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South Korea: Patent term extension in Korea

Under the Korean Patent Act, if a pharmaceutical or agrochemical patent (claimed in the form of a compound, a composition/formulation, or a process for preparation thereof) cannot be practised after registration to acquire marketing approval, according to the relevant acts, the patent term can be extended for a time period of up to five years, the time taken to obtain marketing approval after patent registration. An application for patent term extension must be filed by the patentee within three months of the date of the marketing approval but no later than six months before the expiration date of the patent.

According to the revised Enforcement Decree of the Korean Patent Act, implemented on April 3 2013, patent term extension is possible only based on initial marketing approval for a new substance whose active moiety, showing a pharmacological effect, has a novel chemical structure. Under the current law, it is clear that a patent for a second medical use of a known drug is not eligible for patent term extension. However, no guidelines or explanation have been provided as to what constitutes a new substance.

The trustee of the bankrupt entrepreneur appointed a meeting of creditors on November 29 2017 where the controversial trade mark was going to be sold. The starting price was $50. As a result of the auction the mark was finally sold for $500 to Kantemirovskaya Ltd. An assignment for that mark was signed but as the situation stands on February 20 2018 the assignment is yet to be recorded. As a result, the trade mark is still formally in the name of the bankrupt owner. According to judicial practice (even though it is scant), the period of non-use is not interrupted because of change of ownership. Hence the option of non-use action is still open for Heineken. The new owner may invoke force majeure. Is it worth initiating a non-use case in such circumstances? The answer to this question remains unanswered as yet.

Tretinoin, also known as all-trans retinoic acid, had been marketed for the treatment of acne, fine wrinkles, or dark spots by topical application (e.g. in the form of a cream or ointment), and for the treatment of acute promyelocytic leukemia by oral administration (e.g. in the form of a capsule). In 2013, Alitretinoin, also known as 9-cis retinoic acid, was newly approved by the Ministry of Food and Drug Safety (MFDS) for treating chronic hand eczema, refractory to treatment with strong topical steroids for at least four weeks. Glaxo Group Limited filed applications for patent term extension with regard to patents directed to a medicament for the treatment of eczema comprising 9-cis retinoic acid, a process for the preparation of 9-cis retinoic acid and a new formulation comprising a retinoid such as 9-cis retinoic acid, based on the marketing approval for Alitretinoin.

The examiner rejected all of the applications for patent term extension on the grounds that Alitretinoin, a geometric isomer of Tretinoin previously approved by the MFDS, is not recognised as a new substance, and thus, the marketing approval cannot be used for patent term extension.

On appeal, the Trial Board upheld the final rejection by the examiner, indicating that since Alitretinoin and Tretinoin are geometric isomers converting into each other and have a common property of binding to retinoic acid receptors (RARs), Alitretinoin is not acknowledged as a new substance in which the active moiety exerting a pharmacological effect has a novel chemical structure, and thus the patents relating to Alitretinoin are not eligible for patent term extension.

Reversing the Trial Board decision, however, the Patent Court ruled that Alitretinoin is considered as a new substance on the grounds that:

Geometric isomers have different stereochemical structures and thus may show significant differences in physicochemical properties or biological activities.

  • Tretinoin binds and activates RARs, but not retinoid X receptors (RXRs), whereas Alitretinoin binds and activates RXRs in addition to RARs.
  • Alitretinoin has an additional medical use in the treatment of chronic hand eczema, which cannot be cured by Tretinoin.
  • In view of general properties of geometric isomers, and the action and effect of each active ingredient, Alitretinoin has a different medical use, and the chemical structure of its moiety exerting a therapeutic effect is novel in comparison with the previously approved Tretinoin.

This Patent Court decision suggests that it is possible to obtain patent term extension for patents relating to stereoisomers which have a different mechanism of action and a different therapeutic effect from other stereoisomers, owing to their unique chemical configuration. Therefore, development of new stereoisomers would be a promising approach to secure second generation patents with the possible benefit of patent term extension in Korea.

Meanwhile, the Korean Intellectual Property Office (KIPO) recently announced the following statistics on patent term extension.

As pharmaceuticals or agrochemicals are required to obtain regulatory approval to be marketed in Korea, the patent term extension system should be kept in mind to compensate for time spent in acquiring such approval after patent registration.

Tretinoin (all-trans retinoic acid)

Alitretinoin (9-cis retinoic acid)


Min Son

HANOL Intellectual Property & Law
6th Floor, Daemyung Tower, 135, Beobwon-ro, Songpa-gu
Seoul, 05836
Republic of Korea
Tel: +82 2 942 1100 
Fax: +82 2 942 2600



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