Trastuzumab Biosimilar Use Significantly Increasing in the US

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Analysis shows the rate of use with the originator biologic has decreased from 90% in 2016, to 19% in 2021.

Trastuzumab biosimilar product use among US patients has increased significantly within the last half-decade, according to new analysis.1

An assessment into the utilization of various biosimilars to reference trastuzumab product (Herceptin) conducted by a team of US-based academic and industry investigator showed that cost-efficient alternatives to the HER2 inhibitor biologic have been increasingly prescribed to patients with relevant cancers since their US Food and Drug Administration (FDA) authorizations 6 years ago. The findings, presented in an abstract presented at the International Conference on Pharmacoepidemiology and Therapeutic Risk Management (ICPE) Annual Meeting this year, warrant further assessment into the long-term, real-world efficacy and safety of said biosimilars relevant to their reference biologic product.

A team of investigators led by Mai Xiaodan, PhD, MBBS, of Harvard Pilgrim Health Care Institute and Harvard Medical School, sought to conduct an evaluation of the utilization of reference Herceptin, its biosimilars, and other marketed HER2 inhibitors among patients with various cancers. They additionally observed patient baseline sociodemographic and clinical characteristics relevant to treatment use.

Investigators noted that, despite trastuzumab biosimilars first beginning to reach the US market in 2017, “utilization information on these biosimilars is limited.” By early 2019, a trio of biosimilars had been approved by the FDA;2 to this day, more are in development.3

Xiaodan and colleagues analyzed healthcare claims data derived from the Biologics & Biosimilars Collective Intelligence Consortium (BBCIC) that which includes >95 million person-years of data for commercially insured individuals in the US.1 Product usage data and patient demographics and clinical characteristics were captured through FDA Sentinel analytical tools analyzed data from October 2016 – May 2022.

Eligible patients for assessment were continuously enrolled in their health plan with medical and drug coverage for ≥1 year prior to their first observed data of trastuzumab biosimilar or biologic use in the observed period.

The final analysis included 18 million healthcare plan members representing >33 million person-years of data. Investigators identified 7598 incident treatment episodes; among them, 3920 (52%) involved originator trastuzumab. Mean patient age varied from 53.4 to 64.1 years old in each product arm; more than 4 in 5 episodes for each product included females, due to the highly prevalent use of trastuzumab in the treatment of breast cancer.

Investigators additionally observed a mean comorbidity index score of 1.2 among users of originator trastuzumab versus biosimilars (range, 1.0 – 2.6). Otherwise, clinical characteristics of patients using various forms of trastuzumab product were consistent.

The proportion of total incident episodes using originator trastuzumab biologic decreased from 90% in the pre-biosimilar approval era of 2016, to just 19% in 2021, while biosimilar utilization increased. Of note, trastuzumab-anns (Kanjinti) increased to 28% use in 2021—a rate similar across patients with and without metastatic disease.

Though investigators did not that data from 2020 – 2022 needs to be interpreted “with caution” due to incomplete data from the available sources, they concluded that the utility of trastuzumab biosimilar products has been growing since their introduction in 2017—and will likely continue to rise among US patients.

“Exploration of these biosimilars' comparative benefit and safety to their originator product is warranted and is a priority for future BBCIC analyses,” they wrote.


  1. Mai X, Mendelsohn A, Marshall J, Lin ND, et al. Presented at: Utilization and patient characteristics for the originator and biosimilar trastuzumab products in the United States. International Conference on Pharmacoepidemiology and Therapeutic Risk Management (ICPE) 2023 Annual Meeting. Halifax, Canada. August 25 – 27, 2023.
  2. Columbus G. FDA Approves Third Herceptin Biosimilar. Cure. Published January 18, 2019.
  3. Seymour C. FDA Accepts BLA for Trastuzumab Biosimilar in HER2+ Breast Cancer, Gastric/GEJ Cancer. OncLive. Published April 5, 2023.