Dimerix Completes Recruitment for Phase 3 Trial of DMX-200 in Rare Kidney Disease FSGS
Key Insights
Dimerix has successfully completed recruitment of 286 adult patients for its ACTION3 Phase 3 trial evaluating DMX-200 in focal segmental glomerulosclerosis (search) (FSGS (search)), a rare kidney disease (search).
The trial demonstrated positive interim results in March 2024, showing DMX-200 outperformed placebo in reducing proteinuria, a key marker of kidney disease (search) progression.
With 94% of completed patients entering the open-label extension study and seven successful safety reviews, the company is positioned to advance toward regulatory submission with partner Amicus Therapeutics.
Dimerix Limited (search) has achieved a significant milestone in its Phase 3 clinical program for DMX-200, successfully completing recruitment and dosing of the 286th adult patient in the ACTION3 trial for focal segmental glomerulosclerosis (search) (FSGS (search)). The biopharmaceutical company announced this achievement on December 15, 2025, marking a critical step toward potential regulatory approval for this rare kidney disease (search) treatment.
Trial Design and Patient Population
The ACTION3 Phase 3 study represents a pivotal, multi-centre, randomised, double-blind, placebo-controlled investigation of DMX-200's efficacy and safety in FSGS (search) patients. The trial enrolled patients already receiving stable doses of angiotensin II receptor blockers (ARBs (search)), a standard blood pressure medication. Once ARB dosing was stabilized, patients were randomized to receive either DMX-200 (120 mg capsule, twice daily) or placebo for a comprehensive 2-year treatment period.
The global trial opened 219 sites across 21 countries and regions, including the United States, Europe, United Kingdom, Japan, Mainland China, Hong Kong, Taiwan, Malaysia, Australia, and New Zealand. This extensive international footprint demonstrates the collaborative effort required to study treatments for rare diseases.
Promising Interim Results
The trial has already shown encouraging efficacy signals. In March 2024, Dimerix reported successful interim analysis results from the first 72 randomized patients, demonstrating that DMX-200 performed statistically better than placebo in reducing proteinuria—a surrogate marker of kidney disease (search) progression—in FSGS (search) patients.
Of the 286 adult patients dosed in the trial, 69 have completed the full 2-year treatment period, with 65 of these patients voluntarily entering the Open Label Extension (OLE) study. This represents a remarkable 94% OLE uptake rate, suggesting patients and physicians are observing meaningful benefits from the treatment.
Safety Profile and Regulatory Pathway
The study has successfully passed seven scheduled Independent Data Monitoring Committee (IDMC) reviews with no protocol changes required or safety concerns identified. This consistent safety profile supports the drug's potential for regulatory approval.
Dr. Nina Webster, CEO and Managing Director of Dimerix, emphasized the significance of this achievement: "We are pleased to announce that the recruitment, randomisation and dosing of the 286th patient in the ACTION3 Phase 3 trial has successfully completed, reflecting the commitment and operational excellence of the Dimerix team and our clinical partners. Achieving this milestone in a rare disease setting reflects our ability to execute efficiently in complex environments."
Next Steps and Commercial Partnership
Following successful completion of the PARASOL collaboration data analysis, Dimerix and its U.S. partner, Amicus Therapeutics, plan to seek FDA feedback on the proposed clinical trial endpoints before conducting a blinded analysis of ACTION3 data. The companies intend to pursue feedback on the 104-week endpoints and explore potential submission for accelerated approval.
The trial continues to recruit pediatric patients as an independent cohort, which could potentially expand DMX-200's application to adolescents in key territories if successful.
Mechanism of Action
The ACTION3 study's full title—"Angiotensin II Type 1 Receptor (search) (AT1R (search)) & Chemokine Receptor 2 (search) (CCR2 (search)) Targets for Inflammatory Nephrosis"—reflects DMX-200's dual-target approach to treating FSGS (search). This mechanism aims to address both the inflammatory and fibrotic components of the disease by targeting specific receptors involved in kidney damage progression.
The single Phase 3 trial design focuses on capturing evidence of proteinuria reduction and kidney function preservation (eGFR slope) during the treatment period, generating data intended to support marketing approval for this significant unmet medical need in rare kidney disease (search).