Abstract 454: Evaluating the progression of cutaneous melanoma by the molecular immune response of the sentinel lymph node

Abstract

Abstract Introduction: The sentinel node (SN) has become the standard diagnostic tool for staging melanoma. With the recent development of several potent immunotherapies we hypothesized that the early immune events in melanoma maybe first seen in the SN. Methods: 81 SN from 79 patients were evaluated with microarray technology, qPCR, routine H&E & IHC. We identified immune genes that are present by qPCR in SNs from a random section of the SN, away from the blue dye. Statistical analysis assessed the utility of these markers to predict tumor progression by increasing primary thickness and tumor-positive SN. Results: Of the 79 patients, 48 (61%) were men. Median age was 59 (range 6-95 years). Primary melanomas were most commonly from the trunk (51%) and extremities (40%). The median thickness of the primaries was 0.95mm. In 7 cases the tumor thickness was not measured. 13% of the patients had ulcerated primaries. 29% of the primary tumors had at least 1 mitosis/mm2. 9 (11%) patients had SN metastasis, as determined by conventional H&E and IHC. The incidence of SN positivity was directly related to tumor thickness; the higher the T-stage the greater percentage of SN positivity: 2% T1, 19% T2, 20% T3 and 60% T4 melanoma. 33% of ulcerated primaries and 30% with increased mitotic rate had a tumor-positive SN. Increased mitotic rate (>1 mitosis/mm2) and decreased gene expression of CD80 and ARG2 correlated with T3/4 primaries. By univariate analyses: age (p<0.001), primary site (<0.001), mitotic rate and increasing gene expression of CTLA-4 (p<0.001) and PD-1 (p<0.001) in SN were predictive of SN positivity. Multivariate analysis demonstrates mitoses in the primary and CTLA-4 and PD-1 gene expression in the SN were predictive of metastases in the SN. The up-regulation of CTLA-4 and PD-1 gene expression, in combination with increased mitoses was an accurate determinate of SN metastasis. The AUC values of CTLA-4 and PD-1 expression and increased mitoses at the primary site were 0.8 and 0.73. The positive and negative predictive values of the assays varied with level of gene expression but approached 100% and 90% respectively. Conclusions: The immune molecular profile of the sentinel lymph node in melanoma is altered in the presence or absence of metastases in the lymph node and by progression of the primary melanoma. These alterations in immune profiles may be important for distinguishing the patterns of metastases and ultimately the response to therapy in melanoma. Citation Format: Richard Essner, Alexandra Gangi, David Kaufman, Ke Wei Gong, Myung Sim, Dennis Slamon. Evaluating the progression of cutaneous melanoma by the molecular immune response of the sentinel lymph node. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 454. doi:10.1158/1538-7445.AM2015-454