Prevalence of genetically defined tumor cells in CD7 as well as CD26 positive and negative circulating T-cell subsets in Sézary syndrome

The role of Dipeptidyl Peptidase-4 in cutaneous disease

Dipeptidyl peptidase-4 (DPP4) is a multifunctional, transmembrane glycoprotein present on the cell surface of various tissues. It is present in multiple molecular forms including cell surface and soluble. The role of DPP4 and its inhibition in cutaneous dermatoses have been a recent point of investigation. DPP4 exerts a notable influence on T-cell biology, the induction of skin-specific lymphocytes, and the homeostasis between regulatory and effector T cells. Moreover, DPP4 interacts with a broad range of molecules, including adenosine deaminase, caveolin-1, CXCR4 receptor, M6P/insulin-like growth factor II-receptor and fibroblast activation protein-α, triggering downstream effects that modulate the immune response, cell adhesion and chemokine activity. DPP4 expression on melanocytes, keratinocytes and fibroblasts further alters cell function and, thus, has crucial implications in cutaneous pathology. As a result, DPP4 plays a significant role in bullous pemphigoid, T helper type 1-like reactions, cutaneous lymphoma, melanoma, wound healing and fibrotic disorders. This review illustrates the multifactorial role of DPP4 expression, regulation, and inhibition in cutaneous diseases.

Blood flow cytometry in Sézary syndrome: new insights on prognostic relevance and immunophenotypic changes during follow-up

OBJECTIVES

Sézary syndrome (SS) is characterized by erythroderma, generalized lymphadenopathy, and the presence of circulating atypical lymphocytes, which are difficult to identify by morphologic data.

METHODS

We revised our series of 107 patients in an attempt to better define the phenotypic aberrancies in blood at diagnosis and the immunophenotypic stability over time detected by flow cytometry. Polymerase chain reaction assay was also used to study CD26/dipeptidyl peptidase IV (DPPIV) gene methylation.

RESULTS

The most common aberrancies were represented by the lack of CD26 (96/107) or CD38 (101/107) expression and the presence of a "dim" CD3, CD4, or CD2 population. There was a high variability in CD7 expression. In total, 31% of the patients had phenotypical heterogeneity in CD26 and CD7 expression at diagnosis. The phenotype was stable over time in 73 of 95 patients with available follow-up data, while 22 of 95 patients developed changes in CD26, CD7, or CD2 expression. CD4+CD26- SS showed hypermethylation of the CpG islands for the promoter region of CD26/DPPIV. Multivariate analysis showed that CD26 expression is a favorable prognostic factor (hazard ratio, 2.94; P = .045).

CONCLUSIONS

We confirm the relevance of CD26 negativity in SS diagnosis and monitoring. Nevertheless, the presence of rare CD26+ cases suggests that a multiparameter flow cytometry approach should be used. Changes in methylation profile could account for phenotypical heterogeneity.

Regulation of T-plastin expression by promoter hypomethylation in primary cutaneous T-cell lymphoma

T-plastin (PLS3) is an actin-bundling protein normally expressed in epithelial cells but absent in cells of hematopoietic origin. Aberrant PLS3 expression has been demonstrated in lymphocytes from Sézary syndrome (SS) patients and has been proposed as a biomarker for SS; however, the mechanism underlying dysregulation of PLS3 has not been determined. In this study, PLS3 mRNA expression was demonstrated in 21/35 (60%) SS patients and in 3/8 (38%) mycosis fungoides patients, all of whom had clonal blood involvement. No evidence for PLS3 mutations within coding or promoter regions was found, but significant hypomethylation of CpG dinucleotides 95-99 within the PLS3 CpG island was observed and this was restricted to the PLS3+ population. A polyclonal antibody specific to PLS3 was raised to examine coexpression of PLS3 with a panel of T-cell differentiation markers. All PLS3+ cells were CD3+CD4+ and CD26-, suggesting that loss of CD26 is consistently associated with gain of PLS3, whereas all other markers were distributed heterogeneously. However, a patient-specific TCR copy number assay also demonstrated heterogeneity in PLS3 expression in tumor cell populations. Importantly, our findings demonstrate PLS3 expression in the majority of SS patients and provide insight into the molecular regulation of PLS3 expression in CTCL.

