Amgen announced that the U.S. Food and Drug Administration approved its CD19‑targeted B‑cell therapy UPLIZNA (inebilizumab‑cdon) for the treatment of generalized myasthenia gravis (gMG) in adults who are anti‑acetylcholine receptor (AChR) and anti‑muscle‑specific tyrosine kinase (MuSK) antibody positive. The approval, effective December 11, 2025, adds a twice‑yearly dosing regimen to the drug’s existing indications for neuromyelitis optica spectrum disorder and IgG4‑related disease.
The new indication comes at a time when Amgen’s rare‑disease franchise is a key growth engine. UPLIZNA generated $379 million in sales in 2024 and $422 million in the first nine months of 2025, and the company’s rare‑disease portfolio contributed $1.2 billion to Q3 2024 revenue. The Horizon Therapeutics acquisition in 2023, valued at $27.8 billion, brought in assets such as Tepezza, Krystexxa and UPLIZNA, reinforcing Amgen’s position in high‑margin niche markets.
In the competitive gMG landscape, UPLIZNA faces challengers such as argenx’s Vyvgart and Johnson & Johnson’s Imaav. UPLIZNA’s twice‑yearly dosing schedule is a distinct advantage, reducing treatment burden and potentially improving adherence compared with the quarterly or monthly regimens of its competitors. The drug’s mechanism—selective depletion of CD19‑positive B cells—offers a biologically targeted approach that may translate into durable symptom control.
The approval was supported by the Myasthenia Gravis Inebilizumab Trial (MINT), the largest Phase 3 study for this indication. At 26 weeks, UPLIZNA produced a statistically significant improvement in the MG‑ADL score versus placebo, and exploratory analyses showed sustained benefits in AChR‑positive patients through 52 weeks. These data demonstrate both efficacy and durability, key factors for clinicians and payers evaluating long‑term treatment options.
Management highlighted the approval’s strategic importance. Executive Vice President of Research and Development Jay Bradner said the twice‑yearly dosing “offers a new approach to treatment that addresses a biological root cause of disease and delivers durable efficacy.” The Myasthenia Gravis Foundation of America’s president, Samantha Masterson, noted the drug’s six‑month treatment‑free interval as a meaningful benefit for patients. Investors responded positively, with Amgen’s market capitalization reflecting confidence in the expanded rare‑disease pipeline and the company’s raised full‑year 2025 revenue guidance of $35.8 billion to $36.6 billion.
Pricing for UPLIZNA in the gMG indication is expected to mirror the $1,200–$1,400 per dose range used for its other indications, with reimbursement strategies focused on demonstrating cost‑effectiveness through durable symptom control and reduced healthcare utilization. The company plans to engage payers early to secure coverage and will monitor real‑world data to support value‑based agreements. The approval positions Amgen to capture a significant share of the estimated 80,000 to 100,000 U.S. gMG patients, potentially adding several hundred million dollars in annual sales over the next five years.
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