CU-CPD107 is a potent, selective toll-like receptor 8 (TLR 8) agonist. CU-CPD107 inhibits TLR8 signaling. CU-CPD107 converts to synergistic agonist activities in the presence of ssRNA and induces TLR8 signaling. CU-CPD107 inhibits proinflammatory factor expression and avoids immune responses in the presence of ssRNA.