In yet another high profile loss for the Food and Drug Administration (FDA or Agency) in a challenge to the Agency's interpretation of the Orphan Drug Act (ODA), the Eleventh Circuit's decision in Catalyst Pharmaceuticals, Inc. v. FDA has the potential to significantly broaden the scope of orphan drug exclusivity for drugs that receive marketing approval for orphan indications that are narrower than their orphan-designated conditions.1 If applied across existing and pending orphan exclusivities, this decision could fundamentally change the current planning and expectations of many companies reliant on, or seeking to work around, such exclusivities.
At issue in the case was whether orphan drug exclusivity awarded to a drug approved for a use that is narrower than the full orphan-designated disease or condition should be limited to the drug's approved use or should more broadly cover the full scope of the orphan-designated condition. FDA's longstanding interpretation of the ODA, as codified in the Agency's orphan drug regulations, is that the scope of orphan drug exclusivity is specific to the orphan indication for which a drug obtains marketing approval and does not cover an orphan use or population for which a drug may be designated but is not approved for marketing. In Catalyst, the Eleventh Circuit interpreted the ODA such that orphan exclusivity awarded to an amifampridine drug approved for Lambert-Eaton myasthenic syndrome (LEMS) in adults should have blocked the approval of an amifampridine same drug for the treatment of LEMS generally, including for treatment in a pediatric LEMS population for which the protected drug is not even approved. In response to the Catalyst decision, FDA earlier this month revoked the pediatric LEMS approval of the amifampridine drug in question. It remains to be seen whether FDA will apply the Catalyst decision beyond the drugs that were the subject of the case. As further detailed herein, absent a timely legislative fix, a broad application of the Catalyst decision could have far-reaching implications, including the potential to result in revocation of marketing approvals for certain orphan drugs or indications.
The Catalyst case pertains to FDA's 2019 approval of Jacobus Pharmaceutical Company Inc.'s (Jacobus) Ruzurgi' (amifampridine) for pediatric use in LEMS. Ruzurgi is considered the "same drug" as Catalyst Pharmaceuticals' (Catalyst) Firdapse' (amifampridine). In 2009, Catalyst received orphan designation for amifampridine for the treatment of LEMS. In November of 2018, Catalyst received marketing approval for Firdapse for the treatment of LEMS in adults. Under the orphan drug provisions of the Federal Food, Drug and Cosmetic Act (FDCA), a drug that is designated for a rare disease or condition and then subsequently obtains marketing approval for that rare disease or condition is entitled to a 7-year period of orphan-drug exclusivity during which, with certain exceptions (e.g., a demonstration of clinical superiority), FDA may not approve a drug considered the same drug for the same rare disease or condition.2 To qualify for orphan drug exclusivity, FDA must not have previously approved the same drug for the same orphan...
