Dimerix Ltd (ASX:DXB, OTC:SBMJF) has completed dosing the last adult patient in its ACTION3 Phase 3 trial of DMX-200 for focal segmental glomerulosclerosis (FSGS), with final adult enrolment reaching 333 patients, above the original target of 286.
Adult recruitment is now closed, while paediatric recruitment continues as a separate cohort in the study under arrangements agreed with regulators. Target adult recruitment and dosing had been completed in December 2025, but patients already in screening at that point were allowed to continue through to randomisation and dosing if eligible, resulting in the over-recruitment.
With the last adult patient now dosed, Dimerix expects the full two-year treatment period for the study to conclude in March 2028.
Chief executive officer and managing director Dr Nina Webster said allowing screened patients to continue beyond the 286-patient mark had naturally lifted adult recruitment above target and would support the statistical powering of the study endpoints. She said the company was now looking ahead to further value-inflection points as it advances DMX-200 towards regulatory submission, potential approval and commercialisation.
“I am delighted with the achievement of such a significant milestone in the Company’s clinical development of DMX-200 in FSGS patients. By allowing patients who had been progressing through the screening process at the time 286 patients had been randomised and dosed, we have naturally recruited beyond the targeted 286 adult patients. This will ultimately support the statistical powering of the study endpoints. With this significant catalyst being achieved, we look forward to progressing towards a number of potential key value-inflection points. Dimerix and our current commercial partners are well positioned to continue to advance toward regulatory submission and potential approval and commercialisation of DMX-200. We are sincerely grateful to the patients and their families for their vital contribution to this important program,” Dr Webster said.
Study remains on track after safety reviews
ACTION3 is a pivotal, multi-centre, randomised, double-blind, placebo-controlled Phase 3 study evaluating the efficacy and safety of DMX-200 in FSGS patients receiving a stable dose of an angiotensin II receptor blocker, a standard blood pressure medicine. Patients are then randomised to receive either DMX-200 or placebo over two years. The trial is designed to generate evidence on proteinuria reduction and kidney function decline to support a potential marketing application.
The company said the study has passed 7 scheduled Independent Data Monitoring Committee reviews, with no protocol changes required and no safety concerns identified.
Dimerix also noted that the trial has opened 219 recruitment sites across 21 countries, including the US, Europe, UK, Japan, China, Hong Kong, Taiwan, Malaysia, Australia and New Zealand.
Interim efficacy signal and US next steps
The company pointed to its March 2024 update, in which ACTION3 met a pre-specified interim proteinuria analysis based on the first 72 randomised patients. Dimerix said the analysis showed DMX-200 was performing better than placebo on a statistical basis in reducing proteinuria, a surrogate marker of kidney disease progression, at that stage of the trial.
Following PARASOL collaboration data analysis on eGFR and proteinuria endpoints, Dimerix plans to conduct a blinded statistical powering analysis of the primary endpoint in ACTION3 in line with US Food and Drug Administration guidance.