Platelets induce VISTA expression and modulate the ovarian tumor microenvironment

Immune checkpoint regulators, such as the V-domain Ig suppressor of T cell activation (VISTA), play a critical role in shaping the tumor microenvironment (TME) and facilitating immune evasion. In ovarian cancer, VISTA exhibits more abundant and consistent expression than other immune checkpoints, including Programmed Death-Ligand 1 (PD-L1). This study examined the role of platelets in the regulation of VISTA in ovarian cancer using both in vitro and in vivo models. Our findings demonstrate that platelets upregulate VISTA expression in both myeloid and tumor cells, thereby promoting an immunosuppressive TME. Elevated VISTA levels were associated with higher platelet counts and poorer clinical outcomes. These results highlight that platelet-mediated VISTA upregulation is a potential therapeutic target for improving antitumor immune responses in ovarian cancer.