Vifor files hyperkalaemia drug in Europe ahead of AstraZeneca rival

Vifor Fresenius and Relypsa have filed their drug patiromer in Europe, one of two new treatments for hyperkalaemia reaching the market.

Hyperkalaemia is abnormally high levels of potassium in the blood, and is often caused by acute or chronic kidney disease or heart failure, and affects millions of people worldwide. The condition frequently requires hospitalisation – there are a variety of different existing treatments, but the evidence base for their use is poor.

Patiromer gained US approval in October under the brand name Veltassa, and was the first new treatment for the condition approved in 50 years.

Some analysts are predicting peak annual sales in excess of $1 billion. But it has competition in the shape of AstraZeneca and its drug ZS-9, which is set for an FDA ruling in May.

AstraZeneca acquired ZS-9 when it bought out ZS Pharma for $2.7 billion last year, and believes the drug can be the best-in-class treatment for hyperkalaemia.

This has set up a clear head-to-head in the previously neglected therapy area.

In the US, Relypsa has struck a co-marketing deal with Sanofi, which should help it penetrate the market faster and more effectively. However in Europe, where Vifor is the lead marketing partner, it intends to market the drug without a big pharma partner.

Vifor has submitted pivotal Phase 3 data from its OPAL-HK study of the drug to the European Medicines Agency. This was conducted under a FDA Special Protocol Assessment, and evaluated patiromer in hyperkaliaemic patients with chronic kidney disease (CKD) who were taking renin angiotensin aldosterone system (RAAS) inhibitors.

Another Phase 2 trial, AMETHYST-DN , evaluated its use over 52 weeks in hyperkaliaemic patients with CKD and type 2 diabetes who were taking RAAS inhibitors

A third trial was an open-label, uncontrolled, Phase 1 study that evaluated the onset-of-action of Patiromer hyperkaliaemic CKD patients.

Some forecasts for patiromer aren't so optimistic, estimating peak sales at under $200 million. These analysts believe doctors may be difficult to persuade to switch away from existing, low cost treatments.

Veltassa also carries a black box warning in the US because it binds many other orally administered drugs, which could decrease their absorption and reduce their effects.

The FDA warning recommends taking it and any other orally administered medication at least six hours apart. However Relypsa is requesting the FDA review this guidance, citing data which suggest these interactions aren't as strong as originally suspected.

It is yet to be seen if ZS-9 can gain a more favourable label from the FDA. The US decision on ZS-9 is just a few weeks away, 26 May being the PDUFA decision date, with a planned submission to the EMA also progressing.