South Korean biopharmaceutical firm Celltrion has received US Food and Drug Administration approval to kick off advanced clinical testing for CT-P51, a biosimilar of the breakthrough cancer drug Keytruda, the company announced Monday.

CT-P51 replicates the effects of pembrolizumab, marketed under the brand name Keytruda by Merck & Co., known as MSD outside North America. An immunotherapy agent enhancing the body's immune response against cancer cells, pembrolizumab has demonstrated efficacy in treating malignancies including non-small cell lung cancer, head and neck squamous cell carcinoma, and melanoma. It was the highest-grossing pharmaceutical product in the last fiscal year.

With the drug’s patents set to expire in 2029 in the US and 2031 in Europe, pharmaceutical companies worldwide have been racing to develop biosimilars. Celltrion is now gearing up for a phase three trial involving 606 non-small cell lung cancer patients, conducting a comparative study between CT-P51 and the reference product.

CT-P51 is the latest addition to Celltrion's growing portfolio of targeted therapy drugs, which zero in on specific cancer cell components like proteins or genes that fuel tumor growth. The company's biosimilar lineup already includes trastuzumab (product name Herzuma), bevacizumab (Vegzelma), and rituximab (Truxima).

"We are pushing ahead with CT-P51's development to tap into the global cancer therapy market, valued at approximately $24 billion," a Celltrion spokesperson said. "Our goal is to secure regulatory approval for 11 biosimilar products by 2025, diversifying our portfolio across various therapeutic areas."

Lately, Celltrion has been ramping up efforts to strengthen its foothold in key global markets by broadening its product range to cover treatments for autoimmune disorders, asthma, and macular degeneration. In May, the company's antibody biosimilar Omlyclo, indicated for asthma treatment, became the first biosimilar and first-to-market product to receive official approval in Europe.