Inclusion Criteria:
1. Male or female, aged ≥18 years.
2. Written informed consent and authorization to access personal health information obtained independently from subjects indicating that they understand the purpose of, and procedures required for, the study and are willing to participate.
3. Documented diagnosis of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) consistent with the 2021 EAN/PNS criteria.
4. Current or documented history of significant disability, as defined by an overall adjusted INCAT disability score between 2 and 9. A score of 2 must be exclusively from the lower extremities.
5. Subjects are currently dependent on treatment with immunoglobulins, corticosteroids, or standard of care treatments for CIDP.
6. Weakness of at least two limbs.
7. Subjects should be clinically stable 12 weeks prior to screening date as defined by:
* without a worsening in INCAT score of ≥1 point, AND/OR
* without significant changes in clinical symptoms, AND
* without significant dose changes or requiring additional treatments.
Exclusion Criteria:
1. Pure sensory atypical and multivariant CIDP.
2. Females who are pregnant, breastfeeding, unwilling to practice adequate contraception throughout the study or planning a pregnancy during the course of the study.
3. IG-experienced subjects requiring an IGIV dosage of more than 1.3 g/kg/month OR SCIG pre-treated subjects requiring a SCIG dosage of more than 1.6 g/kg/month.
4. Subjects who have previously failed to respond to IGIV or SCIG.
5. On screening date, a body mass index (BMI) \> 35 kg/m2 or an IGIV dose that puts the patient at risk of fluid overload.
6. CIDP and any neuropathy of other causes not consistent with the 2021 EAN/PNS criteria.
7. Immunoglobulin M (IgM) paraproteinemia, including IgM monoclonal gammopathy with high titer antibodies to myelin-associated glycoprotein.
8. Central demyelinating disorders (e.g, multiple sclerosis) or severe myopathy.
9. Any chronic or debilitating disease, or central nervous disorder that causes neurological symptoms or may interfere with assessment of CIDP or outcome measures
10. Congestive heart failure (New York Heart Association (NYHA) Class III/IV), unstable angina, unstable cardiac arrhythmias, or uncontrolled hypertension
11. History of deep vein thrombosis or thromboembolic events (e.g, cerebrovascular accident, pulmonary embolism) in the past 12 months.
12. Condition(s) which could alter protein catabolism and/or IgG utilization (e.g, protein-losing enteropathies, nephrotic syndrome).
13. Known history of chronic kidney disease, or glomerular filtration rate (GFR) of \<60 milliliter per minute per 1.73 square meter (mL/min/1.73m2) estimated based on an established CKD-EPI equation at the time of screening.
14. Active malignancy requiring chemotherapy and/or radiotherapy, or history of malignancy with less than 2 years of complete remission prior to screening. Exceptions are: adequately treated basal cell or squamous cell carcinoma of the skin, carcinoma in situ of the cervix, and stable prostate cancer not requiring treatment.
15. Hypersensitivity or adverse reactions (e.g, urticaria, breathing difficulty, severe hypotension, or anaphylaxis) to human blood products such as human IgG, albumin, or other blood components.
16. Known history of immunoglobulin A (IgA) deficiency.
17. Known history of autoimmune nodo-paranodopathies causing IG treatment resistance.
18. Abnormal laboratory values at screening:
1. Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) \> 2.5x upper limit of normal (ULN)
2. Platelet count \<100,000 cells/µL.
3. Absolute neutrophil count (ANC) \<1000 cells/µL.
4. Clinically significant anemia defined as hemoglobin (Hgb) level of \< 10.0 g/dL at screening.
19. Ongoing/active infection with hepatitis B virus (HBV), hepatitis C virus (HCV) or HIV Type 1/2 infection. Subjects with chronic hepatitis B or hepatitis C infection currently on treatment may participate as long as they have undetectable viral load within 12 months of screening date.
20. Subjects who have received:
1. Within 2 months before wash-out phase:
* plasma exchange
* change in treatment of methotrexate, azathioprine, or mycophenolate
2. Within 3 months before wash-out phase: Efgartigimod alfa (Vyvgart)
3. Within 5 months before wash-out phase: cyclophosphamide, interferon, tumor necrosis factor-alpha inhibitors, fingolimod, or any other immunosuppressive medications
4. Within 12 months before wash-out phase: rituximab or alemtuzumab
21. Subjects who have received a hematopoietic stem cell transplant.
22. Subjects on corticosteroids for the treatment of CIDP after being fully washed out. Subjects on maintenance doses of corticosteroid may be allowed, if treatment is for conditions unrelated to CIDP (doses usually below 20 mg/day prednisone or equivalent and where the dosage is unlikely to be tapered during the duration of the trial may be allowed).
23. Any disorder or condition that in the investigator's judgment may impede the subject's participation in the study, pose increased risk to the subject, or confound the results of the study.
24. Participation in another clinical study involving an investigational product (IP) or investigational device within 30 days prior to screening visit or is scheduled to participate in another clinical study involving an IP or investigational device during the intended course of this study.
25. History of acquired or inherited thrombophilic disorders. These will include the specific types of acquired or inherited thrombophilic disorders that could put subjects at risk of developing thrombotic events.
26. Previous participation in this clinical study.
27. Any other factor that, in the opinion of the investigator, would prevent the subject from complying with the requirements of the protocol.
