Therapy For Cutaneous T-cell Lymphoma Research Articles

Concomitant Inhibition of FASN and SREBP Provides a Promising Therapy for CTCL.

Simple SummaryThe biosynthesis of fatty acids catalysed by FASN plays an important oncogenic role in various malignancies but has not been reported in CTCL yet. Here, we show that FASN is highly expressed in both cell lines and primary cells from CTCL patients. The inhibition of FASN impairs cell viability, survival, and proliferation. FASN expression is partly controlled by SREBP, and dual inhibition of FASN and SREBP enhances the impairment of cell proliferation. Overall, our data suggest that the combination of FASN and SREBP inhibitors could be a promising novel strategy in CTCL therapy.Cutaneous T cell lymphoma (CTCL) is a group of non-Hodgkin’s primary cutaneous T cell lymphomas, with Mycosis Fungoides and Sézary syndrome (SS) being the two most common subtypes. Fatty acid synthase (FASN) is a crucial enzyme that catalyses the biosynthesis of fatty acids, which has been reported to play an oncogenic role in various malignancies but not in CTCL so far. Herein, we show that FASN is highly expressed in CTCL cell lines and in peripheral blood mononuclear cells (PBMCs) from CTCL patients, while it is not in PBMCs from healthy individuals. The inhibition of FASN in CTCL cell lines impairs cell viability, survival, and proliferation, but, interestingly, it also increases FASN expression. However, inhibiting sterol regulatory element binding protein (SREBP), a transcription factor that promotes the expression of FASN, partially reversed the upregulation of FASN induced by FASN inhibitors. Thus, the combination of FASN and SREBP inhibitors enhanced the effects on both CTCL cell lines and PBMCs from SS patients, where a valid inhibition on cell proliferation could be verified. Importantly, compared to non-malignant cells, primary malignant cells are more sensitive to the inhibition of FASN and SREBP, making the combination of FASN and SREBP inhibitors a promising novel therapeutic strategy in CTCL.

CAR-T cell development for Cutaneous T cell Lymphoma: current limitations and potential treatment strategies.

Chimeric antigen receptor (CAR)-T therapy has demonstrated remarkable outcomes for B cell malignancies, however, its application for T cell lymphoma, particularly cutaneous T cell lymphoma (CTCL), has been limited. Barriers to effective CAR-T cell therapy in treating CTCL include T cell aplasia in autologous transplants, CAR-T product contamination with leukemic T cells, CAR-T fratricide (when the target antigen is present on normal T cells), and tumor heterogeneity. To address these critical challenges, innovative CAR engineering by targeting multiple antigens to strike a balance between efficacy and safety of the therapy is necessary. In this review, we discuss the current obstacles to CAR-T cell therapy and highlight potential targets in treating CTCL. Looking forward, we propose strategies to develop more powerful dual CARs that are advancing towards the clinic in CTCL therapy.

A novel mouse model of cutaneous T-cell lymphoma revealed the combined effect of mogamulizumab with psoralen and ultraviolet a therapy.

Mycosis fungoides (MF) is a subtype of cutaneous T-cell lymphoma (CTCL). Topical or systemic treatment with psoralen, such as 8-methoxypsoralen (8-MOP), followed by ultraviolet A (UVA) irradiation (PUVA therapy) is an effective phototherapy for early-stage MF. However, the efficacy of PUVA therapy for advanced-stage MF is not satisfactory, and the ideal combination partner for PUVA therapy has not yet been found. In this study, we developed a new mouse model of CTCL in which efficacy of PUVA was detected and further evaluated the efficacy of combination treatment of PUVA and mogamulizumab, an anti-CCR4 monoclonal antibody. Cytotoxicity of PUVA therapy against HH cells, a CTCL cell line, was observed in vitro. The cytotoxicity was dependent on both 8-MOP and UVA. Using HH cells, we developed a mouse model in which HH cells were subcutaneously inoculated in the ear. In this model, PUVA therapy suppressed tumour growth with statistical significance, while 8-MOP or UVA alone did not. Combination therapy of PUVA and mogamulizumab showed greater antitumor activity than either monotherapy with statistical significance. In the histological analysis of the tumour tissue, PUVA accelerated tumour necrosis and then induced the infiltration inflammatory cells in the necrotic area, suggesting that these cells served as effector cells for mogamulizumab. This combination therapy is expected to be a beneficial option for CTCL therapy.

