A prospective evaluation of vascular endothelial growth factor (VEGF) and the immune system in stage III/IV melanoma.

Abstract

e20046 Background: The immune system and VEGF may play a role in melanoma behavior. We prospectively collected data in 10 stage III and 22 stage IV melanoma patients to observe factors influencing outcomes. Methods: We assessed median survival (MS), LDH, BRAF, VEGF, Th1/Th2 ratio, regulatory T cells (Tregs) and CD4/CD8 ratio, which were measured upon enrollment. LDH and BRAF were measured in standard commercial labs; VEGF via ELISA at LVHN; Th1/Th2 ratio and CD4/CD8 ratio via flow cytometry at Mayo Clinic. Stage III patients were treated with resection and interferon or observation. Stage IV patients were treated with some or all of the following: resection +/- GM-CSF, IL-2, ipilimumab, vemurafenib, carboplatin/paclitaxel/bevacizumab and temazolamide. Results: MS for stage IV patients was 48 months using a Kaplan-Meier survival curve. The only variable associated with survival was LDH, (HR=1.0017, 95%CI: 1.0003-1.0032, p=0.02). In stage IV patients, there was a positive correlation between VEGF and Tregs (r=.485, n=22 p=0.022) and a negative correlation between Tregs and Th1/Th2 (r=-.470, n=22, p=0.027). In stage III/IV patients who were alive at study completion, there was a positive correlation between CD4/CD8 and VEGF (r=.792, n=10, p=0.006). In patients who died, there was a negative correlation between Tregs and Th1/Th2 (r=-.660, n=12, p=0.02). 7 of the stage IV patients are currently disease free, including 5 of the 10 who received IL-2 +/- metastectomy. Conclusions: While a median survival of 48 months was provocative for stage IV patients, it may reflect referral selection at an IL-2 center. Recent advances such as ipilimumab (which lowers Tregs), BRAF inhibitors, and immunotherapy/aggressive resection as initial therapy may have impacted survival. The literature suggests that an elevated CD4/CD8 ratio predicts better outcomes. Higher VEGF levels have also been associated with lower overall survival in patients treated with IL-2. We found an association between higher VEGF levels and increased Tregs in deceased patients but not in living patients. In patients still alive, higher VEGF was balanced by a higher CD4/CD8 ratio. We did not find a correlation between baseline VEGF and survival.