An EP4 receptor antagonist (IC50 = 6.1 nm in a calcium flux assay); selective for EP4 over EP1, EP2, and EP3 receptors (IC50s = >10,000 nM for all); reverses PGE2-induced ERK phosphorylation in EP4-expressing CHO cells and decreases GM-CSF-induced expression of Il1b, Il4ra, Il6, Arg1, Cox2, and Il10 in RAW 264.7 cells at 10 µM; reduces tumor volume and increases infiltration of CD8+ T cells into tumors in a murine colon carcinoma model at 50 and 150 mg/kg once per day