Association between serum IgG concentrations and the incidence of infections in patients with chronic lymphocytic leukemia and secondary immunodeficiency under treatment with Privigen

Abstract

Objective: To investigate the association between serum immunoglobulin G (IgG) concentrations and the incidence of infections in patients with chronic lymphocytic leukemia (CLL) and secondary immunodeficiency receiving treatment with Privigen.

Materials and methods: Data was analyzed from a non-interventional study conducted in 31 centers in Germany and 1 in Austria. Adult CLL patients with hypogammaglobulinemia and recurrent infections were allowed to enter the study upon signing informed consent, if a prior decision for treatment with Privigen had been made. All infections requiring an antimicrobial treatment were subject to analysis. Patients were stratified according to their mean post-baseline serum IgG trough levels in a group with lower IgG trough levels (≤ 5.0 g/L), and a group with higher IgG trough levels (> 5.0 g/L).

Results: Overall, 89 patients and 840 treatment cycles were analyzed. Up to 11 treatment cycles (average duration 29 days) were documented in each patient. In the group with higher IgG trough levels (> 5.0 g/L, N = 72), significantly fewer infections were observed than in the group with lower IgG trough levels (≤ 5.0 g/L, N = 17), including fewer severe and serious infections. The Privigen dosage was a major determinant of the post-baseline serum IgG levels. Overall tolerability of Privigen was assessed as very good or good in 91% of patients.

Conclusion: This analysis confirms the association of serum IgG trough levels with the incidence of infections and highlights the importance of careful monitoring of IgG levels during treatment of secondary immunodeficiencies in CLL patients.

Figure 1.. Illustration of the analysis rules based on an exemplary treatment course of 36 weeks with 4 Privigen infusions at intervals of 4 weeks (“treatment cycles”), a pause of 3 months, and then 4 further infusions.

Figure 2.. Serum IgG trough levels (A; g/L; mean + SD) and infection rates (B; mean) in the group with lower IgG trough levels (≤ 5.0 g/L) and in the group with higher IgG trough levels (> 5.0 g/L); rates were calculated using the evaluable treatment periods as illustrated in Figure 1; p-value for group comparison: 0.038 (negative binomial regression model for all infections requiring antimicrobial treatment). The lower margin of reference range for serum IgG in adults is given as 7 g/L [31, 32].

Figure 3.. Assessment of overall tolerability of Privigen by the treating physicians in the group with lower IgG trough levels (≤ 5.0 g/L) and in the group with higher IgG trough levels (> 5.0 g/L).