[K Bio Global Phase 3 | [Plan 5] Mezzion takes on the first Fontan treatment... Turn clinical experience into commercialization competitiveness

Udenafil confirmed phase 3 expansion in Europe… The goal is to announce results and apply for FDA approval in the second half of 2027.

The company estimates its highest annual sales in the U.S. to be $3 billion... Production and insurance application preparation in parallel

Mezzion (140410) is attempting to develop the first U.S. Food and Drug Administration (FDA) approved treatment for Fontan surgery patients. We are expanding the patient recruitment base by expanding the phase 3 FUEL-2 confirmatory clinical trial of the oral candidate ‘udenafil’ to Europe, while also preparing for production and insurance coverage required for sales after approval. The plan is to directly pursue approval and commercialization based on the data and experience accumulated from global clinical trials, and utilize the capabilities for follow-up new drug development.

Mezzion began phase 1 and 2 clinical trials targeting Fontan patients in the United States in 2014, and has continued its development through global phase 3, preparation for approval, and additional clinical trials. The company's total research and development scale on a consolidated basis between 2023 and 2025 is approximately 50 billion won, and significant funds have been invested to continue long-term development.

There is a gap in treatment that remains even after surgery… Aimed at improving athletic ability

Fontan surgery is a surgery to change the blood circulation path in patients with congenital heart disease in which one ventricle primarily functions. After surgery, blood must pass through the lungs without the pumping action of the ventricle, which pushes blood to the lungs, so pulmonary vascular resistance has a significant impact on circulation. In this circulatory system, exercise ability may decline as the child grows, so treatment methods are needed to manage functional decline even after surgery.

Udenafil is a PDE5 inhibitor that relaxes pulmonary blood vessels. Its goal is to lower pulmonary vascular resistance, help blood flow smoothly and improve exercise ability. Mezzion estimates that there are about 35,000 Fontan patients in the U.S., and in a situation where there is no FDA-approved treatment for Fontan patients, udenafil could become a new treatment option if approved.

Supplementing the design with the first clinical experience... Target for permit application in the second half of 2027

FUEL-2 reflected the achievements and limitations confirmed in previous clinical trials. FUEL, the first phase 3, did not meet statistical significance in the primary indicator that evaluated oxygen intake during maximum exercise in the entire patient group, but showed improvement in some secondary indicators that evaluated the exercise section before reaching maximum intensity. Afterwards, the researchers analyzed the possibility that the drug response would vary depending on the patient's existing exercise ability, and based on this, specified the criteria for selecting patients for follow-up clinical trials.

Post hoc analysis results supporting this approach were also revealed. In a paper published in the Journal of the American Heart Association in 2025, a significant improvement effect of udenafil compared to placebo was shown in the patient group whose maximum oxygen intake was less than 80% of the normal predicted value. FUEL-2 is designed to recruit patients whose exercise capacity is between 45% and 80% of the predicted value, and to verify its effectiveness in patient groups in need of improvement, excluding patients whose exercise ability is already close to normal. The clinical subjects are approximately 436 patients aged 12 to 18 who underwent Fontan surgery. After administering udenafil or placebo for 26 weeks, changes in maximum oxygen intake are compared through cardiopulmonary exercise stress testing.

We are also expanding our clinical network to support patient recruitment. Mezzion began recruiting FUEL-2 patients at Great Ormond Street Children's Hospital in London, England, on October 1, and plans to expand its recruitment base to 14 hospitals in 6 European countries, including the UK, France, Italy, Germany, the Netherlands, and Slovakia. The company plans to utilize cooperation with these specialized medical institutions that intensively manage Fontan patients for future European approval and market entry.

Mezzion announced in June that an independent blinded statistical review concluded that there was no need to increase the target number of patients. The company aims to complete patient recruitment within 2026 while maintaining the planned recruitment scale, announce major results in the second half of 2027, and pursue application for new drug approval with the FDA. After the end of recruitment, the final results will be derived after 26 weeks of medication for the last patient and data verification and analysis.

Preparation for production and insurance application in parallel… Maximum annual sales in the U.S. estimated at $3 billion

In line with this approval application schedule, Mezzion is simultaneously securing clinical data and preparing for manufacturing and quality control (CMC). The company announced in a notice on July 10 that it had completed the production order for 2 batches of raw drug products. They explained that they plan to pursue discussions with the FDA on manufacturing and quality based on data to be obtained through new batch production, and are also preparing mock inspections in preparation for factory inspections before approval. The production partners listed in the business report are Poland's Polpharma, which is responsible for raw medicines, and Canada's Halopharma, which is responsible for finished medicines. The company has a structure that establishes the necessary foundation for approval screening and commercial supply by cooperating with external production facilities.

Along with production preparations, we are also concretizing drug prices and sales strategies in the U.S. market. In its business report, Mezzion presented the expected annual drug price of udenafil at approximately $180,000 based on a survey of U.S. benefit management companies (PBMs) and prices of similar drugs. Based on various assumptions such as drug price projections and number of patients, the maximum annual sales in the U.S. market estimated by the company is approximately $3 billion. This figure is contained in a written response from the company's IR manager released by Small Insight Research in January 2026, and is based on the year when prescriptions expand after approval and sales peak. The expected drug price is not yet a confirmed launch price, and the actual sales volume may vary depending on the scope of approval, negotiations with insurance companies, and the number of patients prescribed.

The company is preparing insurance coverage and measures to reduce patients' out-of-pocket costs to support expansion of prescriptions. The plan is to increase accessibility so that patients do not give up treatment due to cost burden, while continuing the cooperative relationship with professional medical institutions established during the clinical process as a sales basis. In particular, the plan is to take advantage of the market characteristic of Fontan patients gathering at specific treatment centers to deliver product information centered on professional medical staff and increase the efficiency of sales and marketing in the early stages of launch.

We are also considering commercialization through partnerships outside the United States. The company announced at BIO USA in June that it discussed prescription accessibility, launch preparations, and regional commercialization strategies with global pharmaceutical companies. The goal is to expand the scope of the business by leading clinical trials and approval preparations and establishing sales and cooperation methods appropriate for each market.

Accumulated development capabilities… Expansion into follow-up kidney disease treatments

The data and experience accumulated in the development of Fontan treatments are leading to the development of follow-up indications. The field in which Mezzion is expanding its scope of development is autosomal dominant polycystic kidney disease (ADPKD). It is a hereditary disease in which kidney function declines as cysts form and grow. The company announced in May that it had received written opinions from preliminary consultations with the FDA that existing non-clinical data and clinical and safety experience with udenafil could serve as a reasonable basis to support ADPKD clinical development.

Mezzion announced its goal of starting a phase 2 clinical trial for ADPKD within the year, and announced in September that it had completed the establishment of a U.S. subsidiary dedicated to the global development and commercialization of the treatment. The plan is to have a local corporation take charge of global clinical operations and FDA consultations, add a domestic development system to existing drug data, and prepare for clinical entry for follow-up indications.

Mezzion's challenge continues with the first commercialization of Fontan's treatment and the development of follow-up indications. If efficacy is proven in FUEL-2 and sales begin after FDA approval, long-term research and development investment can be translated into sales, and ADPKD can expand its business area by utilizing existing drug data and the development system in the United States. Laying the foundation for follow-up development while advancing clinical trials, production, and sales preparations is a key task for future growth.