Viridian Therapeutics stock has fallen by 38%, despite its active thyroid eye disease (TED) drug meeting the primary endpoints of a Phase III trial.
In the REVEAL-1 study (NCT06625411), patients treated with elegrobart every four weeks met the US Food and Drug Administration (FDA) primary endpoint with a 54% proptosis responder rate (exophthalmometry), compared to 18% in the placebo cohort. This translated to a 2.33mm reduction in the treated cohort compared to a 0.81mm reduction in the placebo cohort.
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In the eight-weekly dosing group, the proptosis responder rate (as measured by exophthalmometry) was 63% in the treated group, compared to 18% in the placebo cohort. This translated to a 2.5mm reduction in the treated group and 0.81mm in the placebo cohort.
In the primary endpoint for the European Medicines Agency (EMA), in the patients treated every four weeks, there was an overall responder rate (ORR) of 51%, while this endpoint reached 58% in patients treated every eight weeks. This is compared to 16% in the placebo cohort.
Secondary endpoints, including diplopia responder rate and diplopia complete resolution, were also statistically significant.
Dr Prem Subramanian, professor of ophthalmology at Colorado University Anschutz, and chief of neuro-ophthalmology at the Sue Anschutz-Rodgers Eye Center, said: “Subcutaneous elegrobart showed rapid and clinically meaningful reductions in proptosis and diplopia in REVEAL-1 with a highly convenient, well-tolerated dosing profile. Patients are seeking more treatment choices for TED, and there remains a clear need for a more conveniently administered therapy. I am very encouraged to see the data for elegrobart and believe it has the potential to reach more TED patients than an intravenous therapy and to provide them with an attractive treatment option.”
Elegrobart is a subcutaneously delivered, half-life-extended monoclonal antibody targeting the insulin-like growth factor-1 receptor (IGF-1R). It was generally well tolerated in the Phase III trial, with most adverse events (AEs), being mild.
Data from REVEAL-2, the second pivotal trial, is set to be released in Q2 2026, with the company planning to submit a Biologics License Application (BLA) to the FDA for elegrobart in Q1 2027.
Despite this seemingly positive readout, the company’s stock plummeted by 38% on 30 March, from a $27.39 close on 27 March to a $17.00 open on 30 March. This may be due to investors losing confidence as to whether elegrobart can meet current marketed therapies, as well as the PRR being lower than expected.
Viridian Therapeutics is also awaiting an FDA decision on veligrotug, which is under Priority Review at the agency with a Prescription Drug User Fee Act (PDUFA) target action date of 30 June 2026. The company’s stock jumped in September 2024 after it announced that the trial met all of its endpoints in TED.
While Viridian is hoping to take hold of the market with two therapies, Amgen’s Tepezza (teprotumumab-trbw) is already a well-established drug for TED and is a targeted IGF-1R inhibitor. It was the first therapy to gain FDA approval for TED in 2020, and GlobalData predicts a sales forecast of $2.4bn in 2030.
GlobalData is the parent company of Clinical Trials Arena.
