Dimethyl fumarate treatment in relapsed and refractory cutaneous T-cell lymphoma: a multicenter phase 2 study.

Targeted therapies for cutaneous T-cell lymphoma (CTCL) are limited and curative approaches are lacking. Furthermore, relapses and drug induced side effects are major challenges in the therapeutic management of patients with CTCL, creating an urgent need for new and effective therapies. Pathologic constitutive NF-κB activity leads to apoptosis resistance in CTCL cells and, thus, represents a promising therapeutic target in CTCL. In a preclinical study we showed the potential of dimethyl fumarate (DMF) to block NF-κB and, specifically, kill CTCL cells. To translate these findings to applications in a clinical setting, we performed a multicentric phase 2 study evaluating oral DMF therapy in 25 patients with CTCL stages Ib to IV over 24 weeks (EudraCT number 2014-000924-11/NCT number NCT02546440). End points were safety and efficacy. We evaluated skin involvement (using a modified severity weighted assessment tool [mSWAT]), pruritus, quality of life, and blood involvement, if applicable, as well as translational data. Upon skin analysis, 7 of 23 (30.4%) patients showed a response with >50% reduction in the mSWAT score. Patients with high tumor burden in the skin and blood responded best to DMF therapy. Although not generally significant, DMF also improved pruritus in several patients. Response in the blood was mixed, but we confirmed the NF-κB-inhibiting mechanism of DMF in the blood. The overall tolerability of the DMF therapy was very favorable, with mostly mild side effects. In conclusion, our study presents DMF as an effective and excellently tolerable therapeutic option in CTCL to be further evaluated in a phase 3 study or real-life patient care as well as in combination therapies. This trial was registered at www.clinicaltrials.gov as #NCT02546440.

Hydrochlorothiazide and increased risk of atypical fibroxanthoma and pleomorphic dermal sarcoma.

BACKGROUND AND OBJECTIVES: Previous work has demonstrated that hydrochlorothiazide (HCTZ) is a risk factor for squamous cell carcinomas (SCC) and basal cell carcinomas (BCC) due to pro-photocarcinogenic effects. Atypical fibroxanthoma (AFX) and pleomorphic sarcoma (PDS), both ultraviolet-induced cancers, display a rare but rising cutaneous tumor entity. This study aimed to evaluate if the use of HCTZ is higher in patients with AFX/PDS than in patients with SCC/BCC and subsequently may be a risk factor for AFX/PDS-development. PATIENTS AND METHODS: In a retrospective study of four German skin cancer centers, AFX/PDS cases and SCC/BCC controls were sex and age matched (1:3) over a time-period of 7 years (2013-2019) to evaluate the use of HCTZ, immunosuppressive medication, second malignancies, and presence of diabetes mellitus. RESULTS: Overall, 146 AFX/PDS and 438 controls (SCC/BCC) were included in the study. The use of HCTZ was significantly higher in patients with AFX/PDS (44.5%) compared to patients with SCC/BCC (25.3%). Additionally, the presence of diabetes mellitus was significantly higher in AFX/PDS patients. CONCLUSIONS: This study demonstrates a significantly higher use of HCTZ in patients with AFX/PDS compared to SCC/BCC. This result suggests that HCTZ may be a risk factor for AFX/PDS. Additionally, diabetes mellitus or its comorbidities may be associated with an increased risk for AFX/PDS.

Pegylated interferon-α2a in cutaneous T-cell lymphoma - a multicenter retrospective data analysis with 70 patients.

