HLB Therapeutics said on Thursday that it initiated patient dosing in a U.S. phase 3 clinical trial for its neurotrophic keratitis (NK) drug candidate, RGN-259, through its U.S. subsidiary, ReGenTree.

Accordingly, the company said that it plans to conduct the second phase 3 clinical trial, SEER-2, and the third phase 3 clinical trial, SEER-3, simultaneously in the U.S. and Europe, starting with the U.S. site.

RGN-259, a thymosin beta 4 (Tβ4) inhibitor, shows great promise as a drug candidate for treating ophthalmic diseases such as dry eyes and neurotrophic keratitis (NK) by promoting cell migration, reducing inflammation, and aiding wound healing, HLB Therapeutics said.

The company previously demonstrated a clinically significant p-value in its first phase 3 trial (SEER-1) despite a small enrollment of 18 patients. 

Based on these results, the company is conducting two simultaneous clinical trials in the U.S. and Europe to supplement this data.

"Two results from phase 3 trials are typically required for FDA approval of a new drug," said a company official. "Accordingly, HLB Therapeutics plans to conduct two trials (SEER-2 and SEER-3) simultaneously to significantly shorten the development time."

The ongoing phase 3 trial in the U.S. involves 70 NK patients receiving RGN-259 for four weeks and the company plans to expand the trial to more than 30 sites to accelerate patient recruitment.

Although NK is a rare disease, it has a relatively large market with an estimated 20,000 patients per year in the United States alone. Currently, Oxervate (ingredient: cenegermin-bkbj) from Italian manufacturer, Dompé, is the only treatment prescribed in the U.S., but the price of the drug is over $50,000 per month, which poses a great financial burden for patients.

"The primary endpoint to prove efficiency for this drug is defined as complete healing,” said a company representative. "As we have already confirmed the efficacy of the drug in the first phase 3 clinical trial, we will concentrate our efforts so that the European clinical trial can start soon together with the steady progress of the U.S. clinical trial."

Meanwhile, HLB Therapeutics is also conducting clinical trials for RGN-259 to treat dry eyes in an eye drop formulation.