This study has validated the recently proposed ISCL/EORTC staging system and identified new prognostic factors.

No abstract

No abstract

These findings provide a comprehensive assessment of genetic abnormalities in CTCL and a rational approach for further studies.

Tumours lacking argininosuccinate synthetase-1 (ASS1) are auxotrophic for arginine and sensitive to amino-acid deprivation. Here, we investigated the role of ASS1 as a biomarker of response to the arginine-lowering agent, pegylated arginine deiminase (ADI-PEG20), in lymphoid malignancies. Although ASS1 protein was largely undetectable in normal and malignant lymphoid tissues, frequent hypermethylation of the ASS1 promoter was observed specifically in the latter. A good correlation was observed between ASS1 methylation, low ASS1 mRNA, absence of ASS1 protein expression and sensitivity to ADI-PEG20 in malignant lymphoid cell lines. We confirmed that the demethylating agent 5-Aza-dC reactivated ASS1 expression and rescued lymphoma cell lines from ADI-PEG20 cytotoxicity. ASS1-methylated cell lines exhibited autophagy and caspase-dependent apoptosis following treatment with ADI-PEG20. In addition, the autophagy inhibitor chloroquine triggered an accumulation of light chain 3-II protein and potentiated the apoptotic effect of ADI-PEG20 in malignant lymphoid cells and patient-derived tumour cells. Finally, a patient with an ASS1-methylated cutaneous T-cell lymphoma responded to compassionate-use ADI-PEG20. In summary, ASS1 promoter methylation contributes to arginine auxotrophy and represents a novel biomarker for evaluating the efficacy of arginine deprivation in patients with lymphoma.

MicroRNAs are commonly aberrantly expressed in many cancers. Very little is known of their role in T-cell lymphoma, however. We therefore elucidated the complete miRNome of purified T cells from 21 patients diagnosed with Sézary Syndrome (SzS), a rare aggressive primary cutaneous T-cell (CD4 ؉ ) lymphoma. Unsupervised cluster analysis of microarray data revealed that the microRNA expression profile was distinct from CD4 ؉ T-cell controls and B-cell lymphomas. The majority (104 of 114) of SzS-associated microRNAs (P < .05) were down-regulated and their expression pattern was largely consistent with previously reported genomic copy number abnormalities and were found to be highly enriched (P < .001) for aberrantly expressed target genes. Levels of miR-223 distinguished SzS samples (n ‫؍‬ 32) from healthy controls (n ‫؍‬ 19) and patients with mycosis fungoides (n ‫؍‬ 11) in more than 90% of samples. Furthermore, we demonstrate that the downregulation of intronically encoded miR-342 plays a role in the pathogenesis of SzS by inhibiting apoptosis, and describe a novel mechanism of regulation for this microRNA via binding of miR-199a* to its host gene. We also provide the first in vivo evidence for down-regulation of the miR-17-92 cluster in malignancy and demonstrate that ectopic miR-17-5p expression increases apoptosis and decreases cell proliferation in SzS cells. (Blood. 2010;116(7):1105-1113)

Differentiation between Sézary syndrome and erythrodermic inflammatory dermatoses can be challenging, and a number of studies have attempted to identify characteristic immunophenotypic changes and molecular biomarkers in Sézary cells that could be useful as additional diagnostic criteria. In this European multicenter study, the sensitivity and specificity of these immunophenotypic and recently proposed but unconfirmed molecular biomarkers in Sézary syndrome were investigated. Peripheral blood CD4(+) T cells from 59 patients with Sézary syndrome and 19 patients with erythrodermic inflammatory dermatoses were analyzed for cell surface proteins by flow cytometry and for copy number alterations and differential gene expression using custom-made quantitative PCR plates. Experiments were performed in duplicate in two independent centers using standard operating procedures with almost identical results. Sézary cells showed MYC gain (40%) and MNT loss (66%); up-regulation of DNM3 (75%), TWIST1 (69%), EPHA4 (66%), and PLS3 (66%); and down-regulation of STAT4 (91%). Loss of CD26 (≥80% CD4(+) T cells) and/or CD7 (≥40% CD4(+) T cells) and combination of altered expression of STAT4, TWIST1, and DNM3 or PLS3 could distinguish, respectively, 83% and 98% of patients with Sézary syndrome from patients with erythrodermic inflammatory dermatoses with 100% specificity. These additional diagnostic panels will be useful adjuncts in the differential diagnosis of Sézary syndrome versus erythrodermic inflammatory dermatoses.

Key Points Aberrations in genome maintenance and DNA repair genes including POT1 occur at a high frequency in Sézary syndrome. Candidate driver genes and affected pathways in Sézary syndrome show extensive heterogeneity but overlap with other mature T-cell lymphomas.