Polaryx Built One Trial to Answer Four Questions About PLX-200

SOTERIA is set to open in the fourth quarter with FDA clearance, Fast Track designation across every indication and financing in place.

Polaryx Therapeutics (Nasdaq: PLYX) has one lead oral candidate and four rare pediatric diseases it believes that candidate could treat. It intends to test all four at once. SOTERIA, the Phase 2 basket trial Polaryx plans to initiate in the fourth quarter of 2026, will evaluate PLX-200 in children with CLN2 disease, CLN3 disease, Krabbe disease and Sandhoff disease. The company believes those four patient populations together represent approximately one quarter of the lysosomal storage disorder population.

The basket design reflects the breadth of the hypothesis behind PLX-200. Polaryx develops small molecule and gene therapy candidates for rare orphan LSDs, and says its small molecule candidates share similar modes of action, addressing lysosomal dysfunction, neuroinflammation and neuronal loss in validated animal models that closely mimic human clinical phenotypes. PLX-200 targets several LSDs. Rather than pick one and commit, the company built a study that tests the premise across four.

Chair and Chief Executive Officer Alex Yang has said the company wants to learn which of the four diseases responds best, then let that answer shape where the program goes next. In other words, the trial is not only meant to generate data. It is meant to make a decision.

The 96-Week Protocol

SOTERIA is open-label and multicenter, designed to evaluate the safety, tolerability, pharmacokinetics and clinical activity of PLX-200 in participants between two and 15 years of age across the four cohorts. A sentinel group goes first, giving an early assessment of safety and tolerability before enrollment proceeds across the broader study population.

After screening and dose titration, participants are expected to enter a 96-week maintenance period. Polaryx plans an interim analysis of 52-week maintenance data along with regular assessments of endpoints and biomarkers. That interim analysis should give Polaryx its first meaningful read on how the program is behaving across the four cohorts.

The CLN2 and CLN3 Comparison

Clinical activity in CLN2 and CLN3 will be evaluated against established natural history data, a preplanned observational study that tracks the course of the disease. Polaryx says the comparison is meant to place any treatment effect against how these conditions would otherwise be expected to progress, and could shape how it approaches later clinical and regulatory decisions. Should the data demonstrate compelling clinical activity, Polaryx has said it may pursue an expedited approval pathway.

The regulatory and financial groundwork is already set. Polaryx received a safe to proceed letter from the FDA in October 2025. PLX-200 holds Fast Track designation in all four indications planned for the trial, which Yang has said should keep the company in close contact with the agency as data come in. The company completed a $10 million financing it said is intended to support initiation of SOTERIA and key planned clinical milestones, engaged a contract research organization, and registered the study on ClinicalTrials.gov under identifier NCT07740512. Sites are planned in the United States as well as Europe and Asia or other foreign jurisdictions.

Yang said the company’s focus is now “increasingly on clinical execution,” with site activation the next step before enrollment can begin.