Real-world resource use and cost in patients treated with originator or biosimilar rituximab in a large U.S. insurance claims database.

11159 Background: Rituximab-pvvr, Rituximab-arrx, and Rituximab-abbs are monoclonal antibodies approved by the FDA as biosimilars to originator rituximab. All are approved for treatment of non-Hodgkin lymphoma (NHL) and chronic lymphocytic leukemia (CLL). Biosimilars are intended to deliver equal clinical outcomes to originators at a lower cost, but there remains limited ‘real-world’ investigation of these outcomes. This study describes and compares resource use and cost for patients receiving originator or biosimilar rituximab in the Carelon Research Healthcare Integrated Research Database (HIRD). Methods: We conducted a retrospective cohort study of adults with newly diagnosed NHL and CLL identified by ICD-10 codes between 1/1/2018 and 7/31/2024 in the Carelon Research HIRD and treated with rituximab. Included patients had ≥1 claim for originator or biosimilar rituximab after NHL or CLL diagnosis. Baseline demographics were assessed at rituximab initiation ( index date ). Inpatient, outpatient, and emergency department (ED) resource use and medication cost were assessed over one year following rituximab initiation. Costs were inflation-adjusted to 2024 USD. Originator and biosimilar rituximab groups were compared using t-test or ANOVA to assess mean differences in resource use and cost. Results: A total of 11,525 patients met inclusion criteria with mean age of 64.4 years, 57.2% male, and 76.9% reporting white non-Hispanic race/ethnicity. Most of the cohort (89.8%) were diagnosed with NHL. There were no significant differences in mean follow-up duration (p=0.960), rituximab infusions (p=0.987), treatment duration (p=0.106), inpatient hospitalizations (p=0.241), or ED visits between groups (p=0.702) ( see table ). Mean overall medication costs were significantly lower in all biosimilar groups vs. originator (p<0.001). Conclusions: In this large real-world cohort of NHL and CLL patients, resource use was similar in patients treated with originator and biosimilar rituximab, but medications costs were significantly lower in the biosimilar groups. Our findings demonstrate how biosimilar therapies in cancer can deliver similar clinical outcomes to originators, while generating meaningful cost savings for the U.S. healthcare system. Mean 1-Year Outcomes Originator Rituximab (n=7,123) Biosimilar Rituximab-pvvr (n=1,846) Other Rituximab Biosimilars (n=2,556) Follow-Up Duration, Months (SD) 10.8 (2.7) 10.8 (2.7) 10.8 (2.7) Count of Rituximab Infusions (SD) 5.7 (2.5) 5.7 (2.6) 5.7 (2.5) Rituximab Treatment Duration, Months (SD) 4.2 (3.3) 4.1 (3.3) 4.1 (3.3) Count of All-Cause Inpatient Stays (SD) 1.6 (3.1) 1.6 (3.2) 1.5 (2.9) Count of All-Cause ED Visits 0.6 (1.4) 0.6 (1.3) 0.6 (1.2) Medication & Related Costs (SD)* $123,499 ($145,374) $77,728 ($96,377) $90,868 ($122,510) *Includes all medications paid under medical benefit, including rituximab.