activated in malignant lymphocytes from Sezary syndrome (SS) and mycosis fungoides (MF), the most common subtypes of cutaneous T-cell lymphomas. By combining genome-wide expression profiling with pharmacological STAT6 inhibition, we have identified the genes regulated by STAT6 in MF/SS tumors. We found that STAT6 regulates several common pathways in MF/SS malignant lymphocytes that are associated with control of cell-cycle progression and genomic stability as well as production of Th2 cytokines. Using ex vivo skin explants from cutaneous MF tumors as well as Sezary cells derived from the blood of SS patients, we demonstrated that inhibition of STAT6 activation downregulates cytokine production and induces cell-cycle arrest in MF/SS malignant lymphocytes, inhibiting their proliferation but not their survival. Furthermore, we show that STAT6 promotes the protumoral M2-like phenotype of tumor-associated macrophages in the tumor microenvironment of advanced stage MF by upregulating the expression of genes associated with immunosuppression, chemotaxis, and tumor matrix remodeling. Thus, we show STAT6 to be a major factor in the pathogenesis and progression of MF/SS, promoting proliferation and invasion of the malignant lymphocytes while inducing a progressive depression of the antitumor immune response. Together, our results provide new insights into disease pathogenesis and offer new prospective targets for therapeutic intervention., (© 2020 by The American Society of Hematology.)

Background: Systemic chemotherapy is often the last resort of advanced cutaneous T-cell lymphoma (CTCL). Tumor recurrence and adverse effects of systemic chemotherapy are the main limitations., Objective: We aim to investigate the metabolic alterations in tumor cells after CHOP (cyclophosphamide, hydroxydaunorubicin, oncovin and prednisone) chemotherapy., Methods and Results: In advanced CTCL, CHOP chemotherapy has no survival benefit and the duration of response is significantly inferior to other canonical treatments. HIF-1α is significantly elevated in lesions of advanced MF patients as well as tumor cell line Hut78 and tumor xenograft mice model. CHOP therapy also increased glycolytic activities in a HIF-1α-dependent manner. In CTCL xenograft tumor mice model, lesional cells showed a significant increase in IL-17F after chemotherapy, shifting toward a Th17 phenotype, which process is also regulated by HIF-1α. Echinomycin, HIF-1α inhibitor, was co-administered in xenograft tumor mouse models with CHOP and showed a significant reduction in tumor growth., Conclusion: CHOP chemotherapy promotes glycolysis and IL-17 pathways in a HIF-1α-dependent fashion. Furthermore, HIF-1α blockade is promising as an accompanying agent in systemic chemotherapy for patients with advanced CTCL., (© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

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., (© 2020 Japanese Society of Pathology and John Wiley & Sons Australia, Ltd.)

Tumor-associated macrophages (TAMs) recruited from blood monocytes are key in establishing an immunosuppressive tumor microenvironment (TME) for the support of tumor growth. We hypothesize that blocking monocyte trafficking (through the inhibition of specific chemokine receptors) into skin can positively affect tumor development. Herein, the authors examined the effects of oral administration of a small molecule inhibitor for CCR2, CCR2i, which blocks CCR2-mediated chemotaxis of monocytes in a syngeneic mouse T-cell lymphoma in skin. Following CCR2i administration, the depletion of macrophages was achieved as early as 2 days after tumor initiation in ear TME. Quantitative real-time PCR detected an increase in the levels of immune stimulatory inflammatory cytokines, for example, IFN-γ and IL-12, in CCR2i- versus vehicle-treated mice. Within 2 weeks, the tumors from the control groups attained the maximum size, whereas CCR2i-treated mice exhibited much smaller tumor sizes and weights. Immunohistochemistry revealed that CCR2i-treated tumors possessed considerably more CD8+ T cells, which demonstrated their essential role in CCR2i-induced tumor inhibition. Finally, the combination of anti-programmed cell death protein 1 with CCR2i considerably increased the efficacy of tumor eradication related to the activation of IFN-γ-producing CD8 T cells. Our findings provide strong evidence that the CCR2i, particularly in combination with an immune checkpoint inhibitor, reduces tumor growth and is a potential future treatment option for cutaneous T-cell lymphomas., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)

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.

