Amgen (NASDAQ:AMGN) announced the presentation of positive top-line results from the Phase 3 MINT trial evaluating the efficacy and safety of UPLIZNA^® (inebilizumab-cdon) for the treatment of adults with generalized myasthenia gravis (gMG), a rare autoimmune disorder. Results from this randomized, double-blind, placebo-controlled, parallel-group trial will be presented at the Myasthenia Gravis Foundation of America (MGFA) Scientific Session during the American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM) Annual Meeting, taking place Oct. 15-18 in Savannah, Georgia.

The trial met its primary endpoint, with a statistically significant change from baseline in Myasthenia Gravis Activities of Daily Living (MG-ADL) score for UPLIZNA (-4.2) compared with placebo (-2.2) (difference: –1.9, p<0.0001) at Week 26 for the combined study population. The study included patients who are acetylcholine receptor autoantibody-positive (AChR+) and those who are muscle-specific kinase autoantibody-positive (MuSK+), with participants receiving UPLIZNA or placebo on Day 1 and Day 15. UPLIZNA demonstrated continued improvement through Week 26. Notably, patients who entered the study taking corticosteroids were tapered down starting at Week 4 to prednisone 5 mg per day by Week 24. No new safety signals were identified.

"Patients living with generalized myasthenia gravis deserve an effective treatment option that provides long-term symptom relief. Once approved, UPLIZNA is expected to offer a new option for patients earlier in their treatment plan," said Jay Bradner, M.D., executive vice president, Research and Development, and chief scientific officer at Amgen. "UPLIZNA targets CD19+ pre-B cells, mature B-cells and some plasmablasts, which are drivers of the disease. The clinically significant results from the MINT trial further strengthen the growing evidence for UPLIZNA in severe autoimmune diseases and reinforce Amgen's leadership in B-cell targeting therapeutics."

Key secondary endpoints were tested sequentially in a predefined order. UPLIZNA demonstrated a statistically significant and clinically meaningful change from baseline compared to placebo for the first four key secondary endpoints.

• UPLIZNA demonstrated a statistically significant change in Quantitative Myasthenia Gravis (QMG) score for the combined population (-4.8) compared to placebo (-2.3) at Week 26 (difference: -2.5, p=0.0002).
• In the AChR+ population, UPLIZNA demonstrated mean change from baseline (-4.2) in MG-ADL score at Week 26 compared to placebo (-2.4) (difference: -1.8, p=0.0015).
• In the AChR+ population, UPLIZNA demonstrated mean change from baseline (-4.4) in QMG score at Week 26 compared to placebo (-2.0) (difference -2.5, p=0.0011).
• In the MuSK+ population, UPLIZNA demonstrated mean change from baseline (-3.9) in MG-ADL score at Week 26 compared to placebo (-1.7) (difference -2.2, p=0.0297).

Additionally, in the MuSK+ population, the mean change from baseline in QMG score at Week 26 showed a trend favoring UPLIZNA but was not statistically significant (-5.2 for UPLIZNA and -3.0 for placebo, difference -2.3, p=0.1326).

"Myasthenia gravis can have a profound impact on patients by causing severe fatigable muscle weakness that impairs physical functioning, activities of daily living and quality of life," said Richard J. Nowak, M.D., M.S., global principal study investigator and director of the Myasthenia Gravis Clinic at Yale University. "This trial demonstrates clinically meaningful benefits of UPLIZNA, a twice-yearly infused medicine with a unique mechanism of action that selectively targets and depletes CD19+ B cells, which are key upstream drivers of myasthenia gravis. MINT is also the only Phase 3 biologic trial that included a protocol-specified steroid taper, an important consideration for patients as effects of prolonged high-dose steroid use contribute to the overall burden of disease."

The overall safety results during the placebo-controlled period of the trial were consistent with the known safety profile of UPLIZNA. The most common treatment-emergent adverse events were COVID-19, nasopharyngitis, urinary tract infection, infusion related reaction, headache and cough in the combined population.

MINT is the largest placebo-controlled gMG clinical trial for a biologic therapy (238 adults) and enrolled the largest number of patients (48 adults) who are MuSK+. The trial also included 190 adults who are AChR+. Further data will characterize placebo-controlled efficacy and safety of UPLIZNA over 12 months in AChR+ patients with gMG.

At the 2024 AANEM Annual Meeting, Amgen will also be presenting a poster titled, "The Burden of Glucocorticoid Use Among Patients with Generalized Myasthenia Gravis in the United States," highlighting how higher use of glucocorticoids was associated with more toxicities and overall health care resource utilization and costs.

UPLIZNA is currently approved for the treatment of neuromyelitis optica spectrum disorder (NMOSD) in adult patients who are anti-aquaporin-4 (AQP4) antibody positive in the United States, European Union, Brazil and Canada, among other countries. UPLIZNA was also recently granted Breakthrough Therapy Designation for IgG4-Related Diseases by FDA following Phase 3 results announced in June.

Based on the MINT primary results, Amgen is planning to file for approval in the U.S., followed by other key markets.