Insights into Patient Experiences with Facilitated Subcutaneous Immunoglobulin Therapy in Primary Immune Deficiency: A Prospective Observational Cohort.

Background: Immunoglobulin G replacement therapy (IgRT), intravenous (IV) and subcutaneous (SC) routes, is pivotal in treatment of primary immunodeficiencies (PID). In recent years, facilitated subcutaneous immunoglobulin (fSCIG), a combination of rHuPH20 and 10% IgG has emerged as a delivery method to combine advantages of both IV and SC.

Method: In an observational prospective cohort, we investigated patient experience with fSCIG in PID patients from 5 PID centers for up to 12 months. We assessed the efficacy and safety of this treatment with patient/caregiver- and physician-reported indicators. Additionally, we analyzed patient treatment satisfaction (TSQM-9) and quality of life (QoL).

Results: We enrolled 29 patients (22 pediatric and 7 adults; 14 females and 15 males; (median: 15, min-max: 2-40.9 years) who initiated fSCIG as IgRT-naive (n = 1), switched from conventional rapid-push 10% SCIG (n = 6) or IVIG (n = 22). Among the participants, 19 (65%) exhibited antibody deficiencies, 8 (27%) combined immunodeficiencies, and 2 (7%) immune dysregulations. Remarkably, targeted trough immunoglobulin G levels were achieved under all previous IgRTs as well as fSCIG. No severe systemic adverse drug reactions were documented, despite prevalent local (%86.45) and mild systemic (%26.45) adverse reactions were noted with fSCIG. Due to mild systemic symptoms, 2 patients switched from fSCIG to 10% SCIG. The patient satisfaction survey revealed a notable increase at 2-4th (p = 0.102); 5-8th (p = 0.006) and 9-12th (p < 0.001) months compared to the baseline. No significant trends were observed in QoL surveys.

Conclusion: fSCIG demonstrates admissable tolerability and efficacy in managing PIDs in addition to notable increase of patients' drug satisfaction with IgRT. The identified benefits support the continuation of this therapy despite the local reactions.