FDA Accepts, Grants Priority Review to Veligrotug BLA for Thyroid Eye Disease

On December 22, the US Food and Drug Administration (FDA) accepted the Biologics License Application (BLA) for – and granted Priority Review to – veligrotug, an intravenous anti-insulin-like growth factor 1 receptor (IGF-1R) antibody in development for thyroid eye disease (TED).¹

Announced by parent company Viridian Therapeutics, veligrotug’s BLA is supported by positive topline data from the THRIVE and THRIVE-2 phase 3 clinical trials. During both trials, veligrotug achieved the primary and all secondary endpoints, showing a rapid onset of clinical benefit. Additionally, the FDA has announced a PDUFA target action date of June 30, 2026.¹

“We are thrilled that the FDA granted Priority Review for veligrotug, marking another significant milestone for Viridian and the TED community,” Steve Mahoney, president and CEO of Viridian, said in a statement. “This designation is a recognition that, if approved, veligrotug would be a significant improvement in the safety or effectiveness of treating a serious condition.”¹

THRIVE saw veligrotug compared to placebo among patients with moderate to severe TED. To be eligible for inclusion, patients had to have a Clinical Activity Score of ≥3 on the 7-item scale for the study eye and moderate to severe TED with documented evidence of ocular symptoms or signs beginning within 15 months before screening. Patients who had received prior treatment with another anti-IGF-1R therapy, had used systemic corticosteroids or selenium within 2 weeks of Day 1, or had received rituximab, tocilizumab, or other immunosuppressive agents within 8 weeks of Day 1 were excluded, among other criteria.²

Patients were randomized to receive either veligrotug 10 mg/kg or a matching placebo. THRIVE’s primary endpoint was proptosis responder rate in the study eye at week 15. Secondary measures included change from baseline in proptosis as measured by exophthalmometer, change from baseline in Clinical Activity Score, and change from baseline in proptosis as measured by MRI/CT.²

Ultimately, 70% of veligrotug recipients (21/30), who were proptosis responders at week 15 and continued treatment out to the end of the study at 52 weeks, maintained their proptosis response. Additionally, 65% of recipients were proptosis responders after adjusting for placebo. There were no changes to the safety profile for the duration of the follow-up period.³

THRIVE-2 was a randomized, double-masked, placebo-controlled study involving patients with chronic TED. Patients were eligible for inclusion if they exhibited severe chronic TED with documented evidence of ocular symptoms and had a clinical diagnosis of TED with any Clinical Activity Score. Patients were excluded if they had received prior treatment with anti-IGF-1R therapy, systemic corticosteroids, or other immunosuppressive drugs, among other criteria.⁴

Patients were randomly assigned to receive 5 intravenous infusions of either veligrotug 10 mg/kg or a matching placebo every 3 weeks for a duration of 12 weeks. The trial’s primary endpoint was the proptosis responder rate in the most proptotic eye. Secondary endpoints included change from baseline in proptosis, Clinical Activity Responder Rate in the most proptotic eye, and diplopia responder rate, among others.⁴

Ultimately, 56% of veligrotug recipients were proptosis responders, compared to 8% in the placebo arm. Proptosis response was significant at all time points, beginning at 3 weeks after the first infusion, which demonstrated veligrotug’s rapid onset of response. Additionally, the veligrotug arm achieved a mean proptosis reduction of 2.34 mm, compared to 0.46 mm in the placebo arm. THRIVE-2 also saw 56% of veligrotug recipients achieve a diplopia response, compared to 25% in the placebo arm. Rapid onset was observed as early as 6 weeks after the first 2 infusions. 32% of veligrotug recipients achieved complete resolution of diplopia, compared with 14% of the placebo arm.⁵

“We very much appreciate all of the support we’ve received from patients, investigators, and our clinical partners,” Mahoney said in a statement. “We look forward to working closely with the FDA as we advance toward our goal of delivering a potentially transformative therapy to people living with thyroid eye disease and establishing Viridian as a leading commercial company in TED.”¹

References

1. Viridian Therapeutics, Inc. Viridian Therapeutics Announces BLA Acceptance and Priority Review for Veligrotug for the Treatment of Thyroid Eye Disease. Businesswire. December 22, 2025. Accessed December 22, 2025. https://www.businesswire.com/news/home/20251222159703/en/Viridian-Therapeutics-Announces-BLA-Acceptance-and-Priority-Review-for-Veligrotug-for-the-Treatment-of-Thyroid-Eye-Disease

2. Viridian Therapeutics, Inc. A Safety, Tolerability, and Efficacy Study of Veligrotug (VRDN 001) in Healthy Volunteers and Participants With Thyroid Eye Disease (TED) (THRIVE) (THRIVE). ClinicalTrials.gov Identifier: NCT05176639. Updated July 18, 2025. Accessed December 22, 2025. https://clinicaltrials.gov/study/NCT05176639

3. Viridian Therapeutics, Inc. Viridian Therapeutics Announces Positive Long-Term Durability Data from the Veligrotug Phase 3 THRIVE Clinical Trial in Patients with Active Thyroid Eye Disease (TED). May 20, 2025. December 22, 2025. https://investors.viridiantherapeutics.com/news/news-details/2025/Viridian-Therapeutics-Announces-Positive-Long-Term-Durability-Data-from-the-Veligrotug-Phase-3-THRIVE-Clinical-Trial-in-Patients-with-Active-Thyroid-Eye-Disease-TED/default.aspx

4. Viridian Therapeutics, Inc. An Efficacy, Safety, and Tolerability Study of Veligrotug (VRDN-001), in Participants With Chronic Thyroid Eye Disease (TED) (THRIVE-2) (THRIVE-2). ClinicalTrials.gov Identifier: NCT06021054. Updated October 23, 2025. Accessed December 22, 2025. https://www.clinicaltrials.gov/study/NCT06021054

5. Viridian Therapeutics, Inc. Viridian Therapeutics Announces Positive Topline Results from Veligrotug Phase 3 THRIVE-2 Clinical Trial in Patients with Chronic Thyroid Eye Disease. December 16, 2024. Accessed December 22, 2025. https://investors.viridiantherapeutics.com/news/news-details/2024/Viridian-Therapeutics-5: Announces-Positive-Topline-Results-from-Veligrotug-Phase-3-THRIVE-2-Clinical-Trial-in-Patients-with-Chronic-Thyroid-Eye-Disease/default.aspx