The data from our trial are partly in contrast to previous studies that suggested an antidepressant effect of minocycline.23,24,25,26,35,36 However, all RCTs of minocycline in depression were characterized by comparably small sample sizes and highly heterogenous populations of depressed patients.23,24,25,26,37 In TRD, Nettis and colleagues26 have recently published a study suggesting efficacy of minocycline only in participants with higher baseline levels of CRP, while no treatment effects on the primary outcome were identified. The gene discussed is CRP; the disease is depressive disorder.