Subcutaneous immunoglobulin therapy in pediatric primary antibody deficiency

Long-Term Tolerability, Safety, and Efficacy of Recombinant Human Hyaluronidase-Facilitated Subcutaneous Infusion of Human Immunoglobulin for Primary Immunodeficiency

Purpose

Treatment of primary immunodeficiency diseases (PIDD) with subcutaneous (SC) infusions of IgG preceded by injection of recombinant human hyaluronidase (rHuPH20) (IGHy) to increase SC tissue permeability was evaluated in two consecutive, prospective, non-controlled, multi-center studies.

Methods

Subjects >4 years of age received SC IgG replacement at a weekly dose equivalent of 108 % of their previous intravenous (IV) dose, facilitated by prior injection of 75 U/g IgG of rHuPH20. Starting with weekly SC infusions, the interval was increased (ramped-up) to a 3- or 4-week schedule.

Results

Eighty-three subjects (24 < 18 years; 59 ≥ 18 years) received 2729 infusions (excluding ramp-up) at a mean dose of 0.155 g/kg/week in the pivotal and 0.156 g/kg/week in the extension study. IGHy exposure exceeded 30 months in 48 subjects.

During 187.7 subject-years of IGHy exposure, 2005 adverse events (AEs) (10.68 per subject-year) occurred. The rate of related systemic AEs during consecutive 1-year periods remained low; the rate of related local AEs decreased from 3.68/subject-year in months 1–12 to approximately 1.50/subject-year after 30 months of treatment. Fifteen subjects transiently developed anti-rHuPH20 binding antibody. There was no difference in AE rates in these subjects before and after the first titer increase to ≥1:160.

The rate of infections during IGHy exposure was 2.99 per subject-year and did not increase during the studies. Annual infection rates were 3.02 in subjects <18 years and 2.98 in subjects ≥18 years.

Conclusions

Long-term replacement therapy with IGHy was safe and effective in 83 pediatric and adult subjects with PIDD.

Electronic supplementary material

The online version of this article (doi:10.1007/s10875-016-0298-x) contains supplementary material, which is available to authorized users.

Clinical experiences in primary and secondary immunodeficiencies and immune-mediated conditions using Gammanorm(®)

Treatment for primary and secondary immunodeficiency disorders focuses on prevention and management of infections, using immunoglobulin G (IgG) replacement therapy with regular intravenous or subcutaneous IgG (SCIG) infusions. SCIG therapy has many advantages including improved efficacy and tolerability, enhanced patient satisfaction and lower costs. A number of SCIG preparations are available, including Gammanorm(®) (Octapharma AG), a ready-to-use 16.5% liquid preparation of IgG, with low viscosity, well suited to self-administration and a long history of use. Clinical experience with Gammanorm has shown that it is effective and well tolerated in children and adults, including pregnant women, for primary and secondary immunodeficiency disorders. Recent data also suggest SCIG may have a role in the treatment of certain immune-mediated conditions.

Evaluation of correlation between dose and clinical outcomes in subcutaneous immunoglobulin replacement therapy

The importance of serum immunoglobulin (Ig)G concentration in IgG replacement therapy for primary immunodeficiency diseases is established in certain settings. Generally, IgG is infused via the intravenous (IVIG) or subcutaneous (SCIG) route. For IVIG infusion, published data demonstrate that higher IgG doses and trough levels provide patients with improved protection from infection. The same conclusions are not yet accepted for SCIG; data from two recent Phase III studies and a recent post-hoc analysis, however, suggest the same correlation between higher SCIG dose and serum IgG concentration and decreased incidence of infection seen with IVIG. Other measures of clinical efficacy have not been considered similarly. Thus, combined analyses of these and other published SCIG studies were performed; a full comparison of the 13 studies was, however, limited by non-standardized definitions and reporting. Despite these limitations, our analyses indicate that certain clinical outcomes improve at higher SCIG doses and associated higher serum IgG concentrations, and suggest that there might be opportunity to improve patient outcomes via SCIG dose adjustment.