AZ boasts phase 3 win for self-administered gMG drug

News
Photo by Jonah Comstock

Alexion, the rare disease unit acquired by AstraZeneca nearly five years ago, has announced high-level positive results from a phase 3 trial of gefurulimab, a once-weekly self-administered treatment for generalised myasthenia gravis (gMG).

Though the company has not released the full results (which will be shared at an upcoming conference), they reported "statistically significant and clinically meaningful" improvement in the gMG Activities of Daily Living score, as well as a statistically significant and clinically meaningful reduction in disease severity, at week 26 compared to placebo. They also report that the drug was well-tolerated, and the safety profile was consistent with previous trials of C5 inhibitors in gMG.

gMG is a rare but debilitating autoimmune disease that can lead to muscle weakness, breathing troubles, difficulty swallowing, and impaired speech and vision. The study looked at adults in 20 countries with anti-acetylcholine receptor (AChR) antibody-positive (Ab+) gMG.

AstraZeneca's $39 billion acquisition of Alexion has generated most of its value so far from Soliris (eculizumab) and Ultomiris (ravulizumab), both C5 inhibitors that treat gMG among other rare conditions. But Soliris is facing new pressure from biosimilars that have recently become available in the United States.

Those drugs also have to be administered intravenously every two and eight weeks respectively. Gefurulimab, on the other hand, can be self-administered subcutaneously once a week, which AstraZeneca hopes will make it a more convenient option for some gMG patients. 

“Rapidly fluctuating symptoms and the unpredictable disability associated with gMG can affect nearly every aspect of a patient's life, making early intervention and sustained disease control a critical treatment goal," Dr Kelly Gwathmey, the principal investigator on the trial, said in a statement. "A once-weekly, self-administered C5 treatment option would offer patients greater convenience and independence in managing their condition, empowering them to have more control over their therapy.”

There are a couple of subcutaneous treatment options for gMG already on the market, including ArgenX's Vyvgart Hytrulo (efgartigimod alfa) and UCB's Rystiggo (rozanolixizumab) and Zilbrysq (zilucoplan). Of those, only Zilbrysq can be self-administered. Other potential competitors are on the horizon from Amgen and Johnson & Johnson.

At its annual investor day last year, AstraZeneca shared slides suggesting a one to three billion dollar peak year revenue potential for gefurulimab.