Denileukin diftitox for the treatment of cutaneous T-cell lymphoma

Cutaneous T-cell lymphoma/mycosis fungoides (CTCL/MF) is a rare lymphoproliferative disorder which can present as an indolent or as an aggressive process involving skin, lymph nodes, and blood. In stages IA, IB and IIA, it is usually managed with topical medications and phototherapy. If there is progression despite application of these treatments, or if the patient presents with a higher stage of disease, systemic chemotherapy or retinoids, rexinoids, biologic response modifiers are often necessary. Consequently, patients are often treated with a sequence of modalities and drugs. Denileukin diftitox (DD, Ontak®) is a targeted immunotoxin which has biological activity against malignancies expressing the IL-2 receptor. In addition to its unique mechanism of action, DD has a toxicity profile which does not overlap with most commonly used chemotherapeutic agents. CTCL/MF has been found be particularly susceptible to treatment with this agent. This review will describe the development DD, its proposed mechanism of action, the clinical trials which identified its utility in the treatment of CTCL/MF, the common toxicities encountered with this agent, and the management of these toxicities. In addition the incorporation of DD in the sequential treatment of CTCL/MF and data suggesting potential combination therapies employing this novel agent will be discussed

STAT3 dysregulation in mature T and NK cell lymphomas

T cell lymphomas comprise a distinct class of non-Hodgkin’s lymphomas, which include mature T and natural killer (NK) cell neoplasms. While each malignancy within this group is characterized by unique clinicopathologic features, dysregulation in the Janus tyrosine family of kinases/Signal transducer and activator of transcription (JAK/STAT) signaling pathway, specifically aberrant STAT3 activation, is a common feature among these lymphomas. The mechanisms driving dysregulation vary among T cell lymphoma subtypes and include activating mutations in upstream kinases or STAT3 itself, formation of oncogenic kinases which drive STAT3 activation, loss of negative regulators of STAT3, and the induction of a pro-tumorigenic inflammatory microenvironment. Constitutive STAT3 activation has been associated with the expression of targets able to increase pro-survival signals and provide malignant fitness. Patients with dysregulated STAT3 signaling tend to have inferior clinical outcomes, which underscores the importance of STAT3 signaling in malignant progression. Targeting of STAT3 has shown promising results in pre-clinical studies in T cell lymphoma lines, ex-vivo primary malignant patient cells, and in mouse models of disease. However, targeting this pleotropic pathway in patients has proven difficult. Here we review the recent contributions to our understanding of the role of STAT3 in T cell lymphomagenesis, mechanisms driving STAT3 activation in T cell lymphomas, and current efforts at targeting STAT3 signaling in T cell malignancies

Multimodal single-cell analysis of cutaneous T-cell lymphoma reveals distinct subclonal tissue-dependent signatures

Cutaneous T-cell lymphoma (CTCL) is a heterogeneous group of mature T-cell neoplasms characterized by the accumulation of clonal malignant CD4+ T cells in the skin. The most common variant of CTCL, mycosis fungoides (MF ), is confined to the skin in early stages but can be accompanied by extracutaneous dissemination of malignant T cells to the blood and lymph nodes in advanced stages of disease. Sézary syndrome (SS), a leukemic form of disease, is characterized by significant blood involvement. Little is known about the transcriptional and genomic relationship between skin- and blood-residing malignant T cells in CTCL. To identify and interrogate malignant clones in matched skin and blood from patients with leukemic MF and SS, we combine T-cell receptor clonotyping with quantification of gene expression and cell surface markers at the single cell level. Our data reveal clonal evolution at a transcriptional and genetic level within the malignant populations of individual patients. We highlight highly consistent transcriptional signatures delineating skin- and blood-derived malignant T cells. Analysis of these 2 populations suggests that environmental cues, along with genetic aberrations, contribute to transcriptional profiles of malignant T cells. Our findings indicate that the skin microenvironment in CTCL promotes a transcriptional response supporting rapid malignant expansion, as opposed to the quiescent state observed in the blood, potentially influencing efficacy of therapies. These results provide insight into tissue-specific characteristics of cancerous cells and underscore the need to address the patients’ individual malignant profiles at the time of therapy to eliminate all subclones