An agonistic recombinant monoclonal antibody that recognizes the co-stimulatory receptor OX40 (CD134; tumor necrosis factor receptor superfamily member 4; TNFRSF4), with potential immunostimulatory activity. Upon administration, anti-OX40 agonist monoclonal antibody BAT6026 selectively targets, binds to and activates OX40. This may induce the proliferation of memory and effector T-lymphocytes and inhibit the function of T-regulatory cells (Tregs) in the tumor microenvironment (TME). This enhances anti-tumor immune responses and prevents Tregs-mediated immune suppression. OX40, a cell surface glycoprotein and member of the tumor necrosis factor receptor superfamily (TNFRSF), is expressed on T-lymphocytes and plays an essential role in T-cell activation and differentiation.