US FDA will continue to tie orphan exclusivity to uses or indications for which the drug was approved. Attorneys say this buys agency time to sort out complex policy and legal questions and continue to seek legislative fix. Additional litigation is also possible, as happened in Depomed case.

DC Circuit Court upholds FDA’s grant of new chemical entity exclusivity to Sanofi’s multiple sclerosis drug Aubagio (teriflunomide) even though the agency had previously approved teriflunomide as an impurity in Sanofi’s Arava (leflunomide). FDA reviews known impurities in drugs only to assess their impact on safety and efficacy, not to approve them, court says.

FDA didn’t get policy rider it wanted which would have reversed the Catalyst court ruling that the agency cannot limit a drug’s orphan exclusivity to its approved indication. One attorney says the clearest path forward is for FDA to issue new rulemaking and face additional litigation.

The cost of rare diseases to patients and society at large is 10 times higher than for many of the biggest mass market diseases combined. With 95% of rare diseases lacking a treatment or cure, there is an economic imperative for policymakers to keep encouraging pharmaceutical companies to develop more orphan drug treatments. In Vivo looks at the US and EU regulatory impetus to keep rare diseases open for innovation.