Alten R, Markland C, Boyce M, et al. - Researchers designed a phase 3, open‐label extension (OLE) study to compare the long‐term immunogenicity of an adalimumab biosimilar, FKB327 (F), with the reference product (RP). In the OLE, individuals completing 24 weeks of an initial randomized, double‐blind (DB) study (Period 1) with clinical response and randomized no safety concerns to F or RP, so that two‐thirds of patients remained on the same treatment and one‐third switched to the alternate treatment for weeks 24 through 54 (OLE weeks 0‐30; Period 2), then all received F through week 100 (OLE week 76; Period 3). After long‐term administration, the RP and F exhibited comparable immunogenicity characteristics. They found similar development of antidrug antibodies with the RP and F, and was not influenced by switching and double switching between F and RP treatment.