Total skin electron beam therapy for cutaneous T-cell lymphomas in the Netherlands: A retrospective analysis of treatment outcomes and selection for high or low dose schedule

PurposeTotal skin electron beam therapy (TSEBT) is used mostly in the treatment of cutaneous T cell lymphoma. In this study we describe the results of TSEBT applied in the Netherlands using two different schedules, a conventional dose schedule of 35 Gy and a low-dose schedule of 12 Gy. We aimed to evaluate the treatment results in and compare treatment outcomes between the two treatment groups and to further define indications for both doses. MethodsIn the LUMC, Leiden, we performed a retrospective analysis of 51 patients treated with TSEBT between January 2008 and December 2018, with follow-up untill December 2019. Thirty one patients were treated with 35 Gy and twenty with 12 Gy. The dose was chosen based on the severity of skin involvement. Outcome measures were time to meaningful progression, survival, response rate and toxicity. ResultsTime to meaningful progression was 5.1 months with no significant differences between dose groups (P = 0.77). Overall survival was 27.4 months. Both time to progression and survival were significantly better for T2 vs T3 stage. Overall response rate was 80.4 %. Both dose groups showed improvement of symptoms. Treatment was generally well tolerated. ConclusionsBoth high-dose and low-dose TSEBT offer similar results for TMP and OS. It remains unclear which patients benefit most from a high-dose schedule. We propose to use the low-dose schedule as a standard for TSEBT and use supplementary boosts or escalation to high-dose treatment for patients unresponsive to the low-dose schedule.

Epidemiology and status of specialized medical care for patients with cutaneous T-cell lymphomas: A survey of 163 patients of Russian Federation

Background. In the Russian Federation, there are currently no official statistical data concerning the incidence of cutaneous T-cell lymphomas (CTCL) and the prevalence of CTCL due to the absence of isolation rubrics in the headings of lymphoproliferative diseases of the federal state statistical observation of the separate neologies.
 Aim. To obtain and analyze the results of the number of patients with CTCL (mycosis fungoides and Szary syndrome) who were on the dispensary observation in medical organizations of dermatovenereological profile in the period 2015 to 2020, the demographic and clinical-epidemiological characteristics, the applied methods of diagnosis and the therapy.
 Materials and methods. To conduct the study, the questionnaire was developed to obtain the information of the number of patients observed with diagnoses of "mycosis fungoides" and "Szary syndrome" in medical organizations of the dermatovenereological profile of the Federal Subjects of the Russian Federation in the period 2015-2020, were researched the demographic characteristics, the diagnostic methods and the therapy in the studied group of patients.
 Results. From 24 Federal Subjects of the Russian Federation were obtained the data concerning 163 patients with CTCL under the observation in medical organizations in the period 20152020. From 35 Federal Subjects of the Russian Federation the information showed the absence of patients with CTCL under the observation in medical organizations of dermatovenereological profile. We did not receive the data from 10 Federal Subjects of the Russian Federation. Among 163 patients in 144 (89%) were diagnosed mycosis fungoides, in 17 (10%) Szary syndrome and in 2 (1%) patients were diagnosed other variants of CTCL. The data concerning the demographic characteristics, the diagnosis and the therapy of CTCL were obtained in 155 of 167 patients. We showed that in 44% of cases, the disease was detected by dermatovenerologists, and the diagnosis was most often (39%) determined by oncologists. In 49% of cases the diagnosis was determined only on the basis of the results of histological study, the immunohistochemical study and the polymerase chain reaction were used in 33% and in 3% of cases, respectively. From 155 patients, 52% were under dispensary observation by oncologists, 41% by hematologists, 26% of patients were observed by dermatologists; 99 patients were under dispensary observation by only one specialist: 50 (32%) of patients by oncologist, 40 (26%) of patients by hematologist, 9 (6%) of patients by dermatovenerologist. Nine (6%) of patients were under dispensary observation by three specialists. The information concerning the therapy was available in 92 (59%) of 155 patients. The most commonly applied method of treatment was chemotherapy 72%, phototherapy was received by 26%, the same percentage (18%) was received in two groups: the application of interferon 2b and the application of methotrexate, 1% of patients received radiation therapy. The lethal outcome was registered in 53 (34%) patients. Median duration of the disease from the time of diagnosis to death was 3.55.0 years, the median 2 years, the mode 1 year.
 Conclusion. For the first time, the attempt was made to summarize the data of the number of patients with CTCL, to describe the demographic, clinical and epidemiological characteristics, the data concerning diagnostics and the therapy. The obtained preliminary results are required further detailing investigation in close cooperation with the professional specialists such as hematologists and oncologists.