BACKGROUND: Interferon-alpha is an important therapeutic option for the treatment of the cutaneous T-cell lymphomas (CTCL). Since the approved recombinant interferon-α-2a (IFN-α2a) has no longer been produced since January 2020, pegylated interferon-α2a (pegIFN-α2a) can be used as an alternative treatment, even though it is not approved for the treatment of CTCL. The aim of this multicentre study was to generate comprehensive data on the efficacy and tolerability of pegIFN-α2a in the treatment of CTCL. PATIENTS AND METHODS: A multicenter retrospective study was conducted with 70 patients with CTCL from twelve German skin centers. RESULTS: In total, 70 patients were included in the study, with 57.2% male and a mean age of 58.8 ± 14.9 years. Mycosis fungoides was present in 71.4% of cases and Sézary Syndrome in 28.6%. An overall response rate of 55.2% was observed with pegIFNα-2a therapy. In 50% of cases, therapy was discontinued after 63.6 ± 33.5 weeks. The most common reason for discontinuation was adverse events, which occurred in 68.6% of cases and which were classified as severe in 29.2%. Blood count changes, fatigue and liver toxicity occurred most frequently. CONCLUSIONS: Our analysis provides comprehensive data on the efficacy and tolerability of pegIFNα-2a therapy in patients with CTCL. In terms of response rates and side effect profile, pegIFNα-2a appears to be comparable to IFN-α2a therapy.

Epidemiology of mature T/NK-cell lymphomas in Germany - A representative cross-sectional study based on SHI claims data.

BACKGROUND: Primary cutaneous lymphomas (PCL) are rare skin tumors of lymphoproliferative neoplasms and belong to the heterogeneous group of non-Hodgkin's lymphomas. PCL encompass a broad spectrum of clinical and histologic manifestations, with cutaneous T-cell lymphoma (CTCL) being the most common (73%). Due to the rarity of the diseases, population-based studies of care and epidemiology are limited. PATIENTS AND METHODS: Based on anonymized, age- and sex-adjusted SHI (statutory health insurance) claims data of approximately five million SHI-insured patients, a retrospective analysis was conducted over a six-year period (2012-2017) to determine the prevalence, incidence, and lethality in patients with mature-cell T/NK-cell lymphoma in Germany. RESULTS: A total of 1,336 patients with T-cell lymphoma were identified during the observation period. The six-year prevalence ranged from 27.35 to 43.58 per 100,000. Patients were 65% male with a mean age of 66 years (SD 15). There were 246 patients (approx. 20%) who died within the 6 years, up to 7% per year. The calculated incidence in 153 identified patients in 2017 is 3.65 to 3.92 per 100,000. CONCLUSIONS: For the first time, valid epidemiologic findings of patients with mature T-cell and NK-cell lymphomas were obtained using SHI claims data in Germany. Further analyses are needed to gain a deeper insight into the healthcare reality of patients with this rare disease.

Post hoc Analysis of a Randomized, Controlled, Phase 2 Study to Assess Response Rates with Chlormethine/Mechlorethamine Gel in Patients with Stage IA-IIA Mycosis Fungoides.

BACKGROUND: Mycosis fungoides (MF) is the most common form of cutaneous T-cell lymphoma. Patients can be treated using chlormethine gel, a skin-directed therapy developed and approved for MF. In the randomized, controlled 201 trial, chlormethine gel was found to be noninferior to equal-strength chlormethine ointment. However, there remains a need to gain more insight into outcome measures after treatment. OBJECTIVE: The aim of this study was to further investigate the potential of chlormethine gel treatment through a novel post hoc analysis of the 201 trial data (NCT00168064). METHODS: Patients were randomized to chlormethine gel or ointment; response assessments included Composite Assessment of Index Lesion Severity (CAILS) and total body surface area (BSA). In this post hoc analysis, additional subgroup response analyses were performed for stage IA/IB-IIA MF. Very good partial response (75 to <100% improvement) was included as an additional response category. Time to response and overall response trends were determined. Finally, multivariate time-to-event analyses were performed to determine whether associations were observed between treatment frequency, response, and adverse events. RESULTS: Response rates were significantly higher for patients with stage IA MF for CAILS (intent-to-treat [p = 0.0014] and efficacy-evaluable [EE; p = 0.0036] populations) and BSA (EE population [p = 0.0488]) treated with gel versus ointment. Time to first CAILS response and response trends were better for all-stage gel-treated patients overall. No association was seen between treatment frequency and response or occurrence of adverse events at the following visit. An association was observed between the occurrence of contact dermatitis and improved clinical response at the next visit (p = 0.0001). CONCLUSION: This post hoc analysis shows that treatment with chlormethine gel may result in higher and faster response rates compared with chlormethine ointment, which confirms and expands results reported in the original analysis. The incidence of contact dermatitis may potentially be a prognostic indicator for clinical response; this needs to be confirmed in a larger population.

