SOUTH KOREA Trends and Developments Contributed by: Keum Nang Park, Eileen Jaiyoung Shin, Eunkyoung Lyu and Soo Yeon Park, Lee & Ko
Navigating the New Frontier of Pharmaceutical Patent Disputes in South Korea’s Biosimilar Era The onset of the “patent cliff” and a shifting market landscape The South Korean pharmaceutical market is currently standing at a significant crossroads. Between 2025 and 2026, the industry anticipates a so-called “pat- ent cliff”, as patents for numerous global blockbuster biological drugs are set to expire. This development is likely to trigger a surge in the entry of biosimilars into the domestic market. Historically, the Korean biosimilar landscape was dominated by a few specialised biopharmaceuti- cal giants that established robust product portfolios through aggressive development. However, we are now witnessing a strategic diversification. Traditional pharmaceutical companies, previously focused pri- marily on chemical generics, are increasingly stepping up their efforts to enter and expand their biosimilar businesses. This shift, aimed at securing new revenue streams and strengthening global market presence, aligns with the growing international biosimilar mar- ket. Consequently, pharmaceutical patent disputes in Korea are expected to become more frequent, tech- nically complex, and strategically multi-layered in the coming years. The critical role of medicinal use and dosage- regimen patents As the industry shifts from simple chemical structures to complex biologics, the focus of patent disputes is moving toward “medicinal use” and “dosage-reg- imen” patents. In Korea, the legal standing of these patents underwent a landmark change following a 2015 Supreme Court en banc decision, which rec- ognised that dosage and administration parameters are not merely clinical instructions but are essential technical elements of a patented invention. For international clients looking to do business in Korea, understanding the nuances of these patents is vital. Unlike a physical substance patent, a “use” patent is tied to how the drug is administered to treat a specific disease. This creates unique challenges in infringement litigation. For instance, a patent holder must prove that a competitor’s product is intended for the specific patented use. This often leads to “skinny
labelling” strategies, where biosimilar manufacturers intentionally omit certain patented indications or dos- age instructions from their labels to circumvent direct infringement. The challenge of proving infringement in use patents One of the most complex issues in the Korean mar- ket is determining the exact criteria for infringement regarding these dosage patents. Since the “use” itself does not have a physical form at the manufacturing stage, proving that a biosimilar is being produced spe- cifically for a patented use remains a sophisticated legal task. Currently, there is no definitive Supreme Court prec- edent that establishes a uniform standard for deter - mining infringement in such cases, especially when a biosimilar’s labelling differs from the originator’s. This legal ambiguity means that both originators and bio- similar entrants must rely on comprehensive, case- specific arguments. Parties must engage in rigorous legal analysis to determine whether the objective intent of use was established at the time of manufac- ture or export, based on the overall circumstances of the product’s development and its regulatory submis- sion process. Evolution of litigation tactics: beyond the traditional exclusivity In the traditional chemical drug market, the “Nega- tive Scope Confirmation Trial” before the Intellectual Property Trial and Appeal Board (IPTAB) was the pri- mary weapon for generic companies. By successfully challenging a patent, they could secure a nine-month period of market exclusivity under Korea’s drug-pat- ent linkage system. However, the biosimilar era is changing this tactical playbook. Biologics involve much longer and less predictable clinical and regulatory timelines. Conse- quently, the nine-month exclusivity gained through early litigation often holds less strategic value for biosimilar developers compared to chemical generic manufacturers. We are seeing a trend where parties are moving away from simple “exclusivity-seeking” lit- igation toward more comprehensive, long-term patent invalidation or non-infringement strategies that align
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