• Subject is 12 to 75 years of age (inclusive).

• a. Specifically at sites located in the United Kingdom subjects must be 18 to 75 years of age (inclusive)

• Subject must have a minimum body weight of 45 kg

• Subject has a clinical diagnosis of CVID supported by all of the following (a thru c):

‣ A low IgG level compared to age-adjusted reference range \[OR if this cannot be documented, subject must have one of the following: i) absent isohemagglutinins and/or poor response to vaccines; or ii) Low class-switched memory B cells less than 2%\]

⁃ Low IgA and/or IgM compared to age-adjusted reference range

⁃ No identified secondary causes of hypogammaglobulinemia

• Inborn Errors of Immunity/ PID Panel testing:

‣ Lacks an identified pathogenic/likely pathogenic genetic driver for their CVID primary immunodeficiency OR

⁃ Subject has an identified pathogenic/likely pathogenic genetic driver(s) for their CVID limited to the following genes: TNFRSF13B (TACI), TNFRSF13C (BAFFR), CD19, CD20, CD81, CR2 (CD21), LRBA, CTLA4, NFKB1, NFKB2, IKZF1 (excluding variants associated with combined immune deficiency), CARD11 (gain of function), SH3KBP1, SEC61A1 IRF2BP2, CTNNBL1, TWEAK or PTEN.

• Subject has lymphoproliferation, as evidenced by CT imaging: splenomegaly with craniocaudal spleen measurement \>10 cm and/or lymphadenopathy with at least 1 measurable index lymph node (long axis \>1.5 cm) as per Cheson methodology.

• Subject has at least ONE of the following CVID clinical manifestations of immune dysregulation:

‣ Clinical symptoms related to splenomegaly or lymphadenopathy which interfere with activities of daily living or are associated with chronic pain, dyspnea, functional impairment, or limitations in usual activities

⁃ One or more blood cytopenias related to CVID (and not due to other medical conditions such as iron-deficiency or lead exposure) defined as hemoglobin \<10 g/dL, platelet count \<100,000/µL, and/or neutrophil count \<1,000/µL

⁃ Previous pathologic confirmation of ILD and attributed to CVID by the Investigator with quantifiable CT chest imaging findings evident on baseline CT scan

⁃ Clinical diagnosis of CVID enteropathy or other GI tract diagnosis attributable to CVID by the Investigator which involves the small intestine and meets the following enteropathy criteria:

• i. Clinical symptoms of GI disease including at least 1 of: abdominal pain or diarrhea at least 3 days of the week for at least 4 weeks or longer, or dependence on supplemental enteral or parenteral nutrition ii. Lacks a clinical diagnosis of Celiac Disease, and negative human leukocyte antigen (HLA)-DQ2 and -DQ8 testing at screening iii. Presence of small bowel villous shortening/atrophy/blunting with or without intraepithelial lymphocytosis noted in a pathology report pertaining to a small bowel biopsy performed within 5 years of enrollment iv. Negative stool PCR Gastrointestinal Profile at screening

• At screening, vital signs. Ranges:

• Systolic blood pressure 80-159 mm Hg Diastolic blood pressure 50-109 mm Hg Pulse rate 50-110 beats per minute (bpm) Oxygen saturation 93-100%

• Subjects or their legal representatives (for subjects under the age of 18 years) must be able to communicate with the Investigator and understand and comply with the requirements of the study, including an ability to provide written informed consent.