TLR3-IN-1 (CU CPT 4a) is a selective TLR3 inhibitor with an IC50 of 3.44 μM. It blocks dsRNA-induced TLR3 signaling and reduces pro-inflammatory cytokine production, such as TNF-α and IL-1β, in cellular models like RAW 264.7 macrophages, supporting its use in studying innate immunity and inflammatory diseases.