CD8A and melanoma: Human melanoma cells produce minimal serotonin,79 whereas certain solid tumors, classified as neuroendocrine tumors (NETs), can produce serotonin.80,81 We then investigated the therapeutic potential of SSRIs in a PC3 human prostate neuroendocrine cancer xenograft model.81 The PC3 human prostate cancer cell line was similarly engineered to co-express NY-ESO-1, HLA-A2, and the FG dual-reporters (denoted as PC3-A2-ESO-FG; Figure S6K).82 The previously described ESO-T cells were used to model the anti-PC3 human CD8 T cell response (Figure S6K).