The filing with the Ministry of Food and Drug Safety revealed Monday comes about two weeks after rival Samsung Bioepis submitted its own Keytruda biosimilar, SB27, for domestic approval on Aug. 10.
Keytruda, known by its generic name pembrolizumab and developed by U.S.-based Merck, also known as MDS, generated global sales of $31.7 billion last year, cementing its place as the world's top-selling drug.
The medicine binds to the PD-1 immune checkpoint, blocking cancer cells from evading the body's defenses.
Celltrion said CT-P51 is aimed at treating non-small cell lung cancer, melanoma, gastric cancer and head and neck cancer, and that a trial in 228 melanoma patients had confirmed it was pharmacokinetically equivalent to the reference drug, with comparable safety and immunogenicity.
"Building on the successful establishment of targeted therapies such as Herzuma, Truxima and Vegzelma, the addition of CT-P51 will give us a lineup spanning both targeted and immuno-oncology treatments," a Celltrion official said.
Celltrion plans to pursue approvals in the United States, Europe and Canada in turn, while industry watchers expect a domestic green light as early as next year, citing the regulator's move to shorten new-drug reviews to within 240 days.
AJP Takeaways
Celltrion applied to South Korea's Ministry of Food and Drug Safety on Aug. 24, 2026, for approval of CT-P51, its biosimilar version of MSD's Keytruda (pembrolizumab), the world's top-selling drug with global sales of $31.7 billion last year.
The filing lands about two weeks after rival Samsung Bioepis submitted its own Keytruda biosimilar, SB27, to the same regulator on Aug. 10, 2026, intensifying competition between the two dominant South Korean biosimilar developers.
Celltrion said a trial in 228 melanoma patients confirmed CT-P51 was pharmacokinetically equivalent to the reference drug, and it plans to seek approvals in the United States, Europe and Canada, with industry watchers expecting a domestic decision as early as 2027.
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