CTLA4 and neoplasm: Our findings suggest that while OX40 and OX40L expression levels are upregulated, other factors, such as the host environment and immunosuppressive mediators such as elevated PD1, CTLA-4, and significantly reduced IL-2, are deterring costimulatory molecules from functioning normally, leading to disease progression.18, 19, 20Another aspect is the expression of OX40 on Tregs is also important because of its controversial role in the tumor immunity.