@mayo2290 Joe -
You must be feeling very frustrated to finally have an answer, and a potential treatment, only to have your insurance company stall things!
Unfortunately, VEXAS is a very newly diagnosed disease, and it often takes time for insurance companies to catch up with medicine on what are the recommended and covered treatments.
Here are two things you and your doctors can try:
Have the doctor appeal the denial and request an exception.
Search for prescription assistance - sometimes the manufacturer will help, other times the pharmacy can help you find assistance through GooRx or a similar discount program.

I hope with your doctor's help you can get the medication you need.
Sue