PF-06438179/GP1111 (Zessly®; Ixifi®) [hereafter referred to as GP1111] is a biosimilar of the reference monoclonal anti-TNF-α antibody infliximab, and is approved in the EU and USA for the same indications as the reference drug, including rheumatoid arthritis (RA), Crohn's disease, ulcerative colitis (including paediatric ulcerative colitis in the EU), ankylosing spondylitis, psoriatic arthritis and plaque psoriasis; GP1111 is also approved in Japan. GP1111 has similar physicochemical characteristics and pharmacodynamic properties to those of reference infliximab, and the pharmacokinetic similarity of the agents has been shown in healthy volunteers and patients with moderate-to-severe RA despite methotrexate therapy. GP1111 demonstrated clinical efficacy equivalent to that of reference infliximab in patients with moderate-to-severe RA, despite methotrexate therapy, and was generally well tolerated in this population. The tolerability, immunogenicity and safety profiles of GP1111 were similar to those of reference infliximab, and switching from reference infliximab to GP1111 had no impact on safety, efficacy or immunogenicity. The role of reference infliximab in the management of autoimmune inflammatory conditions is well established and GP1111 provides an effective biosimilar alternative for patients requiring infliximab therapy.