Viridian's Veligrotug Nears a June 30 FDA Decision for Thyroid Eye Disease, Pitching a Five-Infusion Course Against Tepezza

Overview

The U.S. Food and Drug Administration is due to decide on Viridian Therapeutics’ thyroid eye disease (TED) candidate veligrotug by June 30, 2026, the Prescription Drug User Fee Act target action date the agency set when it granted the application Priority Review, according to a Viridian release published via BioSpace. Veligrotug is “an intravenously delivered, anti-insulin-like growth factor-1 receptor (IGF-1R) antibody,” the same release states, and the company is positioning it as “a five-infusion treatment course enabling patients to complete treatment in 12 weeks.”

If approved, veligrotug would become the second IGF-1R antibody cleared for TED, entering a market defined since 2020 by teprotumumab (Tepezza). Its central pitch is a shorter treatment course rather than a new mechanism of action.

What We Know

Thyroid eye disease is an autoimmune condition associated with Graves’ disease that can push the eyes forward (proptosis) and cause double vision (diplopia). Both veligrotug and teprotumumab work by binding the IGF-1 receptor.

Veligrotug’s application rests on two Phase 3 trials. The Biologics License Application “is supported by positive data from two of the largest phase 3 clinical trials conducted in TED to date,” and in THRIVE and THRIVE-2, conducted in active and chronic TED patients respectively, “veligrotug met the primary and all secondary endpoints of each study,” the company said.

In THRIVE, the trial in active TED, a total of 113 patients were randomized to veligrotug (n=75) or placebo (n=38) and received “5 IV infusions 3 weeks apart of either 10 mg/kg veligrotug or placebo,” according to the THRIVE Phase 3 topline results published in Endocrine Practice. At 15 weeks, the proptosis responder rate by Hertel exophthalmometry was 70% for veligrotug versus 5% for placebo (p<0.0001), that publication reports. Among patients with diplopia, complete resolution occurred in 54% (27/50) of veligrotug patients versus 12% (3/26) on placebo, the same source states.

In THRIVE-2, the trial in chronic TED, 188 patients were randomized, with 125 assigned to veligrotug and 63 to placebo on the same 10 mg/kg, five-infusion schedule, according to the THRIVE-2 results in the Journal of the Endocrine Society. At week 15, the Hertel proptosis responder rate was 56% versus 8% (p<0.0001), with a mean proptosis reduction of 2.34 mm versus 0.46 mm (p<0.0001), that abstract reports. The diplopia responder rate was 56% versus 25% (p=0.0006), and complete resolution of diplopia reached 32% versus 14% (p=0.0152), the same source states.

The FDA granted the BLA Priority Review, which “shortens the BLA target review timeline to six months from ten months after the FDA accepts the BLA,” the company noted. The agency had earlier granted veligrotug Breakthrough Therapy Designation in May 2025, the same release states. “We are thrilled that the FDA granted Priority Review for veligrotug, marking another significant milestone for Viridian and the TED community,” said Steve Mahoney, Viridian’s President and CEO, according to the release.

Safety Signals

In THRIVE, adverse events occurred in 66 (88%) veligrotug patients versus 24 (63%) on placebo and were mostly mild, with four veligrotug patients experiencing serious adverse events that were all unrelated to treatment, the Endocrine Practice publication reports. Hearing impairment adverse events were reported for 12 (16%) veligrotug patients versus 4 (11%) on placebo in that trial, the same source states. In THRIVE-2, the most common treatment-emergent adverse events were muscle spasms (36% versus 6%), and hearing impairment occurred in 13% of veligrotug patients versus 3% on placebo, according to the Journal of the Endocrine Society. Hearing-related side effects have been a recognized concern across the IGF-1R inhibitor class.

The Competitive Context

Teprotumumab was the incumbent that veligrotug would challenge. “On 21st January 2020, the FDA approved Tepezza (teprotumumab-trbw) for the treatment of active Graves’ orbitopathy (GO) in adults in the US,” representing “the first drug approval for the treatment of GO,” according to a review in PMC. Like veligrotug, teprotumumab “is a fully human monoclonal IgG1 antibody that binds with high selectivity and affinity to insulin-like growth factor 1 receptor (IGF-1R),” the same review states. In its pivotal OPTIC trial, improvement in proptosis at week 24 was observed in 83% of the teprotumumab group versus 10% of the placebo group (p<0.001), the review reports.

The two drugs differ in their treatment burden. Teprotumumab “is administered intravenously at an initial dose of 10 mg/kg thereafter 20 mg/kg every 3 weeks for 21 weeks,” per the PMC review — a longer course than veligrotug’s proposed five infusions over 12 weeks, as described by Viridian. Because the two have not been compared head-to-head, the contrast rests on cross-trial figures rather than a direct comparison.

What We Don’t Know

The THRIVE and THRIVE-2 data have not been tested against teprotumumab in a single trial, so any efficacy or safety comparison rests on cross-trial inference. The FDA’s June 30, 2026 target is an action date, not a guarantee of approval, and the agency has not published its review conclusions. Pricing, the precise approved label, and any post-marketing requirements remain unknown pending the decision.