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.

Prec-P-01 - Preclinical investigation of new targeted combination therapies in cutaneous T-cell lymphoma

Prec-P-01 - Preclinical investigation of new targeted combination therapies in cutaneous T-cell lymphoma

Tre-O2-09 - Dimethyl fumarate (DMF) therapy in CTCL: results from a clinical phase II study

Introduction and objectives: Targeted therapies for cutaneous T-cell lymphoma (CTCL) are limited and curative approaches are still lacking. Relapses and drug induced side effects are main challenges in the therapeutic management of CTCL patients resulting in an urgent need for new, effective therapies. Constitutive NFκB activity leads to apoptosis resistance in CTCL cells which contributes to the pathogenesis and therapy resistance of these cells. We showed in a preclinical study, that both in isolated CTCL patient cells and in a CTCL xenograft mouse model, NFκB inhibition with the small-molecule drug dimethyl fumarate (DMF) effectively and specifically induces CTCL cell death and thus bears promising therapeutic potential in CTCL (Nicolay JP et al.

Bio-P-03 - Bioinformatics insights in etiopathogenesis, diagnosis and therapy of cutaneous T-cell lymphoma

<h3>Introduction:</h3> The pathogenesis of cutaneous T-cell lymphoma (CTCL) remains poorly understood and the histologic diagnosis of early MF is one of the most vexing problems in dermatopathology. Our aim was to apply state-of-the-art bioinformatic tools in order to unravel the mechanisms of CTCL pathobiology, to address new therapeutic possibilities as well as to identify potential biomarkers. <h3>Materials and methods:</h3> Datasets selection: we searched the GEO (http://www.ncbi.nlm.nih.gov/geo/) for gene (GSE143382) and miRNA (GSE109421) expression datasets containing early-stage MF samples and reactive skin lesions (inflammatory dermatosis) as control. Differential expression data analysis: was performed in R programming language using the LIMMA R package. Differentially expressed genes (DEGs) were selected by applying selection thresholds of adjusted p-value < 0.05 and absolute (log2FC) ≥1 (i.e. FC ≥2 or FC ≤0.5). For the case of differentially expressed miRNAs (DEMs) we used as selection criteria the p-value <0.05 and the FC ≥1.2 for the overexpressed miRNAs and FC ≤0.83 for the under-expressed ones. Pathway Enrichment Analysis using DEGs: was performed using the Enrichr, a web-based tool for analyzing gene sets that returns any enrichment of common annotated biological features (https://maayanlab.cloud/Enrichr/). Pathway Enrichment Analysis using DEMs: was performed using the DIANA-mirPath which is a miRNA pathway analysis web-server, which can utilize experimentally validated miRNA interactions derived from DIANA-TarBase v6.0. The enrichment was obtained using information from KEGG Human and the most significantly enriched pathways were selected based on the p-value <0.05. <h3>Results:</h3> Our bioinformatics analysis detected: A list of DEGs in CTCL which are associated with increased cell proliferation decreased apoptosis, increased Th2 differentiation and immune activation leading to generation of malignant CD4+ T-cells clones, propagating the disease. A list of DEMs in CTCL. A more restricted set of overexpressed miRNAs (miR-26a, miR-92a, miR-106b, miR-142, miR-146a, miR-155, miR-181a, miR-222 and miR-494) were selected and could be therefore used as biomarkers. A number of pathways that have been extracted from the genes and miRNAs implicated in the pathogenesis of CTCL and can enlighten its etiopathogenesis. Fourteen percent (14%) of the pathways were common in both analyses including TGF-beta signaling pathway, Pathways in cancer, PI3K-Akt signaling pathway and p53 signaling pathway. <h3>Conclusion:</h3> In this project, the tools of bioinformatics were used as a stepping-stone in a combined approach highlighting differentially expressed genes and miRNAs as well as the implicated pathways involved in CTCL development. These findings formed a resource of genes and miRNAs that will be further tested in vitro and in vivo in order to identify the etiopathogenesis of the disease, discover biomarkers for diagnosis and highlight new therapeutic targets.

