Obinutuzumab Infusion-Related Reactions: Multicenter Retrospective Evaluation of Incidence, Severity, and Risk Factors

Introduction: Despite standard prevention strategies, obinutuzumab carries a significant risk of infusion-related reactions (IRRs) for patients with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). Reported rates of IRRs vary in phase III clinical trials evaluating obinutuzumab-containing regimens. Although obinutuzumab has a higher rate of severe (grade 3 and higher) IRRs than rituximab, clinical risk factors predicting IRR have not been identified, and therefore strata informing patient-specific risk of IRR have not been applied in practice. Methods: This multicenter, retrospective evaluation of patients with CLL/SLL estimated the incidence of obinutuzumab-related IRRs and evaluated risk factors for the development of IRR in a real-world population. Results: 68 patients with untreated or previously treated CLL/SLL were included in the analysis, with the majority being older adult (median age = 70) males (61.8%) with Rai stage III and IV CLL. All-grade IRRs occurred in 25% of patients, and severe IRRs occurred in 1.5% of patients. Of the variables evaluated, absolute lymphocyte count was a significant predictor (p ≤ .05) of the odds of experiencing an IRR in patients receiving obinutuzumab. Conclusion: Obinutuzumab IRR rates in a real-world population were comparable to most phase III clinical trial results succeeding implementation of split dosing and standard premedication. Absolute lymphocyte count is a statistically significant predictor for increased odds of experiencing an IRR. Future research evaluating risk-adapted obinutuzumab administration strategies is needed to recommend a specific approach.