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.

Care structure of patients with mycosis fungoides and Sézary syndrome in Germany - Care research based on SHI claims data.

BACKGROUND: Cutaneous T-cell lymphomas (CTCLs) are rare forms of non-Hodgkin's lymphoma of T-cell origin that occur mainly in the skin. The most common form is mycosis fungoides (MF), but Sézary syndrome (SS), a more aggressive form of CTCL, is another relevant subgroup. Due to the rare nature of the disease, population-based studies of the epidemiology and disease burden and insights into care delivery are limited. PATIENTS AND METHODS: Based on an anonymized, age and sex-adjusted routine dataset comprising approximately five million people with statutory health insurance, a retrospective, longitudinal healthcare research study was conducted over a six-year period (2012-2017). RESULTS: In 55 % of patients with MF and SS, the initial diagnosis was documented in an outpatient setting; in 59 % of cases by a dermatologist. Immunophenotyping by flow cytometry is considered an important investigative tool for the detection and follow-up surveillance of blood involvement of cutaneous lymphomas, as the disease stage is the most important prognostic factor in MF and SS; this was performed in only 10 % of patients. The first-line treatment was topical (76 %), in particular with corticosteroids (66 %). CONCLUSIONS: The findings from this healthcare research point to the need for increased guideline-based care.

Chlormethin-Gel zur Behandlung der Mycosis fungoides: Ein Expertenkonsens aus Deutschland, Österreich und der Schweiz (DACH-Region) zum Therapiemanagement.

HINTERGRUND: Chlormethin-Gel ist in Europa zur Therapie von Patienten mit Mycosis fungoides in allen Krankheitsstadien zugelassen. Die optimalen Behandlungsregime hinsichtlich Frequenz, Dosierung, Kombinations- oder Erhaltungstherapien sind noch nicht vollständig etabliert. METHODIK: Zehn in der Erforschung und Behandlung kutaner T-Zell-Lymphome erfahrene Experten aus Deutschland, Österreich und der Schweiz (DACH-Region) wurden schriftlich zu Indikation, Anwendungsfrequenz, Beurteilung des Therapieerfolgs, Begleittherapie, Nebenwirkungen, Kombinationstherapien in späteren Krankheitsstadien, Erhaltungstherapie und Adhärenz im Rahmen der Therapie der Mycosis fungoides mit Chlormethin-Gel befragt. Die strukturiert aufbereiteten Ergebnisse der Umfrage wurden in einer Konsensuskonferenz diskutiert und Empfehlungen zum Management der Therapie mit Chlormethin-Gel entwickelt. ERGEBNISSE: Wesentlich für die Therapie mit Chlormethin-Gel ist ein individuelles, symptomorientiertes Therapiemanagement. Systemische Nebenwirkungen des Wirkstoffs sind wegen der fehlenden systemischen Verfügbarkeit bei topischer Anwendung unwahrscheinlich. Die häufig auftretende allergische oder irritativ-toxische Kontaktdermatitis kann durch eine Anpassung des Therapieregimes, Therapiepausen sowie nebenwirkungsspezifische und unterstützende Maßnahmen häufig beherrscht werden. Ein einschleichender Therapiebeginn mit Anwendung von Chlormethin-Gel jeden zweiten Tag kann die Tolerabilität wesentlich verbessern, insbesondere wenn die Therapie alternierend mit topischen Kortikosteroiden erfolgt. SCHLUSSFOLGERUNGEN: Die Anwendung von Chlormethin-Gel bei Mycosis fungoides wird durch die begleitende Kontaktdermatitis häufig eingeschränkt. Mit einem geeigneten Therapie- und Nebenwirkungsmanagement können vermeidbare Therapieabbrüche verhindert werden und mehr Patienten von der Therapie profitieren.

The optimal use of chlormethine gel for mycosis fungoides: An expert consensus from Germany, Austria and Switzerland (DACH region).

