Subcutaneous Immunoglobulin Therapy in Patients with Secondary Immunodeficiency – Real-World Data

Study Methodology and Population

A retrospective study conducted at the University Hospital in Padua used clinical records of patients treated between September 2011 and February 2018. Data from a total of 131 patients with SID (average age 70 years; 49.6% women) and 102 with PID (average age 52 years; 51.9% women) were analyzed (see table). Among individuals with SID, 111 had hematological malignancies (55 with chronic lymphocytic leukemia, 22 with multiple myeloma, and 34 with non-Hodgkin lymphoma) and 20 had immunosuppression-induced hypogammaglobulinemia. Among those with PID, 75 had common variable immunodeficiency (CVID), 5 had isolated IgG subclass deficiency, 2 had IgA and IgG subclass deficiency, 1 had antipneumococcal IgG deficiency, 17 had unclassified humoral immunodeficiency, and 2 had agammaglobulinemia.

Patients with SID were treated with SCIG for an average of 45.8 months, those with PID for 73.8 months. Treatment was initiated in SID cases in the presence of hypogammaglobulinemia (< 6 g/l) and an increased incidence of infections without neutropenia requiring antibiotic therapy (> 2 in the last 12 months). Dosage was adjusted based on the target IgG level (> 5 g/l) accompanied by minimal infection incidence.

Table  Baseline Demographic and Clinical Characteristics of Patients

Effectiveness (minimum steady-state IgG level and annual incidence of infections without neutropenia) and safety (local and systemic adverse events related to treatment) of subcutaneous immunoglobulin therapy were evaluated. Serious infectious complications were considered to be serious bacterial infections, including sepsis, pneumonia, osteomyelitis, septic arthritis, visceral abscess, meningitis, or endocarditis.

Results

The average baseline IgG level was 3.68 g/l in patients with SID and 3.46 g/l in those with PID. During treatment, the average minimum IgG level was significantly higher in patients with PID compared to SID (7.67 ± 1.45 g/l vs. 6.80 ± 1.71 g/l; p = 0.0002). In the case of PID, a higher average monthly dose of IgG was needed to achieve a comparable biological effect (309.31 ± 95.33 mg/kg vs. 251.94 ± 82.20 mg/kg; p < 0.0001). The difference was also noticeable among individual SID patient groups, with the highest IgG level in patients with non-Hodgkin lymphoma.

Effectiveness was evaluated in a subgroup of previously untreated patients, namely 85 with SID and 44 with PID. The annual incidence of infections before and after treatment was 3.69 ± 2.81/year and 0.52 ± 1.18/year for PID patients; p < 0.0001. In SID patients, the drop was from 1.01 ± 1.38/year to 0.24 ± 0.44/year; p < 0.0001, which was not statistically significantly different from PID patients.

A total of 14 PID patients and 6 SID patients reported mild treatment-related adverse events: local rash (n = 10), injection site tenderness (n = 3), headache (n = 3), nausea (n = 3), chills (n = 2), fever (n = 2), and skin infection at the injection site (n = 1). No severe treatment-related adverse events were reported, and no patients had to discontinue treatment.

Conclusion

Subcutaneous immunoglobulin therapy is equally effective in reducing infection incidence in patients with primary and secondary humoral immunodeficiencies, regardless of the underlying disease.

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Source: Cinetto F., Neri R., Vianello F. et al. Subcutaneous immunoglobulins replacement therapy in secondary antibody deficiencies: real-life evidence compared to primary antibody deficiencies. PLoS One 2021; 16 (3): e0247717, doi: 10.1371/journal.pone.0247717.