Patterns of Medicare Utilization and Spending on Granulocyte Colony-Stimulating Factors: Filgrastim, Pegfilgrastim, and Their Biosimilars
Authors: Bhanushali Charmi , Gogtay Maya , Bhanushali Vidhi , Babu Kalaivani , Rajarajan Srinishant , Desai Nihar 
Published: December 2024

Introduction:
Granulocyte colony-stimulating factors (G-CSF) are pivotal for aiding in neutrophil production in patients post-chemotherapy. They represent a substantial part of Medicare expenditure. The emergence of biosimilars promises reduced costs and enhanced accessibility without compromising efficacy. However, the adoption of biosimilars in clinical practice has varied, influenced by factors such as physician preferences, patient awareness, and healthcare policies. In this study, we aim to examine Medicare part B spending and utilization trends for Filgrastim, Pegfilgrastim, and their biosimilars from 2018-2022.
Methodology:
We analyzed publicly available datasets from Centers for Medicare & Medicaid Services (CMS) within Medicare Part B and extracted total spending, the number of beneficiaries, and spending per beneficiary. Data for Neupogen and its biosimilars (Zarxio, Nivestym, Granix) and Neulasta and its biosimilars (Fulphila, Udenyca, Ziextenzo and Nyvepria) was extracted. All costs were adjusted for inflation (using Inflation Calculator based on the average Consumer Price Index data) and represented in US dollars.
Results
Filgrastim: From 2018 to 2022, total spending on Neupogen dropped 69%, from $47.63M to $14.52M. Spending on both Granix and Zarxio showed a 70% reduction (from $14.61M to $4.37M and $46.64M to $13.76M respectively).The spending on Nivestym (approved in June 2018) increased from $2.13M in 2019 to $4.19M in 2022. Average spending per beneficiary for Neupogen decreased by 17% from $3,209 in 2018 to $2,654 in 2022. Average spending per beneficiary decreased by 41% for Granix (from $1,745 in 2018 to $1,025 in 2022), 68% for Zarxio (from $2,404 in 2018 to $764 in 2022) and 57% for Nivestym ($2,441 in 2018 to $1,055 in 2022).
PEGfilgrastim: The total spending on Neulasta was highest in 2022 at $342M. The total spending on Nyvepria, Ziextenzo and Fulphila showed an increase since their introduction from $29M in 2021 to $52M in 2022, $18M in 2019 to $79.5M in 2022 and $19.83 in 2018 to $66.30M in 2022 respectively. Total spending on Udencya decreased by 47% from $167M in 2019 to $89M in 2022. Average spending per beneficiary for Neulasta was $6,935 in 2022. The average spending per beneficiary for biosimilars has decreased since their introduction (by 46% for both Fulphila and Udencya, from $11,510 in 2018 to $6,942 in 2002 and from $14,444 in 2019 to $7,742 in 2022 respectively) and by 36% for both Ziextenzo and Nyvepria (from $11,672 in 2020 to $7,402 in 2022 and from $13,981 in 2021 to $8,937 in 2022).
Conclusion
Total spending on Filgrastim and its biosimilars has notably decreased with increased adoption of more cost-effective alternatives like Nivestym. Neupogen is a high-cost option, with its spending declining but still notable compared to its biosimilars. Neulasta continues to dominate total spending, although its biosimilars have shown substantial growth in utilization. Neulasta maintains the lowest average spending per beneficiary, highlighting its ongoing value proposition despite the increasing role of biosimilars in the treatment landscape. In conclusion, by leveraging the market competition from biosimilars, the healthcare system can achieve a more balanced approach to delivering high-quality care while managing costs effectively.