Use of a new chemically modified intravenous IgG preparation in severe primary humoral immunodeficiency: clinical efficacy and attempts to individualize dosage.

Sixteen patients with severe primary humoral immunodeficiency diseases were treated intravenously for 12 months with a beta-propiolactone stabilized preparation of IgG (Intraglobin) as part of a phase II study of safety and efficacy. In order to evaluate the metabolism of IgG in these patients and to determine whether increased doses of IgG would lead to a decrease in the rate of infections, the study was divided into two periods. All patients were infused with a standard dose of 100 mg/kg/month for 6 months and the peak and trough serum IgG concentrations were determined. The half-life of the IgG was determined in each patient after the fourth month and this value was used to calculate the dose necessary to raise the trough serum IgG concentration to a minimum of 200 mg/dl. The patients received this individualized dose in the final 6 months and the half-life determination was repeated at the conclusion of the study. Only 3 of 10 patients who received a higher dose in the second period had a substantial increase in trough serum IgG concentrations, but the failure to achieve higher concentrations was not due to a shortening of the half-life. The Intraglobin was well tolerated with no patient unable to complete the study due to side-effects. Ten percent of the infusions were associated with minor, self-limited reactions, with 16 of the 19 reactions occurring in the first 6 months. There were no life-threatening infections during the 12-month period. A total of 105 episodes of infections were recorded, but only a cumulative total of 51 days of normal school or work activity were lost by the 16 patients during the 12 months of the trial period. Most infectious episodes were due to chronic bronchitis, sinusitis, and otitis. There was no reduction in the number of infections in the second, higher dose period of the study; however, as there was little increase in serum IgG concentration, more data are required before it will be possible to determine if the incidence of chronic infections can be reduced by a further increase in the serum IgG concentration.