The purpose of this study is to assess the efficacy and safety of SM101 in the treatment of Immunoglobulin A nephropathy (IgAN)

Inclusion Criteria:

1. 18 years of age or older at the time of screening
2. Participant may be of any race or ethnicity
3. Participant must have a biopsy-proven diagnosis of IgAN.
4. Participant's blood pressure is ≤130/80 mmHg at Screening
5. Participant is on maximally tolerated dose of an angiotensin-converting enzyme (ACE) inhibitor and/or angiotensin receptor blocker (ARB) for at least 3 months prior to the baseline visit.
6. Participant must present at screening with current proteinuria levels between 1 g/24 h and 3.5 g/24 h, based on spot urine protein-to-creatinine ratio (UPCR)
7. Participant must present at screening with an estimated glomerular filtration rate (eGFR) >40mL/min/1.73m^2
8. If a female of childbearing potential, participant must have a negative pregnancy test at screening, is not currently breastfeeding, and agrees to employ adequate birth control measures for the duration of the study. Male participants with female partners of childbearing potential must agree to use adequate birth control measures for the duration of the study
9. Participant is willing and able to comply with the requirements of this protocol and agrees to sign an informed consent form prior to any study-related activities

Exclusion Criteria:

1. Participant has a history or current evidence of renal disease other than IgAN
2. Participants with evidence of rapidly progressive disease
3. Participant has IgAN with histologic evidence of advanced tubular atrophy and interstitial
4. History or current evidence of other autoimmune disease
5. History or current evidence of any chronic or uncontrolled medical condition which could, in the opinion of the Investigator, affect the participant's safety and ability to adhere to this protocol
6. History or current evidence of a severe acute or chronic infection
7. Use of systemic corticosteroids within 3 months prior to baseline, or anticipated use during the treatment period (Week 1 through Week 4). Note: Corticosteroids administered by inhalation or intranasally, or limited topical use of low-potency topical corticosteroids are allowed throughout the study.
8. Known hypersensitivity or allergic reaction to any E. coli-derived recombinant product, yeast extract, or to the IP or any of its excipients
9. Treatment with any immunomodulatory/immunosuppressive compound or monoclonal antibody for any indication within 6 months (unless otherwise stated) prior to screening (eg, B cell-depleting agents [eg, rituximab, epratuzumab] for ≥48 weeks; B-cell modifying agents [eg, belimumab, atacicept] for ≥24 weeks; IV immunoglobulins for ≥12 weeks and all other immunosuppressive treatments [eg, methotrexate, cyclophosphamide, cyclosporine, tacrolimus, mycophenolate mofetil, azathioprine] for ≥12 weeks)
10. Clinically significant laboratory abnormalities prior to baseline
11. History of any malignancy within past 5 years prior to screening (except for basal and squamous cell carcinomas of the skin, in situ cervical cancer, and stable prostate cancer that does not require treatment)
12. History of tonsillectomy within 2 months prior to screening
13. Participation in another clinical study involving an IP or investigational device within 30 days prior to screening or is scheduled to participate in another clinical study involving an IP or investigational device during the course of this study
14. Participant is a family member or employee of the Investigator
15. A female participant who is pregnant or nursing at the time of screening