Recent advances in primary cutaneous T-cell lymphoma

Cutaneous T-Cell Lymphoma and Microbiota: Etiopathogenesis and Potential New Therapeutic Targets

Objective

To review the scientific literature related to human microbiota and cutaneous T-cell lymphoma. Methodology. An exploratory and systematic review of the articles retrieved from the bibliographic databases MEDLINE (PubMed), Embase, The Cochrane Library, and Scopus, published in the last 10 years with the following descriptors: "lymphoma, T-cell, cutaneous," "microbiota," "Mycosis Fungoides," "Sézary Syndrome," "lymphoma, primary cutaneous anaplastic large cell," "Lymphomatoid Papulosis" and "Microbiota," "microbiota," "Microbial Community," and "Microbial Communities."

Results

Of the 87 references retrieved, after applying the inclusion and exclusion criteria, 21 articles were selected. Most studies linking cutaneous T-cell lymphoma and the microbiota focus on the cutaneous microbiome, with Staphylococcus aureus being the main related agent. Skin colonization by this bacterium could be involved in the hyperactivation of the STAT3 inflammatory pathway and in the overproduction of IL-17, both of which are widely related to the development of more aggressive and advanced forms of cutaneous T-cell lymphoma. We also found evidence of a possible relationship between intestinal dysbiosis and the development of cutaneous T-cell lymphoma, observing a decrease in taxonomic variability and an increase in certain genera such as Prevotella in the intestinal microbiome of patients with cutaneous T-cell lymphoma. The possible etiopathogenic mechanism underlying this relationship could be explained by an increase in systemic cytokine release, promoting the hyperactivation of STAT3 at the skin level.

Conclusion

There appears to be a relationship between cutaneous T-cell lymphoma and the cutaneous and intestinal microbiome, as well as a possible pathophysiological pathway involved. The possible modulation of the cutaneous and intestinal microbiome or the action on the signaling inflammatory pathway, using pharmacological tools such as JAK inhibitors or IL-17 inhibitors in the latter case, could open the possibility for future therapeutic studies for cutaneous T-cell lymphoma.

Mechanism of action of chlormethine gel in mycosis fungoides

Mycosis fungoides (MF), the most common type of cutaneous T-cell lymphoma, is characterized by proliferation of malignant skin-tropic T cells. Progression from early-stage disease (skin patches and/or plaques) to more advanced stages (cutaneous tumours, erythroderma or extracutaneous involvement) occurs slowly and can be discontinuous. Prognosis is poor for the ~25% of patients who progress to advanced disease. Patients at any stage of MF may experience reduced health-related quality of life (QoL) via a spectrum of physically and psychologically debilitating symptoms that can impact many aspects of daily life. Allogeneic stem-cell transplantation is a curative treatment option for some patients with advanced disease, but otherwise there is currently no cure for MF; patients are often refractory to several treatments and require lifelong management. The goals of therapy are symptom control, prevention of disease progression, avoidance of treatment-related toxicity and maintenance/improvement of QoL. Although treatment regimens exist it can be difficult to know how to prioritize them, hence therapies are tailored according to patient needs and drug availabilities, following clinical recommendations. International consensus guidelines recommend skin-directed therapies (SDTs) as first-line treatment for early-stage disease, and SDTs combined with systemic therapy for advanced stages. Chlormethine (CL), also known as mechlorethamine, chlorethazine, mustine, HN2, caryolysine and embichin, is a synthetic deoxyribonucleic acid-alkylating agent that was used as a chemical weapon (mustard gas) during the First World War. Subsequent investigation revealed that survivors of mustard gas exposure had lymphocytopenia, and that CL could inhibit rapidly proliferating malignant T cells. CL has since been developed as a topical treatment for MF and prescribed as such for over 70 years. This review aims to summarize the current knowledge regarding the mechanism of action of CL in the cutaneous micro-environment, in the specific context of MF treatment.

The Role of Tumor Microenvironment in the Pathogenesis of Sézary Syndrome

Sézary syndrome is an aggressive leukemic variant of cutaneous T-cell lymphomas, characterized by erythroderma, lymphadenopathy, and peripheral blood involvement by CD4+ malignant T-cells. The pathogenesis of Sézary syndrome is not fully understood. However, the course of the disease is strongly influenced by the tumor microenvironment, which is altered by a combination of cytokines, chemokines, and growth factors. The crosstalk between malignant and reactive cells affects the immunologic response against tumor cells causing immune dysregulation. This review focuses on the interaction of malignant Sézary cells and the tumor microenvironment.

