Truxima, a biosimilar of Roche's blockbuster Rituxan, secured a 35.8 percent share of U.S. prescriptions by volume in February, according to data from market research firm IQVIA. The achievement comes about six years and three months after the drug's U.S. launch in November 2019, overtaking both the original medicine and rival products to become the most-prescribed rituximab treatment in the country.
The milestone lands in a favorable policy climate.
President Donald Trump signed an executive order in April 2025 calling on the FDA to recommend ways to accelerate approval of biosimilars, and his administration's Section 232 pharmaceutical tariffs announced on April 2 this year explicitly exempted biosimilar products and their ingredients, while imposing levies of up to 100 percent on patented drugs.
South Korea is among the countries whose patented drug exports face a reduced 15 percent tariff under existing trade deals, but the full exemption for biosimilars gives companies like Celltrion a distinct competitive edge.
The prescription gains have translated directly into revenue. Truxima generated more than 300 billion won ($198.8 million) in sales across North America last year, a year-on-year increase exceeding 40 percent. Celltrion's flagship autoimmune treatment Inflectra, the U.S. brand name for infliximab biosimilar Remsima, also held the highest biosimilar prescription share in its category at 30.5 percent, while prescriptions for subcutaneous formulation Zymfentra more than tripled in January from a year earlier.
Newer high-margin products are also gaining traction. Steqeyma, a biosimilar of Stelara launched in March last year, has already captured 10.2 percent of prescriptions after securing preferred formulary status with major pharmacy benefit managers. Avtozma (tocilizumab) and Stoboclo-Osenvelt (denosumab), both launched in the second half of last year, are steadily expanding their reimbursement coverage through PBM contracts.
"As both our legacy and newly launched products continue to deliver strong results across global markets, including the United States, we are confident of meeting our full-year earnings targets," said a Celltrion spokesperson.
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