Inclusion Criteria:  Patients must be 18 to 80 years old A diagnosis of FSGS confirmed by kidney biopsy. Must be receiving a stable dose of an ARB (irbesartan, losartan, valsartan, candesartan, olmesartan medoxomil, or azilsartan medoxomil) at the maximal tolerated dose or willing to transition If taking corticosteroids, the dosage must be stable for ≥4 weeks prior to Screening If taking aldosterone inhibitors, mineralocorticoid receptor antagonists, direct renin inhibitors, or sodium-glucose co-transporter-2 (SGLT2) inhibitors, the dose and regimen must be stable for ≥26 weeks prior to Screening Urine PCR >1.5 g/g (>169.5 mg/mmol) or 24-hour total protein >1.5 g/day based on 24-hour urine collection during Screening. Estimated GFR ≥30 mL/min/1.73 m2 at Screening Seated blood pressure ≤160/100 mm Hg (mean of 3 values) at Screening Body mass index ≤40 kg/m2 at Screening.  A female patient is eligible to participate if she is not pregnant or planning to become pregnant during the study, not breastfeeding, and at least one of the following conditions applies:  Is not of childbearing potential If of childbearing potential and agrees to use a highly effective method of contraception consistently during the treatment period A male patient with a female partner of childbearing potential is eligible to participate if he agrees to use acceptable contraception  Exclusion Criteria:  Has FSGS secondary to another condition. History of type 1 diabetes mellitus, or uncontrolled type 2 diabetes mellitus (defined as glycated hemoglobin [HbA1c] >8%), or non-fasting blood glucose >10 mmol/L at Screening. History of lymphoma, leukemia, or any active malignancy within the past 2 years History of jaundice, active hepatitis, or known hepatobiliary disease (except asymptomatic cholelithiasis). Documented history of heart failure (New York Heart Association Class III/IV) or a major adverse cardiac event within 12 weeks prior to Screening. Has a physical, medical, or psychological condition, that in the opinion of the Investigator, may interfere with the evaluation the study. The patient has a history of alcohol or illicit drug use disorder within 1 year prior to Screening. Had a prior organ transplant or stem cell transplant, with the exception of corneal transplant. Positive screening assessment for viral hepatitis B surface antigen, or anti-hepatitis C virus antibody AND positive HCV RNA, or human immunodeficiency virus 1 and 2. Serum potassium levels >5.5 mmol/L at Screening. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) >2 × upper limit of normal (ULN) at Screening Treatment with immunosuppressant biological drugs, calcineurin inhibitors, cyclophosphamide, azathioprine, or mycophenolate mofetil within 26 weeks prior to Screening. History of serious side effects or allergic response to an angiotensin II antagonist or has a known sensitivity to any components in the Investigational Product. Prior participation in any Dimerix-sponsored DMX-200 clinical study. Participation in a clinical study with an Investigational Product within 28 days or 5 half-lives (whichever is longer) prior to Screening or plans to participate in another study during the course of this study. Compliance to ARB treatment during the Stabilization period Are study site personnel directly affiliated with this study and their immediate families.