Prec-O1-03 - Understanding the function of CD30 in cutaneous T-cell lymphoma: implications for therapy and prognosis

<h3>Introduction and objectives:</h3> Targeted therapies for cutaneous T-cell lymphoma (CTCL) are limited and curative approaches are still lacking. Relapses and drug-induced side effects are major challenges in the therapeutic management of CTCL patients, resulting in an urgent need for new, effective therapies. Expression of CD30 receptor is usually restricted to a small population of activated B- and T-cells, but is also found in hematologic malignancies, such as CTCL. In mycosis fungoides (MF) its expression seems to be associated with advanced disease stage and large-cell transformation. However, the functional role of CD30 in CTCL remains unknown. Consequently, this study aims to determine 1) CD30 and CD30 ligand (CD30L) expression in CTCL cell lines and primary CD4-positive cells from CTCL patients, 2) the dynamics of CD30 expression over time and after treatment, 3) CD30 function <i>in vitro</i>, <i>ex vivo</i> and <i>in vivo</i>, 4) mechanisms involved in CD30 signaling. <h3>Materials and methods:</h3> The CTCL cell lines HH, SeAx and HUT-78 were used for <i>in vitro</i> experiments. For <i>ex vivo</i> analysis, primary CD4-positive T-cells isolated from fresh blood samples of patients with Sézary syndrome were used. Cells were challenged with dimethyl fumarate for 24 hours. CD30 was stimulated via its natural ligand. Methods used for expression and pathway analysis were FACS, western blot, PCR and luciferase assay. For <i>in vivo</i> experiments, CTCL cells were suspended in PBS/Matrigel (1:1, vol/vol) and injected intradermally into the right flank of female NOD/SCID/Il2Rg null (NSG) mice. After development of tumors, CD30L was injected into the lesions. <h3>Results:</h3> We found that CD30 activation can influence viability of CTCL cells <i>in vitro</i>, which is currently under investigation in an <i>in vivo</i> setting. Involved mechanisms include the MEK/ERK and NF-κB pathway. The highest CD30 expression was detected in the HH cell line. The primary CD4-positive cells analyzed so far were negative for CD30 surface expression. However, intracellular CD30 protein was detectable via western blot. CD30 levels were influenced by cell culture conditions in HH cells and significantly reduced upon therapeutic NFκB inhibition in HH, SeAx and HUT-78 cells. <h3>Conclusions:</h3> Our results indicate a therapeutic potential of CD30 receptor stimulation as a new targeted therapy in CD30-positive MF <i>in vitro</i>, which has to be proven <i>in vivo</i>. Furthermore, we found a dynamic nature of CD30 expression in CTCL, which might account for the described effectiveness of the antibody-drug conjugate brentuximab vedotin directed to CD30 also in patients diagnosed as CD30 low-expressing.

Clinical Outcomes of Advanced-Stage Cutaneous Lymphoma under Low-Dose Gemcitabine Treatment: Real-Life Data from the German Cutaneous Lymphoma Network

