PRTN3 and rheumatoid arthritis: Data from the AVERT trial show that abatacept impacts the maturation of ACPA response in early RA: the concentration of ACPA IgG, IgM, and IgA isotypes and the average number of epitopes recognized were reduced by a substantially greater extent with abatacept plus MTX versus abatacept monotherapy or MTX alone over 1 year [66].