Viridian wins FDA approval for thyroid eye disease drug, setting up clash with Amgen

Viridian Therapeutics (VRDN) has secured US regulatory approval for Lumvoa to treat thyroid eye disease, opening a competitive front against Amgen's (AMGN) blockbuster Tepezza, until now the only medicine available for the painful, eye-bulging autoimmune disorder.

The Food and Drug Administration cleared the drug for adults with active or chronic thyroid eye disease, making it the first therapy in its anti-insulin-like growth factor 1 receptor (IGF-1R) class to carry labeling that includes data across both stages of the condition, the company said.

Viridian is also emphasizing a convenience advantage over Tepezza, which shares the same target. "We have a shorter infusion time — 30 to 40 minutes versus 60 to 90 minutes, and we only have five infusions versus eight," said Steve Mahoney, chief executive, in an interview. He noted that Lumvoa requires a 12-week treatment period against 21 weeks for the incumbent.

The company is further highlighting the speed of the drug's effect, with a majority of patients gaining relief from proptosis, or eye-bulging, after a single infusion. Lumvoa is the first approved treatment for the disease to show a statistically significant effect on both improvement and complete resolution of double vision in active and chronic patients, Viridian said.

Although Lumvoa carries the same mechanism of action as Tepezza, it is a "fundamentally different compound," according to Radhika Tripuraneni, chief medical officer. She described Tepezza as a partial antagonist, compared with Lumvoa's binding mechanism, which she said delivered a "more full antagonism approach."

The approval was supported by two phase 3 trials showing that a 12-week course produced statistically significant and clinically meaningful improvements at week 15 across the key signs and symptoms of the disorder.

"We believe Lumvoa has the potential to capture meaningful market share from Tepezza, supported by its competitive clinical profile across both active and chronic TED populations, with potential for modest market expansion," said Lachlan Hanbury-Brown, an analyst at William Blair, in a note to investors. He cautioned, however, that investors "should have modest expectations for revenue in the second half of 2026," given the time required for patients to gain reimbursement.

Thyroid eye disease is an autoimmune condition that inflames the muscles and tissue around the eyes, causing pain that patients often liken to the sensation of sand in the eye. Sufferers can also develop eyelid retraction. The disease mostly affects women in their 40s and 50s.

Lumvoa is the first approved product for Viridian. The Massachusetts-based biotech went public a decade ago as miRagen Therapeutics before acquiring the privately held Viridian in 2020 and adopting its name.

The company plans to launch the drug immediately. The wholesale acquisition cost for an average patient of 75kg is $450,000, which Tony Casciano, chief commercial officer, said brought it into parity with Tepezza on a course-of-therapy basis, since five infusions of Lumvoa cost roughly the same as eight of the rival treatment.

In preparation, Viridian has added about 100 sales representatives and more than doubled its headcount to over 400 employees since Mahoney took charge in 2023. The company closed the first quarter with $762mn in cash. A month ago it agreed a five-year, non-exclusive supply deal for Lumvoa with WuXi Biologics, the Chinese contract manufacturer, according to a regulatory filing.

Amgen, which gained Tepezza through its $27.8bn acquisition of Horizon Therapeutics in 2023, has struggled to lift sales. The drug peaked at $1.97bn in 2022, its second full year on the market following a 2020 approval, and generated $1.90bn last year.