Tocilizumab in Schizophrenia

A pathophysiological role for inflammation in schizophrenia has been one of the more enduring findings in the field. Recently, increased understanding of complex interactions between inflammation and the brain in other chronic diseases has better informed this relationship in schizophrenia. Several trials have found that treatment with non-steroidal anti-inflammatory drugs (NSAIDs), in adjunct to antipsychotics, was associated with significant improvement in psychopathology in schizophrenia. Cytokines are key regulators of inflammation that exert effects in the periphery and the brain. Serum cytokine levels predicted response in two studies, and another study found a trend for improved cognition with adjunctive NSAID treatment.1 These findings provide important empirical support for a pathophysiological role for inflammation in some patients with schizophrenia. Two important limitations of these trials are that: a) the agents investigated have relevant off-target (i.e., non-immune) effects, and b) evidence of inflammation in the peripheral blood was not an inclusion criterion, which may have decreased the signal-to-noise ratio.

Schizophrenia is associated with impaired cognition, which persists despite current treatments, and is an important determinant of quality of life and overall function. Converging lines of evidence suggest that interleukin-6 (IL-6) is a promising therapeutic target for cognitive impairment in schizophrenia. IL-6 is a cytokine produced by peripheral blood leukocytes, and central nervous system (CNS) microglia and astrocytes. The IL-6 gene is a risk factor for schizophrenia and may impact on serum IL-6 levels. Blood and (cerebrospinal fluid) CSF IL-6 levels are altered in schizophrenia. IL-6 levels are associated with psychopathology3 and cognition in schizophrenia. In populations outside of schizophrenia, higher serum IL-6 levels are associated with poorer cognition. In first-episode and chronic schizophrenia, IL-6 levels are a significant predictor of smaller left hippocampal volume.

Along with our other previous work, our preliminary studies provide strong evidence that IL-6 is a novel therapeutic target for cognitive impairment in schizophrenia, and demonstrate the feasibility of the proposed trial. Briefly, in 64 patients with schizophrenia, we found higher blood IL-6 levels were a significant predictor of greater impairment on the Brief Assessment of Cognition in Schizophrenia (BACS) after controlling for multiple potential confounding factors.5 In an 8-week open-label trial in 6 subjects, tocilizumab (a humanized monoclonal antibody against the IL-6 receptor, approved by the US FDA in 2010 for the treatment of adults with moderately to severely active rheumatoid arthritis (RA) who have had an inadequate response to one or more tumor necrosis factor (TNF)-antagonist therapies, administered as an intravenous infusion every 4 weeks), given in adjunct to antipsychotics, was well tolerated and associated with significant improvement in BACS verbal fluency at 4 weeks, BACS digit symbol coding at 2, 4, and 8 weeks, and BACS composite score at 4 and 8 weeks.10

In the first year following the submission, one clinical trial is planned. The investigators will conduct a 12-week randomized, double-blind, placebo-controlled trial to determine the safety, tolerability, and efficacy of tocilizumab as an adjunct to antipsychotic medications in 20 stable outpatients with schizophrenia.

In our previous trial of Tocilizumab, no clinically significant adverse drug reactions occurred. The risks that have been found in people with rheumatoid arthritis are known, but there may be unknown risks when used in schizophrenia. Clinically significant adverse drug reactions include anaphylaxis (0.4%), infections (0.1-7.8%), intestinal perforation, neutropenia (7.0%), and cardiac failure. Known side effects of tocilizumab that are common include: increase in hepatic enzymes (AST, ALT), hypertension, headache, neutropenia, infusion-related reactions, upper respiratory tract infections, and nasopharyngitis.

Subjects with schizophrenia and schizoaffective disorder will be accessed from outpatient psychiatry clinic at Augusta University or other satellite collaborative sites. The study has 6 visits: screening, baseline, and weeks 2, 4, 8, and 12. Subjects will be randomized equally to either tocilizumab (n=10) or placebo (n=10), in adjunct to their current antipsychotic and other psychotropic medications. Tocilizumab will be obtained from the manufacturer, Genentech, through our hospital pharmacy as per our previous trial. Subjects in the tocilizumab group will receive a 4 mg/kg infusion at baseline, and weeks 4 and 8, as per the recommended starting dosing for rheumatoid arthritis. Subjects in the placebo group will receive an infusion of normal saline (with the same packaging and volume as the tocilizumab group) at baseline, and weeks 4 and 8. We will contact the subjects by phone on days 1 and 7 after each infusion to assess for any infusion-related events. We will assess cognition and psychopathology at baseline, and at weeks 2, 4, 8, and 12. We will also measure a multiplex panel of blood cytokines (including IL-6) at baseline, and at weeks 2m 4, 8, and 12. Patients will be withdrawn if they meet any exclusion criterion at any time point.