Background: Gemcitabine is an effective single-agent chemotherapy used in advanced stages of cutaneous T-cell lymphoma (CTCL). However, gemcitabine used in the current standard regimen is frequently associated with adverse events (AE), such as an increased risk for myelosuppression and severe infections. Objectives: We investigated in this retrospective study the effect of low-dose gemcitabine in pretreated advanced-stage CTCL and in blastic plasmacytoid dendritic cell neoplasia (BPDCN) regarding overall response (OR), progression-free survival (PFS), and AE. Material and Methods: A retrospective, multicenter study was conducted on 64 CTCL and BPDCN patients treated with gemcitabine in average absolute dosage of 1,800 mg/m² per cycle, which is 50% lower compared to standard dosage of 3,600 mg/m² per cycle (1,200 mg/m² day 1, 8, 15). Evaluation of response to therapy and AE was done 4–6 weeks after the sixth cycle. Results: OR was 62% with 11% demonstrating a complete response. The median time of PFS was 12 months and median time to next treatment was 7 months. Only 3/63 patients showed serious side effects, e.g., port infection or acute renal failure. Almost 73% of the patients experienced minor to moderate side effects (CTCAE grade 0–2). Fatigue (27.2%), fever (22.7%), and mild blood count alteration (18.2%) were the most common AE. Conclusions: This retrospective analysis supports the use of low-dose gemcitabine therapy in CTCL, demonstrating with 62% OR and PFS of 12 months an almost identical response rate and survival as compared to the standard dose therapy reported in previous studies but with a significantly improved safety profile and tolerability.

Is Durability of Response Reported in Refractory CTCL: A Systematic Review

Introduction: Primary cutaneous T-cell lymphomas (CTCL) are a group of non-Hodgkin lymphomas derived from T-lymphocytes that infiltrate the skin. In refractory CTCL, treatments generally include systemic therapies in conjunction with skin-directed therapies. Numerous assessment criteria are used to evaluate the efficacy of different therapies administered to patients with CTCL. Robust treatment comparisons in CTCL are currently complicated by differences between studies in the efficacy outcomes reported. A systematic review (SR) was performed to summarise published evidence on the efficacy of treatments in patients with relapsed/refractory CTCL.Methods: A SR was performed in January 2017 to identify clinical studies published in the last 10 years enrolling >20 patients treated for refractory CTCL.Results: In total, 63 publications reporting on 54 unique studies and 21 different therapies for refractory CTCL were included in the SR. The majority of included studies (n=49) were single arm investigations. Five of the studies included were randomised controlled trials (RCT) comparing CTCL therapies. Two RCTs compared multiple doses of a single therapy (bexarotene or denileukin diftitox), two compared multiple therapies (interferon and methotrexate vs interferon and retinoids or brentuximab vs methotrexate or bexarotene), and one was a placebo-controlled trial of denileukin diftitox. Patient cohorts ranged in size from 21 to 216 patients and all patients had recurrent or refractory disease following ≥1 therapy for CTCL prior to the therapy for which data were extracted. The most frequently reported outcomes were objective response rate (ORR) reported in 82% of studies, complete response rate (80%), progression-free survival (52%), duration of response (48%), overall survival (24%) and time to tumour progression (20%) (Table 1). However, not all outcomes were reported for all therapies, outcome assessment criteria were not reported in all studies, and durable responses were rarely reported. In addition, there was substantial heterogeneity between studies in terms of patient characteristics, outcome assessment criteria, study design, and follow-up time. As such, a robust comparison of relative efficacy is not feasible. ORR was the most consistently reported outcome across studies and was reported for 19 different therapies in 44 different studies. The assessment criteria for ORR was reported in 15 studies. ORR is a useful measure of efficacy as it is directly attributable to drug effect and can be assessed in single-arm studies; however, as the time-point for assessment of ORR or the definition of ORR differed between studies or was not reported, the durability of response was difficult to interpret. The novel outcomes, objective global responses lasting at least 4 (ORR4) and 6 months (ORR6), were reported in three and two trials investigating the efficacy of brentuximab vedotin, respectively. ORR4 and ORR6 capture both the proportion of patients achieving a response and response duration as a single measurement and were 51-56% and 34%, respectively, following treatment with brentuximab vedotin. Health-related quality of life was investigated in only one study in which key endpoints, such as Skindex-29 symptom domains, were reported. Adverse events were reported following treatment with all therapies for refractory CTCL. However, there was a lack of consistency in the definition of the severity of adverse events reported.Conclusion: Although progress has been made towards the standardisation of response criteria in CTCL, the evaluation of durability of response to treatment remains inconsistent. The routine use of clearly defined efficacy outcomes in clinical trials is required to enable robust comparisons of therapeutic efficacy. [Display omitted] DisclosuresDalal:Takeda Pharmaceuticals International Co: Employment, Equity Ownership. Mitchell:DRG Abacus: Employment. McCloskey:DRG Abacus: Employment. Zagadailov:Millennium Pharmaceuticals, Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Gautam:Takeda Pharmaceuticals International Co: Employment, Equity Ownership.

