Alexion uses priority review voucher for Soliris follow-up

Alexion is pulling out all the stops to get speedy approval for a follow-up to its rare blood disorder therapy Soliris, using a coveted priority review voucher (PRV) to accelerate the FDA’s review.

The company has filed ravulizumab (ALXN1210) for paroxysmal nocturnal haemoglobinuria (PNH), the same indication as Soliris (eculizumab), and is hoping that its more convenient dosing and clinical data will encourage rapid switching to the new drug if it gets approval.

Alexion is sitting on a pair of PRVs awarded for earlier approvals for rare disease therapies (Strensiq and Kanuma), and it’s a measure of the importance the company attaches to ravulizumab that it is prepared to use one of them to slash the FDA’s review time from 12 to eight months.

Like Soliris, ravulizumab is a long-acting complement C5 inhibitor but is administered intravenously every eight weeks rather than every two weeks, cutting the number of doses needed from 26 to six per year.

It showed non-inferiority to Alexion’s established drug in phase III trials but the company says that the new drug actually did better than its predecessor – numerically at least – on all efficacy measures. It also seems to work faster than Soliris at normalising levels of an enzyme biomarker (lactate dehydrogenase or LDH) that provides a measure of red blood cell damage, and was just as good at avoiding the need for blood transfusions in PNH patients.

First launched more than a decade ago, Soliris made $3.1bn in sales last year as a PNH treatment, thanks to its hefty $500,000-plus per year price tag, and was recently also approved for myasthenia gravis, another rare disease that could account for another $500m to $1bn in sales, according to analysts.

Alexion has been working hard to shore up its patent estate for the drug and is claiming protection until 2027, but biosimilar rivals – including a candidate from Amgen – are coming through pipelines.

If the company can build momentum for ravulizumab and switch patients to the new drug from Soliris in the interim it can protect its complement inhibitor franchise any future biosimilar impact. And that’s particularly important, as newer products such as lysosomal acid lipase deficiency treatment Kanuma and Strensiq for hypophosphatasia have a long way to go before they bring in enough revenue to reduce Alexion’s reliance on its cash cow.

Ravulizumab is also in late-stage testing for patients with PNH who have been treated with Soliris, as well as those with atypical haemolytic uremic syndrome (aHUS), another rare and life-threatening blood disorder treated by Soliris.

Alexion says it is planning additional regulatory filings for ravulizumab in Europe and Japan before the end of the year.