Used in immunotherapy research to modulate T-cell activity, particularly in cancer treatment. Targets the ICOS (inducible T-cell co-stimulator) receptor to enhance anti-tumor immune responses. Investigated in clinical trials for solid tumors and hematologic malignancies due to its ability to activate effector T cells and regulatory T cells in the tumor microenvironment. Also employed as a reference standard in antibody development and bioassay calibration.