IVIG Boya: Safety, Efficacy, and Pharmacokinetics

Fifty male or female participants aged 2 to 60 years, either treatment-naive or already receiving intravenous immunoglobulin replacement therapy, will be enrolled, including at least 20 participants aged 2 to 17 years. The study will also examine the pharmacokinetic (PK) profile in adult participants.

After obtaining signed informed consent or assent, screening will include reviewing immunodeficiency history in medical records, performing safety examinations, and assessing eligibility against inclusion and exclusion criteria.

Subjects who pass screening will begin a 6-visit run-in period. For participants already receiving treatment, the interval between intravenous injections should remain as prescribed before enrollment unless modified during the run-in period. During this period, participants will receive the study IVIG. For treatment-naïve participants, the dose and administration interval during the run-in will be determined by the Investigator.

After the run-in, the one-year trial will begin at V0. Study visits will be scheduled every 21 or 28 days, based on the participant's prescribed treatment plan. Each visit will have a ±3-day window around the scheduled date. At each visit, blood samples will be collected immediately before each IVIG dose to measure IgG trough levels. If a visit occurs earlier or later than the scheduled date, whether within or outside the allowed window, the timing of the next visit will be based on the actual date of the previous visit to maintain consistent planned inter-visit intervals throughout the study.

The V0 assessment will begin when participants have IgG concentrations ≥5 g/L on two consecutive infusions under the same dosing conditions. Therefore, the run-in period may include only two visits. If, among the six visits, the trough IgG concentration does not reach 5 g/L on two consecutive visits, the participant will be considered to have failed screening but may be rescreened.

To characterize the pharmacokinetic (PK) profile of the investigational product, at least 20 adult participants will undergo additional blood sampling between two consecutive study visits to measure total IgG concentrations and antigen-specific antibody levels, including anti-pneumococcal capsular polysaccharide, anti-Haemophilus influenzae, and anti-measles antibodies.

PK sampling should preferably be performed at Visit 4 (V4), provided that a stable dosing regimen has been maintained. Participants receiving IVIG on a 21-day schedule should collect seven samples at 30 minutes, 2 hours, 24 hours, 72 hours, 7 days, 14 days, and 21 days post-infusion. Participants receiving IVIG on a 28-day schedule should collect eight additional samples at 30 minutes, 2 hours, 24 hours, 72 hours, 14 days, 21 days, and 28 days post-infusion.

The PK profile should be evaluated only after at least four consecutive dosing intervals with no changes in posology, meaning both the dose and dosing interval remain unchanged, preferably at Visit 4 (V4). If any dose or interval adjustments occur between V0 and V4, PK profile sampling should be delayed until the next visit, after dosage stability is confirmed.

Participants will be contacted weekly between infusions to collect data on adverse events, concomitant medications, duration of infection treatment, and time lost from work or school due to infections during the period.

Additionally, subjects will have continued access to the investigator's team to report adverse events and to receive advice on next steps or additional medical evaluations, if necessary.

Medical evaluation, vital signs, and oximetry, adverse events, and concomitant medication will be assessed at all visits.

Safety laboratory tests (including direct Coombs and pregnancy tests) will be performed at every 4th or 5th visit.