The prognostic significance of VISTA and CD33-positive myeloid cells in cutaneous melanoma and their relationship with PD-1 expression.

V-domain Ig suppressor of T-cell activation (VISTA), which mediates immune evasion in cancer, is mainly expressed on hematopoietic cells and myeloid cells in the tumor. We evaluated correlations among the expression of VISTA, the myeloid-derived suppressor cell marker CD33, and programmed death-1 (PD-1), and determined their relationships with clinicopathological characteristics and disease outcomes in melanoma. Diagnostic tissue from 136 cases of melanoma was evaluated by immunohistochemistry for CD33, VISTA, and PD-1 expression. Dual immunofluorescence using CD33 and VISTA antibodies was performed. VISTA expression positively correlated with CD33 expression in melanoma tissue. Dual immunofluorescence staining revealed that VISTA was expressed by CD33-positive myeloid cells. PD-1 expression correlated with CD33 and VISTA expression. CD33 and VISTA expression were significantly associated with negative prognostic factors, including a deeper Breslow thickness and an advanced stage of disease. High expression of either CD33 or VISTA was associated with worse survival. Positivity for both VISTA and PD-1 predicted worse survival. Multivariate analysis showed that both CD33 and VISTA expression were independent prognostic factors in cutaneous melanoma. VISTA and CD33 expression are independent unfavourable prognostic factors in melanoma, which suggests their potential as therapeutic targets.

Expression of lymphocyte-activating gene 3 and T-cell immunoreceptor with immunoglobulin and ITIM domains in cutaneous melanoma and their correlation with programmed cell death 1 expression in tumor-infiltrating lymphocytes.

BACKGROUND: Lymphocyte-activating gene 3 (LAG-3) and T-cell immunoreceptor with immunoglobulin and immunoreceptor tyrosine-based inhibition motif (TIGIT) domains are emerging checkpoint proteins. OBJECTIVE: We evaluated LAG-3 and TIGIT protein expression patterns, correlated these patterns with programmed cell death 1 (PD-1) protein expression, and determined their effects on clinicopathologic characteristics and biologic responses in melanoma. METHODS: Diagnostic tissue from 124 patients with melanoma were evaluated for LAG-3, TIGIT, and PD-1 expression by immunohistochemistry. Clinicopathologic features and survival were analyzed according to the expression of LAG-3, TIGIT, and PD-1. RESULTS: LAG-3 and TIGIT expression on tumor-infiltrating lymphocytes were significantly correlated with that of PD-1 and was also significantly associated with negative prognostic factors: deeper Breslow thickness, lymph node involvement, and advanced stage of disease. However, PD-1 expression was not associated with clinicopathologic variables of prognostic significance. High expression of either LAG-3 or TIGIT was associated with worse survival. Subgroup analysis on the basis of Breslow thickness showed that both LAG-3 and TIGIT have prognostic significance regardless of tumor thickness. High expression of PD-1 was not predictive of survival. LIMITATIONS: Retrospective study in a single institution and possibility of type 1 error. CONCLUSION: Expression of LAG-3 and TIGIT represents an independent unfavorable prognostic factor in cutaneous melanoma.