A Study to Investigate the Safety, Tolerability, and Preliminary Efficacy With AION-301 Administered by Intravenous Infusion Compared With Placebo Administered by Intravenous Infusion Investigational Intervention in Participants Aged 35 to 75 Years of Age With Chronic Kidney Disease (CKD)

This study is testing a new drug called AION-301, given through an IV infusion, in people with moderate chronic kidney disease (CKD stage 3). The goal is to see if the drug is safe and if it can slow the progression of kidney disease, particularly in people who still have significant protein leaking into their urine despite being on standard medications. **You may be eligible if...** - You are between 35 and 75 years old - You have CKD stage 3, meaning your kidney filtering rate (eGFR) is between 30 and 59, confirmed by at least 2 tests in the last 3 months - You have significant protein in your urine (UACR between 200 and 5000 mg/g) - You are already taking standard kidney-protective medications (such as an ACE inhibitor or ARB, plus an SGLT2 inhibitor) at the maximum tolerated dose, or these drugs are not suitable for you **You may NOT be eligible if...** - You are on dialysis or have had a kidney transplant - You have uncontrolled diabetes, poorly controlled blood pressure, or recent cardiovascular events - You have conditions that could interfere with how the drug is processed in your body - You are pregnant or planning to become pregnant Talk to your doctor to see if this trial is right for you.