Celltrion (068270.KS) has begun the approval process for a biosimilar of Keytruda, the world's top-selling drug with annual sales of about 44 trillion won ($31 billion). Starting at home, the company plans to file for approval successively in the United States, Europe and other major markets, aiming to gain an early foothold in the global immuno-oncology market.
Celltrion said on the 24th that it had applied to the Ministry of Food and Drug Safety for approval of CT-P51, a biosimilar of the global blockbuster immuno-oncology drug Keytruda (active ingredient pembrolizumab).
The application covers the main indications of the original drug, including non-small cell lung cancer, melanoma, gastric cancer and head and neck cancer. Celltrion submitted results from a clinical trial involving 228 patients with completely resected melanoma.
The clinical data showed that CT-P51 met pharmacokinetic (PK) equivalence criteria with Keytruda and produced similar results in safety and immunogenicity.
Keytruda, an immuno-oncology drug used across a range of cancers including non-small cell lung cancer and melanoma, recorded global sales of about $31.7 billion (roughly 44 trillion won) in 2025, making it the world's best-selling drug. Given the size of the market, CT-P51 is seen as a key product to drive Celltrion's future revenue growth and profitability.
Celltrion plans to file for CT-P51 approval successively in major markets including South Korea, the United States, Europe and Canada. The strategy is to enter the global first group and secure market share early.
The addition of CT-P51 will further expand Celltrion's cancer treatment portfolio. The company has launched targeted-therapy biosimilars in global markets, including Herzuma (trastuzumab) for breast and gastric cancers, Truxima (rituximab) for blood cancers, and Vegzelma (bevacizumab) for metastatic colorectal cancer and non-small cell lung cancer. With the addition of the immuno-oncology drug CT-P51, the company will have a cancer treatment lineup spanning both targeted and immuno-oncology therapies.
In particular, because Keytruda and bevacizumab are used in combination for ovarian and cervical cancers, product synergy between CT-P51 and Vegzelma is also expected going forward. Celltrion plans to raise market share and profitability by drawing on its large in-house manufacturing facilities and global direct sales network.
CT-P51 may also be linked to next-generation cancer therapies now under development, such as antibody-drug conjugates (ADCs). Celltrion intends to build on its biosimilar cancer portfolio to expand synergy with new drugs in the future.
A Celltrion official said, "We will carry out the approval process for CT-P51 without disruption in order to target the roughly 44-trillion-won global Keytruda market," adding, "We will push to enter the first group in major global markets and, drawing on our own manufacturing capabilities and global direct sales network, maximize synergy with our existing products and next-generation pipeline."