YKL-40, one of the chitinase-like proteins, is associated with the pathogenesis of a wide variety of human diseases through modulation of inflammation and tissue remodeling by its diverse roles in cell proliferation, differentiation, and survival. Emerging evidence shows that aberrantly expressed YKL-40 promotes the development of malignancies by inducing proliferation of tumor cells, cytokine production, and angiogenesis by acting on various stromal cells, immune cells, and tumor cells. In this study, we investigated the expression and function of YKL-40 in cutaneous T-cell lymphoma (CTCL). We first revealed that serum YKL-40 levels were increased in patients with CTCL and correlated with disease severity markers. We also found that YKL-40 was expressed by epidermal keratinocytes and tumor cells in lesional skin of CTCL by immunohistochemistry. Although YKL-40 did not affect cytokine production from CTCL cell lines, YKL-40 promoted the proliferation of Hut78 cells and HH cells in vitro, which was dependent on extracellular signal-regulated kinase 1/2 pathways. Moreover, exogenous YKL-40 administration enhanced tumor growth of HH cells in vivo. Our study has suggested that YKL-40 produced from epidermal keratinocytes and CTCL cells promoted the proliferation of CTCL cells through extracellular signal-regulated kinase 1/2 pathways in autocrine and paracrine manners, leading to development of CTCL., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)

Cutaneous T cell lymphoma (CTCL) is a rare malignancy of skin-homing T lymphocytes. Advances in whole exome sequencing have identified a vast number of both single nucleotide variants (SNVs) and genomic copy number alterations (GCNAs) as driver mutations present in CTCL cells. These alterations cluster within several key pathways - T cell/NF-κB/JAK-STAT activation, cell cycle dysregulation/apoptosis, and DNA structural dysregulation affecting gene expression - allowing the maintenance of a population of proliferating, activated malignant T lymphocytes. While much of the clinical spectrum, genetic alterations, and oncogenic behavior of CTCL have been elucidated, little is known about the etiology that underlies CTCL malignant transformation and progression. Herein, we review the epidemiology, clinical presentation, and pathophysiology of CTCL to provide a perspective on CTCL pathogenesis. We outline a series of alterations by which mature, activated T lymphocytes are endowed with apoptosis resistance and cutaneous persistence. Subsequent genomic alterations including the loss of chromosomal structural controls further promote proliferation and constitutive T cell activation. CTCL cells are both malignant cells and highly functional T cells that can have major cutaneous and immunologic effects on the patient, including the suppression of cell-mediated immunity that facilitates malignant cell expansion. A deeper understanding of the molecular and cellular underpinnings of CTCL can help guide clinical management as well as inform prognosis and therapeutic discovery., (Copyright ©2020, Yale Journal of Biology and Medicine.)

The skin barrier defect in cutaneous T-cell lymphomas (CTCL) was recently confirmed to be similar to the one observed in atopic dermatitis (AD). We have examined the expression level of cornified envelope (CE) proteins in CTCL, AD and healthy skin, to search for the differences and their relation to the courses of both diseases. The levels of FLG, FLG2, RPTN, HRNR, SPRR1A, SPRR1B, SPRR3 and LELP-1 mRNA were determined by qRT-PCR, while protein levels were examined using the ELISA method in skin samples. We have found that mRNA levels of FLG, FLG2, LOR, CRNN and SPRR3v1 were decreased ( p ≤ 0.04), whereas mRNA levels of RPTN, HRNR and SPRR1Av1 were increased in lesional and nonlesional AD skin compared to the healthy control group ( p ≤ 0.04). The levels of FLG, FLG2, CRNN, SPRR3v1 mRNA increased ( p ≤ 0.02) and RPTN, HRNR and SPRR1Av1 mRNA decreased ( p ≤ 0.005) in CTCL skin compared to the lesional AD skin. There was a strong correlation between the stage of CTCL and increased SPRR1Av1 gene expression at both mRNA (R = 0.89; p ≤ 0.05) and protein levels (R = 0.94; p ≤ 0.05). FLG, FLG2, RPTN, HRNR and SPRR1A seem to play a key role in skin barrier dysfunction in CTCL and could be considered a biomarker for differential diagnosis of AD and CTCL. SPRR1Av1 transcript levels seem to be a possible marker of CTCL stage, however, further studies on a larger study group are needed to confirm our findings.

