Amgen announced promising long-term data from its Phase 3 MINT trial evaluating Uplizna (inebilizumab-cdon) in adult patients with generalized myasthenia gravis (gMG), showing sustained and improved efficacy through 52 weeks of treatment.
The trial results, which will be presented at the upcoming American Academy of Neurology meeting, demonstrated that Uplizna provided durable symptom relief with just two doses per year following an initial loading dose in patients with acetylcholine receptor autoantibody-positive (AChR+) gMG, a chronic autoimmune disorder characterized by muscle weakness affecting breathing, swallowing, and movement.
Sustained Efficacy at One Year
Among AChR+ patients receiving Uplizna, 72.3% achieved a clinically meaningful improvement of ≥3 points in the Myasthenia Gravis Activities of Daily Living (MG-ADL) score at week 52, compared to just 45.2% in the placebo group. This builds upon previously reported data at week 26, when the trial met its primary endpoint with a statistically significant change from baseline in MG-ADL score for Uplizna (-4.2) versus placebo (-2.2).
The 52-week data also showed improvements in objective measures of disease severity. The change from baseline in the Quantitative Myasthenia Gravis (QMG) score was greater for patients in the Uplizna group compared to placebo, with 69.2% of AChR+ patients on Uplizna improving by ≥3 points versus 41.8% in the placebo group.
"These results are particularly encouraging because they demonstrate not only maintenance of effect but continued improvement over time," said a clinical investigator involved in the trial. "For patients with gMG, who often struggle with basic daily activities, these sustained improvements could translate to meaningful quality of life benefits."
Mechanism of Action and Safety Profile
Uplizna is a humanized IgG1 monoclonal antibody that targets CD19, a cell surface antigen present on immature and mature B cells. By depleting B cells that produce disease-causing autoantibodies, Uplizna addresses a key pathological mechanism in myasthenia gravis.
The safety profile observed in the MINT trial was consistent with Uplizna's known safety profile in its currently approved indication. No new safety signals were identified during the 52-week study period, reinforcing the therapy's favorable risk-benefit profile.
Competitive Landscape and Market Implications
Analysts from William Blair noted that Uplizna's efficacy data "look strong" and "solidify a meaningful role for Uplizna in the treatment of myasthenia gravis." The drug's infrequent dosing schedule—every six months after initial loading—may provide a significant advantage over competing therapies that require weekly, monthly, or bimonthly administration.
The gMG treatment landscape has evolved significantly in recent years, with several targeted therapies now available. However, many patients continue to experience inadequate symptom control or intolerable side effects with current options, highlighting the need for additional effective treatments.
Regulatory Pathway
Uplizna is currently approved for the treatment of neuromyelitis optica spectrum disorder (NMOSD) in adult patients who are anti-aquaporin-4 (AQP4) antibody-positive. It is also under priority FDA review for Immunoglobulin G4-related disease with a PDUFA date of April 3.
For the gMG indication, the FDA has granted Uplizna Orphan Drug Designation. Amgen has indicated that regulatory filing activities are underway, with submission anticipated to be complete in the first half of 2025.
Clinical Trial Design
The Phase 3 MINT trial enrolled 238 patients with gMG, including 190 who were AChR+ antibody positive. This subpopulation analysis is particularly relevant as AChR+ patients represent approximately 80-85% of all gMG cases.
The trial design included a 26-week placebo-controlled period followed by an open-label extension. The primary endpoint was the change from baseline in MG-ADL score at week 26, with continued assessment through week 52 to evaluate durability of response.
Unmet Need in Myasthenia Gravis
Generalized myasthenia gravis affects approximately 14-20 per 100,000 people worldwide. Despite existing treatments, including acetylcholinesterase inhibitors, immunosuppressants, and newer targeted therapies, many patients continue to experience debilitating symptoms that significantly impact their quality of life.
"The burden of myasthenia gravis extends beyond physical limitations to encompass psychological, social, and economic impacts," explained a neurology specialist familiar with the condition. "Patients often struggle with unpredictable symptom flares that can lead to hospitalization and, in severe cases, respiratory crisis."
The positive 52-week data from the MINT trial suggest that Uplizna could potentially address this significant unmet need by providing a durable treatment option with an infrequent dosing schedule, potentially improving both efficacy outcomes and treatment adherence for patients with this challenging autoimmune disorder.
