Abstract
Abstract Background and Aims Focal segmental glomerulosclerosis (FSGS) is a disease of podocytes. Complications include nephrotic syndrome and progressive kidney failure. FSGS is a condition with high unmet need and there is no approved treatment. The angiotensin II receptor type 1 (AT1R) and chemokine receptor 2 (CCR2) are G protein coupled receptors that form functional heteromers. Simultaneous antagonism of these receptors suggested synergistic renoprotective effects in preclinical and early phase clinical studies of proteinuric kidney disease. DMX-200 (repagermanium) is a C-C chemokine receptor type 2 (CCR2) inhibitor that, when administered concurrently with an angiotensin II receptor blocker (ARB), is designed to inhibit recruitment of monocytes implicated in the inflammatory chemokine environment of chronic disease. In a Phase 2a open-label study of 27 patients with proteinuric chronic kidney disease, 25% of patients achieved > 50% reduction in uPCR with combined use of DMX-200 and irbesartan. A Phase 2a placebo-controlled cross-over study in 8 patients with primary FSGS receiving stable dose of irbesartan demonstrated evidence of promising efficacy with clinically relevant reduction in uPCR of 17% with DMX-200 compared with placebo. These encouraging data suggest that treatment with DMX-200 may result in clinically meaningful reduction in proteinuria when added to ARB in patients with glomerular diseases such as FSGS. Proteinuria reduction is a positive prognostic sign for preserving kidney function. The observations from earlier trials have led to the initiation of an international randomised double-blind, placebo-controlled Phase 3 clinical trial (ACTION3) to further evaluate the efficacy of DMX-200 in patients with FSGS receiving an ARB. Method Eligible patients are adults (18-80 years) with biopsy-proven primary FSGS, genetic FSGS or FSGS of undetermined cause (FSGS-UC), and uPCR of >1.5g/g based on 24hr urine collection and eGFR of ≥25 ml/min/1.73 m2. Blood pressure ≤160/100 mmHg and BMI ≤40kg/m2. Patients with secondary FSGS or those treated with strong immunomodulatory agents (other than corticosteroids) are excluded. All patients are required to receive concomitant ARB treatment at a dose of at least 50% of the maximum approved dose according to the relevant product label. Patients receiving ACE-inhibitors are required to switch to an ARB. Other background therapies such as SGLT-2 inhibitors and mineralocorticoid receptor antagonists are permitted if receiving a stable dose in the 3 months prior to screening. Patients are randomized in a 1:1 ratio to DMX-200 (120 mg twice daily) or placebo. The primary objective is to evaluate the efficacy of DMX-200 on reduction in PCR after 35 weeks of treatment and eGFR slope after 104 weeks of treatment. Secondary objectives are safety and tolerability of DMX-200 and to evaluate the effect of DMX-200 on response criteria and composite endpoint of worsening kidney function. Exploratory objectives include assessment of changes in inflammatory biomarkers such as MCP-1 and the pharmacokinetic profile of DMX-200. Two interim analyses (IA) are planned, first planned IA for futility will be performed by an Independent Data Monitoring Committee after the first 72 randomized patients (36 patients per group) complete 35 weeks of treatment. A second IA will be performed once approximately 144 enrolled patients complete 35 weeks of treatment. The final analysis will be performed once approximately 286 patients complete 104 weeks of treatment. The study is currently open in 11 countries at approximately 75 investigational sites and will be expanded to include more countries and sites subject to a successful first interim analysis. Results ACTION3 is a trial in progress and is expected to be completed in 2026. Conclusion ACTION3 is a Phase 3 randomized, placebo-controlled efficacy and safety trial which evaluates the novel approach of combining an investigational CCR2 inhibitor, DMX-200, with angiotensin receptor blockade in patients with FSGS.