AION-301

The goal of this clinical trial is to learn about the safety (good or bad) of giving two AION-301 intravenous (IV) infusions, in adults with Stage 3 Chronic Kidney Disease (CKD). It will also help to learn if AION-301 reduces the symptoms of CKD and/or progression. The main questions it aims to answer are:
* Do participants have medical problems (adverse events) after receiving two infusions of AION-301?
* Do participants feel better (have reduced and/or delayed CKD symptoms)?
* To learn about how AION-301 works in participants with CKD?
Researchers will compare AION-301 to a placebo (a look-alike substance that contains no drug) to see if AION-301 works to treat Stage 3 CKD.
Participants will:
* Receive two infusions of AION-301 or placebo on two separate days (Day 0 and Day 4).
* Receive oral vitamins at the clinic and to take at home for 90 days.
* Visit the clinic for a minimum of 9 times, over 6 months for checkups and tests, but could be up to 12 times, over 24 months for checkups and tests.