Longitudinal changes in measles antibody titers in plasma donors and minimum antibody levels of immunoglobulin products for treatment of primary immunodeficiency.

BACKGROUND: To ensure that immunoglobulin (Ig) products have adequate functional antibody, the US Food and Drug Administration (FDA) requires that Ig lots contain minimum levels of measles neutralizing antibody; the current minimum is 0.48 x US Reference Ig 176. STUDY DESIGN AND METHODS: In the first part of the study, measles antibody titers were measured in donor plasma samples collected in 2007, 2011, and 2017. In the second part, trough or steady-state serum levels of measles neutralizing antibody were measured in two studies of patients with primary immunodeficiency (PID) who were treated with intravenous (Study 1; N = 46) or subcutaneous (Study 2; N = 18) Ig replacement therapy, meeting previous requirements for lot potency (≥0.6 x US Reference Ig 176). Serum measles neutralizing antibody titers were then estimated for conditions in which the potency of the Ig replacement product was 0.48 or 0.30 x US Reference Ig 176. RESULTS: Measles antibody titers in donated plasma samples declined in donors born after 1963. In the two studies of patients with PID who were treated with intravenous or subcutaneous Ig replacement therapy, all patients exhibited trough (intravenous Ig) or steady-state (subcutaneous Ig) measles neutralizing antibody titers above 0.12 IU/mL, which has been shown to protect against clinical measles in the general population. Estimates suggest that all patients except one would have continued to meet this standard if the Ig lot potency had been 0.48 or 0.30 x US Reference Ig 176. CONCLUSION: These studies provide supporting evidence that the lot release specification can be safely lowered from 0.48 to 0.30 x US Reference Ig 176, which will accommodate declining measles neutralizing antibody levels in donor plasma.

Efficacy and safety of Privigen(®) in patients with chronic inflammatory demyelinating polyneuropathy: results of a prospective, single-arm, open-label Phase III study (the PRIMA study).

This prospective, multicenter, single-arm, open-label Phase III study aimed to evaluate the efficacy and safety of Privigen(®) (10% liquid human intravenous immunoglobulin [IVIG], stabilized with L-proline) in patients with chronic inflammatory demyelinating polyneuropathy (CIDP). Patients received one induction dose of Privigen (2 g/kg body weight [bw]) and up to seven maintenance doses (1 g/kg bw) at 3-week intervals. The primary efficacy endpoint was the responder rate at completion, defined as improvement of ≥1 point on the adjusted Inflammatory Neuropathy Cause and Treatment (INCAT) disability scale. The preset success criterion was the responder rate being ≥35%. Of the 31 screened patients, 28 patients were enrolled including 13 (46.4%) IVIG-pretreated patients. The overall responder rate at completion was 60.7% (95% confidence interval [CI]: 42.41%-76.43%). IVIG-pretreated patients demonstrated a higher responder rate than IVIG-naïve patients (76.9% vs. 46.7%). The median (25%-75% quantile) INCAT score improved from 3.5 (3.0-4.5) points at baseline to 2.5 (1.0-3.0) points at completion, as did the mean (standard deviation [SD]) maximum grip strength (66.7 [37.24] kPa vs. 80.9 [31.06] kPa) and the median Medical Research Council sum score (67.0 [61.5-72.0] points vs. 75.5 [71.5-79.5] points). Of 108 adverse events (AEs; 0.417 AEs per infusion), 95 AEs (88.0%) were mild or moderate in intensity and resolved by the end of study. Two serious AEs of hemolysis were reported that resolved after discontinuation of treatment. Thus, Privigen provided efficacious and well-tolerated induction and maintenance treatment in patients with CIDP.

Efficacy and safety of hizentra®, a new 20% immunoglobulin preparation for subcutaneous administration, in pediatric patients with primary immunodeficiency.

