Sézary syndrome: old enigmas, new targets

Validation of AAC-11-Derived Peptide Anti-Tumor Activity in a Single Graft Sézary Patient-Derived Xenograft Mouse Model

Sézary syndrome (SS) is an aggressive cutaneous T cell lymphoma with poor prognosis mainly characterized by the expansion of a tumor CD4⁺ T cell clone in both skin and blood. So far, the development of new therapeutic strategies has been hindered by a lack of reproducible in vivo models closely reflecting patients’ clinical features. We developed an SS murine model consisting of the intravenous injection of Sézary patients’ PBMC, together with a mixture of interleukins, in NOD-SCID-gamma mice. Thirty-four to fifty days after injection, mice showed skin disorders similar to that observed in patients, with the detection of epidermis thickening and dermal tumor T cell infiltrates. Although experimental variability was observed, Sézary cells could be tracked in the blood stream, confirming that our model could efficiently exhibit both skin and blood involvement. Using this model, we evaluated the therapeutic potential of RT39, a cell-penetrating peptide derived from the survival protein anti-apoptosis clone 11 (AAC-11), that we previously characterized as specifically inducing apoptosis of Sézary patients’ malignant clone ex vivo. Systemic administration of RT39 led to cutaneous tumor T cells depletion, demonstrating efficient malignant cells’ targeting and a favorable safety profile. These preclinical data confirmed that RT39 might be an innovative therapeutic tool for Sézary syndrome.

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.

Mogamulizumab induces long term immune restoration and reshapes tumor heterogeneity in Sézary syndrome

BACKGROUND

Mogamulizumab, an anti-CCR4 monoclonal antibody, has been shown to increase progression-free survival in cutaneous T-cell lymphoma.

OBJECTIVES

We hypothesized that besides the targeted depletion of Sézary cells (SCs), mogamulizumab may reshape the immune tumor microenvironment.

METHODS

Both malignant and benign compartments from 26 Sézary patients with B2 stage before mogamulizumab initiation were prospectively analyzed using KIR3DL2 and TCR-Vβ markers, serological markers and molecular assessments of clonality.

RESULTS

Prior to mogamulizumab, the benign subset of CD4+ T-cells displayed exhausted phenotypes, with an increased gradient in PD1/TIGIT/DNAM/CD27/CD28 and CD70 expression from age- matched controls to patient benign CD4+T cells and to SCs. All patients presented SCs with heterogeneous phenotypes and differential expression of individual markers were found within distinct malignant subsets. Early complete blood response was observed in 17/26 patients and was associated to a higher baseline CCR4 expression. A drastic decrease in benign T cells and activated Treg counts was observed during the first 4 weeks. Long-term follow-up revealed the emergence of an immune restoration involving CD8+, naive and stem-memory CD4+T cells, with almost complete disappearance of exhausted lymphocytes. Development of resistance/tumor escape to mogamulizumab was associated to the emergence of CCR4- SCs in blood and skin, displaying significant changes in their heterogeneity patterns, and not univocally explained by mutations within CCR4 coding regions.

CONCLUSIONS

Mogamulizumab is likely contributing to the restoration of an efficient immunity and reshapes not only the malignant lymphocyte subset but also the benign subset. These results have potential implications for optimal therapeutic sequences and/or combinations.

Cell signaling in cutaneous T-cell lymphoma microenvironment: promising targets for molecular-specific treatment

Cutaneous T-cell lymphomas (CTCL) result from the infiltration and proliferation of a population of T cells in the skin, inducing changes in the activity of both T cells and surrounding skin cells. In the CTCL microenvironment, cell interactions mediated by cell signaling pathways are altered. Defining changes in cell signaling enables to understand T-cell deregulations in the CTCL microenvironment and thus the progression of the disease. Moreover, characterizing signaling networks activated in CTCL stages can lead to consider new molecular biomarkers and therapeutic targets. Focusing on mycosis fungoides (MF), the most frequent variant of CTCL, and Sézary syndrome (SS), its leukemic variant, this review highlights recent molecular and genetic findings revealing modifications of key signaling pathways involved in (1) cell proliferation, cell growth, and cell survival such as MAP kinases and PI3K/Akt; (2) immune responses derived from TCR, TLR, JAK/STAT, and NF-kB; and (3) changes in tissue conditions such as extracellular matrix remodeling, hypoxia, and angiogenesis. Alterations in these signaling networks promote malignant T-cell proliferation and survival, T-cell migration, inflammation, and suppression of immune regulation of malignant T cells, making a skin microenvironment that allows disease progression. Targeting key proteins of these signaling pathways, using molecules already available and used in research, in clinical trials, and with other disease indications, can open the way to different therapeutic options in CTCL treatment.