Increased Chlormethine-Induced DNA Double-Stranded Breaks in Malignant T Cells from Mycosis Fungoides Skin Lesions

Mycosis fungoides (MF) is a type of cutaneous T-cell lymphoma. Chlormethine (CL) is recommended as first-line therapy for MF, with a major purpose to kill tumor cells through DNA alkylation. To study the extent of treatment susceptibility and tumor specificity, we investigated the gene expression of different DNA repair pathways, DNA double-stranded breaks, and tumor cell proliferation of clonal TCR Vβ+ tumor cell populations in cutaneous T-cell lymphoma skin cells on direct exposure to CL. Healthy human T cells were less susceptible to CL exposure than two T-lymphoma cell lines, resulting in higher proportions of viable cells. Interestingly, in T cells from MF lesions, we observed a downregulation of several important DNA repair pathways, even complete silencing of RAD51AP1, FANC1, and BRCA2 involved in homologous recombination repair. In the presence of CL, the double-stranded DNA breaks in malignant MF skin T cells increased significantly as well as the expression of the apoptotic gene CASP3. These data point toward an important effect of targeting CL on MF skin tumor T cells, which support CL use as an early cutaneous lymphoma treatment and can be of synergistic use, especially beneficial in the setting of combination skin-directed therapies for cutaneous T-cell lymphoma.

Mycosis fungoides and Sézary syndrome

Mycosis fungoides (MF) and Sézary syndrome (SS) are primary cutaneous T-cell lymphomas (CTCL) with not yet fully understood etiology and pathogenesis. Conceptually, MF and SS are classified as distinct entities arising from different T helper cell subsets. MF is the most common CTCL entity, while SS is very rare. MF presents clinically with patch, plaque and/or tumor stages, but can also evolve as erythroderma, which in turn is pathognomonic for SS. SS is characterized by a detectable tumor-cell burden (Sézary cells) in the peripheral blood consistent with advanced-stage disease and a poor prognosis. In early-stage disease of MF, which is the predominant form, the prognosis is generally favorable. However, in up to 30 % of patients, there is progression of skin lesions, which can ultimately lead to visceral involvement. The histological manifestation of MF can be subtle in early-stage disease and therefore a careful clinicopathological correlation is paramount. The treatment of MF/SS is dependent on the disease stage. Therapeutic options include both skin-directed and systemic regimens. Apart from allogeneic stem cell transplantation (alloSCT), there is as yet no curative therapy for MF/SS. Accordingly, the treatment approach is symptom oriented and aims to reduce the tumor burden and improve health-related quality of life. However, the therapeutic landscape for CTCL is constantly being expanded by the discovery of novel therapeutic targets.

Chlormethine Gel for the Treatment of Skin Lesions in All Stages of Mycosis Fungoides Cutaneous T-Cell Lymphoma: A Narrative Review and International Experience

Mycosis fungoides (MF), the most common form of primary cutaneous T-cell lymphoma, is a disease typically with an indolent course that is initially characterized by localized patches and plaques. In the early stages of the disease, treatment involves skin-directed therapies (SDTs) such as topical corticosteroids and retinoids. Chlormethine gel (also known as mechlorethamine) was the first SDT purposely developed to treat MF and is currently endorsed by international guidelines for the treatment of adult patients with MF as a first-line therapy. While chlormethine is an efficacious therapy, its usage may be complicated by the development of cutaneous reactions at the sites of application. Herein, we discuss the supportive guidelines for MF and the suitability of chlormethine as a therapeutic option in patients with MF. In addition, we present real-world experience on the use of chlormethine gel from clinics in the USA, Israel, and France with the aim of demonstrating the efficacy of chlormethine gel in routine clinical practice and outlining strategies that are being used to manage emergent cutaneous reactions.

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

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

Cucurbitacin E and I target the JAK/STAT pathway and induce apoptosis in Sézary cells

