Inclusion Criteria:

• Treatment-naïve or relapsed/refractory CLL patients undergoing CLL antineoplastic treatment. Diagnosis of B-cell CLL established according to International Workshop on Chronic Lymphocytic Leukemia (iwCLL) criteria and documented within medical records.
• Hypogammaglobulinemia (IgG levels < 5 g/L) as confirmed by the Central Laboratory.
• ≥ 18 years of age.
• Voluntarily given, fully informed written and signed consent obtained before any study-related procedures are conducted.

Exclusion Criteria:

• IgG treatment within 3 months prior to Screening.
• Antibiotic prophylaxis and/or treatment within 7 days prior to Baseline (with the exception of trimethoprim-sulfamethoxazole [TMP/SMX], diaminodiphenyl sulfone [dapsone] and pentamidine inhalation).
• Current major infection or > 1 major infection in the previous 6 months before Baseline.
• History of anaphylaxis or severe systemic response to immunoglobulin, blood or plasma-derived products or any Panzyga component.
• History of a non-CLL malignancy or other medical condition with life-expectancy of less than two years.
• Severe liver disease, with signs of ascites and/or hepatic encephalopathy.
• Severe kidney disease (as defined by estimated glomerular filtration rate [eGFR] 140 kg.
• Eastern Cooperative Oncology Group (ECOG) performance score of > 2.
• Female patients of childbearing potential unwilling to use a protocol-required method of contraception from the Screening Visit throughout the study treatment period and for 30 days following the last dose of study drug.
• Human immunodeficiency virus (HIV) infection at Screening (defined for the study as positive HIV antibody test).
• Patients found to be chronic carriers of hepatitis B virus (HBV), defined by positive surface antigen (HBsAg), positive Hepatitis B core antibodies (HBcAb) and/or low HBV titers, who will not receive targeted antiviral therapy while undergoing CLL therapy, and patients with active HBV, defined as high HBV titers.
• Uncontrolled hepatitis C infection at Screening (defined for the study as positive hepatitis virus C [HCV] polymerase chain reaction [PCR]).
• Pregnant and lactating women.
• Subjects with a history of thromboembolic events (TEE) such as deep vein thrombosis, pulmonary embolism, myocardial infarction, ischemic stroke, transient ischemic attack, peripheral artery disease (Fontaine IV) within 6 months before Baseline.
• Planned or ongoing immunosuppressive treatment (other than for CLL or corticosteroids) or other forbidden medication during the entire study duration after study enrollment.
• Participation in another interventional clinical trial that is either blinded or involves an investigational (not approved) product within 3 months before Baseline or during the course of the clinical study. Participation in observational clinical trials or open-label trials involving an approved product may be permitted after consultation with the medical monitor.

Eligibility last updated 3/18/22. Questions regarding updates should be directed to the study team contact.