JTE-607, a highly selective inflammatory cytokine synthesis inhibitor, protects from endotoxin shock in mice. JTE-607 inhibits inflammatory cytokine production, including TNF-α, IL-1β, IL-6, IL-8 and IL-10, from LPS-stimulated human PBMCs, with IC50s of 11, 5.9, 8.8, 7.3 and 9.1 nM, respectively. Cleavage and Polyadenylation Specificity Factor 3 (CPSF3) is the target of JTE-607.