Uptake of rituximab biosimilars in Medicare and Medicaid in 2019-2022.

Objectives: This study evaluated the uptake and costs of 3 biosimilars among Medicare and Medicaid populations for 2019 to 2022: rituximab-abbs (Truxima), rituximab-pvvr (Ruxience), and rituximab-arrx (Riabni).

Study design: A retrospective, descriptive study.

Methods: Using the annually aggregated, product-level utilization and cost data of biologic and biosimilar rituximab products from CMS drug spending data, total claims and costs (reimbursement and out of pocket) for all rituximab products were identified and extracted from Medicare Part B, Medicare Part D, and Medicaid. Average spending per dosage unit (ASPDU) of individual rituximab products was also extracted, and their annual growth rates in 2022 (vs 2021) were calculated. Descriptive data analyses were performed using Microsoft Excel 2016.

Results: Four years after entering the US market, rituximab biosimilar use increased from between 0% and 7% in 2019 to 60%, 41%, and 61% of all rituximab claims paid by Medicare Part B, Medicare Part D, and Medicaid, respectively, in 2022. Corresponding total costs for rituximab biosimilars also reached 45%, 32%, and 47% of all rituximab products. The ASPDU of biologic rituximab increased 2% in Medicare Part B in 2022 (vs 2021) but decreased by 2% in Medicaid. The ASPDU of rituximab biosimilars (rituximab-abbs and rituximab-pvvr) decreased between 15% and 26% in 2022 in Medicare Part B and Medicaid, while their ASPDU slightly increased between 1% and 2% in Medicare Part D.

Conclusions: Significant uptake of rituximab biosimilars in Medicare and Medicaid occurred within the first 4 years of marketing in the US.