[Edaily Reporter NA EUN-KYUNG ] Samsung Bioepis has filed for U.S. marketing approval for a biosimilar (generic version of a biopharmaceutical) of “Keytruda,” the world’s best-selling immuno-oncology drug. Following its application for approval with the Ministry of Food and Drug Safety last August—the first such application by a Korean company—the company has now begun the process for commercialization in the U.S., the world’s largest pharmaceutical market.

On the 30th, Samsung Bioepis announced that it had filed a marketing authorization application with the U.S. Food and Drug Administration (FDA) for “SB27” (active ingredient: pembrolizumab), its Keytruda biosimilar candidate. This is the first instance in which a Korean company has publicly disclosed that it has filed a U.S. marketing authorization application for a Keytruda biosimilar it developed.

Keytruda is an immunotherapy drug developed by Merck (MSD) in the U.S. It blocks the action of PD-1, an immune checkpoint protein involved in helping cancer cells evade attack by immune cells, thereby enabling immune cells to attack cancer cells. It is used to treat various types of cancer, including melanoma, non-small cell lung cancer, and head and neck cancer. This U.S. marketing authorization application for SB27 includes a total of 18 indications.

Keytruda was the best-selling drug worldwide last year. According to MSD’s earnings report, Keytruda’s global sales in 2025 totaled $31.681 billion (approximately 42 trillion won), including the subcutaneous injection formulation “Keytruda Qurex.” Sales in the first half of this year reached $16.4 billion (approximately 22 trillion won), an increase of about 8.2% compared to the same period last year. Of this amount, sales of the existing intravenous (IV) formulation totaled $15.81 billion (approximately 21 trillion won).

Since 2024, Samsung Bioepis has been conducting a Phase 1 clinical trial involving 163 patients across four countries and a Phase 3 clinical trial involving 555 patients across 14 countries. Through these trials, the company has confirmed equivalence with the originator drug, and both clinical trials are scheduled to be completed within this year.

Shin Dong-hoon, Executive Vice President and Head of Clinical Medicine at Samsung Bioepis, stated, “We will once again demonstrate our R&D capabilities during the U.S. marketing authorization review process for SB27, and we will strive to expand treatment options and improve access for patients through biosimilars in the field of immuno-oncology.”

In South Korea, Celltrion(068270)is competing with Samsung Bioepis to develop a Keytruda biosimilar. Following Samsung Bioepis’s submission of a marketing authorization application for SB27 to the Ministry of Food and Drug Safety on August 7, Celltrion also filed for domestic marketing authorization for “CT-P51” on the 21st of the same month. Samsung Bioepis was two weeks ahead in South Korea, and it was also the first to file for approval in the U.S. Celltrion plans to expand its approval applications to the U.S., Europe, and Canada in the future.

In the global market, there are companies that entered the U.S. approval process before Samsung Bioepis. “FYB206,” a Keytruda biosimilar jointly developed by Germany’s Formicon and India’s Zydus Life Sciences, received confirmation from the FDA on the 13th that its marketing authorization application had been accepted. The two companies explained that this marks the first publicly disclosed instance in which the U.S. FDA has accepted a Keytruda biosimilar marketing authorization application for review.

The Kytruda biosimilar market is expected to truly take off after 2028, when the key patents for the originator drug expire. In its annual report filed with the U.S. Securities and Exchange Commission (SEC), MSD stated that Keytruda’s key U.S. substance patent expires in December 2028 and predicted that biosimilar competition in 2028–2029 would have a significant impact on sales. However, since some related patents remain in effect until 2029, the actual launch date may vary depending on factors such as patent disputes.