Samsung Bioepis gains edge in Keytruda biosimilar race

SB27 meets primary endpoints in both global Phase I and Phase III trials…company aims to complete clinical development this year

Expected to stand out among competitors with robust clinical data amid streamlined FDA approval pathway

MSD's SC formulation change and patent expirations remain key commercialization variables

Samsung Bioepis’ headquarters

Samsung Bioepis has taken the lead in the race to develop a biosimilar to the blockbuster immuno-oncology drug Keytruda, becoming the first company to disclose Phase III clinical data.

With the patent expiration of Keytruda, which has exceeded $30 billion in global sales, approaching, it is assessed that Samsung Bioepis has established the foundation for a follow-up approval strategy targeting the large-scale immuno-oncology biosimilar market by leveraging its extensive clinical data.

Secures ‘Phase III data… differentiates regulatory positioning

Samsung Bioepis recently announced that SB27, its Keytruda biosimilar candidate, met the primary efficacy endpoints in both global Phase I and Phase III clinical studies, demonstrating equivalence to the original product.

The Phase I trial enrolled 163 participants across four countries, including South Korea. The company reported that pharmacokinetic analyses of the area under the plasma level-time curve (AUC) met the predefined equivalence criteria.

The Phase III trial enrolled 555 patients in 14 countries. In patients with non-small cell lung cancer (NSCLC), SB27 demonstrated efficacy equivalent to the reference product based on the objective response rate (ORR) at Week 24, the study's primary endpoint. Comparable safety and immunogenicity profiles were also observed.

The significance of these findings lies in Samsung Bioepis becoming the first developer to present topline results from a global Phase III study in the Keytruda biosimilar race, thereby securing clinical evidence that could strengthen its regulatory competitiveness. By completing both global Phase I and Phase III studies, the company has assembled a comprehensive clinical package expected to enhance its position during future regulatory review and commercialization.

According to the company, both clinical studies are scheduled to be fully completed within this year. However, completion of the trials does not necessarily mean regulatory submissions or product launch will occur within the same timeframe.

Even after clinical completion, biosimilar approval requires additional steps, including data collection and analysis, preparation of regulatory data, and development of country-specific submission strategies.

USD 31.7 billion market fuels intensifying competition

The fierce competition surrounding Keytruda biosimilars reflects the enormous size of the original’s market. According to MSD's 2025 financial results, combined annual sales of Keytruda and the subcutaneous formulation Keytruda Qlex reached USD 31.7 billion (approximately KRW 46 trillion), making it one of the world's highest-selling pharmaceutical products.

Keytruda is a PD-1 immuno-oncology drug indicated for a wide range of cancers, including non-small cell lung cancer, melanoma, and head and neck cancer, giving it a broad treatment base and substantial prescribing volume.

Given the product's commercial value, multiple developers are racing to develop biosimilars. The compound patent is scheduled to expire sequentially beginning in 2028 in Korea, 2029 in the United States, and 2031 in Europe, intensifying global competition to secure early market entry.

Celltrion is conducting a global Phase III trial of its Keytruda biosimilar CT-P51, while China's Bio-Thera Solutions has initiated an integrated Phase I/III study of BAT3306. Other global biosimilar developers, including Formycon and Sandoz, are also pursuing pembrolizumab biosimilars.

Samsung Bioepis' key advantage lies in having completed both global Phase I and Phase III studies, providing a robust clinical evidence package that goes beyond the minimum regulatory requirements and is expected to strengthen physician trust.

MSD’s Keytruda

This is particularly meaningful because large immuno-oncology biosimilars require complex trial designs and extensive patient recruitment. Demonstrating success in both Phase I and Phase III studies is expected to carry significance in future regulatory submissions and partnership discussions.

Another noteworthy development is the evolving regulatory strategy among competitors. As the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA) move toward streamlining biosimilar approval requirements, companies such as Sandoz and Formycon have discontinued Phase III trials and are instead pursuing regulatory approval based solely on Phase I data.

While Samsung Bioepis benefits from having completed conventional global Phase I and Phase III studies, some competitors may seek approval through these alternative regulatory pathways under the evolving framework.

Nevertheless, because Samsung Bioepis adopted an overlapping strategy by initiating Phase I and Phase III studies simultaneously, its extensive efficacy and safety data from a large-scale Phase III trial are expected to serve as a major competitive advantage in the prescription conservative oncology market, building physician trust and supporting future market penetration.

Another challenge will be overcoming MSD's evergreen strategy aimed at extending the commercial life of Keytruda. To defend against biosimilar competition, MSD is actively transitioning patients from the intravenous (IV) formulation to a more convenient subcutaneous (SC) formulation, pursuing regulatory approvals in major markets in an effort to contain as many patients as possible before biosimilars become available.

For Samsung Bioepis, successful commercialization will depend not only on regulatory approval timelines but also on product differentiation, manufacturing and supply capabilities, reimbursement and tender strategies in individual markets, and commercial partnership capabilities.

The company stated that it is still too early to disclose specific launch plans or commercialization strategies for SB27.

However, because patent expiry is expected earlier in Korea than in many other markets, industry observers believe the product could potentially be launched first in Korea in 2028. However, the actual launch timing will ultimately depend on regulatory review, patent litigation, and market conditions in each country.

Dong-hoon Shin, Executive Vice President of Clinical Science at Samsung Bioepis, said, "Demonstrating equivalence between SB27 and the reference product represents a meaningful achievement that showcases Samsung Bioepis' global biosimilar development capabilities. Building on our rigorous quality management system, we will continue to strive to improve patient access to immuno-oncology therapies through biosimilars."