This open-label Phase 2 study will characterize the safety and efficacy of JADE101 in participants with IgA nephropathy, and the results will contribute to the overall clinical characterization of JADE101 in this patient population.

Inclusion Criteria:

1. Male or female participants 18-60 years of age, inclusive, and of local legal consenting age at the time of signing the informed consent
2. eGFR ≥ 30 mL/min/1.73 m2
3. Biopsy-confirmed primary IgAN
4. Receiving stable and maximally tolerated doses of either ACEi or ARB as per standard of care (SoC) and applicable guidelines for at least 12 weeks prior to the initial screening visit, with no intention to alter the dose or discontinue treatment, unless medically necessary
5. UPCR ≥ 0.75 g/g
6. Willing to provide written informed consent
7. Willing and able to comply with scheduled study visits, treatment plans, laboratory tests, and other study procedures
8. Willing and able to comply with contraceptive and lifestyle requirements

Exclusion Criteria:

1. Secondary forms of IgAN
2. Known or suspected coexisting Chronic Kidney Disease (CKD) other than IgAN
3. Known or suspected rapidly progressive glomerulonephritis (RPGN)
4. Evidence of pathological findings in the kidney biopsy in addition to IgAN (eg, minimal change disease, diabetic kidney disease, membranous nephropathy, focal segmental glomerulosclerosis, or lupus nephritis); hypertensive vascular changes are acceptable
5. Known or suspected primary or secondary immunodeficiency disorder
6. Evidence of tuberculosis infection at screening
7. Any chronic infectious disease
8. Any acute infectious disease at time of screening
9. Received bone marrow, hematologic stem cell transplantation, or a solid organ transplant, including kidney
10. Known or suspected alcohol or drug abuse
11. Any clinically significant and/or unstable or uncontrolled medical condition as assessed by the investigator
12. Malignancy within the past 5 years; nonmelanoma skin cancer and curatively treated cervical carcinoma in situ are allowed

Other protocol-defined inclusion/exclusion criteria may apply