Celltrion Receives European Phase 3 Approval for Darzalex Biosimilar Targeting Annual 20 Trillion Won Market

Celltrion has received approval from the European Medicines Agency (EMA) for an amendment to the Phase 3 trial protocol for CT-P44, a biosimilar of Johnson & Johnson’s (J&J) multiple myeloma treatment Darzalex (ingredient: daratumumab). Darzalex was J&J’s top-selling drug in 2025, with global sales of approximately $14.351 billion (about 20 trillion won), and Celltrion has begun targeting this market.

Trial design targets annual 20 trillion won blockbuster market

Celltrion said in a filing with the Data Analysis, Retrieval and Transfer System (DART) on the 21st that the EMA had approved the amendment to CT-P44’s Phase 3 trial protocol. The application was submitted July 13, and approval was granted Sept. 18 (local time). Under revised European clinical trial regulations, the review is divided into Part 1, which evaluates the trial design and research methods, and Part 2, which evaluates trial sites and implementation. The trial cannot proceed in practice until Part 2 has also been approved.

CT-P44 is being evaluated in a global Phase 3 trial involving 394 patients with refractory or relapsed multiple myeloma. The study compares the efficacy and safety of subcutaneous CT-P44 with the originator drug Darzalex, in combination with lenalidomide and dexamethasone. It is designed as a double-blind, randomized, active-controlled, parallel-group study and will run for 2 years. The number of participants was adjusted from 486 to 394 to support more efficient and faster trial execution.

More than 90% of demand in the Darzalex market has shifted from the intravenous (IV) formulation, which requires a lengthy administration time, to the easier-to-administer subcutaneous (SC) formulation. Celltrion is also developing CT-P44 as an SC formulation in line with this global trend, making demonstration of equivalence with the originator’s SC formulation a key factor that will determine its future competitiveness.

Development accelerated through simultaneous engagement with global regulators

Just before the EMA’s approval in Europe, Celltrion received approval from South Korea’s Ministry of Food and Drug Safety on Sept. 7 for the amended Phase 3 plan for CT-P44. The company has secured the lead in clinical development by meeting the standards of domestic and global regulatory agencies simultaneously. In addition, CT-P51, Celltrion’s biosimilar of Keytruda, the world’s highest-selling immuno-oncology drug, has received successive Phase 3 approvals in the United States, Europe and South Korea, expanding the company’s pipeline beyond its previous focus on breast and gastric cancers to major blockbuster oncology drugs more broadly.

In a Sept. 12 analysis, global pharmaceutical and biotechnology publication EmergPharma said, “Celltrion is systematically preparing biosimilars of the world’s most valuable oncology brands,” adding that “the approaching patent cliffs for Darzalex and Keytruda represent an enormous opportunity to improve access to care in emerging markets such as the Middle East and North Africa, and Celltrion’s pipeline is a top-priority target for global partners that should begin licensing negotiations immediately.”

Celltrion, however, said the statistical probability that a clinical trial drug will ultimately receive marketing approval as a medicine is approximately 10%. The company added that clinical trial and marketing authorization results may fall short of expectations and that it could therefore change or abandon its commercialization plans.

Precision commercialization strategy aligned with patent expiry dates

Darzalex’s key substance patents are expected to expire in the United States in 2029 and in Europe around 2031. Given that the Phase 3 trial will take 2 years, Celltrion appears to be following an optimized timeline that would allow it to launch the product immediately in each region when the relevant patents expire.

A small number of global competitors, including Shanghai Henlius and Xbrane Biopharma, have also begun developing daratumumab biosimilars. Celltrion, however, is expected to rapidly capture share from the originator market soon after launch, leveraging its expertise in the technically challenging SC formulation and its established global direct-sales network. If CT-P44 is successfully commercialized, it would become a new flagship K-biotech product following Remsima and Truxima, and South Korea’s biotechnology industry could expect to generate substantial exports in the global multiple myeloma treatment market, valued at 20 trillion won annually.