The US House of Representatives has passed a bill reauthorizing the FDA priority review voucher (PRV) program, a key incentive for developing drugs targeting rare diseases.

 

The PRV program, which must be periodically reauthorized due to a “sunset clause,” had lapsed in December 2024 amid debates over its effectiveness and concerns about soaring PRV prices.

 

Dan Williams, CEO of SynaptixBio, a biotech developing a treatment for H-ABC, a rare and deadly disease, called the program a “vital lifeline” for small companies working on rare disease therapies.

 

“Developing therapies for rare diseases is a moral imperative. Whilst individually rare, together millions worldwide are affected,” Williams said.

 

He added, “The PRV scheme means smaller biotechs can see a meaningful return on the very high investment needed to develop and take a rare disease drug through clinical trials.”

 

Once the Senate approves the measure, known as the Mikaela Naylon Give Kids a Chance Act, it will go to President Trump for final sign-off.

 

SynaptixBio currently holds two Rare Pediatric Disease Designations from the FDA—one for H-ABC and another for Isolated Hypomyelination, a rarer form of TUBB4A leukodystrophy—and hopes these will lead to PRV awards.

 

Originally launched in 2007 to address neglected tropical diseases, the PRV program was expanded in 2012 to include rare pediatric diseases. PRVs are highly prized in the biopharma industry, allowing companies to cut FDA drug application review times from 10 months to six.

 

PRVs have recently fetched huge sums on the market. In August 2024, Ipsen sold a PRV for $158 million after approval of its rare disease drug Sohonos. In May, Abeona Therapeutics sold a PRV for $155 million just two weeks after gaining approval for its gene therapy Zevaskyn.

 

Earlier this year, SynaptixBio selected its lead candidate, an antisense oligonucleotide (ASO), to advance into clinical trials. ASOs are a form of gene-silencing technology that stop mutated genes from forming toxic proteins without altering the gene itself.

 

Williams highlighted the role of small biotechs in rare disease drug development: “Structurally, it has been the smaller biotechs that have worked on rare diseases therapies. Bigger pharma companies are much more inclined to invest in mass-market drugs.

 

“However, once a smaller biotech’s candidate orphan drug has passed toxicology tests and proceeded to clinical trials, Big Pharma’s strengths in navigating regulatory approvals, making deals with Governments and health services, and manufacturing, then prove vital.

 

“It may be that there is obvious synergy here; Big Pharma doesn’t face the high investment risk of developing a rare disease drug, and the smaller biotech has a natural target for selling its PRV.”