Data from several earlier randomized clinical trials of abatacept in RA, as well as real-world clinical evidence, suggest that patients with RA who have high titers of ACPA early in their disease course demonstrate greater benefit from abatacept than from treatments with a mechanism of action other than T-cell co-stimulatory blockade [17–19, 31–35]. This evidence concerns the gene PRTN3 and rheumatoid arthritis.