Polaryx Therapeutics is preparing to start its Phase 2 SOTERIA trial of PLX-200 in children with four rare lysosomal storage disorders after securing FDA authorisation and Fast Track Designation.

Polaryx prepares SOTERIA trial

The company said clinical trial start-up activities are progressing with its contract research organisation (CRO), with the study expected to begin in the fourth quarter of 2026.

The SOTERIA trial will evaluate PLX-200 in paediatric patients with CLN2 disease, CLN3 disease, Krabbe disease and Sandhoff disease. The open-label, multicentre Phase 2 basket trial is designed to assess the safety, tolerability, pharmacokinetics and clinical activity of the oral drug candidate.

Polaryx has received FDA authorisation to proceed with the study and secured Fast Track Designation for PLX-200 across all four planned indications. The trial has also been registered on ClinicalTrials.gov under NCT07740512, with participating sites expected to be added as they are activated.

Polaryx said it has also completed a $10 million financing intended to support the SOTERIA trial and planned clinical development milestones.

Alex Yang, chair and chief executive officer of Polaryx Therapeutics, said: “With the key regulatory, clinical and financial elements supporting SOTERIA in place, our focus is increasingly on clinical execution.”

Four lysosomal storage disorders

SOTERIA is designed to enrol children aged between two and 15 across the four disease cohorts.

The trial will initially include a sentinel group to provide an early assessment of safety and tolerability before wider enrolment. Participants will undergo screening and dose titration before entering a planned 96-week maintenance period.

Polaryx plans an interim analysis using 52-week maintenance data, alongside regular assessments of clinical endpoints and biomarkers throughout the study.

For the CLN2 and CLN3 cohorts, the company will also assess clinical activity against established natural history data. This is intended to provide a comparison with the expected progression of the diseases and help inform future clinical and regulatory development of PLX-200.

The four conditions are rare, progressive lysosomal storage disorders that can cause significant neurological impairment during childhood.

PLX-200 development strategy

Polaryx said the basket trial design is intended to allow the company to evaluate PLX-200 across multiple indications within a single clinical programme.

Yang said: “Our objective is to efficiently identify the indications in which PLX-200 may demonstrate the greatest potential and use those findings to inform the most appropriate development path for the program.”

The company said Fast Track Designation across all four indications will allow it to maintain discussions with the FDA as clinical data become available.

The SOTERIA trial is expected to begin in the fourth quarter of 2026, with the planned 52-week interim analysis providing an early assessment of clinical data before completion of the full maintenance period.