Immunocytokines: the long-awaited therapeutic magic bullet in rheumatoid arthritis?
Modulatory cytokines such as IL-4 and IL-10 looked promising biologicals, but suffered from poor exposure at the inflamed joints, when administered via the patient friendly subcutaneous route. Immunocytokines have now been engineered with tissue targeting potential and are a challenging solution to this problem. Local inflammatory processes cause destruction of extracellular matrix components (ECM) leading to neo-eptitopes and/or elicit the synthesis of new ECM components. This makes ECM elements interesting targets for antibody mediated recognition and retention, to achieve higher levels of immunocytokines at the site of therapeutic interference. The study presented by Schwager et al. showed that targeted delivery of IL-10 is more efficacious in experimental arthritis. Clinical studies are warranted to show whether this strategy works for all RA-patients or better in subgroups with a defined ECM phenotype. In principle the scFv-tageting system is plastic enough to allow for personalized strategies.