BACKGROUND: In Europe chlormethine gel is licensed for the management of patients with mycosis fungoides of all stages. However, the optimal regimen regarding frequency and dosing as well as combination and maintenance therapy is not well established. METHODS: Ten experts experienced in research and management of cutaneous T-cell lymphomas from Germany, Austria, and Switzerland (DACH region) were asked in written form to report on indication for chlormethine gel, frequency of use, monitoring, concomitant therapies, adverse effects, combination therapies in later stages of the disease, maintenance therapy, and adherence to this therapy for mycosis fungoides. The structured answers were discussed in a consensus conference and recommendations were developed. RESULTS: Essential for therapy with chlormethine gel is an individualized and symptom-oriented management. Because of the lack of systemic resorption of topically administered chlormethine gel, systemic adverse events are unlikely. An allergic or irritative-toxic contact dermatitis is common but manageable with adaptation of the regimen, interruption of administration, and symptom-specific supportive measurements. A step-up initial approach with application of chlormethine gel every other day is associated with a better tolerability, especially if it is alternated with topical corticosteroids. CONCLUSIONS: The use of chlormethine gel in the management of mycosis fungoides is often limited by a concomitant contact dermatitis. An adequate therapeutic regimen and the management of adverse effects can preclude an unnecessary withdrawal of therapy so that more patients can benefit from this treatment option.

Increase of atypical fibroxanthoma and pleomorphic dermal sarcoma: a retrospective analysis of four German skin cancer centers.

BACKGROUND AND OBJECTIVES: In recent years, considerable insight has been gained into the pathogenesis, diagnosis and treatment of cutaneous sarcomas, including atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS). Both entities have shown increasing incidence rates in the last decade. This study was initiated to evaluate how these new insights impact the number of diagnoses of AFX/PDS compared to other cutaneous sarcoma entities. PATIENTS AND METHODS: In a retrospective study of four German skin cancer centers, all histopathological reports of cutaneous sarcomas (AFX, PDS, dermatofibrosarcoma protuberans, cutaneous leiomyosarcoma, angiosarcoma, and Kaposi sarcoma) confirmed by board-certified dermatopathologists were analyzed during a time-period of seven years (2013-2019). Additionally, utilization of immunohistochemical markers (including pan-cytokeratin, S100, desmin, CD34, CD10, procollagen-1, CD99, CD14, and CD68) as an adjunct to diagnose AFX/PDS was recorded. RESULTS: Overall, 255 cutaneous sarcomas were included in the present study. The diagnosis of a cutaneous sarcoma has consequently risen from 2013 to 2019 (from 16 to 52 annual cases). The results of AFX/PDS revealed 4.6 times more diagnoses in 2019 than in 2013. Atypical fibroxanthoma represented the most common subtype, displaying 49.3 % of all diagnosed cutaneous sarcomas. Additionally, the increase of AFX/PDS was linked to the use of immunohistochemistry, with specific immunohistochemical markers used in 57.1 % of cases in 2013 compared to 100 % in 2019. CONCLUSIONS: This retrospective study of four German skin cancer centers demonstrates a substantial rise of AFX/PDS, possibly due to recently established diagnostic and terminology standards. This rise is probably linked to increased utilization of specific immunohistochemical markers. Atypical fibroxanthoma/PDS may be more common than previously thought and seems to represent the most frequent cutaneous sarcoma subtype.

Zunahme des atypischen Fibroxanthoms und pleomorphen dermalen Sarkoms: eine retrospektive Analyse vier deutscher Hauttumorzentren.

