Safety and Efficacy of STL303 In Patients With Primary Immunoglobulin A (IgA) Nephropathy

Prior treatment

• Any organ transplant recipients except corneal.
• Use of immunosuppressive drugs within 90 days or 5 half-lives.
• Prior oral budesonide (Nefecon/Tarpeyo/Kinpeygo) within 6 months.
• Prior complement inhibitors within 30 days, 5 half-lives, or residual effect period.

Other illness

• Other systemic diseases causing proteinuria/CKD or severe urinary obstruction.
• Major systemic diseases preventing participation (e.g., NYHA IV, severe pulmonary disease).
• History of malignancy within 5 years (exceptions apply).
• History of meningococcal, pneumococcal, or Hib infection.
• Chronic/recurrent infections in past year (e.g., liver abscess, pyelonephritis).
• Active systemic infections within 2 weeks or fever greater than 38°C within 7 days.

Lab values

• Rapidly progressive IgAN (eGFR decline greater than or equal to 50% in 3 months, or less than 50% but at high risk).
• Significantly abnormal liver function (greater than 3× ULN enzymes or greater than 2× ULN bilirubin).

Other

• Secondary IgAN or unclear exclusion of secondary causes.
• Known or suspected immunodeficiency or hereditary complement deficiency.
• Poorly controlled blood pressure (SBP greater than 150 or DBP great than 90).
• QTcF greater than 500 ms.

• Male and female patients aged 18 years and older, with primary IgAN confirmed by renal biopsy:
• eGFR (Chronic Kidney Disease Epidemiology Collaboration \[CKD-EPI\] formula) greater than or equal to 30 mL/min/1.73 m2 at screening and after completion of run-in.
• UPCR greater than or equal to 0.75 g/g at screening and after completion of run-in.
• Vaccinated against Neisseria meningitidis and Streptococcus pneumoniae before the first dose.
• Have received stable treatment with RASis (ACEi or ARB) at the maximum recommended dose or MTD for at least 90 days prior to the first dose.
• If the patient has been treated with SGLT2i, diuretics, other antihypertensive treatments, ERA, and/or hydroxychloroquine for IgAN prior to the first dose, the drug should also be used stably for at least 90 days.