Credit: NPG

Regulators reward company for developing an enzyme replacement therapy for a rare paediatric indication with only 800 estimated patients in the United States.

The lowdown: In 2012, the FDA Safety and Innovation Act (FDASIA) introduced a new priority review voucher (PRV) to encourage drug makers to develop therapies for rare paediatric diseases. Modelled after the tropical disease priority review voucher (TD-PRV), the paediatric PRV entitles a successful sponsor of a rare paediatric disease drug to an 8-month priority review of the drug of its choice.

With the US Food and Drug Administration (FDA)'s approval of the enzyme replacement therapy elosulfase alfa for patients with mucopolysaccharidosis type IVA (also known as Morquio A syndrome), BioMarin became the first company to receive a paediatric PRV. BioMarin tested its drug in patients aged 5–57 years old.

PRVs, and the 4 months faster market access they enable, have been estimated to be worth between US$50 million and $300 million. To date, only two TD-PVRs have been granted, to Novartis for Coartem (artemether plus lumefantrine) and to Janssen for bedaquiline. Novartis used its PRV to expedite the review of canakinumab in gouty arthritis, but the FDA rejected the application (Nature Rev. Drug Discov. 10, 721; 2011). As Nature Reviews Drug Discovery went to press, a regulatory decision was pending on the approval of Paladin's hexadecylphosphocholine, for leishmaniasis, which is eligible for a third TD-PRV. But whereas a TD-PRV can only be sold once to a new sponsor, the paediatric PRV can be traded multiple times, potentially increasing its value and the likelihood of a sale.

A limited, but unset, number of paediatric PRVs are up for grabs: the FDA will stop granting them after the last day of a 1-year period that will begin when the third voucher is awarded.