Alexion's Ultomiris Shows Compelling, Durable Efficacy In Rare Muscle Weakness Disorder

Alexion Pharmaceuticals Inc ALXN announced topline results from a Phase 3 study evaluating Ultomiris (ravulizumab-cwvz) in adults with generalized myasthenia gravis (gMG).
The study met its primary endpoint, with a statistically significant change in MG-ADL score from baseline through Week 26 for Ultomiris compared to placebo (-3.1 versus -1.4).
Myasthenia Gravis-Activities of Daily Living Profile (MG-ADL) is a patient-reported scale to assess MG symptoms and their effects on daily activities.
30% of Ultomiris patients experienced an improvement of at least 5 points in their MG clinical severity score than 11.3% on placebo.
These improvements were observed as early as Week 1 and were sustained through Week 26.
The proportion of patients who improved at least 3 points in MG-ADL score (56.7% versus 34.1% placebo) was not considered statistically significant.
On the safety front, the most frequently observed adverse events were headache (Ultomiris: 18.6%; placebo: 25.8%), diarrhea (15.1% vs. 12.4%), and nausea (10.5% vs. 10.1%).
The most frequently observed serious adverse events were MG crisis (Ultomiris: 1.2%) and MG worsening (placebo: 3.4%).
Alexion plans to submit regulatory filings in the U.S., European Union, and Japan in late 2021/early 2022.
Price Action: ALXN shares closed at $180.51 on Thursday.