A Randomized Controlled Trial With Rituximab - for Schizophrenia Spectrum Disorder in Adults

Immunological factors are assumed to be determinants for some psychiatric disorders, thus anti-inflammatory drugs may be helpful. However, studies on such treatments are scarce. An inflammatory modulating drug rituximab, cluster of differentiation antigen 20 antibodies (anti-CD20 antibodies), is a standard treatment for e.g. multiple sclerosis.The investigators aim to test rituximab in a randomised placebo-controlled double-blinded, add-on treatment trial in 104 participants (18-51 years) with schizophrenia spectrum disorder. Sampling from blood for analyses of inflammatory mediators are investigated at gene and protein levels and resting state functional magnetic resonance imaging (rsfMRI) and lumbar puncture are optional. Biomarkers will be investigated in relation to treatment response.

Inclusion Criteria:ages 18 to 51 yearsduration of illness exceeding 1 yeardiagnosed with Schizophrenia spectrum disorder (SSD) according to The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5).if female and with any risk for pregnancy, willing to use contraceptives or abstinence if normal and preferred lifestyle.participants should be judged by the investigator to be lucid and oriented to person, place, time, and situation when giving the informed consent.insufficiently recovered from previous antipsychotic treatments.a minimum score of 4 (moderately ill) in Clinical global impression - severity (CGI-S) at baseline.Exclusion Criteria:pregnancy or breast-feedingweight below 40 kgclinically relevant ongoing infection at the discretion of the physicianchronic infectionspositive test for hepatitis B, hepatitis C, HIV, or tuberculosismalignancy currently or within 2 years prior to inclusioncurrent severe heart failure (NYHA grade IV) or any other severe heart disease (e.g. or history of cardiac arrhythmia or myocardial infarction)any change of antipsychotic medication within the previous 4 weeksunable to make an informed decision to consent to the trialongoing clozapine treatmentongoing immunomodulatory treatmenttreatments with monoclonal antibodies within 1 year before the inclusion