Leukaemic variants of cutaneous T-cell lymphoma: Erythrodermic mycosis fungoides and Sézary syndrome.

Mycosis fungoides (MF) and Sézary syndrome (SS) are the most common types of cutaneous lymphoma, accounting for approximately 60% of cutaneous T-cell lymphomas. Diagnosis requires correlation of clinical, histologic, and molecular features. A multitude of factors have been linked to the aetiopathogenesis, however, none have been definitively proven. Erythrodermic MF (E-MF) and SS share overlapping clinical features, such as erythroderma, but are differentiated on the degree of malignant blood involvement. While related, they are considered to be two distinct entities originating from different memory T cell subsets. Differential expression of PD-1 and KIR3DL2 may represent a tool for distinguishing MF and SS, as well as a means of monitoring treatment response. Treatment of E-MF/SS is guided by disease burden, patients' ages and comorbidities, and effect on quality of life. Current treatment options include biologic, targeted, immunologic, and investigational therapies that can provide long term response with minimal side effects. Currently, allogeneic stem cell transplantation is the only potential curative treatment.

IPH4102, a monoclonal antibody directed against the immune receptor molecule KIR3DL2, for the treatment of cutaneous T-cell lymphoma.

INTRODUCTION: Therapeutic options for mycosis fungoides and Sézary syndrome include a variety of immunomodulatory, epigenetic, and cytotoxic options; however, none has been demonstrated to be efficacious for all patients, or to deliver deep and durable responses to the majority of patients. In this review, we examine the monoclonal antibody, IPH4102, a novel agent for the treatment of cutaneous T-cell lymphoma. Areas covered: In this review, we examine data demonstrating the tissue specificity of KIR3DL2 receptor, which is highly expressed on the malignant cells in cutaneous T-cell lymphoma, including mycosis fungoides and Sézary syndrome. This specificity has led to the development of the agent IPH4102. Preclinical data showing efficacy of IPH4102 in vivo are outlined, as well as the results from Phase I clinical trials, which suggest that the agent is both efficacious and well-tolerated. Larger scale clinical trials are to follow. Expert Opinion: We examine the putative benefit of IPH4102 in comparison to established agents already in the clinic, highlighting its efficacy and relative safety. We also examine possible directions that may better define the role of IPH4102 in the treatment of T-cell lymphoma in the future.

Activation-Induced Killer Cell Immunoglobulin-like Receptor 3DL2 Binding to HLA-B27 Licenses Pathogenic T Cell Differentiation in Spondyloarthritis.

OBJECTIVE: In the spondyloarthritides (SpA), increased numbers of CD4+ T cells express killer cell immunoglobulin-like receptor 3DL2 (KIR-3DL2). The aim of this study was to determine the factors that induce KIR-3DL2 expression, and to characterize the relationship between HLA-B27 and the phenotype and function of KIR-3DL2-expressing CD4+ T cells in SpA. METHODS: In total, 34 B27+ patients with SpA, 28 age- and sex-matched healthy controls (20 B27- and 8 B27+), and 9 patients with rheumatoid arthritis were studied. KIR-3DL2 expression and other phenotypic characteristics of peripheral blood and synovial fluid CD4+ T cells were studied by flow cytometry, quantitative polymerase chain reaction, and Western blotting. T cell receptor clonality was determined by template-switch anchored reverse transcription-polymerase chain reaction and sequencing analysis. Cytokines were measured by enzyme-linked immunosorbent assay. RESULTS: Cellular activation induced KIR-3DL2 expression on both naive and effector CD4+ T cells. KIR-3DL2 binding to B27+ cells promoted expression of KIR-3DL2, the Th17-specific transcription factor retinoic acid receptor-related orphan nuclear receptor γt, and the antiapoptotic factor B cell lymphoma 2. KIR-3DL2+CD4+ T cells in patients with ankylosing spondylitis were oligoclonal and enriched for markers of T cell activation and for the gut homing receptor CCR9. In the presence of B27+ antigen-presenting cells, KIR-3DL2+CD4+ T cells produced less interleukin-2 (IL-2) but more IL-17. This effect was blocked by HC10, an antibody that inhibits the binding of KIR-3DL2 to B27 heavy chains. CONCLUSION: KIR-3DL2 binding to HLA-B27 licenses Th17 cell differentiation in SpA. These findings raise the therapeutic potential of targeting HLA-B27-KIR-3DL2 interactions for the treatment of B27+ patients with SpA.

