Low Dose Entecavir Formulation in Korean Patent held as being Obvious by the IPT of KIPO

Entecavir is the active ingredient in Baraclude tablets of BMS. The drug has been sold for the treatment of chronic hepatitis B virus infection in Korea. When Korean generic companies noticed that a US district court found that entecavir would have been obvious in light of the prior art, they filed an invalidity trial to challenge the validity of the corresponding Korean compound patent, too. The invalidity case is pending in the IPT of KIPO.

On the other hand, Baraclude is covered by another patent for low dose formulation of entecavir. Several companies including those want to launch generic versions of Baraclude after expiry of extecavir compound patent, filed separate proceedings to challenge non-obviousness of law dose formulation over the prior art. The subject Korean patent is No. 757,155 that claims low dose entecavir formulations of 0.5mg or 1.0 mg for the treatment of chronic hepatitis B virus infection. The prior art discloses enetcavir compound, its use, a range of doses and animal test data, but did not disclose claimed doses.

On April 30, 2013, the IPT held that low dose entecavir formulations of 0.5mg or 1.0 mg should be regarded being obvious over the prior art. To the IPT decision, the patentee BMS appealed to the Patent Court and argued that a person of ordinary skill could have neither anticipated nor determined the claimed low dose formulations of 0.5mg or 1.0 mg entecavir from the prior art. Oral hearings were held two days for expert witness examination and BMS’s expert argued at the Patent Court that determining specific doses for human required numerous trials. The panel of 3 judges in the Patent Court will decide the case on March 14, 2014.