Introduction : The cutaneous lymphocyte antigen interacts with E-selectin on endothelial cells and is expressed on 15% of circulating T-cells. Skin-homing T-cells express the cutaneous lymphocyte antigen and play a role in local cutaneous immunity in inflammatory reactions and neoplastic conditions. Areas covered : Lymphocyte extravasation is the essential para-physiological mechanism enabling immune surveillance of tissues for tumors as well as effector cell recruitment to inflammatory sites.The authors focused on skin inflammatory disorders, on cutaneous lymphoproliferative disease, and on other skin malignancies. Expert opinion : Interfering with leukocyte extravasation has been regarded as an attractive strategy in skin disorders, in the past for inflammatory conditions and more recently for cutaneous T-cell lymphomas. Therapeutic blocking of skin-homing interactions has been attempted in psoriasis and atopic dermatitis and has been achieved in the treatment of cutaneous T-cell lymphomas. Cutaneous lymphocyte antigen is a potential molecular target for both systemic and skin-directed therapy for cutaneous T-cell lymphomas.

Background: The voltage-gated potassium channel Kv1.3 (KCNA3) is expressed by effector memory T cells (TEM) and plays an important role in their activation and proliferation. Mycosis fungoides (MF), the most common subtype of cutaneous T-cell lymphoma (CTCL), was recently proposed to be a malignancy of skin-resident TEM. However, the expression of Kv1.3 in CTCL has not been investigated., Objectives: This study aims to examine the expression of Kv1.3 in situ and in vitro in CTCL., Methods: The expression of Kv1.3 was examined by immunohistochemistry in skin lesions from 38 patients with MF, 4 patients with Sézary syndrome (SS), and 27 patients with benign dermatosis. In 4 malignant T-cell lines of CTCL (Myla2059, PB2B, SeAx, and Mac2a) and a non-malignant T-cell line (MyLa1850), the expression of Kv1.3 was determined by flow cytometry. The proliferation of those cell lines treated with various concentrations of Kv1.3 inhibitor ShK was measured by 3H-thymdine incorporation., Results: Half of the MF patients (19/38) displayed partial Kv1.3 expression including 1 patient with moderate Kv1.3 positivity, while the other half (19/38) exhibited Kv1.3 negativity. An almost identical distribution was observed in patients with benign conditions, that is, 44.4% (12/27) were partially positive for Kv1.3 including 1 patient with moderate Kv1.3 positivity, while 55.6% (15/27) were Kv1.3 negative. In contrast, 3 in 4 SS patients displayed partial Kv1.3 positivity including 2 patients with weak staining and 1 with moderate staining, while 1 in 4 SS patients was Kv1.3 negative. In addition, all malignant T-cell lines, and a non-malignant T-cell line, displayed low Kv1.3 surface expression with a similar pattern. Whereas 2 cell lines (PB2B and Mac2a) were sensitive to Kv1.3 blockade, the other 2 (Myla2059 and SeAx) were completely resistant., Conclusions: We provide the first evidence of a heterogeneous Kv1.3 expression in situ in CTCL lesions., (© 2019 S. Karger AG, Basel.)

Aims: Patients with aggressive CD8+ cutaneous T-cell lymphomas (CTCLs) progress rapidly and respond poorly to therapy. Confounding treatment planning, there is clinicopathological overlap between aggressive CD8+ CTCLs and other lymphoproliferative disorders (LPDs). Hence, improved diagnostic methods and therapeutic options are needed. The aim of this study was to examine C-C chemokine receptor 4 (CCR4) expression as a diagnostic and therapeutic biomarker in CD8+ CTCLs/LPDs., Methods and Results: Forty-nine cases (41 patients) with CD8+ CTCLs/LPDs were examined, including CD8+ mycosis fungoides (MF) (n = 14), aggressive epidermotropic CD8+ cytotoxic T-cell lymphoma (AETCL) (n = 8), subcutaneous panniculitis-like T-cell lymphoma (SPTCL) (n = 7), CD30+ LPDs (n = 6), primary cutaneous γδ T-cell lymphoma (GDTCL) (n = 6), and others (n = 8). Immunohistochemical tissue staining was performed with a CCR4 monoclonal antibody on formalin-fixed paraffin-embedded tissue sections. CCR4 immunostaining was graded as percentage infiltrate, i.e. high (>25%) and low (≤25%), and the results were correlated with clinicopathological diagnoses. CCR4 expression was seen in 69% of the studied cases. Any CCR4 positivity was seen in all CD8+ MF cases, in 83% of CD30+ LPD cases, in 75% of AETCL cases, in 33% of GDTCL cases, and in none of the SPTCL cases. High CCR4 expression was seen in 79% of CD8+ MF cases versus 33% of CD30+ LPD cases, in 17% of GDTCL cases, and in 12.5% of AETCL cases. Patients with more advanced MF stage had higher CCR4 expression., Conclusions: CCR4 immunohistochemistry may be an adjunct in distinguishing advanced CD8+ MF from other CD8+ CTCLs/LPDs. Although CCR4 expression may justify therapeutic targeting of this receptor in CD8+ MF, the role of such therapies in other CD8+ CTCLs/LPDs is not yet clear., (© 2019 John Wiley & Sons Ltd.)

