Intravenous Immunoglobulin Reduces Infections for Patients with Chronic Lymphocytic Leukemia: A Single-Center Retrospective Analysis

Abstract Hypogammaglobulinemia is common in patients with chronic lymphocytic leukemia (CLL). Prior studies demonstrated that intravenous immunoglobulin (IVIG) reduced infections without survival benefit. We conducted a single-institution retrospective cohort study of infectious outcomes in CLL patients who received IVIG between 2005 and 2022 to assess the impact of IVIG across evolving CLL treatment paradigms, including the introduction of targeted agents. 52 patients met inclusion criteria of IVIG use for hypogammaglobulinemia and recurrent infections, with also any infection up to 1 year prior to the initiation of IVIG. Baseline mean IgG prior to IVIG was 389 mg/dL (range 93 – 891 mg/dL). By design, all 52 patients (100%) experienced at least one CTCAE grade ≥ 2 infection in the 12 months prior to IVIG initiation. In the 12 months following IVIG initiation, only 17 patients (33%) experienced a grade ≥ 2 infection. IVIG therapy was associated with a 67% reduction in risk of grade 2 infections (RR 0.33, 95% CI 0.22 – 0.48; p 0.0001), corresponding to an absolute risk reduction of 67% and a number needed to treat of 1.5. The mean number of infections per patient also reduced from 2.1 to 0.4. Baseline IgA and IgG levels, as well as recent CLL treatment, were not predictors of residual post-IVIG infections. These findings suggest IVIG may yield meaningful improvements in patient quality of life by reducing infections.