Baraclude tablets are a blockbuster drug of BMS that has
been sold for the treatment of chronic hepatitis B virus infection in Korea.
BMS listed 2 patents in Green List of KFDA that is a local version of the
Orange Book of US FDA. Entecavir compound is the active ingredient of
Baraclude.
Korean generic companies obtained MA for generic
versions to Baraclude and are ready to launch their generic products to the local
market. BMS filed patent infringement lawsuits against Korean pharmaceutical
companies recently.
Before BMS patent infringement lawsuits,
local companies filed invalidity trials to challenge the validity of the
corresponding Korean entecavir compound patent. Also, they filed trials to
confirm the scope of patent right about the corresponding Korean low dose
formulation patent. The invalidity case of the compound patent is pending in
the IPT of KIPO. But the IPT decided that generic products do not infringe the
scope of the low dose formulation patent. In appeal, the Patent Court upheld the
IPT decision that low dose entecavir formulations of 0.5mg or 1.0 mg should be
regarded being obvious over the prior art and that generic drug do not infringe
the subject patent.
Korea has the bifurcated system that allocates
decision power to separate authorities. Patent infringement issue and patent invalidity
issue must be decided by two separate and independent courts. Patent infringement
and invalidity challenge may occur simultaneously but two proceedings are
correlated.
In the patent infringement lawsuits,
defendants Korean companies will raise an affirmative defense about invalidity of
entecavir compound patent. Such invalidity defense is allowed and the court may
stay the infringement lawsuit proceeding on its discretion until the IPT of
KIPO decides validity issue.
On the other hand, defendants are quite
safe from patent infringement liability of low dose formulation patent because
they had prior decisions from the IPT and the Patent Court that their products
are out of the scope of the patent claims in issue.