IL-2R pathway is a key regulator in the development of immune cells and has emerged as a promising drug target in cancer treatment, but there is a scarcity of related inhibitors. TPD7 is a novel biphenyl urea taspine derivate, which has been shown anti-cancer effect. Here, we demonstrated the anti-cancer activity of TPD7 in cutaneous T cell lymphoma and investigated the underlying mechanism of TPD7 through IL-2R signalling. The inhibitory effect of TPD7 on cell viability exhibited a strong correlation with the expression level of IL-2R, and cutaneous T cell lymphoma H9 and HUT78 cells were most sensitive to TPD7. TPD7 was nicely bound to IL-2R and down-regulated the mRNA and protein levels of IL-2R. Furthermore, TPD7 suppressed the downstream cascades of IL-2R including JAK/STAT, PI3K/AKT/mTOR and PLCγ/Raf/MAPK signalling, resulting in Bcl-2 mitochondrial apoptosis pathway and cell cycle proteins CDK/Cyclins regulation. And, these were verified by flow cytometry analysis that TPD7 facilitated cell apoptosis in H9 cells via mitochondrial pathway and impeded cell cycle progression at G2/M phase. TPD7 is a novel anti-cancer agent and may be a potential candidate for cutaneous T cell lymphoma treatment by regulating IL-2R signalling pathway., (© 2019 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.)

Background: Galectin-9, a member of the galectin family, can promote tumor growth through inducing apoptosis in anti-tumor immune cells via T cell immunoglobulin and mucin domain 3 (TIM-3). On the other hand, galectin-9 also induces tumor cell apoptosis in many malignancies and thought to have potential as an anti-cancer agent., Objective: To examine the expression and therapeutic applicability of galectin-9 in cutaneous T-cell lymphoma (CTCL)., Methods: Galectin-9 expression in lesional skin and sera was measured using CTCL samples. The effect of galectin-9 on CTCL cell lines was investigated in vitro. We also examined effect of galectin-9 on tumor growth of CTCL cells in immune-deficient mice. Moreover, we examined the efficacy of galectin-9, anti-TIM-3 blocking antibody, or their combination on tumor growth of EL-4 cells in wild-type mice., Results: Galectin-9 was expressed on tumor cells in lesional skin of CTCL and the expression levels were associated with decreased CD8 + T-cell infiltration. Serum galectin-9 levels were correlated with disease severity markers. High-dose galectin-9 induced cell death of CTCL cell lines through activation of caspase-3 and caspase-9, independently of TIM-3. High-dose galectin-9 suppressed the growth of CTCL cells and EL-4 cells in vivo. Furthermore, additional anti-TIM-3 blocking antibody administration to galectin-9 achieved greater inhibition of tumor growth compared to single administration., Conclusion: Galectin-9 expression on tumor cells may be associated with CTCL progression through attenuating anti-tumor immunity. On the other hand, exogenous high-dose galectin-9 administration can be a therapeutic strategy for CTCL and anti-TIM-3 blocking antibody can augment the efficacy of galectin-9., (Copyright © 2019 Japanese Society for Investigative Dermatology. Published by Elsevier B.V. All rights reserved.)

