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.

Sézary syndrome preceded by mycosis fungoides and complicated by tumor lysis syndrome and macrophage activation syndrome

Sir, Mycosis fungoides (MF) and Sézary syndrome (SS) are the most common malignancies of cutaneous T-cell lymphoma [1]. Herein, we report a case of SS complicated by tumor lysis syndrome and macrophage activation syndrome. A 54-year-old patient, followed since October 2017 for mycosis fungoides and undergoing various treatments (PUVA therapy, methotrexate, chlorambucil + prednisone), presented with an aggravation of lesions toward extensive and intensely pruritic. A clinical examination revealed dry erythroderma, scratch marks, wart plaques, an accentuation of frontal wrinkles and nasolabial folds (leonine facies), palmoplantar fissuring keratoderma, xanthopachyonychia of all nails, and a carapace-like appearance of the scalp (Figs. 1 – 3). Generalized lymphadenopathy, hepatomegaly, and a state of anasarca-type edema caused by hypoalbuminemia were also found. A skin biopsy revealed lymphoproliferation of CD4+ T-cells and an aberrant loss of pan-T antigens. The CD4-to-CD8 ratio was at 48.5% and Sézary cells were 6960 (absolute value). A lymph node biopsy showed a dense infiltration of Sézary cells. A PET scan revealed hypermetabolism in the entire skin and at the lymph node level. Tumor lysis syndrome was evident, with high levels of blood uric acid (at 182 mg/L), elevated LDH (at 924 U/L), and functional kidney failure. Macrophage activation syndrome was also present, with fever, anemia and thrombocytopenia, liver cytolysis, hypertriglyceridemia, and hyperferritinemia. The patient received an albumin infusion, oral corticosteroid therapy to treat the syndrome, and rasburicase for hyperuremia. Despite this, the patient died before multiagent chemotherapy could have been started. On rare occasions, SS may be preceded by a prior history of classic MF. The International Society for Cutaneous Lymphomas (ISCL) recommends that such cases be designated “SS preceded by MF” [2]. Traditionally, SS is defined as a leukemic form of CTCL associated with erythroderma. Sézary cells are a population of large lymphocytes in the peripheral blood, with grooved and lobulated nuclei, in the case of SS, numbering 1000 cells/mL or more [2]. The histopathologic findings in the skin often resemble those observed in MF, with less prominent epidermotropism. As in MF, immunohistochemical studies showing a CD4 predominance and loss of pan-T-cell markers may be helpful. Lymph node involvement is characterized by the complete effacement of the nodal architecture by the infiltrating Sézary cells (2). The poor prognostic factors in Sézary syndrome include an advanced stage of the disease, an older age at onset, and large cell transformation [3]. While high response rates may be achieved with systemic chemotherapy, they are frequently short-lived and associated with significant toxicities [2]. The management of SS is complicated and requires multidisciplinary collaboration between dermatologists, hematologists, biologists, and reanimators.

What factors guide treatment selection in mycosis fungoides and Sezary syndrome?

Cutaneous T-cell lymphoma (CTCL) comprises a spectrum of T-cell lymphomas with primary skin involvement. Mycosis fungoides (MF) and Sezary syndrome (SS) are the common subtypes of CTCL in which patients present with widely diverse profiles of skin involvement and varying extents of extracutaneous disease. Patients with early-stage disease have an excellent prognosis and are managed primarily with skin-directed therapies; however, those with advanced-stage MF or SS often require multiple lines and recurrent courses of systemic therapies. Many options are available when considering systemic agents, and it is often challenging to know how to prioritize therapies to address a patient's objective disease and quality of life issues. Appreciating the disease heterogeneity and understanding the patient's overall disease profile (eg, skin, lymph nodes, blood, large cell transformation) serve as a useful framework in aligning therapies that can optimally treat active sites of disease. Tissue or blood biomarkers can be integrated into our process of prioritizing therapies and personalizing management in MF or SS. Multidisciplinary management and optimizing supportive care are additional key elements for a favorable outcome. Appropriate patients with high-risk disease should be considered for allogeneic hematopoietic stem cell transplant.

