Korea's Daewon Pharmaceutical said Monday it is moving forward with a phase 3 program for DW4421, a potassium-competitive acid blocker (P-CAB) aimed at treating gastroesophageal reflux disease (GERD), after posting positive results in a domestic phase 2 trial.

The company submitted clinical trial applications for two late-stage studies to the Ministry of Food and Drug Safety on April 30.

DW4421, also known as padoprazan, is being positioned as Korea’s fourth homegrown P-CAB after HK inno.N’s K-CAB (tegoprazan), Daewoong Pharmaceutical’s Fexuclue (fexuprazan), and Jeil Pharmaceutical’s Jaqbo (zastaprazan). The class has gained momentum as an alternative to traditional proton pump inhibitors, thanks to faster onset and food-independent dosing.

Daewon’s two-pronged phase 3 strategy will evaluate DW4421 in patients with both erosive reflux disease (ERD) and non-erosive reflux disease, the two primary subtypes of GERD. In the erosive group, a randomized, double-blind, active-controlled, multicenter trial will enroll 246 patients over roughly 36 months. The non-erosive trial will recruit 324 patients in a placebo-controlled design with a similar timeline.

In the completed phase 2 trial, Daewon said 147 ERD patients were randomized to receive high-dose or low-dose DW4421 or an active comparator over eight weeks. The primary endpoint -- complete mucosal healing -- favored both DW4421 arms, with additional improvements in symptom relief and a clean safety profile.

“In this phase 2 trial, both doses of DW4421 showed higher healing rates and strong safety and tolerability compared to the control,” Daewon said in Monday's release. “We plan to accelerate development and pursue approval for expanded indications as we move into phase 3.”

Originally discovered by Yunovia, the drug is now co-developed under a 2024 licensing agreement between Daewon and the Ildong Pharmaceutical Group’s new drug subsidiary. Daewon has since taken the clinical lead.