A major South Korean patent dispute concerning the gastroesophageal reflux disease treatment K-CAB tablets (tegoprazan) reached a resolution on November 20 2025. The Korean Supreme Court affirmed earlier rulings in favour of the patentee by dismissing the final three appeals lodged by generic companies without further substantive review.
The generics had argued that the scope of the substance patent during the patent term extension (PTE) should be limited to the drug’s initially approved indications, but this position was rejected at every judicial level. The Supreme Court’s dismissal effectively marks the end of the generic companies’ attempts to circumvent the extended patent, reinforcing the principle that minor adjustments to generic drug products – rather than through genuine, substantive contributions to drug development – will not withstand judicial scrutiny.
Background
K-CAB tablets received their initial marketing approval in 2018 for two indications:
(i) The treatment of erosive gastroesophageal reflux disease; and
(ii) The treatment of non-erosive gastroesophageal reflux disease.
The approvals were later updated for additional indications:
(iii) The treatment of gastric ulcers (2019);
(iv) Antibiotic combination therapy for the eradication of Helicobacter pylori in patients with a peptic ulcer and/or chronic atrophic gastritis (2020); and
(v) Maintenance therapy after the treatment of erosive gastroesophageal reflux disease (2022).
The PTE for the substance patent covering K-CAB tablets was obtained based on the initial approval, extending its expiry date to August 25 2031.
Beginning in 2023, approximately 70 generic companies filed scope confirmation trials before the Intellectual Property Trial and Appeal Board (IPTAB) as part of a strategy to accelerate the launch of generic versions of K-CAB. The companies argued that their generic tegoprazan products – limited to indications (iii), (iv), or (v) – did not fall within the scope of protection of the substance patent during the PTE period.
Their arguments relied on Article 95 of the Korean Patent Act, which limits the scope of protection during a PTE period to acts of practising the patented invention with respect to the product whose marketing approval served as the basis for the extension (and, where the approval was obtained for a specific use, for that specific use only).
The patentee prevails at all instances
The IPTAB rejected the arguments raised by the generic companies. Most of the companies that lost in the first instance appealed to the Intellectual Property High Court (the IP High Court), which likewise ruled in favour of the patentee. Of these, eight cases, involving 13 companies, were appealed to the Supreme Court. However, all the appeals were sequentially dismissed without substantive review. The key IP High Court rulings can be summarised as follows.
The IP High Court first addressed two cases in which the generic companies argued that the scope of the PTE should not cover tegoprazan generic products limited to indication (iv), as it was not among the initially approved indications that served as the basis for the PTE.
On this issue, the IP High Court determined that the term “use”, as stipulated in Article 95 of the Patent Act, should not be limited to the indications initially approved under the Pharmaceutical Affairs Act. Instead, use should be assessed by determining whether the therapeutic effect and medicinal use of the approved product serving as the basis for a PTE are substantially the same as those under the Patent Act, taking into account the specification.
From this perspective, the IP High Court ruled that the initially approved indications (i) and (ii) and the later approved indication (iv) substantially embodied the same unique technical concept disclosed in the patented invention: namely, the medical use of tegoprazan for “treating acid-related diseases by inhibiting gastric acid secretion through an acid-pump antagonism”.
Following the Supreme Court’s dismissals of the generics’ appeals, the IP High Court sequentially issued similar rulings in the remaining cases involving generic tegoprazan products limited to indications (iii), (iv), and (v). In short, the IP High Court reiterated that Article 95 provides no basis to limit the concept of use to the indications initially approved under the Pharmaceutical Affairs Act, and held that the initial indications and the additional indications implemented the same medical use of tegoprazan.
In these subsequent cases, some generic companies further argued that the additional indications had different therapeutic effects due to variations in dose and dosage regimen. However, the IP High Court rejected all such arguments, arguing that it is common knowledge that therapeutic responses may vary depending on drug dosage, and therefore a change in dosage range alone could not be considered to alter the therapeutic effects of the active ingredient. The generic companies appealed, but the Supreme Court again dismissed the cases without further review.
Implications of the Korean Supreme Court’s rulings
The Supreme Court’s recent decisions in the K-CAB patent dispute clarify that the scope of patent rights during an extended term need not be limited to the indications for which the product was initially approved under the Pharmaceutical Affairs Act. As a result, the strategy adopted by generic companies, seeking to avoid only the initially approved indications in an effort to sidestep PTE protection and accelerate market entry, has been rendered ineffective.
These precedents are significant as they strengthen the effectiveness and practical value of the Korean PTE system and reinforce the legal framework supporting continued investment in original drug development.