Subcutaneous IgG treatment for primary immunodeficiencies (PI) is particularly well suited for children because it does not require venous access and is mostly free of systemic adverse events (AEs). In a prospective, open-label, multicenter, single-arm, Phase III study, 18 children and five adolescents with PI were switched from previous intravenous (IVIG) or subcutaneous (SCIG) IgG treatment to receive dose-equivalent, weekly subcutaneous infusions of Hizentra(®) for 40 weeks. Mean IgG trough levels were maintained in patients previously on SCIG, or increased in those previously on IVIG, regardless of age. No serious bacterial infections were reported during the efficacy period of the study. The rates of non-serious infections were 4.77 (children) and 5.18 (adolescents) infections per patient per year. Related AEs were observed in seven children (38.9%) and two adolescents (40%). Three serious AEs and two AEs leading to discontinuation (all unrelated) were reported in children. Hizentra(®) is an effective and well-tolerated treatment for pediatric patients.

Pharmacokinetics of subcutaneous immunoglobulin and their use in dosing of replacement therapy in patients with primary immunodeficiencies.

Bioavailability and pharmacokinetics of subcutaneous IgG (SCIG) and intravenous IgG (IVIG) differ. It is not clear if and/or how the dose should be adjusted when switching from IVIG to SCIG. Area under the curve (AUC) of serum IgG versus time and trough level ratios (TLRs) on SCIG/IVIG were evaluated as guides for adjusting the dose. The mean dose adjustments required for non-inferior AUCs with 2 different SCIG preparations were 137% (± 12%) and 153% (± 16%). However, there were wide variations between adjustments required by different subjects, and in the resulting TLRs. In contrast, combined data from multiple studies allow estimation of the ratio of IgG levels with different dose adjustments, and of the steady state serum levels with different SCIG doses. When switching a patient from IVIG to SCIG, individualizing the dosage based on measured serum IgG levels and the clinical response is preferable to using mean pharmacokinetic parameters.

Efficacy and safety of a new 20% immunoglobulin preparation for subcutaneous administration, IgPro20, in patients with primary immunodeficiency.

Subcutaneous human IgG (SCIG) therapy in primary immunodeficiency (PID) offers sustained IgG levels throughout the dosing cycle and fewer adverse events (AEs) compared to intravenous immunoglobulin (IVIG). A phase I study showed good local tolerability of IgPro20, a new 20% liquid SCIG stabilized with L-proline. A prospective, open-label, multicenter, single-arm, phase III study evaluated the efficacy and safety of IgPro20 in patients with PID over 15 months. Forty-nine patients (5-72 years) previously treated with IVIG received weekly subcutaneous infusions of IgPro20. The mean serum IgG level was 12.5 g/L. No serious bacterial infections were reported. There were 96 nonserious infections (rate 2.76/patient per year). The rate of days missed from work/school was 2.06/patient per year, and the rate of hospitalization was 0.2/patient per year. Ninety-nine percent of AEs were mild or moderate. No serious, IgPro20-related AEs were reported. IgPro20 effectively protected patients with PID against infections and maintained serum IgG levels without causing unexpected AEs.

Carimune NF Liquid is a safe and effective immunoglobulin replacement therapy in patients with primary immunodeficiency diseases.

Subjects with primary immune deficiency diseases treated with intravenous immunoglobulin (n=42) received intravenous infusions of Carimune NF Liquid every 3-4 weeks for 6 months without routine premedication. The mean dose/patient/infusion was 278.5-800.7 mg/kg. Also, 80.4% of infusions achieved maximum rates of >or=3.5 mg/kg/min; 32% of infusions were associated with adverse events during or within 48 h of their end (upper 95% confidence interval was 39.4%, meeting the Food and Drug Administration (FDA) criterion for acceptable tolerability), and 54.8% of subjects had at least one temporally associated adverse event considered at least possibly drug-related (headache: 35.7% of subjects, 12.4% of infusions; nausea: 14.3%, 3.5%; myalgia: 14.3%, 3.2%; fatigue: 11.9%, 5.7%). The frequencies of these were highest after the first infusion. There were no serious drug-related adverse events or acute serious bacterial infections. Serum IgG trough levels were unchanged from baseline. Carimune NF Liquid, a ready-to-use, high-concentration, liquid immunoglobulin preparation is safe and effective.