Dimerix Recruits First Paediatric Patient in Pivotal ACTION3 Kidney Trial

Dimerix Advances Paediatric Kidney Disease Trial

Dimerix Limited (ASX: DXB) has announced the recruitment of the first paediatric patient into its pivotal ACTION3 Phase 3 clinical trial, marking a significant step forward in developing DMX-200 as a treatment for Focal Segmental Glomerulosclerosis (FSGS) in children aged 12 to 17 years. This milestone, achieved at a specialist site in Manchester, UK, underscores the company’s commitment to addressing the unmet medical needs of paediatric kidney disease patients.

FSGS is a rare but serious kidney condition that causes scarring of the glomeruli, leading to irreversible kidney damage and eventual failure. It is a leading cause of nephrotic syndrome in children, accounting for approximately 20% of paediatric cases. Currently, there are no approved drugs specifically for FSGS, highlighting the potential impact of DMX-200 if successful.

Global Paediatric Recruitment Strategy

The ACTION3 trial is a multi-centre, randomised, double-blind, placebo-controlled study designed to evaluate the efficacy and safety of DMX-200 in patients with FSGS who are already receiving standard angiotensin II receptor blocker therapy. The paediatric cohort is being recruited across 19 specialist kidney centres in the UK, USA, Mexico, and Argentina, reflecting a broad international effort to gather robust data.

Importantly, the dosing regimen for paediatric patients aged 12-17 mirrors that of adults, 120 mg twice daily, based on interim safety and pharmacokinetic analyses from the adult cohort. The Independent Data Monitoring Committee (IDMC) has confirmed that the safety margin supports this dosing approach, enabling the trial to proceed confidently in this younger population.

Pathway to Regulatory Approval

Dimerix’s paediatric development plan aims to generate sufficient evidence to seek marketing approval for DMX-200 in children over one year old, aligning with FDA and EMA expectations. The strategy includes in silico modelling and extrapolation from the ACTION3 data to support a smaller open-label study in children aged 1 to 11 years.

With interim data collection anticipated in August 2025 and full recruitment expected by late Q3 2025, the trial is on track to provide critical insights into DMX-200’s potential to slow kidney function decline and reduce proteinuria in paediatric patients. Success in this cohort could pave the way for expanded indications and access to treatment in key markets including the US and Europe.

Broader Implications for FSGS Treatment

FSGS remains a challenging condition with limited treatment options and a poor prognosis, particularly in children. The average progression to kidney failure occurs within five years of diagnosis, and recurrence rates post-transplant are high. DMX-200’s orphan drug designation in both the US and Europe underscores its potential to fill a significant therapeutic gap.

Dimerix’s innovative approach, leveraging its proprietary Receptor-HIT technology to identify DMX-200 as a CCR2 antagonist adjunctive to standard ARB therapy, positions the company at the forefront of kidney disease drug development. The successful recruitment of paediatric patients signals confidence in the trial’s design and the drug’s safety profile, setting the stage for potentially transformative outcomes.