Dimerix (ASX: DXB) Clears 100-Patient Phase 3 Treatment Mark

Dimerix has reported that the first 100 patients in its ACTION3 Phase 3 trial of kidney disease drug DMX-200 have completed the full two-year double-blind treatment period, reducing some of the operational risk attached to the long-running global study.

The milestone covers almost one-third of the trial’s fully recruited adult cohort of 333 patients. It does not provide an efficacy readout, but shows that a substantial group has remained in the study through the required treatment period.

For Dimerix, participant retention and treatment adherence are important execution risks because the trial spans two years and targets focal segmental glomerulosclerosis, or FSGS, a rare kidney disease. The ACTION3 trial remains in progress, with other patients continuing treatment and follow-up.

Of the first 100 patients to finish blinded treatment, 93 elected to enter the open-label extension study. This gives all continuing participants access to DMX-200, including those who received placebo during the double-blind phase.

The 93% continuation rate will also allow Dimerix to gather additional long-term safety and clinical outcome data that may support future regulatory activities. Because every participant receives DMX-200 in the extension, the continuation figure should not be interpreted as evidence of efficacy from the blinded trial.

Adult study moves deeper into follow-up

The ACTION3 adult cohort completed recruitment across 219 sites in 21 countries, including the United States, Europe, Japan, China, Australia and New Zealand. All 333 adult participants have been randomised and dosed.

The final adult patient started treatment in March 2026, shifting the study from recruitment into treatment and follow-up. Dimerix expects that participant to complete dosing in March 2028, leaving the company with a lengthy execution period before the entire adult cohort finishes treatment.

ACTION3 is a randomised, placebo-controlled study assessing DMX-200 in patients who are also receiving a stable dose of an angiotensin II receptor blocker. Participants receive either a 120-milligram DMX-200 capsule twice daily or placebo.

The trial is designed to assess proteinuria and the slope of estimated glomerular filtration rate, a measure of kidney function. Dimerix aims to use evidence from the single Phase 3 trial to support an application for marketing approval.

FSGS causes progressive scarring in the kidney’s filtering units, leading to protein loss and declining kidney function. Dimerix said more than 40,000 adults and children in the US are estimated to have the disease, for which there are no specifically approved therapies in that market.

DMX-200 is a CCR2 antagonist intended to be administered alongside existing angiotensin receptor blocker therapy. Separately, recruitment continues for an independent ACTION3 cohort of patients aged 12 to 17, which may support future expansion into adolescent indications in key markets.