This is a parallel, Phase 2a, double-blind, 6-arm study for the treatment of primary focal segmental glomerulosclerosis (FSGS) or primary minimal change disease (MCD).

The purpose of this study is to measure the change in proteinuria and its impact on the rates of remission of nephrotic syndrome with frexalimab, brivekimig, or rilzabrutinib compared with placebo in participants with primary FSGS or primary MCD aged 16 to 75 years.

Study details for each participant include:

The study duration will be up to 76 weeks. The treatment duration will be 24 weeks. There will be up to 18 visits.

Inclusion Criteria:

• Biopsy report indicative of primary FSGS or primary MCD, with supportive clinical presentation per Investigator's judgement.
• UPCR ≥3 g/g at screening, or ≥ 1.5 g/g in those with eGFR ≥ 60.
• eGFR ≥45 mL/min/1.73 m^2 at screening.
• Documented history of UPCR (or 24-hour urine protein) reduction by >40% in response to corticosteroid or other immunosuppressive therapy when pre-treatment UPCR was ≥3.5 g/g (or pre-treatment 24-hr urine protein was ≥3.5 g/day if 24-hour urine protein is used).
• ≤10 mg/day prednisone or equivalent and stable starting at least 1 week prior to randomization.
• For those on a RAAS inhibitor prior to screening, the dose must be stable ≥4 weeks prior to screening; starting RAAS inhibitors or changing the dose will not be allowed during the double-blind or OLE treatment period.
• For those on an SGLT2 inhibitor prior to screening, the dose must be stable ≥4 weeks prior to screening; starting SGLT2 inhibitor treatment or changing the dose will not be allowed during the double-blind or OLE treatment periods.
• Body weight within 45 to 120 kg (inclusive) at screening.

Exclusion Criteria:

• Genetic or secondary FSGS or MCD. Those with APOL1 risk alleles are eligible.
• Collapsing variant of FSGS.
• ESKD requiring dialysis or transplantation.

The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.

Qualified researchers may request access to patient level data and related study documents including the clinical study report, study protocol with any amendments, blank case report form, statistical analysis plan, and dataset specifications. Patient level data will be anonymized and study documents will be redacted to protect the privacy of trial participants. Further details on Sanofi's data sharing criteria, eligible studies, and process for requesting access can be found at: https://vivli.org