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

Abstract

Objective High dose IL-2 (HDIL-2) is associated with complete and durable responses in only 5–10% of patients with stage IV melanoma and the toxicity profile is significant. In vivo human models have recently demonstrated 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 non-responders. Methods High-dose IL-2 (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 hours during treatment. PBMCs were isolated and underwent intracellular cytokine and extracellular receptor staining for flow cytometry. Results 5 of 6 patients clinically progressed on HDIL-2 therapy, and these patients demonstrated an increase in the frequency of regulatory T cells on day 4 of treatment. A single patient responded to HDIL-2 therapy and demonstrated 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 of IFNγ+Th17 cells in the responder when compared to all non-responders. As such, all non-responders demonstrated a negative IFNγ+Th17:TREG ratio, whereas the complete responder demonstrated a positive IFNγ+Th17:TREG ratio. Conclusion Our results suggest a distinct immunophenotype may be associated with response to HDIL-2. The peripheral Th17: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

“…The most frequently studied cytokine producing cells are T-lymphocytes [ 190 ] but also other cell populations, including basophils [ 191 ], neutrophils [ 192 , 193 ], NK cells [ 194 ], monocytes [ 192 ] and mast cells [ 195 ] are investigated. In melanoma, flow cytometry was applied to study mechanisms of effects of immunotherapies, such as a PD-1 protein blockade by monoclonal antibodies pembrolizumab or nivolumab [ 196 , 197 , 198 ], CTLA-4 blockade with ipilimumab [ 198 , 199 , 200 , 201 ] or high-dose IL-2 therapy [ 202 , 203 ]. Intracellular cytokine staining can be used to monitor tumour antigen-specific T-cell functions [ 204 , 205 , 206 ] in the search for anti-tumour competent cytotoxic T-cells.…”

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

“…Given previous findings demonstrating the capacity for FoxP3 + CD4 + T cell and Th17 cell inter-conversion, it is interesting to speculate that inflammation (systemic or within the tumor microenvironment) could drive FoxP3 + T REGs into IL-17 secreting cells, thus promoting tumor regression. In support of this hypothesis, we observed a single patient within the studied cohort who demonstrated a complete response to treatment, and this was associated with a high Th17:T REG ratio within the peripheral blood [52]. Therefore, understanding the mechanisms by which Th17 cells expand and interrelate with the FoxP3 + CD4 + T cell compartment is clinically relevant both in the setting of HDIL-2 and other immunomodulatory regimens.…”