Aims: Brentuximab vedotin is a monoclonal anti-CD30 antibody-drug conjugate that has been used to treat a variety of CD30+ neoplasms. The phenomenon of antigen loss has been observed in patients treated with the anti-CD20 antibody rituximab. This study seeks to assess for antigen loss in the setting of recurrent CD30+ neoplasms treated with brentuximab vedotin., Methods: We report nine cases of persistent/recurrent cutaneous CD30+ lymphoid neoplasms that demonstrated variable CD30 expression after treatment with brentuximab vedotin. Cases include MF (n = 6), cutaneous T-cell lymphoma, not otherwise specified (n = 1), and anaplastic large cell lymphoma (ALCL), both primary (n = 1) and systemic (n = 1)., Results: Immunohistochemical staining revealed decreased CD30 expression following brentuximab vedotin therapy in seven of nine cases. In these seven cases, the pre-treatment percent of tumor cells staining for CD30 ranged from 10% to 100% (mean 50.0%, SD 27.8%), compared to 5% to 50% (mean 14.5%, SD 14.8%, P = 0.003) at recurrence., Conclusions: This case series highlights the finding that CD30 positivity can be variable in recurrences after treatment with anti-CD30 antibodies. This serves to raise awareness of the phenomenon of antigen loss after treatment with brentuximab vedotin and underscores the utility of performing multiple biopsies and/or employing molecular diagnostic techniques in patients with recurrent/persistent disease., (© 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Cell adhesion molecule 1 (CADM1) is aberrantly expressed by T-cell neoplasms such as adult T-cell leukemia/lymphoma (ATLL) and mycosis fungoides (MF). We studied the expression of CADM1 and its splicing variants in Sézary syndrome (SS), MF, other cutaneous T-cell lymphoma (CTCL), and cell lines derived from T- and B-cell lymphomas. Soluble CADM1 was measured in the patients' sera. CADM1+ cells in the blood and skin lesions were examined by flow cytometry and immunostaining, respectively. Soluble CADM1 was measured by ELISA, and the splicing variants of CADM1 transcripts were determined by reverse transcriptase-polymerase chain reaction, followed by sequencing. As a result, circulating CADM1+ cells were significantly increased in seven out of 10 patients with SS, ranging from 7.9% to 74.5% of the CD3+CD4+ fractions (median 33.7%; cut-off value 6.5%). The percentages of CADM1+ cells were usually less than those of circulating Sézary cells. CADM1 was expressed, to various degrees, in six of nine T-cell lines derived from SS, MF, ATLL, and anaplastic large cell lymphoma (ALCL), but negative in B-cell lymphoma-derived cell lines. CADM1+ cells were present in the skin infiltrates of MF, SS, ATLL and ALCL. Serum levels of soluble CADM1 were not significantly elevated in SS/MF. Three major splicing variants of CADM1 expressed by neoplastic T-cells contained different combinations of the exons 7, 8, 9 and 11, including a putative oncogenic variant composed of exons 7-8-9-11. In conclusion, CADM1 is frequently expressed in Sézary cells and cell lines from CTCL., (© 2019 Japanese Dermatological Association.)

It has been proposed that CD4 T-cell responses to Staphylococcus aureus (SA) can inadvertently enhance neoplastic progression in models of skin cancer and cutaneous T-cell lymphoma (CTCL). In this prospective study, we explored the effect of transient antibiotic treatment on tumor cells and disease activity in 8 patients with advanced-stage CTCL. All patients experienced significant decrease in clinical symptoms in response to aggressive, transient antibiotic treatment. In some patients, clinical improvements lasted for more than 8 months. In 6 of 8 patients, a malignant T-cell clone could be identified in lesional skin, and a significant decrease in the fraction of malignant T cells was observed following antibiotics but an otherwise unchanged treatment regimen. Immunohistochemistry, global messenger RNA expression, and cell-signaling pathway analysis indicated that transient aggressive antibiotic therapy was associated with decreased expression of interleukin-2 high-affinity receptors (CD25), STAT3 signaling, and cell proliferation in lesional skin. In conclusion, this study provides novel evidence suggesting that aggressive antibiotic treatment inhibits malignant T cells in lesional skin. Thus, we provide a novel rationale for treatment of SA in advanced CTCL.