A Phase I Trial Assessing the Feasibility of Romidepsin Combined with Brentuximab Vedotin for Patients Requiring Systemic Therapy for Cutaneous T-Cell Lymphoma

A Phase I Trial Assessing the Feasibility of Romidepsin Combined with Brentuximab Vedotin for Patients Requiring Systemic Therapy for Cutaneous T-Cell Lymphoma

Role of Mir-29b in T-Cell Development and in Cutaneous T-Cell Lymphoma Pathogenesis

The role of microRNA (miR) is rapidly advancing with numerous functions discovered in cancer pathogenesis. We had previously shown a significant decrease in miR-29b levels in malignant cells isolated from peripheral blood of cutaneous T-cell lymphoma (CTCL) (Kohnken et al. Blood, 2018). Replenishing miR-29b levels in vitro induced apoptosis in leukemic cells suggesting its role as tumor suppressor miR in CTCL patients. In this study, we focused on the role of mir-29b on early T-cell development and homeostasis using the miR-29b-/- mouse model. Using knockout mouse model, we show that the homozygous deletion of miR-29b locus results in an overall decrease in T-cell numbers and density in primary and secondary lymphoid organs. We observed an early thymic involution in miR-29b-/- mice, with a 5-fold decrease in the total number of thymocytes and altered T-cell development. Using the surface expression of CD25 and CD44 on double-negative (DN) cells, we observed significant decrease of the absolute counts in the four early differentiation stages (DN1-4) in miR-29b-/- mice compared to age-matched wild-type (WT) mice: DN1 (miR-29b-/- vs. WT: 4.5 x 105 ± 1.04 vs. 1.12 x 105 ± 0.201, N=4 and 6 respectively, p &amp;lt; 0.05); DN2 (miR-29b-/- vs. WT: 0.83 x 105 ± 0.07 vs. 0.051 x 105 ± 0.021, N=4 and 6 respectively, p &amp;lt; 0.001); DN3 (miR-29b-/- vs. WT: 4.05 x 105 ± 0.38 vs. 0.54 x 105 ± 0.16, N=4 and 6 respectively, p &amp;lt; 0.001) and DN4 (miR-29b-/- vs. WT: 2.871 x 105 ± 0.578 x 105 vs. 0.569 ± 0.14, N=4 and 6 respectively, p &amp;lt; 0.01). Furthermore, miR-29b-/- mice show a significant increase in regulatory T cells in comparison to WT mice in the spleen (miR-29b-/- vs. WT: 18.48 ± 0.89 vs. 10.89 ± 0.41, N=4 and 6 respectively, p &amp;lt; 0.001) thymus (miR-29b-/- vs. WT: 5.80 ± 0.44 vs. 3.65 ± 0.004, N=4 and 6 respectively, p &amp;lt; 0.01) and bone marrow (miR-29b-/- vs. WT: 50.04 ± 3.14 vs. 37.52 ± 3.29, N=4 and 6 respectively, p &amp;lt; 0.05). Using single-cell RNA sequencing (scRNA-seq), we found a framework of putative genes in miR-29b deficient T-cells that overlap with CTCL pathogenesis: Ccr7, Cd69, Cd74, and Lef-1. Among thymic T cells, Ccr7 affects physiologic homing of T-cells to lymph nodes and facilitate nodal metastasis in CTCL patients. As T-cells progenitors originate from the bone marrow, we observed a severe impairment in the progenitor cell population in miR-29b-/- mice and over 4-fold reduction in the absolute number of Lin-Sca1+ckit+ cell (miR-29b-/- vs. WT: 28.42 x 103 ± 4.13 vs. 5.98 x 103 ± 1.01, N=4 and 3 respectively, p &amp;lt; 0.01). Using the surface expression of CD48 and CD150 on Lin-Sca1+ckit+, we observed a significant decrease in hematopoietic stem cells and multipotent progenitor cells in miR-29b-/- mice. Since impairment in T-cells development can be linked to hematopoietic stem cell defects, we interrogated the engraftment capacity of Lin-Sca1+ckit+ cells into committed cell lineages in vivo. To evaluate whether the defect in T-cells development is due to reduced ability of precursor cells, we performed transplantation of Lin-Sca1+ckit+ cells from the bone marrow of miR-29b and WT (CD45.1) mice in lethally irradiated WT (CD45.2) mice. Our results show a significant reduction in T-cells reconstitution in mice transplanted with miR-29b-/- Lin-Sca1+ckit+ cells versus the bone marrow counterpart. These deficits in T-cells populations were observed in peripheral blood, thymus, spleen, and bone marrow in miR-29b-/- transplanted mice. ScRNA-seq profiling of Lin- bone marrow cells show significant changes in miR-29b-/- and WT mice. Among the upregulated genes in the mir-29b-/- mice, several genes showed greater than a 10-fold increase in the thymus (Ifna2, Zmynd10, Plekha4, Etl4, and Gm38004). In conclusion, our results highlight the importance of mir-29b in early defects in T-cells development and help us understand the complex miR-29b regulated cellular transformation machinery in CTCL pathogenesis, thus paving path to develop novel therapeutic approaches targeting miR-29b in CTCL therapy. Disclosures No relevant conflicts of interest to declare.

