The IL-6 antagonist tocilizumab is associated with worse depression and related symptoms in the medically ill.

Because medical illness is associated with increased inflammation and an increased risk for treatment-resistant major depressive disorder, anti-cytokine therapy may represent a novel, and especially efficacious, treatment for depression. We hypothesized that blockade of the interleukin (IL)-6 signaling pathway with tocilizumab would decrease depression and related symptomatology in a longitudinal cohort of allogeneic hematopoietic stem cell transplantation (HCT) patients, a medically ill population with a significant inflammation and psychopathology. Patients undergoing allogeneic HCT received either a single dose of tocilizumab one day prior to HCT (n = 25), or HCT alone (n = 62).