Clinical Efficacy and Safety of Intramuscular Injections of Autologous Total <scp>IgG</scp> in Patients With Chronic Spontaneous Urticaria: An Open‐Label Prospective Pilot Trial

Chronic spontaneous urticaria (CSU) remains challenging to manage in patients who do not respond adequately to antihistamines or currently available immunomodulatory therapies. Intramuscular injection of autologous total IgG (autologous immunoglobulin therapy: AIGT) has demonstrated clinical efficacy, safety and immunomodulatory effects in patients with moderate-to-severe atopic dermatitis in a randomized placebo-controlled clinical trial. However, the clinical usefulness of AIGT in patients with CSU has not been evaluated. We conducted a prospective open-label pilot study to assess the efficacy and safety of AIGT in antihistamine-refractory CSU. Fifteen adults with CSU received nine weekly intramuscular injections of 100 mg autologous IgG from Week 0 through Week 8 (inclusive). The primary outcome was the change in Urticaria Activity Score over 7 days (UAS7) at Week 12 from baseline. Secondary outcomes included the Urticaria Control Test (UCT), chronic urticaria-specific quality of life (CU-QoL) scores and patient-reported disease burden using a visual analogue scale (VAS). The median change in UAS7 at Week 12 from baseline was -13.0 (p < 0.001). Significant improvements in UCT, CU-QoL and VAS were also observed at Week 12 from baseline (p < 0.05). In longitudinal analyses, improvements in symptom burden and quality of life were detectable from Week 4 and were maintained through Week 24. Serum total IgG increased by a median of +68.0 mg/dL from baseline to Week 12 (p < 0.05). No serious adverse events occurred. In conclusion, AIGT improved disease activity, urticaria control, quality of life and patient-reported burden in patients with antihistamine-refractory CSU. Further studies are needed to evaluate the clinical usefulness of AIGT in CSU.