The Evaluation of Efficacy and Safety of Rituximab in Refractory CIDP Patients With IgG4 Autoantibodies

Inclusion Criteria: 1. Patients with definite CIDP diagnosed according to the modified diagnostic criteria of European Federation of Neurological Societies/Peripheral Nerve Society (EFNS/PNS) (2010) by the time of enrollment in the study 2. Patients meeting one of the following conditions: (i) Patients with positive serum IgG4 autoantibody (CNTN-1 or NF-155) confirmed by the time of enrollment in the study (ii) Patients with negative serum IgG4 autoantibody (CNTN-1 and NF-155) confirmed by the time of enrollment in the study 3. Patients with refractory CIDP not responding adequately to treatment with corticosteroid for 12 weeks, and intravenous immunoglobulin therapy (IVIg) for 8 weeks by the time of enrollment in the study, or those who are unable to administer or continue corticosteroid and IVIg 4. Patients with total adjusted Inflammatory Neuropathy Cause and Treatment (INCAT) Disability Scale scores of 2 to 8 at both preliminary enrollment and enrollment, and with the total score at enrollment equal to or worse than that at preliminary enrollment 5. Patients aged 12 years or older at informed consent 6. Patients who give their voluntary written consent after having received adequate information on this study (legally acceptable representatives should also give consent for underage patients, and informed assent should be obtained from children aged 12 to 15) Exclusion Criteria: 1. Patients with disease meeting one of the following exclusion criteria defined in the modified EFNS/PNS diagnostic criteria (2010). (i) Borrelia burgdorferi infection (Lyme disease), diphtheria, drug or toxin exposure probably to have caused the neuropathy Hereditary demyelinating neuropathy (ii) Prominent sphincter disturbance (iii) Diagnosis of multifocal motor neuropathy (iv) IgM monoclonal gammopathy with high titre antibodies to myelin-associated glycoprotein (v) Other causes for a demyelinating neuropathy including POEMS syndrome, osteosclerotic myeloma, diabetic and non-diabetic lumbosacral radiculoplexus neuropathy PNS lymphoma and amyloidosis may occasionally have demyelinating features 2. Patients who have started or have increased the dose of corticosteroid for CIDP within 12 weeks prior to the enrollment 3. Patients who have started or have increased the dose of IVIg within 8 weeks prior to the enrollment 4. Patients who have underwent plasmapheresis within 8 weeks prior to the enrollment or patients with refractory disease not responding adequately to 8 weeks of plasmapheresis (plasma exchange or double-filtration plasmapheresis) 5. Patients who have started or have increased the dose of an immunosuppressant (azathioprine, cyclophosphamide, cyclosporine, mycophenolate mofetil, interferon alpha, interferon beta, etanercept, methotrexate, mitoxantrone, alemtuzumab, cladribine, tacrolimus, fingolimod) within 12 weeks prior to the enrollment 6. Patients who have underwent hematopoietic stem cell transplant prior to the enrollment 7. Patients who have used rituximab (genetical recombination) prior to the enrollment 8. Patients who have participated in another clinical study within 3 months prior to the enrollment (enrollment is allowed for those participating in a clinical study in the range of Indications or Dosage and Administration in Japan) or patients who are participating in another study 9. Patients with poorly controlled diabetes (HbA1c of 7 % or higher) 10. Patients who have or are suspected to have active infection (infection requiring treatment with systemic antimicrobial, antifungal, or antiviral agents) at the time of the enrollment 11. Patients tested positive for HBs antigen, HBs antibody, HBc antibody, and/or HCV antibody (patients with positive HBs antibody or HBc antibody can be enrolled when a hepatitis B virus-DNA test is negative \[below the limit of detection\], and hepatitis B virus-DNA and aspartate/alanine transaminase levels are monitored at fixed intervals), or patients with positive HIV antibody or HTLV-1 antibody at the time of the enrollment 12. Patients with leukopenia (less than 2,000 /mm3), neutropenia (less than 1,000 /mm3), or lymphopenia (less than 500 /mm3) at the time of the enrollment 13. Patients with history of serious hypersensitivity or anaphylactic reaction to one of the ingredients in the investigational drug or murine protein-containing products 14. Patients with serious comorbidity (e.g., hepatic, renal, cardiac, lung, hematologic, or brain disease) 15. Female patients who are pregnant, lactating, or potentially pregnant, or patients who are not willing to use contraceptive measures during the study period 16. Patients who are judged to be unsuitable by the investigator or a sub-investigator