Single-Cell Heterogeneity of Cutaneous T-Cell Lymphomas Revealed Using RNA-Seq Technologies.

Cutaneous T-cell lymphomas (CTCLs) represent a large, heterogeneous group of non-Hodgkin lymphomas that primarily affect the skin. Among multiple CTCL variants, the most prevalent types are mycosis fungoides (MF) and Sézary syndrome (SS). In the past decade, the molecular genetics of CTCL have been the target of intense study, increasing the knowledge of CTCL genomic alterations, discovering novel biomarkers, and potential targets for patient-specific therapy. However, the detailed pathogenesis of CTCL development still needs to be discovered. This review aims to summarize the novel insights into molecular heterogeneity of malignant cells using high-throughput technologies, such as RNA sequencing and single-cell RNA sequencing, which might be useful to identify tumour-specific molecular signatures and, therefore, offer guidance for therapy, diagnosis, and prognosis of CTCL.

New opportunities of systemic therapy of CD30-positive primary cutaneous T-cell lymphomas

Relevance. Cutaneous T-cell lymphomas (CTCL) are not common diseases which are associated with a decrease in quality of life. Currently available systemic therapy rarely provides a stable and long-termed response. In Russia, current CTCL therapy is a big issue due to the limited access to modern targeted therapy, an absence of a National CTCL registry, and the difficulties in morphological diagnosis of these rare diseases. Since June 17, 2019, a new indication of brentuximab vedotin as a new treatment option for patients with CD30+ CTCL after at least one line of previous systemic therapy was registered. Brentuximab vedotin is a conjugate of a CD30 directed monoclonal antibody and an antitumor agent. Brentuximab vedotin is a CD30-directed monoclonal antibody conjugated to an antitumor agent.&#x0D; Aim. To identify the unresolved issues of current clinical practice and to adapt available approaches to the treatment and diagnosis of CD30 + CTCL given new therapeutic opportunities.&#x0D; Results. The available approaches to the systemic CTCL therapy in Russia routine clinical practice have been discussed, the unresolved issues of therapy and diagnosis have been identified, the routing of patients with CD30 + CTCL in Russia has been discussed, the importance of CD30 testing has been established, the profiles of patients with CTCL for treatment with brentuximab vedotin have been determined.