Xenograft and cell culture models of Sézary syndrome reveal cell of origin diversity and subclonal heterogeneity

Sézary Syndrome (SS) is a rare aggressive epidermotropic cutaneous T-cell lymphoma (CTCL) defined by erythroderma, pruritis, and a circulating atypical CD4 + T-cell clonal population. The diversity of Sézary cell (SC) phenotype and genotype may reflect either plasticity or heterogeneity, which was difficult to evaluate dynamically until the achievement of long-term SC expansion. Therefore, we developed six defined culture conditions allowing for the expansion of SC defined by their phenotype and monoclonality in four of seven SS cases. Engraftment of SC through the intrafemoral route into immunodeficient NOD.Cg-Prkdc(scid)Il2rg(tm1Wjll)/SzJ (NSG) mice was achieved in 2 of 14 SS cases. Secondary xenograft by percutaneous injection mimicked most of the features of SS with dermal infiltration, epidermotropism, and blood spreading. These models also allowed assessing the intra-individual heterogeneity of patient SC. Subclones sharing the same TCR gene rearrangement evolved independently according to culture conditions and/or after xenografting. This clonal selection was associated with some immunophenotypic plasticity and limited genomic evolution both in vitro and in vivo. The long-term amplification of SC allowed us to develop eight new SC lines derived from four different patients. These lines represent the cell of origin diversity of SC and provide new tools to evaluate their functional hallmarks and response to therapy.

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

[Treatment of mycosis fungoides and Sézary syndrome]

Adequate therapeutic management of cutaneous T-cell lymphoma (CTCL) requires the identification of the exact CTCL stage and entity within the current WHO classification. There is no curative therapy for CTCL yet, so that treatment currently aims at improving symptoms and quality of life as well as reducing relapse rates. The treatment has to be stage-adapted. Therapeutic options comprise skin-directed as well as systemic treatment. In early stages, phototherapy and local steroids are the first-line therapeutic options. For the therapy of higher stages, interferon alpha and the RXR-specific retinoid bexarotene are used as first-line medications. Second-line treatment comprises monochemotherapy with agents like gemcitabine or liposomal doxorubicine. Nevertheless, the high relapse rates in higher stages make novel alternative treatment options necessary. As future therapy, especially the fusion protein brentuximab-vedotin directed against CD30 shows promising potential in clinical studies.

Origin, function and role in the development of skin diseases CLA+T-lymphocytes

The idea of CLA+T-lymphocytes, which are a special subpopulation of cells with a tropic to the skin, is given. The issues of maturation, migration and functional features of CLA+T-cells are considered. Special attention is paid to the different phenotype of memory T-cells. Modern data concerning the role of CLA+T-cells in the pathogenesis of autoimmune and allergic dermatoses, as well as malignant skin tumors are also presented. The conclusion about the necessity of further study of CLA +T-lymphocytes for detailed understanding of pathogenesis and search of variants of targeted therapy in psoriasis, atopic dermatitis, skin lymphomas and other skin diseases is made.

NRAS mutations in cutaneous T cell lymphoma (CTCL) sensitize tumors towards treatment with the multikinase inhibitor Sorafenib

Therapy of cutaneous T cell lymphoma (CTCL) is complicated by a distinct resistance of the malignant T cells towards apoptosis that can be caused by NRAS mutations in late-stage patients. These mutations correlate with decreased overall survival, but sensitize the respective CTCL cells towards MEK-inhibition-induced apoptosis which represents a promising novel therapeutic target in CTCL. Here, we show that the multi-kinase inhibitor Sorafenib induces apoptosis in NRAS-mutated CTCL cells. CTCL cell lines and to a minor extent primary T cells from Sézary patients without NRAS mutations are also affected by Sorafenib-induced apoptosis suggesting a sensitizing role of NRAS mutations for Sorafenib-induced apoptosis. When combining Sorafenib with the established CTCL medication Vorinostat we detected an increase in cell death sensitivity in CTCL cells. The combination treatment acted synergistically in apoptosis induction in both non-mutant and mutant CTCL cells. Mechanistically, this synergistic apoptosis induction by Sorafenib and Vorinostat is based on the downregulation of the anti-apoptotic protein Mcl-1, but not of other Bcl-2 family members. Taken together, these findings suggest that Sorafenib in combination with Vorinostat represents a novel therapeutic approach for the treatment of CTCL patients.

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.