Astra could use a voucher to cement roxadustat’s head start

The market for priority review vouchers isn’t what it used to be. And Astrazeneca looks like it has bagged a relative bargain, paying Sobi $95m to get a head start for one of its pipeline candidates.

Astra has not yet said if it has a particular therapy in mind for the voucher, but its anaemia project roxadustat seems like a good bet. The Fibrogen-originated asset is vying with several others in the same class for a piece of what is expected to be a multi-billion dollar market.

Under priority review the US FDA aims to make an approval decision within six months, versus the standard 10-month review. Companies have therefore used the vouchers when there is a good reason to hasten a drug to market, for example where competition is set to be fierce and first-mover advantage could be vital.

Another contender for the voucher might be trastuzumab deruxtecan, an Her2-targeting antibody-drug conjugate that Astra licensed from Daiichi Sankyo in March. However, the companies are pitching this as a better version of the well-established drug Herceptin, so time is not exactly of the essence here.

It is worth remembering that Astra now has two priority review vouchers, having gained another, still apparently unused, from Wellstat in 2014.

Perhaps Astra just saw a chance to get its hands on a voucher at a good price, particularly as these were changing hands for as much as $350m at their peak. But as more US priority review vouchers have been issued following the programme’s 2016 reauthorisation their resale value has fallen. The $95m Astra has given Sobi is in the $80-105m range of this year’s three other disclosed voucher sales.

A net total of eight existing vouchers are thought not to have been sold on or redeemed, though additional vouchers might have been issued without this fact having been disclosed.

Anaemia race

Roxadustat does look like an ideal candidate for the voucher. The project is one of several HIF-PHI inhibitors in late-stage development, and the market could be very large indeed: Stifel analysts note that the erythropoiesis-stimulating agents HIF-PH developers are hoping to displace sell around $6bn per year. 

Roxa currently leads the race, but cementing this head start could be invaluable. The project is set to be submitted to the FDA in October; if approved, Astra will be responsible for US commercialisation.

Competitors are not too far behind. Akebia's vadadustat and Glaxosmithkline's daprodustat are both filed in Japan, but the US will be the main battleground, and both projects are due to yield phase III data in late next year. 

However, there are still question marks over roxa's safety following a confusing update from a pooled analysis earlier this year (Roxadustat safety analysis provokes more questions than answers, May 10, 2019). Toxicity concerns look like the only thing that might scupper roxa, which has met efficacy endpoints in pivotal trials in various settings. A priority review voucher would not be much help if the FDA did have worries here.

The safety question might be answered by the further US and European data that are due to be presented at the American Society of Nephrology meeting in Washington, DC, in November. Roxa is also likely to be the subject of a US FDA adcom next year.

Meanwhile, roxa was approved in China today for a new use: patients with anaemia caused by chronic kidney disease who are not dependent on dialysis. This adds to its Chinese approval last December in dialysis-dependent patients. Astra and Fibrogen plan to launch roxa in China, where they have a 50/50 profit share agreement, in the second half of this year.

Astra reckons it is several years ahead of its HIF-PHI rivals in China. In the US the stakes are higher, and timelines look tighter, so using the voucher could be a good move.

The table in this story has been updated to reflect information from Novo Nordisk about the company's two separate vouchers.