Therapeutic options for cutaneous T-cell lymphoma (CTCL) are limited and curative treatment regimens are not available. Thus, new targeted and well-tolerated therapeutic approaches are urgently needed. In this respect, we have recently shown that dimethyl fumerate (DMF) inhibits NF-κB acting as a survival factor in CTCL. Similarly, inhibition of the antiapoptotic protein B-cell lymphoma 2 (Bcl-2) has been shown to induce cell death in CTCL especially when combined with histone deacetylase inhibitors. Therefore, we hypothesized that inhibition of Bcl-2 should potentiate NF-κB inhibition in a novel combination treatment of CTCL. We show that, in vitro, the Bcl-2 inhibitors ABT-199 and ABT-263 induced specific cell death in primary CD4 + cells from CTCL patients as well as in the CTCL cell line SeAx, but not in T cells of healthy donors nor in the CTCL cell line HH, which lacks Bcl-2. Combined treatment with ABT-199 and DMF caused synergistic cell death specifically in CTCL cells engaging 2 independent signaling pathways. To verify these findings in vivo, we performed combined ABT-199 and DMF treatment in a xenograft mouse model for CTCL. The combined treatment effectively reduced tumor growth and increased overall survival via synergistic induction of CTCL cell death and suppression of tumor cell proliferation. Essentially, the combination treatment was superior to ABT-199 monotherapy with respect to both efficacy and tolerability. To sum up, our data provide proof of principle for the therapeutic potential of combining Bcl-2 and NF-κB inhibitors in treating CTCL. Next, this potential should be explored further in a clinical study., (© 2019 by The American Society of Hematology.)

Background: Treatment for Cutaneous T Cell Lymphoma (CTCL) is generally not curative. Therefore, selecting therapy that is effective and tolerable is critical to clinical decision-making. Histone deacetylase inhibitors (HDACi), epigenetic modifier drugs, are commonly used but effective in only ~30% of patients. There are no predictive markers of HDACi response and the CTCL histone acetylation landscape remains unmapped. We sought to identify pre-treatment molecular markers of resistance in CTCL that progressed on HDACi therapy., Methods: Purified T cells from 39 pre/post-treatment peripheral blood samples and skin biopsies from 20 patients were subjected to RNA-seq and ChIP-seq for histone acetylation marks (H3K14/9 ac, H3K27ac). We correlated significant differences in histone acetylation with gene expression in HDACi-resistant/sensitive CTCL. We extended these findings in additional CTCL patient cohorts (RNA-seq, microarray) and using ELISA in matched CTCL patient plasma., Findings: Resistant CTCL exhibited high levels of histone acetylation, which correlated with increased expression of 338 genes (FDR < 0·05), including some novel to CTCL: BIRC5 (anti-apoptotic); RRM2 (cell cycle); TXNDC5, GSTM1 (redox); and CXCR4, LAIR2 (cell adhesion/migration). Several of these, including LAIR2, were elevated pre-treatment in HDACi-resistant CTCL. In CTCL patient plasma (n = 6), LAIR2 protein was also elevated (p < 0·01) compared to controls., Interpretation: This study is the first to connect genome-wide differences in chromatin acetylation and gene expression to HDACi-resistance in primary CTCL. Our results identify novel markers with high pre-treatment expression, such as LAIR2, as potential prognostic and/or predictors of HDACi-resistance in CTCL., Funding: NIH:CA156690, CA188286; NCATS: WU-ICTS UL1 TR000448; Siteman Cancer Center: CA091842., (Copyright © 2019. Published by Elsevier B.V.)

Context.—: The evaluation of cutaneous lymphoid infiltrates, both neoplastic and inflammatory, occurs very frequently in routine dermatopathologic examination and consultation practices. The "tough" cutaneous lymphoid infiltrate is feared by many pathologists; skin biopsies are relatively small, whereas diagnostic possibilities are relatively broad. It is true that cutaneous lymphomas can be difficult to diagnose and that in many circumstances multiple biopsies are required to establish a correct diagnostic interpretation. As a reminder, one should understand that low-grade cutaneous lymphomas are indolent disorders that usually linger for decades and that therapy does not result in disease cure. It is also important to remember that in most circumstances, those patients will die from another process that is completely unrelated to a diagnosis of skin lymphoma (even in the absence of specific therapy)., Objective.—: To use a clinicopathologic, immunophenotypic, and molecular approach in the evaluation of common lymphocytic infiltrates., Data Sources.—: An in-depth analysis of updated literature in the field of cutaneous lymphomas was done, with particular emphasis on updated terminology from the most recent World Health Organization classification of skin and hematologic tumors., Conclusions.—: A diagnosis of cutaneous lymphoid infiltrates can be adequately approached using a systematic scheme following the proposed ABCDE system. Overall, cutaneous T- and B-cell lymphomas are rare and "reactive" infiltrates are more common. Evaluation of lymphoid proliferations should start with a good sense of knowledge of the clinical presentation of the lesions, the clinical differential considerations, and a conscientious and appropriate use of immunohistochemistry and molecular tools.

