Analysis of CTLA4 expression on T regulatory cells in patients with advanced stage melanoma in the setting of high dose IL-2 (HDIL-2).

Abstract

9043 Background: HDIL-2 is associated with long-term remissions in stage IV melanoma, but in less than 10% of patients. Combination therapy with HDIL-2 and agents immunomodulating CTLA-4 have been undertaken. We investigated the effect of HDIL-2 on CTLA4 expression on T cell subsets in patients with melanoma. Methods: Peripheral blood was collected at baseline and serially post-treatment at 24, 48, 72, and 96 hours from 6 patients with advanced stage melanoma undergoing HDIL-2. All patients were treatment naive with regard to anti-CTLA4 therapy. PBMCs were isolated and restimulated ex vivo for 4 hours using PMA/ionomycin. Fluorophore conjugated anti-CTLA4 antibody was added at time of restimulation and incubated with cells for 4 hours. Intracellular and extracellular cytokine staining was then performed and co-signaling molecule expression was quantified via flow cytometry and measured on a continuous scale. Statistical analysis was performed using paired t tests via Prism 6.0e software. Results: HDIL-2 r...