Alexion touts new PhIII data of Soliris successor as planned AstraZeneca takeover looms
A little less than a week before AstraZeneca’s takeover of Alexion is expected to be completed, the rare disease biotech offered up a cut of data for its Soliris successor.
In a Phase III study for Ultomiris looking at adults with generalized myasthenia gravis, the drug met its primary endpoint of significantly improving scores on a patient-reported assessment compared to placebo after 26 weeks, Alexion announced Thursday afternoon. Alexion hopes the topline results represent what could be Ultomiris’ third approval, after it notched OKs for a rare blood disorder called PNH and an ultra-rare chronic disease that damages the kidneys.
Should the FDA give Ultomiris the go-ahead, the drug would be available for a broader disease population than Soliris, as the older medicine is only approved for those with severe symptoms and complications, Alexion R&D chief John Orloff said in a statement.
The hope is to be able to treat patients “with milder symptoms or earlier in their treatment journey, while still offering clinically meaningful benefits that were seen as early as Week 1 and maintained up to 52 weeks,” Orloff said.
Generalized myasthenia gravis is a rare autoimmune disorder caused by inflammation that damages the connection point between nerve cells and muscles. The damage leads to a “breakdown in communication” between the brain and muscles, Alexion said, causing loss of muscle function and severe weakness. It can occur at any age, but begins most commonly for women under 40 and men over 60.
Alexion enrolled 175 individuals in the Phase III study who were randomized 1-to-1. Patients in the drug arm received a “weight-based loading dose” on day 1, followed two weeks later by a maintenance dose. Subsequent dosing took place every eight weeks after that until the study was completed.
The primary endpoint, a patient-reported test on daily living, showed those taking the drug saw average scores -1.6 points below baseline compared to placebo, good for a sparkling p-value of p<0.001. Some secondary endpoints also reached statistical significance, including a clinician assessment of severity (p<0.001) and total number of patients reaching at least 5 points of improvement in that score relative to the control (p=0.005).
Other secondary goals looking at quality of life, however, did not reach the magic p=0.05 number. One rating scale examining quality of life just barely missed with a p=value of p=0.064, while another measuring fatigue whiffed badly, coming in at p=0.373.
Alexion said side effects were comparable between the two groups, with the most commonly reported event of headache occurring more frequently in the placebo arm. Diarrhea and nausea were the next most common side effects. Serious adverse events such as myasthenia gravis crisis were observed in 1.2% of patients in the drug arm, while more patients saw disease worsening in the placebo group at 3.4%.
An open-label extension period of an additional 26 weeks showed another 75 patients from the drug arm maintaining their disease, Alexion added.
The topline results released Thursday could bring good tidings to Alexion’s new partners at AstraZeneca, where the biotech is expected to become the company’s entire rare disease unit. In addition to Soliris, which pulled in more than $4 billion in sales last year, Ultomiris will likely play a key role in AstraZeneca’s stable of drugs. Alexion has positioned Ultomiris to soak up most of the older drug’s sales, despite facing new competition from Apellis’ Empaveli.
AstraZeneca’s planned $39 billion acquisition cleared its final regulatory hurdle earlier this week, when the UK’s financial watchdog gave the deal the thumbs-up. The transaction is expected to close on July 21, with Alexion shares $ALXN being converted to AstraZeneca stock $AZN and removed from Nasdaq trading the next day.