A Sequential Phase 2/3 Study of APL2 in Patients With Focal Segmental Glomerulosclerosis

Inclusion Criteria: * Age * Phase 2: adults aged ≥18 years * Phase 3: adults aged ≥18 years; if and where approved, adolescents (aged 12--17 years) at the time of signing the informed consent and assent form * Weight ≥30 kg and ≤100 kg at screening * FSGS diagnosis * Phase 2: primary, genetic, or undetermined FSGS diagnosed by kidney biopsy * Phase 3: primary, genetic, or undetermined FSGS diagnosed by kidney biopsy or by recognized podocyte genetic mutation * At least 1.5 g/day of proteinuria on a screening 24-hour urine collection and a uPCR of at least 1.5 g/g in at least 2 FMU samples collected during screening * Estimated glomerular filtration rate (eGFR) ≥25 mL/min/1.73 m2 * Stable regimen for FSGS treatment for at least 12 weeks prior to randomization, with no planned or anticipated adjustments or dose changes to the stable treatment regimen Exclusion Criteria: * Previous exposure to APL2 * Evidence of improving kidney disease in the 8 weeks prior to screening or during the screening period according to available data * FSGS secondary to another condition (eg, infectious, diabetic, drug-induced, obesity, prematurity, sickle-cell, vesicoureteral reflux, congenital anomalies of the kidney, and urinary tract) * Type 1 or uncontrolled (HbA1C ≥8%) type 2 diabetes mellitus * History of kidney transplant * Current or prior diagnosis of HIV, hepatitis B, or hepatitis C infection or positive serology or viral load during screening that is indicative of active infection with any of these viruses * Hypersensitivity to APL2 or to any of the excipients * Significant other kidney disease that would, in the opinion of the investigator, confound interpretation of study results * Use of rituximab, belimumab, or any approved or investigational anticomplement therapy within 5 half-lives of that product prior to the screening period