Amgen's Uplizna proves its worth in another rare disease, setting up regulatory filings in US and beyond

The CD19-targeted rare disease medicine Uplizna was one of the crown jewels in Amgen’s $27.8 billion buyout of Horizon Therapeutics. Now, with a phase 3 triumph in progressive fibroinflammatory disorder immunoglobulin G4-related disease (IgG4-RD), the medicine appears to be moving toward a label expansion.

In the MITIGATE study of 135 adults with IgG4-RD, treatment with 300 mg of intravenous Uplizna reduced the risk of a disease flare by 87% compared to placebo over 52 weeks, Amgen announced in a Wednesday press release.

Secondary endpoints showcasing the drug's ability to reduce disease flares and enable disease remission were also met, the company said, with investigators finding no new safety signals. Amgen said it will present the full trial data at a future medical meeting.

"MITIGATE is a landmark study with results that demonstrate an important advance in the treatment of patients with IgG4-RD, a devastating and rare disease that currently has no approved therapy,” Amgen’s chief scientific officer and executive vice president of R&D, Jay Bradner, M.D., said in the release.

IgG4-RD is a chronic immune-mediated disease that can progressively affect “almost any organ in the body,” often multiple at a time, and is hallmarked by periods of remission and unpredictable disease flares, according to Amgen. The condition can cause irreversible organ damage with or without symptoms.

MITIGATE marks the first placebo-controlled trial to deliver strong evidence for treating the disease with a “novel, steroid-sparing” regimen, the company added. The research could pave the way for a reduced toxicity treatment approach.

With the trial win in hand, Amgen will file for U.S. approval in IgG4-RD and in other "key markets." Uplinza is currently indicated to treat rare autoimmune disease neuromyelitis optica spectrum disorder in several regions.

The drug has changed hands several times since its original 2020 FDA approval, which was won by AstraZeneca subsidiary Viela Bio. Viela was a standalone inflammation and autoimmune drugmaker that was spun out of AZ’s now-retired R&D brand MedImmune in 2018.

Horizon Therapeutics took on Viela for $3 billion in a 2021 deal that centered on Uplinza and a clinical-stage pipeline. Amgen then bought out Horizon for $27.8 billion in 2023.

With $154 million in 2022 sales and $80 million over this year’s first quarter, the drug could prove a key growth driver for Amgen.

Amgen is also studying the drug in myasthenia gravis with a phase 3 readout slated for the second half of this year.