Inclusion Criteria:
- Weight of at least 40 kg
- On a stable prescribed standard of care (SoC) treatment regimen according to local guidelines and the specific requirements for each disease
- Systolic blood pressure ≤160 mmHg and diastolic blood pressure ≤90 mmHg at Screening. For participants aged ≥10 to <18 years, the average of 3 separate systolic and/or diastolic blood pressures <95th percentile for age, gender, and height
Diagnosis of IgAN, IgAVN, pMN, MCD, FSGS, or primary nephrotic syndrome
For patients enrolling in IgAN cohorts (eligibility varies by cohort):
- Age ≥ 10 years
- Biopsy proven IgAN or IgAVN,
- UPCR ≥ 0.5 g/g
- eGFR≥ 20 mL/min/1.73m2
For patients enrolling in pMN cohorts (eligibility varies by cohort):
- Age ≥ 18 years
- Biopsy-proven pMN
- Anti PLA2R antibodies ≥ 25 RU/mL
- UPCR ≥ 1.5 g/g
- At low risk for spontaneous remission (based on severity or duration of disease)
For patients enrolling in Nephrotic Syndrome cohorts (MCD, FSGS, or pediatric idiopathic nephrotic syndrome):
- Age ≥ 10 years
- eGFR≥30 mL/min/1.73m2
- Biopsy diagnosis of primary MCD or FSGS (adults) or challenging clinical course with steroids in children (frequenlty relapsing, steroid-dependent, or steroid-resistant)
- UPCR ≥ 1.0 g/g at Screening,
- Evidence of anti-nephrin antibodies
- Evidence of rapidly progressive glomerulonephritis (loss of ≥50% of eGFR) within 3 months prior to and at Screening)
- Active viral or bacterial infections
- Existing conditions or clinically significant laboratory abnormalities that may interfere with participation in this study
- Administration of live and live-attenuated vaccinations within 30 days prior to enrollment
- Known hypersensitivity to atacicept or any component of the formulated atacicept
- Additional criteria apply to each cohort/disease.
