First Steps with Facilitated Subcutaneous Immunoglobulin (fSCIg) Therapy: A Single Center Experience

Introduction Several studies have shown that facilitated subcutaneous immunoglobulin (fSCIg) is as good as intravenous (IVIg) and conventional subcutaneous immunoglobulin (cSCIg) preventing infections in innate errors of immunity (IEIs). Presentation The objective is to describe the follow-up of 29 patients with fSCIg treatment in the last 3 years in a single center in Argentina (April 2022 – June 2025). 29 patients (p) were included who diagnosed with (15p) common variable immunodeficiency, (5p) specific antibody deficiency with normal Ig levels and normal B cells, (2p) hypogammaglobulinemia and specific antibody deficiency, (2p) primary hypogammaglobulinemia, (1p) x-linked agammaglobulinemia, (1p) specific antibody deficiency with IgA deficiency, (1p) specific antibody deficiency and familial Mediterranean fever, (1p) LRBA deficiency, and (1p) autoimmune lymphoproliferative syndrome and IgA deficiency. Mean time of follow-up with fSCIg was 20 months [1.1 – 38.6]. Mean dose was 560 mg/kg/month [345 – 1,360]. 76% received fSCIg every 4 weeks, the others more frequently. Mean serum IgG level was 1,274 mg/dl [range 615 – 3,014]. Annual rate of infection was 0.27 infections/year of follow-up. 8/29p suffered 13 cases of bacterial infections: 3 pneumonia, 3 bronchitis, 2 acute media otitis, 1 giardiasis, 1 adenitis, 1 bacterial parotitis, 1 pharyngitis, and 1 tracheitis. One patient with low adherence to treatment required two hospitalizations (pneumonia, adenitis). Tolerance 9p (31%) reported local symptoms: erythema (5p), swelling (4p), pain (2p), and pruritus (2p); most of them lasted less than 24 hours; only 3p reported erythema (1p) and swelling (2p) of 4-5 days of duration; none of the local symptoms required treatment. 4p reported systemic adverse reactions (headache and/or fever) during the first infusions. Discussion fSCIg therapy is safe and effective for replacement treatment in patients with IEIs. Further systemic clinical studies are needed to better define optimal dosage and application intervals.