Cutaneous T-cell lymphomas and leukemias (CTCLs) are a heterogeneous group of extranodal non-Hodgkin's lymphomas. These are characterized by an accumulation of malignant CD4⁺ T-lymphocytes in the skin, lymph nodes, and peripheral blood. Novel treatment options are needed for patients who progress to advanced stage disease. Cucurbitacin I has previously shown promising results in Sézary syndrome (Sz). A plethora of cucurbitacins, however, have not yet been tested in CTCL. Herein, we investigated the effect of cucurbitacin E and I in two CTCL cell lines. We show that both cucurbitacins decrease viability and cause apoptosis in these cell lines, although HuT-78 was more affected than SeAx (IC₅₀ of 17.38 versus 22.01 μM for cucurbitacin E and 13.36 versus 24.47 μM for cucurbitacin I). Moreover, both cucurbitacins decrease viability of primary cells of a Sz patient (56.46% for cucurbitacin E and 59.07% for cucurbitacin I). Furthermore, while JAK2 inhibition leads to decreased viability in SeAx cells (IC₅₀ of 9.98 and 29.15 μM for AZD1480 and ruxolitinib respectively), both JAK1 and JAK3 do not. This suggests that JAK2 has a preferential role in promoting survival. Western blotting in SeAx cells revealed that both cucurbitacins inhibit STAT3 activation (P < 0.0001), while only cucurbitacin I inhibits STAT5 activation (P = 0.05). This suggests that STAT3 plays a preferential role in the mechanism of action of these cucurbitacins. Nevertheless, a role of STAT5 and JAK2 cannot be excluded and should be explored further. This knowledge could contribute to the development of effective therapies for CTCL and other malignancies involving dysfunction of the JAK/STAT pathway.

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Cucurbitacin E and I decrease viability and cause apoptosis in Sézary cell lines

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Both cucurbitacins decrease viability of primary cells of a Sézary patient

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STAT3 appears to play a role in the mechanism of action of cucurbitacin E and I

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

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

Investigative drugs for the treatment of cutaneous T-cell lymphomas (CTCL): an update

Introduction: Cutaneous T-cell lymphoma (CTCL) is a heterogeneous group of skin-homing T-cell neoplasms, which represent approximately 75% of all primary cutaneous lymphomas. Mycosis fungoides and Sézary syndrome are the most common CTCL. Early stage disease follows a protracted course, carries a 5-year disease specific survival of 97% and can be treated with skin-directed therapies. Widespread, advanced disease has a 5-year OS of less than 25% and necessitates systemic treatment. Allogeneic stem cell transplantation is a potentially curative treatment option for advanced CTCL, however, transplant-related morbidity and mortality must be considered and a risk-benefit assessment performed on individual basis. Areas covered: Herein, we provide a review of investigative drugs in early-stage trials for the treatment of cutaneous CTCL, including topically applied immunomodulators such as replicating herpes virus or toll-like receptor 7/8 agonist resiquimod and systemic therapies with monoclonal antibodies, such as anti-CD47, recombinant cytotoxic interleukin 2 fusion protein anti-KIR3DL2 antibody and anti-miR-155 antibody. Expert Opinion: Among the reviewed drugs, resiquimod shows promising clinical efficacy with good tolerability in early CTCL. In refractory or relapsed disease, intratumoral anti-CD47-, anti-CCR4- and anti-KIR3DL2-antibodies show high response rates, however, latter two also show considerable toxicity. Larger trials are needed to better evaluate the discussed therapies.

SARC018_SPORE02: Phase II Study of Mocetinostat Administered with Gemcitabine for Patients with Metastatic Leiomyosarcoma with Progression or Relapse following Prior Treatment with Gemcitabine-Containing Therapy

Histone deacetylase inhibitors (HDACi) can reverse chemoresistance, enhance chemotherapy-induced cytotoxicity, and reduce sarcoma proliferation in cell lines and animal models. We sought to determine the safety and toxicity of mocetinostat and its ability to reverse chemoresistance when administered with gemcitabine in patients with metastatic leiomyosarcoma resistant to prior gemcitabine-containing therapy. Participants with metastatic leiomyosarcoma received mocetinostat orally, 70 mg per day, three days per week, increasing to 90 mg after three weeks if well tolerated. Gemcitabine was administered at 1,000 mg/m² intravenously at 10 mg/m²/minute on days five and 12 of every 21-day cycle. Disease response was evaluated with CT or MRI. Twenty participants with leiomyosarcoma were evaluated for toxicity. Median time to disease progression was 2.0 months (95% CI 1.54–3.12). Eighteen participants were evaluated for radiologic response by RECIST 1.1. Best responses included one PR and 12 SD. Tumor size reduced in 3 patients. Most common toxicities were fatigue, thrombocytopenia, anemia, nausea, and anorexia. One patient experienced a significant pericardial adverse event. No study-related deaths were observed. Rechallenging with gemcitabine by adding mocetinostat was feasible and demonstrated modest activity in patients with leiomyosarcoma. Further studies are needed to better define the role of HDAC inhibitors in patients with metastatic leiomyosarcoma.