HINTERGRUND UND ZIELE: In den letzten Jahren konnten umfassende Erkenntnisse über die Pathogenese, Diagnostik und Behandlung von kutanen Sarkomen, insbesondere des atypischen Fibroxanthoms (AFX) und pleomorphen dermalen Sarkoms (PDS) gesammelt werden. Beide Entitäten zeigten innerhalb der letzten Dekade steigende Inzidenzraten. Die vorliegende Studie diente der Untersuchung, welchen Einfluss die neuen Erkenntnisse auf die Fallzahlen von AFX/PDS im Vergleich zu anderen Sarkom-Entitäten haben. PATIENTEN UND METHODIK: Diese retrospektive Studie wurde an vier deutschen Hauttumorzentren durchgeführt und alle von zertifizierten Dermatopathologen bestätigten histopathologischen Befunde von kutanen Sarkomen (AFX, PDS, Dermatofibrosarcoma protuberans, kutanes Leiomyosarkom, Angiosarkom und Kaposi-Sarkom) in einem Zeitraum von sieben Jahren (2013-2019) evaluiert. Zusätzlich wurde der Einsatz von immunhistochemischen Markern als diagnostische Hilfe (Panzytokeratin, S100, Desmin, CD34, CD10, Prokollagen-1, CD99, CD14 und CD68) erfasst. ERGEBNISSE: Insgesamt konnten 255 kutane Sarkome in die vorliegende Studie eingeschlossen werden. Die Zahl der kutanen Sarkome nahm kontinuierlich von 2013 bis 2019 zu (von 16 auf 52 Fälle im Jahr). Die Diagnose eines AFX/PDS konnte in 2019 4,6-mal häufiger als in 2013 gestellt werden. Das AFX stellte mit 49,3 % aller kutanen Sarkome den häufigsten Sarkom-Subtypen dar. Zusätzlich war der Anstieg von AFX/PDS mit dem Einsatz von Immunhistochemie assoziiert. Der Einsatz von spezifischen Immunhistochemischen Markern stieg von 57,1 % im Jahr 2013 auf 100 % in 2019. SCHLUSSFOLGERUNGEN: Diese retrospektive Studie von vier deutschen Hauttumorzentren demonstriert eine substanzielle Zunahme von AFX/PDS, wahrscheinlich infolge kürzlich etablierter beziehungsweise verbesserter diagnostischer und terminologischer Standards. Dieser Anstieg ist vermutlich mit dem vermehrten Einsatz von bestimmten immunhistochemischen Markern assoziiert. AFX/PDS treten wahrscheinlich häufiger auf als bisher vermutet und repräsentieren möglicherweise den häufigsten kutanen Sarkom-Subtyp.

Low-dose total skin electron beam therapy: Quality of life improvement and clinical impact of maintenance and adjuvant treatment in patients with mycosis fungoides or Sezary syndrome.

PURPOSE: Total skin electron beam therapy (TSEBT) has proved to be a safe and effective treatment for cutaneous T­cell lymphomas. Here, we examined the impact of this treatment on patient quality of life and outcome. PATIENTS AND METHODS: Forty-four patients with mycosis fungoides (MF) or Sezary syndrome (SS) received 48 TSEBT courses with a median dose of 12 Gy within the past 8 years at our institute. Patient and treatment characteristics for these cases as well as the impact of TSEBT on quality of life and duration of response were retrospectively analyzed and compared. RESULTS: The median modified Severity-Weighted Assessment Tool score before the start of TSEBT was 44. The overall response rate was 88%, with a complete response (CR) rate of 33%. The median follow-up period was 13 months. The median duration of response (DOR) and progression-free survival (PFS) for the entire cohort were 10 months and 9 months, respectively. Patient-reported symptom burden was measured with the Dermatological Life Quality Index and Skindex-29 questionnaires. The mean symptom reductions were 6 ± 8 (P = 0.005) and 21 ± 24 (P = 0.002), respectively. In the Functional Assessment of Cancer Therapy-General Assessment, significant improvements in the emotional (P = 0.03) domains were observed after TSEBT. Patients who received maintenance or adjuvant treatments had a longer PFS (P = 0.01). CONCLUSION: TSEBT improved disease symptoms and significantly improved emotional domains of patients' quality of life in patients with MF or SS. In addition, our results indicate that maintenance or adjuvant therapy after TSEBT may improve the PFS.

Key Role of Reactive Oxygen Species (ROS) in Indirubin Derivative-Induced Cell Death in Cutaneous T-Cell Lymphoma Cells.

