A Study of SNP-ACTH (1-39) Gel in Patients With Primary Membranous Nephropathy

Inclusion Criteria: * Biopsy-proven membranous glomerulonephritis or a diagnosis of MN in patients with Nephrotic Syndrome and a positive anti PLA2R antibody test. * Patients classified to be at a High Risk for progressive loss of kidney function, as defined by Kidney Disease Improving Global Outcomes (KDIGO) 2021-Glomerular Diseases Guideline. * eGFR by Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formula ≥40 mL/min/1.73 m\^2 * Patients who have had CR or PR in response to immunosuppressive therapy, but then relapsed can participate in the study if it has been more than 3 months since their last dose of high dose glucocorticoids, calcineurin inhibitors or mycophenolate mofetil * Patients who have had CR or PR in response to IS therapy, but then relapsed can participate in the study if it has been more than 6 months since their last dose of chlorambucil or cyclophosphamide * Patients who have had CR or PR in response to immunosuppressive therapy, but then relapsed can participate in the study if it has been more than 12 months since their last dose of rituximab. * Life expectancy \> 24 months. * Other inclusion criteria may apply. Exclusion Criteria: * Secondary membranous nephropathy as defined by history, physical exam, kidney biopsy results or serologies. * Patients who have had a ≥ 50% reduction in serum titers of PLA2R auto-antibody within 1 year before screening. * Type 1 or 2 diabetes mellitus * Patients who must be initiated on drugs likely to affect renal function if not properly dosed. * Surgery within 1 month of study entry * History of sensitivity to proteins of porcine origin. * Other exclusion criteria may apply.