Natural killer cell and gamma delta T cell alterations in enthesitis related arthritis category of juvenile idiopathic arthritis.

Enthesitis related arthritis (ERA) is associated with increased frequency of Th17 cells and synovial fluid (SF) IL-17 levels. Natural killer (NK) and gamma delta T cells have been recently shown to produce IL-17, thus we studied the NK and gamma delta-T cells in peripheral blood (PB) of 50 ERA, 16 other JIA patients and 19 healthy controls. We have analyzed the frequency of NK (total, CD56dim, CD56bright) and gamma delta-T cells, perforin and KIR3DL1/2 expression on NK cells and IL-17 and IFN-gamma production by them using flow cytometry. ERA patients had more NK cells with reduced perforin expression and IFN-gamma production but increased KIR3DL1/2 expression and IL-17 production as compared to controls. Also IL-17 producing gamma delta-T were increased in PB of ERA patients. Paired SF samples had NK cells with reduced perforin and KIR3DL expression. Thus increased NK and gamma delta-T cells may contribute to the inflammation in ERA by producing IL-17.

IL-17-producing CD4+ T cells are increased in early, active axial spondyloarthritis including patients without imaging abnormalities.

OBJECTIVE: Increased numbers of IL-17-producing CD4(+) T cells have been observed in AS. However, it is not known whether these CD4(+) T cells are already present in early disease or if this is a late disease phenomenon only. Therefore we aimed to investigate whether IL-17-producing CD4(+) T cells are involved in early active axial SpA, including patients without imaging abnormalities, by determining the frequency and phenotype of IL-17-producing CD4(+) T cells in these patients. METHODS: Flow cytometry was used to analyse cytokine production and surface marker expression of peripheral blood mononuclear cells from 31 patients suffering from early active HLA-B27-positive axial SpA fulfilling the Assessment of SpondyloArthritis International Society criteria with or without MRI abnormalities and 21 healthy controls. RESULTS: Patients with early active axial SpA showed an increased percentage of IL-17-producing CD4(+) T cells compared with healthy controls (mean 1.1% vs 0.4%, respectively; P = 0.013). The percentage of IL-17-producing CD4(+) T cells was equally increased in patients with and without MRI abnormalities (1.2% vs 1.1%, respectively; P = 0.81). These IL-17-producing CD4(+)T cells expressed the αß T cell receptor but not the γδ T cell receptor, exhibited a memory phenotype and expressed CD161, but only sporadically expressed killer cell immunoglobulin-like receptor 3DL2 (KIR3DL2). CONCLUSION: IL-17-producing CD4(+) T cells are increased in patients with early active axial SpA both with and without MRI abnormalities. This finding shows that the frequency of IL-17-producing CD4(+) T cells is enhanced in the early stages of disease.

KIR3DL2/CpG ODN interaction mediates Sézary syndrome malignant T cell apoptosis.

We previously identified the NK cell receptor KIR3DL2 as a valuable diagnostic and prognostic marker for the detection of the tumoral T cell burden of Sézary syndrome (SS) patients. However, the function of this receptor on the malignant T lymphocyte population remained unexplored. We here demonstrate that engagement of KIR3DL2 by its recently identified ligand CpG oligodeoxynucleotide (ODN) induces the internalization of the receptor and leads to a caspase-dependent apoptosis of malignant T cells. This process of cellular death is correlated to a dephosphorylation of the transcription factor STAT3 (signal transducer and activator of transcription 3), which is found constitutively phosphorylated and activated in Sézary cells. Our results indicate that KIR3DL2 can directly promote SS malignant cell death through the use of CpG ODN.

IPH4102, a humanized KIR3DL2 antibody with potent activity against cutaneous T-cell lymphoma.