Maintenance Therapy for Cutaneous T-cell Lymphoma After Total Skin Electron Irradiation: Evidence for Improved Overall Survival With Ultraviolet Therapy

BackgroundTreatment of cutaneous T-cell lymphoma (CTCL) with total skin electron beam (TSEB) therapy has been associated with deep responses but short progression-free intervals. Maintenance therapy might prolong the response duration; however, limited data assessing the outcomes with maintenance therapy after TSEB are available. We evaluated the effect of maintenance therapy on the outcomes for patients with CTCL receiving TSEB therapy. Materials and MethodsWe conducted a single-center retrospective analysis of 101 patients with CTCL who had received TSEB therapy from 1998 to 2018 at the Winship Cancer Institute of Emory University and compared the overall survival (OS) and progression-free survival (PFS) for patients had received maintenance therapy, including retinoids, interferon, ultraviolet therapy, nitrogen mustard, and extracorporeal photopheresis compared with those who had not. ResultsWe found that pooled maintenance therapies improved PFS (hazard ratio [HR], 0.60; P = .026) but not OS (median HR, 0.73; P = .264). The median PFS and OS was 7.2 months versus 9.6 months and 2.4 years versus 4.2 years for the no maintenance and maintenance groups, respectively. On exploratory analysis of the individual regimens, ultraviolet therapy was associated with improved OS (HR, 0.21; P = .034) and PFS (HR, 0.26; P = .002) compared with no maintenance. ConclusionAmong the patients with CTCL who had received TSEB therapy, maintenance therapy improved PFS for all patients, and ultraviolet-based maintenance improved both PFS and OS in a subset of patients.

503 Outcomes of patients with cutaneous T-cell lymphoma (CTCL) treated with extracorporeal photopheresis (ECP): A single institution experience

ECP is an established therapy for CTCL yet patterns of utilization, complication rates, and outcomes vary widely among treatment centers. We hereby report our experience with 13 patients (pts) treated with ECP from 2013-2019; median age was 65 (range 47-87) years. All pts had advanced stage CTCL; 8 (61.5%) with mycosis fungoides (MF) and 5 (38.5%) with Sezary syndrome (SS). Median time from diagnosis to pheresis start was 2.8 months with a median of 2 lines of prior therapy. All pts initially started on a ECP regimen of 2 consecutive days per week with 8 (61.5%) pts concurrently using oral bexarotene (Bex) and subcutaneous interferon alpha (IFN), 2 pts on ECP alone (15.4%), 2 (15.4%) with Bex only, and 1 (7.7%) with IFN only.

Screening Novel Agent Combinations to Expedite CTCL Therapeutic Development

Screening Novel Agent Combinations to Expedite CTCL Therapeutic Development

The Th9 Axis Reduces the Oxidative Stress and Promotes the Survival of Malignant T Cells in Cutaneous T-Cell Lymphoma Patients.

Immune dysfunction is critical in pathogenesis of cutaneous T-cell lymphoma (CTCL). Few studies have reported abnormal cytokine profile and dysregulated T-cell functions during the onset and progression of certain types of lymphoma. However, the presence of IL9-producing Th9 cells and their role in tumor cell metabolism and survival remain unexplored. With this clinical study, we performed multidimensional blood endotyping of CTCL patients before and after standard photo/chemotherapy and revealed distinct immune hallmarks of the disease. Importantly, there was a higher frequency of "skin homing" Th9 cells in CTCL patients with early (T1 and T2) and advanced-stage disease (T3 and T4). However, advanced-stage CTCL patients had severely impaired frequency of skin-homing Th1 and Th17 cells, indicating attenuated immunity. Treatment of CTCL patients with standard photo/chemotherapy decreased the skin-homing Th9 cells and increased the Th1 and Th17 cells. Interestingly, T cells of CTCL patients express IL9 receptor (IL9R), and there was negligible IL9R expression on T cells of healthy donors. Mechanistically, IL9/IL9R interaction on CD3+ T cells of CTCL patients and Jurkat cells reduced oxidative stress, lactic acidosis, and apoptosis and ultimately increased their survival. In conclusion, coexpression of IL9 and IL9R on T cells in CTCL patients indicates the autocrine-positive feedback loop of Th9 axis in promoting the survival of malignant T cells by reducing the oxidative stress. IMPLICATIONS: The critical role of Th9 axis in CTCL pathogenesis indicates that strategies targeting Th9 cells might harbor significant potential in developing robust CTCL therapy.