With a label expansion for Uplizna pushing the drug into an untouched rare disease market, Amgen is getting its money’s worth out of another drug from its $27.8 billion Horizon Therapeutics buy.
Uplizna is the first drug to win an FDA approval for immunoglobulin G4-related disease (IgG4-RD), a chronic inflammatory condition that can present in multiple organs and cause fibrosis and permanent organ damage, with or without symptoms.
The CD19-targeted therapy made strides in treating the disease in its phase 3 MITIGATE trial. In the study, Uplizna demonstrated an 87% reduction in the risk of IgG4-RD flares over placebo during the 52-week placebo-controlled period, with 10.3% of those on Uplizna experiencing a flare-up compared to 59.7% of those taking placebo.
With the approval, patients and physicians now have a “proven treatment that targets a key driver of the disease, reducing the risk of flares and reliance on harmful long-term steroid use,” Amgen’s executive vice president of R&D Jay Bradner, M.D., said in a company release. “This approval underscores Amgen's ongoing commitment and leadership in developing innovative treatments targeting CD19+ B-cells across multiple therapeutic areas."
Now, the road ahead for Amgen's success in IgG4-RD lays in raising awareness of the rare disease, which was only recently established with an International Classification of Diseases code in 2023. About 20,000 people are estimated to have the disease in the U.S., but the exact number is hard to pinpoint due to limited data, according to Amgen.
Still, the rare disease is a key stop on the rapid Uplizna expansion road map for Amgen. Beyond IgG4-RD, the drug has potential in other immune-mediated diseases, Bradner said in his statement, including generalized myasthenia gravis (gMG).
Last year, the company unveiled phase 3 results proving the drug's “clinically meaningful and statistically significant benefit” in treating gMG. While the gMG space is full of formidable competition with established treatments by AstraZeneca, Argenx and most recently UCB, Amgen’s offering has an advantageous dosing schedule and works “upstream” of other approved treatments, the company’s former rare disease chief, Vikram Karnani, said in a webcast at the time.
Amgen expects to wrap up its FDA submission for Uplizna in gMG in the first half of this year.
The quick expansion push for Uplizna comes after the drug was first approved in 2020 for neuromyelitis optica spectrum disorder (NMOSD), another rare autoimmune disease. Amgen reported $379 million in 2024 Uplizna sales from the sole indication but the newly unlocked IgG4-RD market could be a “meaningful expansion opportunity” as it adds a treatable patient population that’s double the size of that of NMOSD, William Blair analyst Matt Phipps wrote in a note last year.