Abstract B16: The immune profile of sentinel lymph nodes in melanoma

Abstract

Abstract Background: Immune cell composition and immune-mediated processes occurring in the sentinel lymph node (SLN) of melanoma patients regulate generation of tumor-specific effector T-cell responses and ultimately tumor control. We hypothesized that comprehensive analysis of these immune-associated processes in the SLN biopsy may identify patients at high risk of melanoma recurrence. Methods: We analyzed 38 formalin-fixed, paraffin-embedded sentinel lymph nodes from melanoma patients undergoing SLN biopsy from 2009-2012 using the NanoString nCounter® PanCancer Immune Profiling panel. The panel included 770 immune related genes. Results: Of 38 patients, 19 were SLN negative and 19 were SLN positive. Among SLN-negative patients (n=19), the median Breslow depth was 1.25 mm, and 21% (n=4) had developed recurrence at median follow-up of 6.2 years. Among SLN-positive patients, the median Breslow depth was 3.35 mm and 37% (n=7) had developed recurrence at median follow-up of 6.5 years. There were 31 genes significantly differentially expressed (P<0.01) in SLN positive compared to SLN negative, including higher relative expression of B-cell signaling markers (CD19, CD22, Pax5, CXCR5, CD79B). Among all 38 patients, there were 13 genes differentially expressed (P<0.05) between patients with and without recurrence, including higher relative expression of IL6 in patients with recurrence compared to no recurrence. Further analysis is ongoing. Conclusion: In this retrospective series, we found the immunologic gene expression profile of melanoma SLNs was significantly different in SLN negative versus SLN positive. There were also significant differences in the profile between patients who developed melanoma recurrence versus no recurrence regardless of SLN status. We aim to build on these pilot data. The goal is to use this profile to predict patients at high risk of recurrence after SLNB who may benefit from adjuvant therapy. Citation Format: Georgia M. Beasley, Eda K. Holl, Norma E. Farrow, Margaret G. Leddy, April K. Salama, Brent A. Hanks, Smita K. Nair. The immune profile of sentinel lymph nodes in melanoma [abstract]. In: Proceedings of the AACR Special Conference on Melanoma: From Biology to Target; 2019 Jan 15-18; Houston, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(19 Suppl):Abstract nr B16.