Advanced cutaneous T-cell lymphoma (CTCL) remains an unmet medical need, which lacks effective targeted therapies. In this study, we report the development of IPH4102, a humanized monoclonal antibody that targets the immune receptor KIR3DL2, which is widely expressed on CTCL cells but few normal immune cells. Potent antitumor properties of IPH4102 were documented in allogeneic human CTCL cells and a mouse model of KIR3DL2(+) disease. IPH4102 antitumor activity was mediated by antibody-dependent cell cytotoxicity and phagocytosis. IPH4102 improved survival and reduced tumor growth in mice inoculated with KIR3DL2(+) tumors. Ex vivo efficacy was further evaluated in primary Sézary patient cells, sorted natural killer-based autologous assays, and direct spiking into Sézary patient peripheral blood mononuclear cells. In these settings, IPH4102 selectively and efficiently killed primary Sézary cells, including at unfavorable effector-to-target ratios characteristic of unsorted PBMC. Together, our results offer preclinical proof of concept for the clinical development of IPH4102 to treat patients with advanced CTCL.

KIR3DL2 binds to HLA-B27 dimers and free H chains more strongly than other HLA class I and promotes the expansion of T cells in ankylosing spondylitis.

The human leukocyte Ag HLA-B27 (B27) is strongly associated with the spondyloarthritides. B27 can be expressed at the cell surface of APC as both classical ß2-microglobulin-associated B27 and B27 free H chain forms (FHC), including disulfide-bonded H chain homodimers (termed B27(2)). B27 FHC forms, but not classical B27, bind to KIR3DL2. HLA-A3, which is not associated with spondyloarthritis (SpA), is also a ligand for KIR3DL2. In this study, we show that B27(2) and B27 FHC bind more strongly to KIR3DL2 than other HLA-class I, including HLA-A3. B27(2) tetramers bound KIR3DL2-transfected cells more strongly than HLA-A3. KIR3DL2Fc bound to HLA-B27-transfected cells more strongly than to cells transfected with other HLA-class I. KIR3DL2Fc pulled down multimeric, dimeric, and monomeric FHC from HLA-B27-expressing cell lines. Binding to B27(2) and B27 FHC stimulated greater KIR3DL2 phosphorylation than HLA-A3. B27(2) and B27 FHC stimulated KIR3DL2CD3ε-transduced T cell IL-2 production to a greater extent than control HLA-class I. KIR3DL2 binding to B27 inhibited NK IFN-γ secretion and promoted greater survival of KIR3DL2(+) CD4 T and NK cells than binding to other HLA-class I. KIR3DL2(+) T cells from B27(+) SpA patients proliferated more in response to Ag presented by syngeneic APC than the same T cell subset from healthy and disease controls. Our results suggest that expansion of KIR3DL2-expressing leukocytes observed in B27(+) SpA may be explained by the stronger interaction of KIR3DL2 with B27 FHC.

Estimation of the size of the alloreactive NK cell repertoire: studies in individuals homozygous for the group A KIR haplotype.

Stem cell transplantation across HLA barriers may trigger NK cell-mediated graft-vs-leukemia effects leading to improved survival for patients with hematological malignancies. However, the genetic algorithm based on killer cell Ig-like receptor (KIR) and HLA genes used to predict NK cell alloreactivity have yielded discrepant results. Accordingly, it has been difficult to define transplantation settings that favor NK cell alloreactivity. In this study, we have used multiparameter flow cytometry to simultaneously analyze the cell surface expression of all four major inhibitory KIR and CD94/NKG2A to determine the size of the alloreactive NK cell repertoires in 31 individuals homozygous for the group A KIR haplotype. We observed a vast variability in the frequencies of cells with an alloreactive potential, ranging from 0 to 62% of the total NK cell population depending on which, and how many, KIR ligands were missing in theoretical recipients. This analysis required a functional examination of KIR3DL2-single positive NK cells, showing that this subset was hyporesponsive in individuals harboring the cognate ligands HLA-A3/A11. The results provide new insights into the variability of the functional alloreactive NK cell repertoire and have implications for donor selection in hematopoietic stem cell transplantation and adoptive NK cell-based immunotherapy.