Accelerated, untargeted metabolomics analysis of cutaneous T-cell lymphoma reveals metabolic shifts in plasma and tumor adjacent skins of xenograft mice

Cutaneous T-cell lymphoma (CTCL) is a heterogeneous group of skin-homing T-cell neoplasms. Clinical management is stage based but diagnosis and prognosis could be extremely challenging. The presented study aims to explore the metabolic profiling of CTCL by an accelerated untargeted metabolomics data analysis tool "Mummichog" to facilitate the discoveries of potential biomarkers for clinical early stage diagnosis, prognosis, and treatments in CTCL. Ultra high-performance liquid chromatography-quadrupole time-of-flight-based untargeted metabolomics were conducted on the skin and plasma of CTCL mice. It showed that the metabolism of skin changed greatly versus control samples in the development of CTCL. Increased l-glutamate and decreased adenosine monophosphate were the most essential metabolic features of CTCL tumor and tumor adjacent skins. Unique metabolism changes in tumor adjacent non-involved skin tissues (ANIT) occurred in the progress of carcinogenesis, including upregulated cytidine-5'-triphosphate, aberrant biosynthesis of prostaglandins, pyrimidine, mevalonate pathway, and tryptophan degradation. Sharply elevated 5-phospho-α-d-ribose 1-diphosphate (PRPP) marked the final state of tumor in CTCL. In the plasma, systematic shifts in corticosterone, sphingolipid, and ceramide metabolism were found. These uncovered aberrant metabolites and metabolic pathways suggested that the metabolic reprogramming of PRPP in tumor tissues may cause the disturbance of cytidine and uridine metabolic homeostasis in ANIT. Accumulative cytidine-5'-triphosphate in ANIT may exert positive feedback on the PRPP level and leads to CTCL further development. In addition, the accelerated data analysis tool "Mummichog" showed good practicability and can be widely used in high-resolution liquid chromatography mass spectrometry-based untargeted metabolomics.

PAK1 overexpression promotes cell proliferation in cutaneous T cell lymphoma via suppression of PUMA and p21

BACKGROUND

Cutaneous T cell lymphoma (CTCL) comprises a heterogeneous group of skin-homing T cell tumors. The small guanosine triphosphate effector p21-activated kinase 1 (PAK1) plays an important role in many fundamental cellular functions, including cell motility, proliferation, and apoptosis. The expression of PAK1 is up-regulated in several types of human cancers. However, little is known about the role of PAK1 in the pathogenesis of CTCL.

OBJECTIVE

The aim of this study was to evaluate the expression pattern and underlying mechanism of PAK1 in CTCL.

METHODS

Quantitative real-time polymerase chain reaction(qRT-PCR) was used to detect PAK1 mRNA expression in the peripheral blood mononuclear cells (PBMCs) of patients with CTCL. The expression of PAK1 protein in CTCL tumor tissues was determined by immunohistochemistry. CTCL cell lines were treated with a small molecule inhibitor of PAK1, p21-activated kinase inhibitor III (IPA3), at concentrations of 2, 3.5 and 5 μM for 24 h. Hut 78 and HH CTCL cells were transfected with lentiviral-based PAK1 gene knockdown vectors. We determined the effects of PAK1 knockdown on cell proliferation and apoptosis in CTCL cells by MTS assay and flow cytometry. Animal experiments were performed to investigate the effects of PAK1 knockdown on the growth of tumors in vivo. Transcriptomic sequencing was performed to detect the direct downstream targets of PAK1 silencing. Reverse transcription polymerase chain reaction and western blot analysis were applied to verify the results of the transcriptomic analysis.

RESULTS

We detected PAK1 overexpression in PBMCs and skin lesions from patients with CTCL compared with benign inflammatory dermatoses (BID). Knockdown of PAK1 inhibited cell proliferation and promoted spontaneous apoptosis. In addition, the inhibitory effect of IPA3 was validated in the CTCL cell lines. Additionally, mice injected with PAK1-silenced cells presented with a decreased rate of tumor growth compared with the control groups. Moreover, the mRNA and protein expression of PUMA (BBC3) and p21 (CDKN1A) were increased in PAK1-silenced Hut 78 and HH cells.

CONCLUSIONS

Our data indicated that PAK1 is upregulated in CTCL. PAK1 silencing induced apoptosis and inhibited cell growth by stimulating the expression of PUMA and p21. Thus, PAK1 may be a potential tumor marker and therapeutic target of CTCL.

