Final Zemiglo use patent invalidated in Korea

Supreme Court dismisses LG Chem appeal in use-patent invalidation case… generic companies secure final win

Use patent expiring in 2039 invalidated… generics can be launched after substance patent expires in 2030

Dispute over scope of rights also nearing conclusion following patent invalidation… Generic company’s patent risk resolved

The dispute surrounding the use patent for LG Chem’s diabetes treatment Zemiglo (gemigliptin) has ended with a final victory for generic companies. With this ruling, generic companies will be able to launch generic versions of Zemiglo after the substance patent expires in January 2030.

Supreme Court issues discontinuance of trial on LG Chem’s appeal… use patent finally invalidated

According to the industry sources on the 10th, the Supreme Court issued a discontinuance of trial in the final appeal of the Zemiglo use-patent invalidation case filed by LG Chem against Celltrion Pharm, Dongkoo Bio & Pharma, Daehwa Pharmaceuticals, Jeil Pharmaceutical, and Boryung.

A discontinuance of trial means that the Supreme Court affirms a lower court’s ruling without reviewing the merits of the case, having determined that the grounds for the appeal do not meet legal requirements. Consequently, the second-instance ruling, in which LG Chem lost, has been finalized. The use patent for Zemiglo has therefore been invalidated.

LG Chem and generic drug companies had been in dispute over the use patent, which expires in October 2039. This patent covers the combined administration of gemigliptin and insulin. Celltrion Pharm and others filed a petition for invalidation in 2023, arguing that the patent lacked inventive step.

The Intellectual Property Trial and Appeal Board (first instance) and the Intellectual Property Court (second instance) both ruled in favor of the generic companies. The Supreme Court then reached the same conclusion, putting an end to a legal battle that had lasted nearly 3 years.

Impact of the final invalidation ruling… scope-confirmation litigation previously won by LG Chem also heading toward closure

This ruling is expected to influence a separate litigation regarding the scope of rights currently underway concerning the same use patent.

Until now, disputes over Zemiglo’s use patent had proceeded along two separate tracks - the ‘invalidity lawsuit’ and the ‘scope of rights confirmation lawsuit.’ While the generic company won both disputes in the first instance, the rulings diverged in the second instance. While the generic drug companies prevailed in the invalidity suit regarding the use patent, the original manufacturer, LG Chem, won the dispute over the scope of rights.

Because of those conflicting second-instance rulings, uncertainty grew over the timing of the early generic launch. At the time, there were concerns that if LG Chem ultimately succeeded in defending the patent, a generic launch could be delayed until after 2039.

However, the situation has now reversed with the Supreme Court ruling. Legally, once a patent is definitively invalidated, the rights associated with it are deemed to have never existed from the outset. That means the favorable ruling LG Chem obtained in the scope-confirmation litigation loses legal effect, because the patent in question, which served as the basis for comparison, is now interpreted as “non-existent.”

From the perspective of generic drug companies, this ruling effectively allows them to bring forward the launch of Zemiglo generics by 9 years, to a date after January 2030, when the substance patent expires. Although Zemiglo has a salt and hydrate patent set to expire in October 2031, generic drug companies have already successfully circumvented it.

Zemiglo is LG Chem’s flagship drug. According to market research firm UBIST, the combined prescription sales of the ‘Zemiglo family’, which includes Zemiglo, Zemimet, Zemidapa, and Zemiro, totaled KRW 159.1 billion last year, a 4% increase from the previous year. Among these, Zemiglo alone recorded KRW 41.4 billion in prescription sales, accounting for 26% of the total family product prescriptions.