Clinical end points and response criteria in mycosis fungoides and Sézary syndrome: a consensus statement of the International Society for Cutaneous Lymphomas, the United States Cutaneous Lymphoma Consortium, and the Cutaneous Lymphoma Task Force of the European Organisation for Research and Treatment of Cancer

Mycosis fungoides (MF) and Sézary syndrome (SS), the major forms of cutaneous T-cell lymphoma, have unique characteristics that distinguish them from other types of non-Hodgkin's lymphomas. Clinical trials in MF/SS have suffered from a lack of standardization in evaluation, staging, assessment, end points, and response criteria. Recently defined criteria for the diagnosis of early MF, guidelines for initial evaluation, and revised staging and classification criteria for MF and SS now offer the potential for uniform staging of patients enrolled in clinical trials for MF/SS. This article presents consensus recommendations for the general conduct of clinical trials of patients with MF/SS as well as methods for standardized assessment of potential disease manifestations in skin, lymph nodes, blood, and visceral organs, and definition of end points and response criteria. These guidelines should facilitate collaboration among investigators and collation of data from sponsor-generated or investigator-initiated clinical trials involving patients with MF or SS.

Telomerase-specific GV1001 peptide vaccination fails to induce objective tumor response in patients with cutaneous T cell lymphoma

BACKGROUND

There is currently no curative therapy for cutaneous T cell lymphoma (CTCL). New therapies are therefore needed. Telomerase, the enzyme that allows for unrestricted cell divisions of cancer cells, is a promising target for cancer therapy. The telomerase-specific peptide vaccination GV1001 has shown promising results in previous studies. Since telomerase is expressed in malignant cells of CTCL, GV1001 vaccination in CTCL is a promising new therapeutic approach.

OBJECTIVE

We sought to investigate the efficacy of GV1001 vaccination in CTCL patients and characterize the induced immune response.

METHODS

Six CTCL patients were vaccinated with the GV-peptide using granulocyte/macrophage colony-stimulating factor as adjuvant. Objective clinical response and the T cell response were assessed.

RESULTS

None of the patients demonstrated objective clinical response to the vaccination whereas one patient showed disease progression. 1/6 patients acquired a GV1001-specifc T cell response with a Th1 cytokine profile and expression of skin-homing receptors. This hTERT-specific T cell response was not associated with beneficial modulation of the tumor-infiltrating leukocytes. Furthermore, removal of regulatory T cells did not enhance responsiveness to GV1001 in vitro in any of the patients analyzed.

CONCLUSIONS

Our results suggest that the GV1001 vaccination is not effective in CTCL patients and disease progression in 1/6 patients raises concerns about its safety. By analyzing skin-homing properties of GV1001-specific T cells and the involvement of regulatory T cells we nevertheless provide insight into vaccine-induced immune responses which may help to improve vaccine strategies in CTCL.

Downregulation of Fas gene expression in Sézary syndrome is associated with promoter hypermethylation

Sézary Syndrome (SS) is an aggressive leukemic variant of primary cutaneous T-cell lymphoma characterized by the presence of tumor or Sézary cells that generally display a mature memory T-cell immunophenotype. Sézary cells proliferate poorly and therefore their accumulation may be due to defective T-cell homeostasis involving resistance to apoptosis. In this study, we analyzed Fas expression in CD4+ lymphocytes at the mRNA and protein levels in a large cohort of SS patients as compared with healthy controls. Fas mRNA expression was dysregulated in 34/47 patients, with significant under- and overexpression of Fas mRNA detected in 21 and 13 patients respectively (P<0.01). Examination of cell-surface Fas expression showed correlation with the observed downregulation of mRNA in CD4+ T cells. Mutational analysis demonstrated that functional FAS gene mutations are rare. Moreover, 16 SS patients who showed significant under-expression of Fas mRNA also showed significant positional hypermethylation within the FAS CpG island, which was not present in healthy controls or SS patients determined to have normal or overexpression of Fas mRNA. These data demonstrate that dysregulation of Fas expression is a common feature of SS, and provide a rationale for targeted therapies to restore the extrinsic Fas-dependent apoptotic pathway in this malignancy.