Cutaneous T-cell lymphoma (CTCL) is associated with the downregulation of miR-337 expression, although the exact underlying mechanism is unknown. In the present work, we investigated the molecular mechanism and function of miR-337 in regulating CTCL cell viability and invasion. We observed that miR-337 expression was downregulated in both CTCL tumors and cell lines. Furthermore, CCK assay, BrdU incorporation assay, and flow cytometry revealed that transfection with the miR-337 mimic resulted in decreased proliferation and increased apoptotic levels in CTCL cells. Results of the Transwell migration assay indicated that the miR-337 mimic decreased CTCL cell invasion in vitro . Both bioinformatics prediction and the dual-luciferase reporter assay revealed that miR-337 targets the 3'-UTR of STAT3 for silencing. Overexpression of STAT3 counteracted the pro-apoptotic influence of miR-337 in CTCL cell lines and restored their invasion properties. The results thus indicate that the miR-337-STAT3 axis inhibits the proliferation of malignant T cells and that miR-337 may serve as a promising therapeutic target for CTCL.

Background: Mycosis fungoides (MF) is indolent, but may disseminate to leukemia. We reported that C-C motif chemokine ligand 21 (CCL21) is associated with MF invasion and progression. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), a long noncoding RNA, is associated with several cancer types, however, how it interacts with CCL21 to regulate MF progression, remains unclear., Materials and Methods: Expression of long noncoding RNAs MALAT1, antisense noncoding RNA in the INK4 locus (ANRIL), Hox antisense intergenic RNA (HOTAIR), highly up-regulated in liver cancer RNA (HULC), and leukemia-associated non-coding insulin-like growth factor 1 receptor activator RNA 1 (LUNAR1) in tissues from MF was studied using polymerase chain reaction and RNA interference in MF cell line MyLa were used to address this question., Results: Expression of MALAT1 was selectively increased in MF tissues. C-C Chemokine receptor type 7 (CCR7) expression was found to be increased in MyLa cells. CCL21 was found not only to mediate migration, but also to enhance MALAT1 and mammalian target of rapamycin (mTOR) activation in MyLa cells. Knockdown of MALAT1 abrogated CCL21-mediated migration, but not mTOR activation. In contrast, mTOR inhibition reduced CCL21-mediated migration and MALAT1 expression., Conclusion: CCL21 induced mTOR activation in MyLa cells, followed by expression of MALAT1, causing cell migration. MALAT1 and mTOR are potential therapeutic targets for MF., (Copyright© 2019, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

A crucial question pertains to a role of IL-10 as a tumorigenic factor, or just a marker of advanced disease in cutaneous T-cell lymphoma (CTCL). Herein, we measured significantly elevated IL-10 mRNA in a cohort of skin samples of patients with CTCL. Increased IL-10 was also detected in the tumor microenvironment of an established inflammation-dependent murine model of using MBL2 T lymphoma cells. Conditioned media from MBL2 cells was able to stimulate IL-10 production in bone marrow-derived macrophages in an IL-4-dependent manner. Implanted MBL2 T-cell lymphomas in IL-10KO mice were 50% smaller, accompanied by decreased numbers of infiltrating macrophages and reduced efficiency of M2-polarization compared with wild-type mice. With anti-IL-10R mAb treatment, both wild-type tumor-bearing mice and IL-10KO mice exhibited a further growth inhibition. Our data indicate that targeting IL-10 signaling with neutralizing antibodies to IL-10 or its receptor may have a great potential for advanced CTCL therapy.