PMX205 is a blood-brain barrier (BBB)-permeable and orally active cyclic hexapeptide th at acts as a high-affinity and potent antagonist against complement C5a receptor C5aR1. Unlike its structural analog PMX53, PMX205 is resistant to intestinal metabolism and shows 10-30-times higher in vivo efficacy when administered orally (mortality rate = 1/9 with 0.1 mg/kg/day PMX205 vs. 2/10 with 1 mg/kg/day PMX53 in a r at colitis model) despite similar in vitro potency (PMX205/PMX53 pIC50 = 6.50/6.38 against 50 pM C5a by competitive binding, 9.03/8.24 against C5a-induced human PMN MPO release). PMX205 shows in vivo efficacy in animal models of AD (3-6 mg/kg/day p.o., mice), ALS (1 mg/kg/day p.o., rats), and HD (10 mg/kg/day p.o., rats).
