DMX-200 ACTION3 PHASE 3 TRIAL COMPLETES RECRUITMENT

• Recruitment successfully completed in Dimerix' ACTION3 Phase 3 clinical trial^[1], which has recruited and dosed its target 286^th adult patient
• The ACTION3 Phase 3 trial explores the efficacy and safety of DMX-200 in FSGS patients when dosed in combination with standard-of-care blood pressure medication over 2 years
• Of the 286 adult patients dosed in the trial, 69 have already completed the full 2-year treatment period and of those, 65 entered voluntarily into the Open Label Extension (OLE) study, representing 94% OLE uptake
• The study has now successfully passed seven scheduled Independent Data Monitoring Committee (IDMC) reviews with no changes to the protocol required or safety concerns identified^[2]
• Following the successful outcome of the PARASOL collaboration data analysis (PARASOL Findings), Dimerix and its U.S. partner, Amicus Therapeutics, intend to seek feedback from the FDA on the proposed clinical trial endpoints, prior to a blinded analysis of ACTION3 data^[3]
• Recruitment of pediatric patients remains ongoing as an independent cohort in the trial, and if successful, may allow Dimerix to expand its application for DMX-200 to adolescents in key territories
• Dimerix continues to maintain a strong cash position to fund its operations, including the ongoing ACTION3 Phase 3 clinical trial as well as assess new R&D opportunities

MELBOURNE, Australia, Dec. 15, 2025 /PRNewswire/ -- Dimerix Limited (ASX: DXB), a biopharmaceutical company with a Phase 3 clinical asset in kidney disease, today announces that the ACTION3 Phase 3 trial of DMX-200 in patients with focal segmental glomerulosclerosis (FSGS) has now successfully completed the planned recruitment and dosing of the 286^th adult patient^[1].

The ACTION3 Phase 3 study is a pivotal Phase 3, multi-centre, randomised, double-blind, placebo-controlled study of the efficacy and safety of DMX-200 in patients with FSGS who are receiving a stable dose of a blood pressure medication known as an angiotensin II receptor blocker (ARB). Once the ARB dose is stable, patients are then randomised to receive either DMX-200 (120 mg capsule, twice daily) or placebo for a 2-year treatment period. The single Phase 3 trial in FSGS patients is designed to capture evidence of proteinuria reduction and kidney function (eGFR slope) during the trial, aimed at generating sufficient evidence to support marketing approval.

In accordance with the trial protocol, patients were first recruited and then stabilised on background medications before undergoing a second screening. Only those who successfully passed this re-screening were randomised to receive either the DMX-200 or placebo. As per standard practice, patients currently recruited and in the stabilisation phase will be allowed to continue in the study (if still eligible) and, once dosed, will confirm the anticipated last patient and last dose date.

Notably, in March 2024, Dimerix announced that the ACTION3 Phase 3 trial of DMX-200 in patients with focal segmental glomerulosclerosis (FSGS) was successful in the pre-specified interim analysis of the proteinuria (efficacy) endpoint from the trial's first 72 randomised patients.^[4] The analysis indicated that, using a statistical measure, DMX-200 was performing better than placebo in reducing proteinuria (a surrogate marker of kidney disease progression^[5]) in patients with FSGS at that point in time.^[6]

"We are pleased to announce that the recruitment, randomisation and dosing of the 286^th 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. With patient data now being collected across a 2-year treatment period, we are progressing towards a number of key value-inflection points. With the successful achievement of the study's target recruitment, this positions Dimerix and our commercial partners to continue to advance toward regulatory submission and potential commercialisation. We are sincerely grateful to the patients and their families for their vital contribution to this important program."

Dr Nina Webster, CEO & Managing Director, Dimerix

The ACTION3 trial opened 219 sites for recruitment across 21 countries and regions, including US, Europe, UK, Japan, Mainland China, Hong Kong, Taiwan, Malaysia, Australia and New Zealand.

Next Steps in the U.S.

Dimerix and its U.S. partner, Amicus Therapeutics, intend to seek feedback from the FDA on the 104-week endpoints and potential submission for accelerated approval.

About ACTION3 FSGS Phase 3 Study

The Phase 3 study, which is titled "Angiotensin II Type 1 Receptor (AT1R) & Chemokine Receptor 2 (CCR2) Targets for Inflammatory Nephrosis", or ACTION3 for short, is a pivotal (Phase 3), multi-centre, randomised, double-blind, placebo-controlled study of the efficacy and safety of DMX-200 in patients with FSGS who are receiving a stable dose of an angiotensin II receptor blocker (ARB).

Further information about the study can be found on ClinicalTrials.gov (Study Identifier: NCT05183646) or Australian New Zealand Clinical Trials Registry (ANZCTR) (Study Identifier ACTRN12622000066785).

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