In a study reported in Clinical Cancer Research, Bartlett and colleagues found that melanoma metastases exhibit site-specific antigen heterogeneity that correlates with T-cell infiltration.
A total of 3,086 metastatic tumors involving various anatomic sites were assessed for a panel of melanocyte differentiation antigens, which revealed a site-specific pattern of antigen expression that was highest in the brain, intermediate in soft tissues/lymph nodes, and lowest in visceral metastases. Hierarchical clustering analysis supported the finding of a phylogenetically determined pattern of antigen expression varying by anatomic site of the metastases. Expression of the melanocyte differentiation antigen tyrosinase was more frequently lost in metastatic sites other than the brain and was correlated with endogenous CD8-positive and CD4-positive T-cell infiltrates.
The investigators concluded, “Site-specific antigen heterogeneity represents a novel attribute for human melanoma metastases that should be considered in future therapy development and when assessing the responsiveness to antigen-specific immunotherapies.” ■
Bartlett EK, et al: Clin Cancer Res 20:2607-2616, 2014.