A study of filgrastim and pegfilgrastim biosimilars demonstrated data are sufficiently large to support an investigation on the effectiveness of these agents.
Use of biosimilar forms of filgrastim and pegfilgrastim, both granulocyte-colony stimulating factor (G-CSF) agents, continues to increase over time, although the number of patients using both the reference and biosimilar versions has remained constant, according to a study presented at the National Comprehensive Cancer Network 2020 Virtual Annual Conference.
The Biologics and Biosimilars Collective Intelligence Consortium (BBCIC), a nonprofit initiative convened in 2015 under auspices of the Academy of Managed Care Pharmacy (AMCP), evaluated data for 38 million patients covered by commercial or Medicare-Advantage health insurance. The data were derived from a distributed research network (DRN) that includes medical and pharmacy claims data on patients from multiple research partners.
The study presented at the NCCN meeting was designed to help inform future priorities for the BBCIC, and investigators concluded that there is sufficient utilization of biosimilar G-CSFs to support a comparative safety and effectiveness study using the BBCIC DRN.
G-CSF products are used after chemotherapy to help patients’ white blood cell counts recover. Biosimilar G-CSF products began to appear on the US market in 2015. Three filgrastim products and 2 pegfilgrastims were included in the analysis; these included the reference products.
Data were analyzed for “new,” or incident, users, who were defined as not having had G-CSF treatment in the 183 days prior to the episode included in the study: 31,023 filgrastim reference (Neopogen), 5325 tbo-filgrastim (Granix), 6305 filgrastim-sndz (Zarxio), 82,671 pegfilgrastim reference (Neulasta), and 192 pegfilgrastim-jmdb (Fulphilia) incident users were identified. Granix is approved as a biologic in the United States and as a biosimilar in Europe.
Because of the relatively short 183-day interval, it was possible for a single patient to have more than 1 episode of use included in the study.
Other biosimilar versions of filgrastim and pegfilgrastim have been approved more recently than these other agents and could not be included in the study.
Reference filgrastim users numbered over 6000 in 2014 but declined to around 2000 by 2018; use of filgrastim-sndz climbed from 0 users in 2015 to roughly 2000 by 2018; and tbo-filgrastim users climbed from 0 to around 1000 between 2014 and 2018.
Of incident filgrastim-sndz users, 9.5% had a recorded history of filgrastim use and 17.1% had a history of pegfilgrastim use. Of filgrastim users, 1.0% had prior use of filgrastim-sndz and 20.4% had prior use of pegfilgrastim. “This suggests some switching between products occurred,” investigators said.
From 2013 to 2018, reference filgrastim use dropped from a 100.0% share to 37.4%. From 2016, to 2018, the share ascribed to filgrastim-sndz climbed from 21.7% to 43.9%, and from 2014 to 2018, the share attributed to tbo-filgrastim changed from 9.4% to 18.8%.
Use of pegfilgrastim relative to filgrastim remained relatively constant: roughly 66% versus 34%, respectively.
Lockhart CM, McDermott CL, Marshall J, et al. Longitudinal evaluation of characteristics, treatment patterns, and general outcomes among patients using granulocyte colony stimulating factors: a Biologics and Biosimilars Collective Intelligence Consortium study. Poster presented at: National Comprehensive Cancer Network 2020 Virtual Annual Conference; March-May, 2020. nccn.org/professionals/meetings/2020/posters.aspx