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Study Suggests Oncologists' Use of Biosimilars Grew From Trickle to Flood


When biosimilars emerged in oncology, oncologists dipped in a toe and then got serious, according to a retrospective study on usage and savings presented at ASCO 2021.

Eleven biosimilars for use in oncology have been launched since the start of 2019, and investigators who sought to measure oncologists’ response to these agents reported initial hesitation, followed by robust uptake and hefty savings.

They noted that the biosimilar competition had little effect on reference product prices, which “remained stable.”

We conclude that uptake of biosimilars among oncology providers between 2019-2020 was rapid, although the extent of biosimilar prescribing varied among products. Biosimilars offered greatly reduced costs to providers, although reference product prices remained stable despite increased biosimilar competition.

The findings were reported in an abstract published at the ASCO 2021 meeting. Investigators drew their data from prescription information published by Wolters Kluwer (n = 130,836), sales data from IQVIA, and dosage information published by ION Solutions.

Investigators found that in 2020, 8.2% of new prescriptions for bevacizumab, rituximab, and trastuzumab were for biosimilar versions. For bevacizumab, there are currently 2 biosimilars available; rituximab, 3; and trastuzumab, 5.

Findings for use of trastuzumab biosimilars revealed a dramatic increase from the first year of availability to the next. In the first 3 months of 2019, 7.3% of initiating first-line patients were prescribed trastuzumab biosimilar vs reference product. In the first quarter of 2020, when all 5 trastuzumab biosimilars had become available, the new prescriptions rate was 80.5% for patients receiving first-line care.

Uptake rates differed for individual biosimilars. The investigators reported that Ruxience, the first available rituximab biosimilar, had initial uptake of just 2.3%.

And further, they did observe willingness among oncologists to switch patients from reference products to biosimilars. They said 11.1% of patients (bevacizumab, 11.3%; trastuzumab, 14.1%; rituximab, 7.9%) were transitioned from the reference biologics to biosimilars during treatment.

“Uptake was particularly rapid for trastuzumab biosimilars,” investigators said. “Among patients on trastuzumab at the time of its first biosimilar launch, 18.2% switched to [the Kanjinti trastuzumab biosimilar] in the first 90 days postlaunch.”

Significant savings were a feature of the use of biosimilars in the oncology practices, the authors said. Costs per biosimilar prescription were lower than the reference product prescription cost by 42.0%, 29.9%, and 89.5% for trastuzumab, rituximab, and bevacizumab, respectively.

“However, biosimilar launches had little impact on reference product pricing, with 2019 to 2020 year-over-year (YOY) differences in price per prescription close to the YOY averages in previous years (2015-2019) for all 3 reference products,” the authors wrote.


McGlynn KA, McGarry J, Patel KB, Clinton N. Real-world trends in biosimilar prescribing among oncology providers, 2019-2021. Presented at: ASCO 2021: June 3-7, 2021. Abstract e18701.

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