HLB Therapeutics misses primary end point in phase 3 SEER-3 trial of RGN-259

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South Korean company HLB Therapeutics has announced that its US subsidiary, ReGenTree, failed to meet the primary end point in a European phase 3 trial (SEER-3) of RGN-259, a thymosin beta-4–based eye drop designed to rival Dompé’s Oxervate, the only FDA-approved prescription eye drop to treat people with neurotrophic keratitis.

Unlike Oxervate, which requires refrigeration, dosing every 2 hours, and an 8-week regimen, RGN-259 can be stored at room temperature and used 5 times a day for 4 weeks in single-use vials. RGN-259 had been positioned as a lower-cost, more convenient alternative to Oxervate, with a broader mechanism of action targeting epithelial migration, stem cell recruitment, and inflammation.

According to the company, the SEER-3 trial did not show a statistically significant difference in complete corneal healing at 4 weeks compared with placebo.

A stronger-than-expected placebo effect in the control arm “led to a puzzling outcome,” a company spokesperson told Korea Biomedical Review, noting that only topline data had been received so far.

Additionally, the company stated that although it did not achieve the expected results in the European trial, negotiations with global pharmaceutical companies would continue, as the phase 3 trial for RGN-259 is currently underway in the US.

Ahn Gi-hong, CEO of HLB Therapeutics, said, “We will precisely analyze the results of all evaluation variables to closely identify the causes and swiftly reorganize the overall clinical strategy. Based on this, the company will focus all its resources on the ongoing US phase 3 trial [SEER-2] to achieve successful results more quickly.”

HLB Therapeutics has also faced adversity in the US, as it received a complete response letter in March 2025 from the FDA for its rivoceranib combination therapy for liver cancer.

References

1. Heo JY. HLB Therapeutics reports no efficacy in European keratitis treatment trial. Chosun Biz. June 24, 2025. Accessed June 30, 2025. https://biz.chosun.com/en/en-science/2025/06/24/GWCSHCC43BCWXAIMCYVQRUE23Q/

2. SEER-3: a phase 3, multi-center, randomized, parallel, double masked, placebo-controlled clinical study to assess the safety and efficacy of 0.1% RGN-259 ophthalmic solution for the treatment of neurotrophic keratopathy. https://euclinicaltrials.eu/ctis-public/view/2022-502697-16-00

3. Kim JH. HLB’s eye drop rival to Dompé’s Oxervate misses mark in EU phase 3. Korea Biomedical Review. June 24, 2025. Accessed June 30, 2025. https://www.koreabiomed.com/news/articleView.html?idxno=27996