Combining biologics with methotrexate in psoriasis: a systematic review

Funding sources: none. Conflicts of interest: M.B.A.vD. has acted as a consultant for Abbott, Janssen, LEO Pharma and Pfizer, and has been an investigator for Eli Lilly, Idera Pharmaceuticals and Novartis. T.vG. has been on the speakers' bureau or worked as consultant for Sandoz, Novartis, Astellas and Roche. E.P.P. has acted as a consultant for AbbVie, Astra‐Zeneca, Baxter, Janssen‐Cilag, Novartis and Pfizer, and has received investigator‐initiated research grants from Pfizer, Janssen‐Cilag and AbbVie. Dear Editor, Biological drugs (‘biologics’) have revolutionized the treatment of patients with extensive and therapy‐resistant psoriasis.1 Unfortunately, biologics [the antitumour necrosis factor (TNF)‐α agents adalimumab, infliximab and etanercept, and the anti‐p40 (interleukin12/23) ustekinumab] appear to lose efficacy over time and many patients are eventually switched to another biologic.2 For the monoclonal antibody‐based anti‐TNF‐α drugs, this loss of efficacy has been partly attributed to immunogenicity. Neutralizing antidrug antibody (ADA) formation against the biologic drug leads to inhibition of function and formation of drug–antibody complexes, resulting in accelerated clearance from the circulation.3