The FDA has approved the CD19+ B-cell targeted therapy inebilizumab-cdon (Uplizna, Amgen) for the treatment of adults with generalized myasthenia gravis (gMG) who test positive for anti-acetylcholine receptor (AChR) or anti-muscle-specific tyrosine kinase (MuSK) antibodies. 

“The approval offers patients a new targeted treatment option that has the potential for long-term disease control with just two doses a year, after two initial loading doses,” Amgen said in a news release. 

“This approval marks an important milestone, offering durable efficacy and a dosing schedule that provides people living with generalized myasthenia gravis 6 months of treatment-free time between maintenance doses,” added Samantha Masterson, president and CEO of the Myasthenia Gravis Foundation of America. 

Inebilizumab-cdon is already approved in the US for neuromyelitis optica spectrum disorder and immunoglobulin G4-related disease. 

gMG is a rare chronic B-cell-mediated autoimmune disorder that impairs neuromuscular communication and can cause fluctuating muscle weakness. The disease is thought to be primarily driven by AChR and MuSK autoantibodies produced by CD19+ B cells.

The approval of inebilizumab-cdon in gMG was supported by results from the phase 3 randomized, placebo-controlled MINT trial, which enrolled 238 adults with gMG (AChR+, n = 190; MuSK+, n = 48).

At week 26, inebilizumab-cdon demonstrated a statistically significant 1.9-point difference in the Myasthenia Gravis Activities of Daily Living score compared with placebo (-4.2 vs -2.2; P < .0001), the company noted. 

The benefits in the AChR+ patient subgroup continued through 52 weeks, “the longest randomized-controlled period for a phase 3 trial in gMG,” the company said. 

The MINT study also included a novel steroid tapering protocol. Patients on steroids at baseline began tapering at week 4 to reach prednisone 5 mg per day by week 24. By week 26, 87% of patients taking inebilizumab-cdon and 85% of those taking placebo had reduced their steroid dose to 5 mg or less per day, the company said. 

“Uplizna showed strong efficacy at 26 weeks in both AChR+ and MuSK+ patients, with AChR+ patients continuing to improve through 52 weeks in MINT,” Richard J. Nowak, MD, global principal investigator and director of the Myasthenia Gravis Clinic at Yale University, New Haven, Connecticut, said in the news release.

“MINT also uniquely required steroid tapering, recognizing that long-term steroid use adds to the overall burden of disease. This approval brings a new first-in-class approach to gMG, expanding treatment options for clinicians and patients,” Nowak added.

The most common adverse reactions were headache and infusion-related reactions. Full prescribing information is available online.