T-cell Lymphoma Epidemiology: the Known and Unknown

T-cell lymphoma, a collection of subtypes of Non-Hodgkin lymphoma, is a rare malignancy. The low prevalence of this disease has made it challenging to identify subtype-specific risk factors. Potential risk factors could enable us to identify high-risk patients and predict patient outcomes. Here, we report on the current epidemiologic and prognostic factors data associated with the individual subtypes both of peripheral T-cell lymphoma (PTCL) and cutaneous T-cell lymphoma (CTCL) found in large cohort and case studies. Additionally, with recent findings, as well as updates in the new World Health Organization (WHO) classification of lymphoid neoplasms, we consider what this could do to change our approach to this group of diseases.

Epigenetic silencing of tumor suppressor genes: Paradigms, puzzles, and potential

Cancer constitutes a set of diseases with heterogeneous molecular pathologies. However, there are a number of universal aberrations common to all cancers, one of these being the epigenetic silencing of tumor suppressor genes (TSGs). The silencing of TSGs is thought to be an early, driving event in the oncogenic process. With this in consideration, great efforts have been made to develop small molecules aimed at the restoration of TSGs in order to limit tumor cell proliferation and survival. However, the molecular forces that drive the broad epigenetic reprogramming and transcriptional repression of these genes remain ill-defined. Undoubtedly, understanding the molecular underpinnings of transcriptionally silenced TSGs will aid us in our ability to reactivate these key anti-cancer targets. Here, we describe what we consider to be the five most logical molecular mechanisms that may account for this widely observed phenomenon: 1) ablation of transcription factor binding, 2) overexpression of DNA methyltransferases, 3) disruption of CTCF binding, 4) elevation of EZH2 activity, 5) aberrant expression of long non-coding RNAs. The strengths and weaknesses of each proposed mechanism is highlighted, followed by an overview of clinical efforts to target these processes.

Thyroid hormones and their membrane receptors as therapeutic targets for T cell lymphomas

Thyroid hormones (THs) are important regulators of metabolism, differentiation and cell proliferation. They can modify the physiology of human and murine T cell lymphomas (TCL). These effects involve genomic mechanisms, mediated by specific nuclear receptors (TR), as well as nongenomic mechanisms, that lead to the activation of different signaling pathways through the activation of a membrane receptor, the integrin αvβ3. Therefore, THs are able to induce the survival and growth of TCL. Specifically, the signaling induced by THs through the integrin αvβ3 activates proliferative and angiogenic programs, mediated by the regulation of the vascular endothelial growth factor (VEGF). The genomic or pharmacologic inhibition of integrin αvβ3 reduces the production of VEGF and induces cell death both in vitro and in xenograft models of human TCL. Here we review the mechanisms involved in the modulation of the physiology of TCL induced by THs, the analysis of the interaction between genomic and nongenomic actions of THs and their contribution to T cell lymphomagenesis. These actions of THs suggest a novel mechanism for the endocrine modulation of the physiopathology of TCL and they provide a potential molecular target for its treatment.

The European Hematology Association Roadmap for European Hematology Research: a consensus document

The European Hematology Association (EHA) Roadmap for European Hematology Research highlights major achievements in diagnosis and treatment of blood disorders and identifies the greatest unmet clinical and scientific needs in those areas to enable better funded, more focused European hematology research. Initiated by the EHA, around 300 experts contributed to the consensus document, which will help European policy makers, research funders, research organizations, researchers, and patient groups make better informed decisions on hematology research. It also aims to raise public awareness of the burden of blood disorders on European society, which purely in economic terms is estimated at €23 billion per year, a level of cost that is not matched in current European hematology research funding. In recent decades, hematology research has improved our fundamental understanding of the biology of blood disorders, and has improved diagnostics and treatments, sometimes in revolutionary ways. This progress highlights the potential of focused basic research programs such as this EHA Roadmap.The EHA Roadmap identifies nine 'sections' in hematology: normal hematopoiesis, malignant lymphoid and myeloid diseases, anemias and related diseases, platelet disorders, blood coagulation and hemostatic disorders, transfusion medicine, infections in hematology, and hematopoietic stem cell transplantation. These sections span 60 smaller groups of diseases or disorders.The EHA Roadmap identifies priorities and needs across the field of hematology, including those to develop targeted therapies based on genomic profiling and chemical biology, to eradicate minimal residual malignant disease, and to develop cellular immunotherapies, combination treatments, gene therapies, hematopoietic stem cell treatments, and treatments that are better tolerated by elderly patients.