Strengths and limitations of this study
psychosis
Adopting a randomised controlled trial design and patient selection based on elevated level of interleukin 6 (IL-6) (in addition to other criteria) will help examine the causal role of IL-6, and the therapeutic potential of targeting IL-6 pathway, in psychosis.The use of target-specific intervention (anti-IL6R monoclonal antibody tocilizumab) will help assess the clinical relevance of IL-6 and related upstream and downstream inflammatory cytokines in psychosis.The use of neuroimaging, cognitive tests and extensive peripheral blood biomarker exploration before and after tocilizumab treatment to assess potential mechanisms of effect.One dose of tocilizumab is unlikely to be sufficient to test the efficacy of this drug as a potential treatment for psychosis, which is not the intention of this study.Tocilizumab inhibits both IL-6 classical and trans signalling, and consequently the trial will not be able to distinguish between the effects of modulating these two signalling pathways specifically in psychosis.