In recent years, Korean courts have increasingly recognized that inventions on drug dosage regimens should be patentable contrary to longstanding prior practice, but the Korean Intellectual Property Office (KIPO), including the Intellectual Property Trial and Appeal Board (IPTAB), have continued to be reluctant to grant dosage regimen patents to any significant degree, by and large finding them to lack inventiveness. A recent decision from the Korean Patent Court reversed a decision from the IPTAB that had affirmed a Final Rejection of a dosage regimen invention targeting a specific patient group, again indicating that dosage regimens should be patentable under current Korean law, and perhaps leading to greater openness toward such inventions from KIPO in the future.

Inventiveness standards for dosage regimen inventions in Korea

In an en banc decision in 2015, the Supreme Court indirectly supported the potential validity of dosage regimen patents, by holding that a dosage regimen can be considered as a constitutional element when evaluating the patentability of a medicinal use invention. The Patent Court subsequently ruled in another case in 2017 that a targeted patient group can also be a constitutional element in assessing the patentability of a medicinal use invention. The Supreme Court provided further guidance in 2017 that in order to be patentable, a dosage regimen should lead to a remarkable or qualitatively different effect that could not have been predicted by a person of ordinary skill in the art as of the filing date.  
 
In practice at KIPO, however, the inventiveness of dosage regimen inventions has been routinely denied even after the above court decision, generally on the basis that optimizing a drug dosage regimen to increase the desired efficacy while reducing adverse effects is a routine practice within the ordinary creativity of a skilled person in the art.

The new Patent Court decision and its expected impact 

In the case at issue, KIPO again issued a Final Rejection against a patent application claiming a dosage regimen invention. Specifically, the application claimed a pharmaceutical composition containing a bispecific antibody for use in a method to ameliorate or prevent adverse effects, mediated by administrating said bispecific antibody into a specific target patient group using a particular dosage regimen, when treating malignant CD19 positive lymphocytes (that is, a dosage regimen invention for a targeted patient group).

KIPO originally denied inventiveness on the basis that (i) the dosage regimen and the target patient group easily could have been conceived through simple modifications of the prior art, and (ii) the claimed composition did not show any unexpectedly remarkable effects over the prior art in specifying the dosage regimen and the target patient group. This Final Rejection was upheld by the IPTAB, and then appealed to the Patent Court. 

The Patent Court reversed the IPTAB and overturned the Final Rejection, finding that (i) identifying a specialized dosage regiment for a specific target high-risk patient group had a technical significance distinguishable from the prior art which would not have been obvious during a conventional dosage optimization process, and (ii) the dosage regimen invention did exhibit qualitatively different or unexpectedly remarkable effects due to specifying the patient group, which could not have been predicted from the prior art. In arriving at its conclusions, the Patent Court carefully reviewed the state of the art and determined that it was at a nascent stage as of the priority date (with very little prior research in the field), in contrast to the KIPO and the IPTAB who simply summarily dismissed the invention as routine optimization without considering the state of the art. 

The Patent Court's decision is significant because it emphasizes the importance of establishing the true state of the art at the priority date as important background for evaluating the technical significance and unexpected effect of a targeted dosage regimen invention, which may signal that more such inventions may be granted as patents in the future.