Fig. 1.

Hypothesized model of anti-OX40-mediated tumor destruction. Anti-OX40 administration can enhance the function, accumulation, and survival of differentiated effector T cells (CD4 and CD8). The anti-OX40 enhancement of CD4 T cell function leads to increased IL-2 and IFNγ secretion, “helping” the effector CD8 T cells (CTL). In addition, OX40-engement increases differentiated effector CD8 T cell accumulation and production of IFNγ and granzymes that ultimately mediate the killing of tumor cells. Coinciding with the previous enhancements, anti-OX40 can abrogate the suppressive activity of Tregs on the anti-tumor response