PDCD1 and prostate cancer: In this research, we focused on the effects of fucoidans from three different species (Fucus vesiculosus, Undaria pinnatifida and Macrocystis pyrifera) alone, and in combination with a T cell activator (anti-CD3), and an ICI (Nivolumab, anti-PD-1) on human PBMCs and a hormone resistant prostate cancer cell line, PC-3.