Alexion's cash cow Soliris just got fatter as FDA greenlights another blockbuster indication
Alexion has scored an additional FDA OK for its keystone rare therapy Soliris, unlocking what a key analyst calls a significant part of its C5 franchise and elevating that portfolio further up the blockbuster ranks.
The drug is now approved to treat neuromyelitis optica spectrum disorder, a rare autoimmune condition characterized by sudden attacks on the central nervous system. The disease often strikes women in their 30s and 40s, and could be confused with multiple sclerosis. While off-label Rituxan helps most patients — approximately 70% — keep the disease at bay, relapses still threaten to do irreversible harm and cause severe disability to those for whom the standard of care doesn’t work.
In a Phase III testing the drug in patients who had multiple relapses despite prior immuno-suppressive therapies, Soliris reduced the risk of NMOSD relapse by 94.2% compared to placebo (p<0.0001) — a stellar result. And in the latest data cut at 144 weeks, 96% of the Soliris group didn’t experience an attack, compared to 45% of patients in the placebo arm who remained relapse-free.
Notably, regulators did not limit Soliris’ use to non-responders, offering a blanket label that covers any patient with anti-aquaporin-4 antibodies — which is believed to activate the complement system that Soliris inhibits.
That surprised SVB Leerink’s George Porges, a big cheerleader of the drug, but he is careful to note that a broader label does not guarantee a broader patient population.
Despite the label, we don’t think Soliris will capture significant use in front line treatment given Rituxan’s favorable cost-benefit profile (~70% disease control under Rituxan and ~$60K first year cost compared ~$700K first year cost for Soliris). We expect most insurance payers to require evidence of Rituxan failure before reimbursing for Soliris in this disease, but do expect relatively open access to Soliris for relapsed patients in late line treatment.
He notes that Alexion is soon starting a Phase III trial in the same indication for Ultomiris, its followup to Soliris that’s easier to use. By his estimates, between the two drugs the NMOSD sales alone will bring in around $1 billion in 2028, representing one-fifth of the total C5 franchise that year.
As far as competition goes, Roche and its Chugai subsidiary has some Phase III data to show for its IL-6 inhibitor satralizumab. AstraZeneca spinout Viela Bio is fast on its heels with the CD-19 inhibitor inebilizumab. But with no direct rival in the C5 class, Porges sees Soliris capturing the dominant share in relapse cases.
For Alexion’s part, R&D chief John Orloff is happy to highlight the fact that Soliris is the first drug approved to reduce the risk of NMOSD relapse. Reviews in Europe and Japan are ongoing.