Once a drug has been approved for some use it can be legally prescribed for any use. New uses for old drugs are often discovered. When physicians learn of these new uses, prescribing practices move beyond the uses that the FDA has evaluated and permitted. In Outdated Prescription Drug Labeling, Shea et al. compare off-label uses for cancer drugs that are graded as “well-accepted” by the National Comprehensive Cancer Drugs & Biologics Compendium (NCCN) with the labelled, “FDA-approved” uses. What they find is that most drugs have multiple off-label uses that are significantly different from FDA approved uses.
Our analysis of the NCCN Compendium and FDA drug labels for 43 cancer drugs approved between 1999 and 2011 identified hundreds of off-label uses, most of which were strongly supported by NCCN expert panels.
…Additionally, of the 253 off-label uses, 165 (65.2%) were categorized as “new indications,” meaning they were in disease settings not represented on labels
In my work on off-label prescribing (and with Klein) I have emphasized that the off-label world offers a window on what the larger world would look like with much less FDA control over new drug approvals. Notice that even today it’s physicians and the private approval process, as represented by the compendia, that determine actual prescribing and payment.
We found that 4 of the 5 largest private payers, as well as Medicare, cover over 90% of uses listed on the NCCN Compendium (uses graded 1 and 2A), suggesting widespread acceptance of these uses by diverse stakeholders. While standards for FDA approval differ from standards for coverage determinations, these findings indicate that the gulf between labeled uses and covered uses may be needlessly wide.
To bring FDA labeling up to real-world practice the authors recommend “a collaboration between the FDA and the developers of clinical guidelines and drug compendia to evaluate existing evidence about approved drugs and suggest updates to labeling.” In other words, the decentralized, private approval system should be used to determine which new uses of old drugs are safe and effective and those determinations should then be adopted by the FDA. I agree. But if private practices can be used to approve new uses for old drugs, why shouldn’t similar procedures be used to approve new uses for new drugs?