Polaryx Therapeutics Advances SOTERIA Phase 2 Basket Trial Toward Q4 2026 Initiation

Polaryx Therapeutics, Inc. (Nasdaq: PLYX), a clinical-stage biotechnology company developing novel, disease-modifying therapies for rare pediatric lysosomal storage disorders (LSDs), is advancing operational readiness for SOTERIA, its Phase 2 basket trial evaluating lead candidate PLX-200 across four rare pediatric LSDs. The company remains on track to initiate the trial in the fourth quarter of 2026, following FDA authorization, engagement of a contract research organization (CRO), and Fast Track Designation across all four planned indications.

Polaryx has established several key elements supporting trial initiation, including receipt of authorization from the U.S. Food and Drug Administration (FDA) to proceed with SOTERIA, engagement of an experienced CRO to support trial execution, FDA Fast Track Designation for PLX-200 across all four indications planned for the study, and completion of a $10 million financing intended to support initiation of SOTERIA and key planned clinical milestones. SOTERIA has also been registered on ClinicalTrials.gov under study identifier NCT07740512, which provides information related to eligibility; participating site information will be made available and updated as sites are activated.

SOTERIA is a Phase 2, open-label, multicenter basket trial designed to evaluate the safety, tolerability, pharmacokinetics and clinical activity of PLX-200 in pediatric patients with CLN2 disease, CLN3 disease, Krabbe disease and Sandhoff disease. The study is designed to enroll participants between two and 15 years of age across the four disease cohorts. The trial incorporates a sentinel group designed to provide an early assessment of safety and tolerability before enrollment proceeds across the broader study population. Following screening and dose titration, participants are expected to enter a 96-week maintenance period. An interim analysis of 52-week maintenance data is also planned along with planned regular assessments of endpoints and biomarkers.

For the CLN2 and CLN3 cohorts, clinical activity will also be evaluated against established natural history data. This approach is intended to enable Polaryx to assess potential treatment effects in the context of the expected course of these progressive diseases and may help inform subsequent clinical and regulatory development strategies. Should the data demonstrate compelling clinical activity, Polaryx may seek conditional marketing authorization.

The FDA granted Fast Track Designation to PLX-200 for the treatment of Juvenile Neuronal Ceroid Lipofuscinosis (JNCL/CLN3 disease), Krabbe disease (globoid cell leukodystrophy), and Sandhoff disease (GM2 gangliosidosis Type II) in April 2026. Following the March 2026 grant of FTD to PLX-200 in treatment of Late-Infantile Neuronal Ceroid Lipofuscinosis (LINCL/CLN2 disease), PLX-200 now holds FTD for all four prospective indications to be studied in the SOTERIA Phase 2 basket trial. The Fast Track program is designed to facilitate and expedite the review of therapies intended to treat serious or life-threatening conditions with unmet medical need. Companies receiving Fast Track Designation may benefit from more frequent interactions with the FDA and the potential for rolling review of a future marketing application.

Polaryx selected a leading CRO for SOTERIA in February 2026. The CRO brings meaningful experience working with and managing LSD and rare pediatric trials, as well as deep-rooted relationships with the dedicated key opinion leaders and patient advocacy groups who work closely with patients and their families.

Polaryx received a safe to proceed letter from the FDA in October 2025 and plans to initiate SOTERIA in the fourth quarter of 2026 in trial sites in the United States as well as in Europe and Asia or other foreign jurisdictions. The trial is designed to be flexible, resource-efficient, and provide important data and information important to PLX-200's future clinical development, including the initiation of potentially pivotal trials.

PLX-200 is an orally available compound comprised of gemfibrozil. Gemfibrozil is an FDA-approved lipid regulating agent in the fibrate family which has only been approved in a capsule form for adult patients with very high elevations of serum triglyceride levels to decrease serum triglycerides and very low-density lipoprotein cholesterol and increase high density lipoprotein cholesterol. The ability of gemfibrozil to cross the blood-brain barrier (BBB) has been documented in third-party preclinical trials and safe use of gemfibrozil in adults has been well-established over several decades of clinical investigation and commercial use. Polaryx believes the unique ability of PLX-200 to cross the BBB, along with its widely applicable mechanism of action, positions PLX-200 to potentially address the immense unmet need in multiple rare, catastrophic LSD indications.

Polaryx Therapeutics, Inc. is a clinical-stage biotechnology company focused on developing patient-friendly small molecule and gene therapy treatments for rare orphan lysosomal storage disorders (LSDs). Founded in 2014, Polaryx seeks to deliver safe, effective, and patient-friendly treatments that address the underlying pathophysiology of these catastrophic diseases and their significant unmet need. The company's approach integrates small molecule therapies, including a combination therapy, and a gene therapy, positioning it to potentially address both the genetic and downstream pathological features of LSDs. Its most advanced product candidate, PLX-200, targets several LSDs.