Cutaneous T-cell lymphoma (CTCL) may develop a highly malignant phenotype in its late phase, and patients may profit from innovative therapies. The plant extract indirubin and its chemical derivatives represent new and promising antitumor strategies. This first report on the effects of an indirubin derivative in CTCL cells shows a strong decrease of cell proliferation and cell viability as well as an induction of apoptosis, suggesting indirubin derivatives for therapy of CTCL. As concerning the mode of activity, the indirubin derivative DKP-071 activated the extrinsic apoptosis cascade via caspase-8 and caspase-3 through downregulation of the caspase antagonistic proteins c-FLIP and XIAP. Importantly, a strong increase of reactive oxygen species (ROS) was observed as an immediate early effect in response to DKP-071 treatment. The use of antioxidative pre-treatment proved the decisive role of ROS, which turned out upstream of all other proapoptotic effects monitored. Thus, reactive oxygen species appear as a highly active proapoptotic pathway in CTCL, which may be promising for therapeutic intervention. This pathway can be efficiently activated by an indirubin derivative.

Primary cutaneous diffuse large B-cell lymphoma, NOS and leg type: Clinical, morphologic and prognostic differences.

BACKGROUND AND OBJECTIVES: Primary cutaneous diffuse large B-cell lymphoma, NOS (PCLBCL/NOS) is a rare PCLBCL. Only few data are available for this tumor. The aim of this study was to identify clinical and/or immunohistochemical markers (in addition to Bcl-2) that characterize PCLBCL/NOS, assist in differentiating it from PCLBCL, leg type (PCLBCL/LT) and help to assess the clinical course/prognosis. PATIENTS AND METHODS: Bcl-2- PCLBCL/NOS) cases (n = 14 were compared with Bcl-2+ PCLBCL/LT cases (n = 29). RESULTS: PCLBCL/NOS patients were younger, predominantly male and had better survival rates than patients with PCLBCL/LT. Patients with PCLBCL/NOS presented more often with larger plaques limited to one or two contiguous body regions, whereas PCLBCL/LT cases often presented with disseminated lesions. Neoplastic cells had a higher proliferation rate (Ki67) in PCLBCL/LT patients. The tumor microenvironment of PCLBCL/NOS had a more prominent CD3+ infiltrate. Overall survival data for the whole cohort (n = 37) revealed that female gender and Bcl-2 expression correlated with a worse survival rate. Bcl-6 expression and centroblastic subtype correlated with better outcomes. None of the other markers studied (e.g. GCB/non-GCB subtype) correlated with survival rate. CONCLUSIONS: PCLBCL/NOS and PCLBCL/LT differ in their clinical behavior and outcomes. Bcl-2 still seems to be the best marker for discriminating between these two subgroups. Bcl-2, female gender and Bcl-6 represent prognostic markers for PCLBCL.

Dimethyl fumarate restores apoptosis sensitivity and inhibits tumor growth and metastasis in CTCL by targeting NF-κB.

Despite intensive efforts in recent years, a curative therapy for cutaneous T-cell lymphoma (CTCL) has not yet been developed. Therefore, the establishment of new therapeutic approaches with higher efficacy rates and milder side effects is strongly desired. A characteristic feature of the malignant T-cell population in CTCL is resistance toward cell death resulting from constitutive NF-κB activation. Therefore, NF-κB-dependent cell death resistance represents an interesting therapeutic target in CTCL because an NF-κB-directed therapy would leave bystander T cells widely unaffected. We investigated the effects of dimethyl fumarate (DMF) on CTCL cells in vitro and in vivo. DMF induced cell death in primary patient-derived CD4(+) cells and CTCL cell lines, but hardly in T cells from healthy donors. DMF-induced cell death was linked specifically to NF-κB inhibition. To study the impact of DMF in vivo, we developed 2 CTCL xenograft mouse models with different cutaneous localizations of the T-cell infiltrate. DMF treatment delayed the growth of CTCL tumors and prevented formation of distant metastases. In addition, DMF induced increased cell death in primary CTCL tumors and in liver metastases. In summary, DMF treatment represents a remarkable therapeutic option in CTCL because it restores CTCL apoptosis in vitro and in preclinical models in vivo and prevents spreading of the disease to distant sites. DMF treatment is of particular promise in CTCL because DMF is already in successful clinical use in the treatment of psoriasis and multiple sclerosis allowing fast translation into clinical studies in CTCL.