The reasons for biosimilar brand preference in a recent rituximab study were unclear, but investigators said it is clear that savings were a likely factor.
German investigators had difficulty understanding why a Sandoz rituximab biosimilar was preferred over a Celltrion rituximab biosimilar in a 2-year retrospective study in clinics across the country; however, they concluded that providers were willing to use both of these products on an increasing basis to treat their patients.
“The affordability crisis in oncology is believed to be unsustainable,” said the investigators, who looked at the uptake of biosimilar rituximab beginning from its introduction in Germany in July 2017 through June 2019. They found that providers tended to stick with reference rituximab if that was the medication their patients had begun, but for patients newly started on therapy, providers tended to become more comfortable over time using biosimilars.
“A greater focus on value, alongside efficacy and safety, needs to be implemented across both healthcare systems and industry to prevent restricted access to life-saving treatments,” investigators wrote in their report.
Although rituximab biosimilars have been on the market in Germany since 2017, the first rituximab biosimilar was introduced to the US market in November 2019, and this was at a discount of 10% to the reference product.
“Biosimilar and generic medicines provide 1 option to combat the increasing costs of cancer drugs. However, any improvements in sustainability afforded by biosimilars rely entirely on their uptake,” the investigators said.
Over the 24-month study, 38 rituximab-containing protocols were used 1540 times to treat patients with non-Hodgkin lymphoma (NHL) and chronic lymphocytic leukemia (CLL). This indicated a “high acceptance of biosimilars, even in extrapolated indications.”
Biosimilars were used in more than 50% of patients both in first-line and second-line or later treatment. The use of biosimilar rituximab grew 7-fold, driven mostly by an increase in Sandoz biosimilar rituximab prescriptions. Investigators were at a loss to explain why Sandoz became the preferred treatment versus the Celltrion biosimilar.
“From our data, it is not possible to explain this phenomenon; certainly, it was not driven by the list price, and there are few, if any, other differentiating factors between the 2 medicines,” the investigators wrote.
They speculated that the high cost of rituximab in general may have been the reason for the use of biosimilars. The Sandoz product was available for a discount of 11% to the reference product. They did not provide comparative price information for the Celltrion biosimilar.
Over the study period, the proportion of rituximab biosimilar prescriptions in the total patient population increased from 12% to 83%.
“Only a small number of switches were recorded in our study, suggesting that physicians generally maintain their original treatment choice. The switches that did occur included the entire gamut of possible changes, including reference medicine to biosimilar, between different biosimilar medicines, and from biosimilar to reference medicine,” the investigators said.
The authors concluded that more real-world study is needed “to evaluate the long-term effect of biosimilar rituximab on health economics, patient access, and the overall sustainability of cancer care.”
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