Real-World Data Reveal Higher Risk of Serious Infections in Patients With CLL/SLL

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A real-world study, presented at ASCO 2025, used data from the Symphony Health Solutions database to assess the incidence of serious infections in patients with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) treated with venetoclax plus obinutuzumab or zanubrutinib. The analysis included patients who initiated obinutuzumab between April 2016 and August 2022 and those who started zanubrutinib between November 2019 and August 2023.

Patients in the obinutuzumab cohort were required to begin obinutuzumab within 90 days of their first venetoclax prescription. The index date was defined as the first date of venetoclax use for obinutuzumab-treated patients and the first date of zanubrutinib use for the zanubrutinib cohort. Serious infections were defined as the use of intravenous antibiotics or antivirals within 15 days during a hospitalization. The study evaluated infection rates at 12 and 18 months after treatment initiation.

Inverse probability of treatment weighting (IPTW) and Cox proportional hazards models were used to adjust for baseline differences between cohorts, including age, sex, race/ethnicity, Charlson Comorbidity Index (CCI), and geographic region.

A total of 2,104 patients received obinutuzumab and 2,650 received zanubrutinib. At 12 months, 7.9% of the obinutuzumab cohort experienced a serious infection compared to 4.8% of the zanubrutinib cohort. The hazard ratio (HR) for serious infection in the obinutuzumab group relative to the zanubrutinib group was 1.57 (95% confidence interval [CI], 1.23–1.99).

At 18 months, 10.1% of patients in the obinutuzumab cohort had a serious infection versus 5.6% in the zanubrutinib cohort. The HR for the obinutuzumab group compared with the zanubrutinib group at this time point was 1.72 (95% CI, 1.38–2.13). Kaplan-Meier analysis showed a higher cumulative proportion of serious infections in the obinutuzumab cohort at both 12 and 18 months.

“This real-world study showed that patients diagnosed with CLL/SLL treated with [obinutuzumab] had a higher risk of serious infections than those treated with [zanubrutinib],” study authors wrote.

“In patients with a higher risk of infections, [zanubrutinib] could be considered as a treatment option in lieu of [obinutuzumab].”