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| IP Newsletter | Spring 2016 | |
The Korean Supreme Court recently upheld the validity of a second medicinal use patent based on pregabalin for use as a pain reliever. Pregabaln is the main indication for Lyrica®, one of Pfizer's best selling drugs. (Supreme Court Decision Nos. 2013 Hu 2873 and 2880 (consolidated) rendered on January 14, 2016.) This is the first case in Korea where the validity of a second medicinal use invention patent was upheld by the Supreme Court. In doing so, the Supreme Court has provided new important principles for determining the inventiveness of an invention based on the descriptions in prior art references.
Issues Before the Supreme Court
The subject invention is directed to the new use of a known compound (pregabalin) for pain relief. Before the priority date, pregabalin was known for its anticonvulsant effect.
13 generic companies filed invalidation actions, making several different arguments why the subject invention could have been easily conceived from the prior art references. After losing in both the first and second instances, i.e., the Intellectual Property Trial and Appeal Board and the Patent Court, two generic companies (CJ and Samjin) pursued appeals before the Supreme Court.
In the Supreme Court case, the generic companies argued that the subject invention lacked inventiveness based on two grounds. First, Cited Reference 1 describes that pregabalin increases GABA levels in the brain. The generic companies argued that the increase of GABA levels was known to be related to pain relief. Thus, pregabalin's pain relief effect could have been easily derived from the prior art. Second, Cited Reference 2 describes that gabapentin binds to the α2δ subunit of calcium channels and pregabalin also binds to the subunit better than gabapentin. The generic companies argued that it was suggested that the α2δ subunit could be the very target for gabapentin to show its anticonvulsant effect. The generic companies then argued that it was also known that a calcium channel blocker can be effective for the treatment of pains. Thus, the generic companies concluded that pregabalin's pain relieving effects could have been easily derived from the prior art.
In reviewing the above arguments, the important issues were: (i) how a person skilled in the art would interpret the description in Cited Reference 1 that pregabalin racemate increases GABA levels in brain; and (ii) whether a person skilled in the art can conceive from the prior art that pregabalin is a calcium channel blocker. As such, the issues presented to the Supreme Court were how to interpret the descriptions from the prior art references in determining the inventiveness of an invention.
Supreme Court Holdings
The Supreme Court upheld the inventiveness of the subject invention and rejected the generics' arguments.
As to the first issue, the Supreme Court noted that Claim 15 of Cited Reference 1 teaches that GABA levels in the brain are increased by pregabalin. However, the Court found that a person skilled in the art would not accept these teachings in view of other portions of the same reference and additional prior art references.
As to the second issue, the Supreme Court noted that a person skilled in the art might recognize from Cited Reference 2 that gabapentin's anticonvulsant effect has a relationship with the α2δ subunit. However, the Court noted that when considering the overall descriptions or experimental results in Cited Reference 2 and other prior art references that are inconsistent with Cited Reference 2, it is uncertain whether gabapentin's anticonvulsant effect comes from binding to the α2δ subunit. Thus, the Court concluded that it is not easy for a person skilled in the art to conceive from the prior art references that pregabalin would have pain relieving effects.
Based on the above analysis, the Supreme Court issued the following new important principles.
"To determine whether the inventiveness of an invention is denied over a certain prior art reference, not only the specific portion of the prior art reference, which may be the basis for denying inventiveness, but also the matters that those skilled in the art could reasonably recognize from the entire prior art reference should be considered. Further, if there are other prior art references that contradict or question said specific portion of the prior art reference, then such references should also be considered in determining whether those skilled in the art could have easily conceived the invention at issue therefrom." (Supreme Court Decision Nos. 2013 Hu 2873 and 2880 (consolidated) rendered on January 14, 2016.)
Significance of the Case
This case is highly significant as it is the first case in Korea where the Supreme Court recognized the inventiveness of a second medicinal use invention.
Further, the Supreme Court has provided important new principles on how to interpret prior art references in determining the inventiveness of an invention. Under Korean patent law, the inventiveness of an invention has been easily denied based on certain descriptions in the prior art references even if the descriptions are not fully supported or verified. For example, Supreme Court Decision No. 95 Hu 1302 (October 29, 1996) held that even if a cited reference discloses an incomplete invention, it can still be used to deny the inventiveness of a claimed invention. Further, Supreme Court Decision No. 2004 Hu 2307 (March 24, 2006) held that a prior art reference can be compared with a claimed invention even if it has insufficient or defective descriptions as long as a person skilled in the art can easily understand its content.
In this case, the Supreme Court has provided new principles that are more suitable for determining the inventiveness of pharmaceutical or biotech inventions where predictability is low compared to other inventions such as mechanical inventions.
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Young KIM ykim@kimchang.com |
In Hwan KIM ihkim@kimchang.com |
Jung-Yeon KIM jykim@kimchang.com |