just look at the FEHB policy for guidance.
http://www.charitedisc.com/charitedev/domestic/patients...sement/fedappeal.pdf
This policy gives you backgroud/purpose and policy.
Basically, If any drug, medical device, or biological product is FDA approved it can no longer be deemed "investigational" and/or "experimental" and should (must) be covered by one's health insurance plan if (1) it is being used for it's intended purpose and (2) it is deemed medically necessary and appropriate for the patient as determined by their treating medical professionals.
Using the FEHB standard...keeps the law and coverage consistent for federal and private employees and should included Medicare recipients too.