Study of Efficacy and Safety of Privigen in Subjects With Chronic Inflammatory Demyelinating Polyneuropathy

Inclusion Criteria: IVIG-untreated subjects: * Either subjects with newly diagnosed CIDP (developing over at least 2 months) or subjects with an IVIG treatment interruption for at least 1 year with a progressive disease (deteriorating in the last 2 months) prior to enrolment. * Actual diagnosis (including electrophysiology) of CIDP with progressive or relapsing dysfunction from motor and sensory or symmetric motor nerve only in at least 1 limb resulting from neuropathy. Criteria for definite or probable CIDP according to EFNS/PNS guideline. * Age ≥18 years. * Male or female. * Written informed consent for study participation obtained before undergoing any study specific procedures. IVIG-pretreated subjects: * Being treated regularly with IVIG on a fixed cycle length of 2 to 6 weeks ± 5 days in the last 6 months, on a fixed dosage of ± 20 % in the last 6 months and deteriorating by at least 1 INCAT score point during the Washout Period of up to 10 weeks (except for an increase from 0 to 1 solely due to upper limb score). * Historic diagnosis of CIDP with progressive or relapsing dysfunction from motor and sensory or symmetric motor nerve only in at least 1 limb resulting from neuropathy. Criteria for definite or probable CIDP according to EFNS/PNS guideline. * Age ≥18 years. * Male or female. * Written informed consent for study participation obtained before undergoing any study specific procedures. Exclusion Criteria: * A motor syndrome that fulfils criteria for multifocal motor neuropathy (MMN) with conduction block (i.e., upper limb motor weakness without sensory deficit and with a 50% decrease in action potential amplitude or area on proximal compared with distal stimulation in motor nerves). * CIDP with monoclonal gammopathy of uncertain significance (CIDP-MGUS) with anti-MGUS antibodies and patients with distal acquired demyelinating symmetric (DADS)neuropathy. * Any disease (mainly neurological or chronic orthopedic) that may cause symptoms or may interfere with treatment or outcome assessments with the INCAT (e.g., diphtheria, drug or toxin exposure and diabetes mellitus likely to have caused the neuropathy, IgM paraproteinemia, familial neuropathy, borreliosis with radiculopathy, post-polio-syndrome,M. Parkinson, stroke). * Current malignancy. * History of cardiac insufficiency (New York Heart Association \[NYHA\] III/IV), cardiomyopathy, significant cardiac dysrhythmia requiring treatment, unstable or advanced ischemic heart disease, congestive heart failure or severe hypertension. * History of thrombotic episodes (deep vein thrombosis, myocardial infarction, cerebrovascular accident). * Migraine associated with IVIG infusion in the last 3 months prior to enrolment. * Known allergic or other severe reactions to blood products including intolerability to previous IVIG (i.e. severe headache, hypersensitivity, intravascular hemolysis). * Subjects with serum IgA level less than 50% of the lower normal limit. * Known hyperprolinemia. * Any condition (including alcohol, drug or medication abuse) that is likely to interfere with evaluation of the study product or satisfactory conduct of the study. * Plasma exchange 3 months prior to enrolment. * Treatment with immunomodulatory agents others than steroids, methotrexate or azathioprine (e.g. interferon, TNF-α inhibitors) within 6 months before enrolment. * Treatment with rituximab in the 12 months before enrolment. * Abnormal laboratory parameters: creatinine \> 1.5 times the upper normal limit (UNL), lactate dehydrogenase (LDH) \> 1.5 times the UNL, C-reactive protein (CRP) \> 1.5 times the UNL, hemoglobin (Hb) \< 10 g/dL. * Ongoing HIV, hepatitis C and hepatitis B infection. * Participation in another clinical study (or use of another investigational medicinal product \[IMP\]) within 3 months prior to enrolment * Not able to comply with study procedures and treatment regimen. * Employee at the study site, or spouse/partner or relative of any study staff (e.g., investigator, sub-investigators, or study nurse). * Pregnancy or nursing mother. * Intention to become pregnant during the course of the study. * Female subjects of childbearing potential either not using, or not willing to use, a medically reliable method of contraception for the entire duration of the study, or not sexually abstinent for the entire duration of the study, or not surgically sterile.