Case Report: Graft Versus Tumor Effect After Non-Myeloablative Allogeneic Stem-Cell Transplantation in a Patient With Brentuximab-Vedotin Refractory Sezary Syndrome

Sezary Syndrome (SS) is a rare leukemic variant of primary cutaneous T-cell lymphoma. Relapsed or refractory disease is generally considered incurable by conventional therapeutic approaches, although durable responses can be achieved with novel monoclonal antibodies. Allogeneic hematopoietic stem cell transplantation (alloHSCT) may have potential value by inducing graft vs-lymphoma (GvL) effects, but there is currently no consensus regarding the timing of alloHSCT or type of conditioning regimen. Here we present the case of a male patient who achieved a complete remission (CR) of primary refractory SS after non-myeloablative alloHSCT. Patient: Two years prior to HSCT, the patient had been refractory to CHOEP-based chemotherapy, interferon, extracorporeal photopheresis (ECP), and bexarotene. Directly prior to alloHSCT brentuximab-vedotin (BV) was applied resulting in a partial remission of the skin compartment and overall in a stable disease. Prior to HSCT, flow cytometry of the bone marrow and peripheral blood showed an infiltration with T-cells positive for CD5, CD4, low CD3, low CD2 and negative for CD7, CD38, HLA-DR and CD8. The trephine biopsy showed a 7% infiltration of SS cells. The CD4:CD8 ratio in peripheral blood (pb) was massively increased at 76.67, with 63.5% of white blood cells expressing a SS immune phenotype. The conditioning regimen included 30 mg/m2 fludarabine on days -5, -4 and -3 and total body irradiation with 2 Gy on day -1. Immunosuppression consisted of cyclosporine A from day-1 and mycophenolate mofetil from day 0. The patient received 6.55x106 CD34+ cells and 1.11x108 CD3+ cells/kg body weight. Bone marrow evaluation on day 28 still showed persistent SS cells by flow cytometry. After tapering immunosuppression until day 169, the CD4:CD8 ratio in pb normalized. CR was documented on day 169 after alloHSCT and is now ongoing for almost 3 years after alloHSCT. Conclusions: We confirm that an alloHSCT can be a curative option for refractory patients with SS. The achievement of a CR after tapering the immunosuppressive therapy indicates a significant role of the GvL effect. In present treatment algorithms for patients with SS, the timing of an alloHSCT and the intensity of conditioning should be further explored.

Roles of OX40 and OX40 Ligand in Mycosis Fungoides and Sézary Syndrome

Mycosis fungoides (MF) and Sézary syndrome (SS), the most common types of cutaneous T-cell lymphoma (CTCL), are characterized by proliferation of mature CD4+ T-helper cells. Patients with advanced-stage MF and SS have poor prognosis, with 5-year survival rates of 52%. Although a variety of systemic therapies are currently available, there are no curative options for such patients except for stem cell transplantation, and thus the treatment of advanced MF and SS still remains challenging. Therefore, elucidation of the pathophysiology of MF/SS and development of medical treatments are desired. In this study, we focused on a molecule called OX40. We examined OX40 and OX40L expression and function using clinical samples of MF and SS and CTCL cell lines. OX40 and OX40L were co-expressed on tumor cells of MF and SS. OX40 and OX40L expression was increased and correlated with disease severity markers in MF/SS patients. Anti-OX40 antibody and anti-OX40L antibody suppressed the proliferation of CTCL cell lines both in vitro and in vivo. These results suggest that OX40–OX40L interactions could contribute to the proliferation of MF/SS tumor cells and that the disruption of OX40–OX40L interactions could become a new therapeutic strategy for the treatment of MF/SS.