Key Highlights

  • The first patient has completed four continuous years in Dimerix’s DMX-200 clinical program.
  • The milestone combines two years in the blinded ACTION3 Phase 3 trial with two years in the open-label extension.
  • Of 96 patients completing ACTION3 to date, 89 entered the optional extension, representing a 93% continuation rate.
  • The adult ACTION3 cohort is fully recruited, while treatment and follow-up continue.

Dimerix Limited (ASX:DXB) has recorded a long-duration milestone in its DMX-200 program, with the first patient completing two years in the ACTION3 Phase 3 study followed by another two years in its open-label extension. The four-year participation period adds a new layer of long-term observation to a program focused on focal segmental glomerulosclerosis, or FSGS.

Four Years of Continuous Clinical Participation

The patient first completed the two-year randomised, blinded ACTION3 study and then elected to enter the optional two-year open-label extension. Every participant in the extension receives DMX-200, irrespective of whether they were assigned DMX-200 or placebo during the blinded portion. Dimerix designed the extension to collect additional long-term safety and efficacy information after completion of the pivotal trial.

A 93% Continuation Rate Adds More Long-Term Data

Participation in the extension has been high among eligible patients. Dimerix reported that 96 patients had completed ACTION3 at the time of the announcement and 89 had chosen to continue into the extension, equating to 93%. The company expects data from this phase to contribute to future regulatory and commercial work. Patients completing the extension are also intended to be offered continued DMX-200 access through a post-trial program once the necessary ethics approvals are secured in the relevant territories.

ACTION3 Moves Through Treatment and Follow-Up

The adult cohort of ACTION3 is fully recruited with 333 patients randomised and dosed across 219 sites in 21 countries. The final adult patient began treatment in March 2026, shifting the adult study from recruitment into treatment and follow-up. Dimerix expects the final adult patient to complete dosing in March 2028. A separate paediatric cohort for patients aged 12 to 17 remains part of the broader program.

The Clinical Question Is Still Ahead

DMX-200 is being studied as a CCR2 antagonist alongside an angiotensin II receptor blocker in FSGS. The open-label extension provides useful duration of exposure, but it does not replace the need for the pivotal trial to establish efficacy and safety. Dimerix is also progressing DMX-652 in acute kidney injury, giving the company a second renal program while ACTION3 continues toward its later-stage readout.

For Dimerix, the extension milestone adds duration to the clinical record while ACTION3 remains the decisive late-stage program. Continued patient follow-up, post-trial access approvals and eventual pivotal outcomes will determine how the long-term dataset fits into the regulatory case for DMX-200.