On June 12, 2013, FDA issued a Final Rule amending the 1992 Orphan Drug Regulations to implement the Orphan Drug Act. The Final Rule largely reflects the 2011 Proposed Rule (see our previous blog on the draft rule here) to amend the Orphan Drug Regulations with several changes for clarity and accuracy. FDA explicitly stated that the Final Rule has no effect on the scope of, or eligibility for, orphan-drug-exclusive approval, because it merely clarifies existing and longstanding FDA practices. The Final Rule will take effect on August 12, 2013.
The two most important amendments and clarifications in the final rule are the new definition of “orphan subset” and the various clinical superiority requirements for designation requests and exclusive approvals for a subsequent drug for the same use or indication.
To qualify as an “orphan subset” drug (21 CFR §316.3(b)(13)), the drug sponsor must show that while the drug is safe and effective in the orphan subset population, the drug is not suitable for use in those persons outside of the orphan subset (i.e., those persons who have the same non-rare disease or condition). Such non-suitability must be based on either a pharmacokinetic property (such as toxicity and mechanism of action), or previous clinical experience with the drug.