Abstract PS19-03: Contemporary patterns of Medicare Utilization and Spending on Herceptin and its Biosimilars in Breast Cancer

Abstract Introduction: A biosimilar is a biological product that is highly similar to and has no clinically meaningful differences from an existing FDA-approved reference product. Trastuzumab biosimilars are significant in HER2-positive breast cancer due to their cost savings and increased access to HER2-targeted therapy in early-stage and metastatic cases. The six FDA approved Herceptin biosimilars are: Ogivri, Herzuma, Ontruzant, Trazimera, Kanjinti, and Hercessi. Our objective is to analyze the trends of utilization, spending and cost of these biosimilars as compared to Herceptin (transtuzumab). Methodology: We analyzed publicly available datasets from Centers for Medicare & Medicaid Services (CMS) within Medicare Part D. We extracted total spending, spending per claim, the number of beneficiaries, and spending per beneficiary for trastuzumab and its biosimilars. Kanjinti, Ontruzant, Trazimera were approved in 2019, so we examined changes between 2020 and 2022. All costs were adjusted for inflation and represented in 2022 US dollars. Because all data were deidentified and publicly available, the study was deemed exempt from institutional review board. Results: From 2020 to 2022, total spending on Herceptin significantly decreased from $13,633,376 to $5,953,812, while spending on all biosimilars increased. Trazimera had the steepest increase ($70,717.28 in 2020 to $2,940,700.78 in 2022). Kanjinti had the highest spending among biosimilars in 2022 at $4,193,266.07. The total dosage units for Herceptin decreased by 50% (from 7,184 in 2020 to 3,586 in 2022), while Trazimera saw an increase from 18 to 1,659 units. Herceptin claims dropped by 48% (from 1,995 in 2020 to 1,044 in 2022), whereas biosimilar claims increased, with Kanjinti having the highest number in 2022 at 881 claims, and Herzuma the lowest at 38 claims. In 2022, Herceptin had the highest average spending per claim at $5,702.89, followed by Herzuma at $5,566.46. Kanjinti and Ontruzant had lower average spending per claim at $4,759.67 and $4,418.89, respectively. The number of beneficiaries for Herceptin decreased by 44.5% (from 292 in 2020 to 162 in 2022), while it increased significantly for Kanjinti (from 34 in 2020 to 138 in 2022) and Trazimera (from 34 in 2021 to 115 in 2022). On the other hand, the beneficiaries for Ogivri fluctuated slightly (from 45 in 2020 to 58 in 2022). Average spending per beneficiary for Herceptin was $36751.93 in 2022 (vs 45299.84 in 2020). In comparison, the average spending per beneficiary in 2022 for all biosimilars was lower ($24359.03 for Ogivri; $25571.31 for Trazimera; $30385.99 for Kanjinti; $32110.63 for Ontruzant). Conclusion: There has been a significant decline in Herceptin utilization and spending, accompanied by a shift towards biosimilars; reflecting changing trends in HER2-positive breast cancer treatments. Kanjinti and Trazimera, in particular, experienced substantial increases in spending, dosage units, claims, and beneficiaries, indicating growing acceptance and usage. Despite these increases, total spending and claims for Herceptin remain higher than for its biosimilars. The average spending per beneficiary and per claim is higher for Herceptin compared to its biosimilars. However, the decrease in these costs from 2020 to 2022 possibly indicate a favorable outcome as a result of market competition from biosimilars. The diversification provided by biosimilars has expanded patient options, potentially reduced costs and improved access to essential therapies. Continuous monitoring and analysis will be crucial to understanding the long-term impacts on healthcare costs and patient outcomes. Citation Format: Charmi Bhanushali, Vidit Majmundar, Vaibhavi Mukhtiar, Vidhi Bhanushali, Kalaivani Babu, Srinishant Rajarajan, Kala Seetharaman. Contemporary patterns of Medicare Utilization and Spending on Herceptin and its Biosimilars in Breast Cancer [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2024; 2024 Dec 10-13; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(12 Suppl):Abstract nr PS19-03.