RITUXIMAB for Fibromyalgia

Inclusion criteria

• {"criterion_text":"- The study participant must have provided written informed consent.\n- The study participants must have been vaccinated with at least three doses of a COVID-19 vaccine or have measurable titers of anti-COVID-19 antibodies.\n- Age 18–65 years\n- Patients with a diagnosis of fibromyalgia (FM) who meet the diagnostic criteria for FM and have been diagnosed by a treating pain specialist or rheumatologist trained in the use of these criteria (AAPT core diagnostic criteria 1990 and revised criteria from 2016).\n- FM disease duration since diagnosis no more than 2 years, and since symptom onset no more than 5 years.\n- FM disease burden with VAS pain ≥ 50 mm (0-100mm)\n- The patient has tested positive for FM-associated antibodies (Camilla Svensson’s laboratory, Biomedicum, Karolinska Institutet) (2,3), according to current reference intervals.\n- Pain treatment must have been stable without any change in medication or dosage during the 6 weeks prior to screening. For permitted substances, please see section 7.9.\n- Women of childbearing potential must have a negative pregnancy test and use effective contraceptive methods throughout the entire study participation period, from baseline and for one year thereafter.\n- The study participants must be able and willing to comply with all study procedures."}

Exclusion criteria

• {"criterion_text":"- Diagnosis of another autoimmune disease, exclusive stable, substituted hypothyreosis.\n- Severe heart failure (New York Heart Association Class IV) or severe uncontrolled heart disease.\n- Hypersensitivity to the active substance, murine proteins, or any other substance in the investigational medicinal product\n- Participation in any other clinical trial of an investigational drug, or exposure to any investigational product or procedure within 6 months prior to screening.\n- Any medical condition that, in the judgment of the study physician, may interfere with the patient’s participation in the study, pose additional risk to the patient, or complicate the assessment of the patient.\n- BMI > 35.\n- Vaccination less than 4 weeks prior to inclusion.\n- Previous use of rituximab for any indication.\n- Any other disease, medical condition, or planned procedure that, in the opinion of the study physician, constitutes a contraindication for participation.\n- Ongoing or recently discontinued (within the last 6 months) immunosuppressive treatment.\n- Known immunodeficiency.\n- Neuropsychiatric diagnosis.\n- Use of opioids or benzodiazepine\n- Active malignancy within the past 5 years.\n- Ongoing or planned pregnancy or breastfeeding.\n- Severe infection within the past 3 months.\n- Any ongoing acute or chronic systemic infection, including HIV, latent tuberculosis, hepatitis B or C, or any other infection considered clinically significant by the study physician and not treated with appropriate antimicrobial therapy."}

Primary endpoints

• {"endpoint_text":"- The primary outcome measure is mean reduction of pain in VAS (mm) 16 weeks after rituximab treatment.","definition_or_measurement_approach":"Mean reduction of pain measured on a Visual Analogue Scale (VAS) in millimetres at 16 weeks after rituximab treatment."}

Secondary endpoints

• {"endpoint_text":"- Secondary outcome measures are improvement in patient perceived FM symptoms measured by Fibromyalgia Impact Questionnaire (FIQ) and Patient Global Impression of Change (PGIC) and objective reduction of % of satellite glia cell binding human IgG, which are regarded to mediate pain at week 16.","definition_or_measurement_approach":"Improvement in patient-perceived FM symptoms as measured by the Fibromyalgia Impact Questionnaire (FIQ) and Patient Global Impression of Change (PGIC); and objective reduction in percentage of satellite glia cell binding human IgG at week 16."}

Sweden

Earliest CTIS Part Ii Submission Date

30-01-2026

Latest Decision Or Authorization Date

12-02-2026

Processing Time Days

13

Number Of Sites

3

Number Of Participants

15

Primary sponsor

Full Name

Region Stockholm – SLSO

Organisation Type

Hospital/Clinic/Other health care facility

Country Of Registered Address

Sweden