Patient and medical groups blast Trump administration drug pricing proposal in new ad campaign

In particular, ACS-CAN and the other patient advocacy groups are concerned about changes to Medicare's "protected classes," which include drugs that treat AIDS, cancer, some mental illnesses, and seizure disorders like epilepsy. They also include drugs for patients who received transplants.

Under current rules, Medicare Part D plans must cover nearly every drug for these conditions, with some exceptions. That's different than the rules for other diseases, where Medicare plans only need to cover two drugs per condition.

But even within these protected classes, Medicare plans are allowed to use certain tools to negotiate prices down with drug companies, according to an HHS manual. Those include prior authorization — where a drug is only covered if the doctor submits a special request — and step therapy — where a more expensive drug is only covered if a patient first tries a different cheaper drug but it doesn't work.

Plans can only use those tools if a patient is not currently taking the drug. If a patient is already undergoing cancer treatment with a certain medicine, their Medicare provider can't require prior authorization in the middle of the treatment.

In November, the Centers for Medicare and Medicaid Services put forward changes that would allow Medicare plans to use these tools for patients who are currently being treated. The changes would also apply to HIV drugs. Public comments are due on the proposed rule next Friday.