Bozzi, Sylvie

ABSTRACTIntroductionRituximab is used off‐label for treating cold agglutinin disease (CAD) in the United States; however, real‐world data on its use are limited.MethodsThis study examined (1) treatment patterns, (2) prespecified safety outcomes, and (3) changes in hemolytic markers post rituximab infusion (threshold change from baseline: hemoglobin [Hb]: ≥2 g/dL increase; bilirubin or lactate dehydrogenase [LDH]: ≥50% decrease). Of 611 patients with CAD (Cohort 1) identified using Optum's de‐identified Market Clarity database (2007‐2021), 94 who received rituximab (Cohort 2) were included.ResultsRituximab was predominantly used as monotherapy; the median (interquartile range; IQR) number of rituximab courses per patient was 1.0 (1.0–2.0); 24 (25.5%) patients had ≥1 incomplete course and 37 (39.4%) required blood transfusion. The incidence rate (IR) of serious infections per 1000 patient‐years (95% CI) post rituximab initiation was three times higher than before rituximab initiation (637.1 [242.2–1032.0] vs. 245.4 [125.1–365.6]). Cohort 2 had a similar IR of thromboembolic events and slightly higher hospitalization rates and deaths than Cohort 1. After the first course of rituximab, 69.5% (41/59), 59.6% (28/47), and 31.3% (10/32) of patients reached thresholds for Hb, bilirubin, and LDH, respectively. The median (IQR) duration of improvement was 44 (13.3–90.8), 98 (29.0–257.0), and 93 (21.3–161.8) days for Hb, bilirubin, and LDH, respectively. Reversal from threshold occurred in 68.3% (28/41), 53.6% (15/28), and 80.0% (8/10) of patients for Hb, bilirubin, and LDH, respectively.ConclusionRituximab showed a limited durability of response and an increased risk of infection, suggesting the need for more effective and safer treatment options.Trial Registration: The authors have confirmed clinical trial registration is not needed for this submission.