- The Food and Drug Administration has approved Alexion Pharmaceuticals Inc.'s blockbuster drug Soliris for patients who have an uncommon, muscle-weakening disease, expanding the addressable market for the pricey med.
- While there are several subgroups of myasthenia gravis (MG), Alexion's drug is now OK'd to treat the patients with the generalized kind who have antibodies that impair acetylcholine receptors — proteins that play a vital role in muscle movement.
- About 15 to 40 people per 100,000 have autoimmune MG, according to the National Organization for Rare Disorders (NORD). The last treatment for generalized MG to gain an FDA green light came more than 60 years ago, according to Alexion.
Soliris (eculizumab) is Alexion's most vital asset. With indications for atypical hemolytic uremic syndrome (aHUS) and paroxysmal nocturnal hemoglobinuria (PNH) already under its belt, the drug brought in $814 million worth of net product sales during the second quarter, accounting for nearly 90% of Alexion's total revenue.
Understandably, Alexion has worked to keep the blockbuster franchise well-oiled. The company announced in August that it had secured three new U.S. patents that extend to 2027 and cover Soliris' composition of matter, pharmaceutical formulations and method of treating PNH patients. As of early 2017, the drug's composition of matter patent in the U.S. was set to expire in 2021.
Expanding the drug's label has been another key strategy. Soliris is currently in mid- to late-stage trials for a couple other indications, including relapsing neuromyelitis optica spectrum disorder.
Soliris' approval in generalized MG, meanwhile, hinged on data from the Phase 3, placebo-controlled REGAIN study. Though the drug failed to meet the study's primary endpoint, it hit statistical significance in 18 of 22 pre-specified analyses, which included parameters like change from baseline in Quantitative Myasthenia Gravis total score and in the proportion of patients who needed no rescue therapy and who had at least a 3-point reduction in their Myasthenia Gravis-Activities of Daily Living Profile total scores.
"While the REGAIN study narrowly missed statistical significance on the primary endpoint, the totality of data from this landmark trial supports the potential of eculizumab to provide an early, sustained, and substantial response in patients with refractory gMG," said Martin Mackay, Alexion's then-global head of R&D, in a July 7, 2016, statement.
Notably, REGAIN tested Soliris in an ultra-rare portion of the generalized MG population who did not respond to previous immunotherapies. Alexion submitted a Biologics License Application targeting that refractory population, but the FDA approval is only specific to patients who are anti-acetylcholine receptor (AchR) antibody-positive.
Approval despite the trial miss gives further evidence of the FDA's willingness to be more flexible in considering drugs for patients populations with few other options — a trend reinforced by Comissioner Scott Gottlieb's leadership.
Even so, Soliris gives generalized MG patients another form of treatment. Typically, those patients receive anticholinesterases or immunosuppressants, according to NORD.
"It is particularly significant that this approval of Soliris will provide a new option for those with gMG and especially for those who do not respond adequately to or cannot tolerate standard treatment options," Nancy Law, CEO of the Myasthenia Gravis Foundation of America, said in a statement.
Alexion stock was up 4.5% to $141.31 per share at market's open Tuesday, though shares fell back down to $136.66 apiece by market's close.