In Phase I clinical trials in rheumatoid arthritis and psoriasis, the C5aR cyclic peptidomimetic antagonist PMX-53 (Cephalon, now Arana) was found safe and well tolerated, and able to block C5aR at a stage in immune and inflammatory processes earlier than other current anti-inflammatory drugs, but has been discontinued in 2012 due to poor pharmacokinetic profile and off-target side effects. This evidence concerns the gene C5AR1 and rheumatoid arthritis.