Exogenous IL-2 Induces FoxP3+ Th17 Cells In Vivo in Melanoma Patients

Targeting regulatory T cells for immunotherapy in melanoma

Regulatory T cells (Tregs) are essential in the maintenance of immunity, and they are also a key to immune suppressive microenvironment in solid tumors. Many studies have revealed the biology of Tregs in various human pathologies. Here we review recent understandings of the immunophenotypes and suppressive functions of Tregs in melanoma, including Treg recruitment and expansion in a tumor. Tregs are frequently accumulated in melanoma and the ratio of CD8+ T cells versus Tregs in the melanoma is predictive for patient survival. Hence, depletion of Tregs is a promising strategy for the enhancement of anti-melanoma immunity. Many recent studies are aimed to target Tregs in melanoma. Distinguishing Tregs from other immune cells and understanding the function of different subsets of Tregs may contribute to better therapeutic efficacy. Depletion of functional Tregs from the tumor microenvironment has been tested to induce clinically relevant immune responses against melanomas. However, the lack of Treg specific therapeutic antibodies or Treg specific depleting strategies is a big hurdle that is yet to be overcome. Additional studies to fine-tune currently available therapies and more agents that specifically and selectively target tumor infiltrating Tregs in melanoma are urgently needed.

Complete response to high-dose IL-2 and enhanced IFNγ+Th17 : TREG ratio in a melanoma patient

High-dose IL-2 (HDIL-2) is associated with complete and durable responses in only 5-10% of patients with stage intravenous melanoma and the toxicity profile is significant. In-vivo human models have recently shown a stimulatory effect of exogenous IL-2 on both the Th17 and regulatory T-cell (TREG) compartments. We investigated and compared the effect of HDIL-2 on the Th17 and TREG compartments in HDIL-2 responders versus nonresponders. HDIL-2 was administered at a dose of 720 000 IU/kg to patients with melanoma (n=6) and peripheral blood was collected at baseline and at 24, 48, 72, and 96 h during treatment. Peripheral blood mononuclear cells were isolated and subjected to intracellular cytokine and extracellular receptor staining for flow cytometry. Five of six patients progressed clinically on HDIL-2 therapy, and these patients showed an increase in the frequency of TREGs on day 4 of treatment. A single patient responded to HDIL-2 therapy and showed a decrease in the frequency of TREG cells on day 4 of treatment. We found that HDIL-2 resulted in a larger increase in the frequency and total numbers of IFNγTh17 cells in the complete responder compared with all nonresponders. As such, the complete responder showed a high IFNγTh17 : TREG ratio. Our results suggest that a distinct immunophenotype may be associated with response to HDIL-2. The peripheral IFNγTh17 : TREG ratio may serve as an early biomarker in the setting of HDIL-2 to help identify those patients who would benefit from subsequent cycles.

Advances in Proteomic Techniques for Cytokine Analysis: Focus on Melanoma Research

Melanoma is a skin cancer with permanently increasing incidence and resistance to therapies in advanced stages. Reports of spontaneous regression and tumour infiltration with T-lymphocytes makes melanoma candidate for immunotherapies. Cytokines are key factors regulating immune response and intercellular communication in tumour microenvironment. Cytokines may be used in therapy of melanoma to modulate immune response. Cytokines also possess diagnostic and prognostic potential and cytokine production may reflect effects of immunotherapies. The purpose of this review is to give an overview of recent advances in proteomic techniques for the detection and quantification of cytokines in melanoma research. Approaches covered span from mass spectrometry to immunoassays for single molecule detection (ELISA, western blot), multiplex assays (chemiluminescent, bead-based (Luminex) and planar antibody arrays), ultrasensitive techniques (Singulex, Simoa, immuno-PCR, proximity ligation/extension assay, immunomagnetic reduction assay), to analyses of single cells producing cytokines (ELISpot, flow cytometry, mass cytometry and emerging techniques for single cell secretomics). Although this review is focused mainly on cancer and particularly melanoma, the discussed techniques are in general applicable to broad research field of biology and medicine, including stem cells, development, aging, immunology and intercellular communication.