Viridian's VRDN-008 sustains IgG suppression through 8 weeks in phase 1

Viridian Therapeutics, has reported positive phase 1 results for VRDN-008, an investigational neonatal Fc receptor (FcRn) inhibitor that the company says could be dosed subcutaneously as infrequently as every 8 weeks.¹

The data mark the company's most significant step outside of TED to date and position VRDN-008 to enter registrational development in myasthenia gravis (MG)—an autoantibody-mediated disease with well-recognized ocular presentations.¹

Phase 1 study design and findings

The phase 1 trial evaluated subcutaneous VRDN-008 in healthy volunteers, each of whom received 2 doses: one at study start and a second at week 4.¹ According to a company filing, the cohort included 6 participants.²

VRDN-008 is a bifunctional molecule licensed from Paragon Therapeutics that combines an Fc fragment with an albumin-binding domain, a design intended to extend circulating half-life and prolong suppression of immunoglobulin G (IgG).¹ FcRn normally protects IgG from lysosomal degradation and recycles it back into circulation; blocking the receptor accelerates clearance of IgG, including pathogenic autoantibodies.

Key results reported by the company include:¹

• Half-life extension: a half-life of 15 to 18 days, which Viridian describes as up to 6 times longer than first-generation Fc fragments.
• IgG suppression: deep and sustained IgG reduction through 8 weeks after dosing, with a 74% reduction at peak.
• Safety: albumin and LDL levels were spared, and the agent was generally well tolerated, with no serious adverse events or dose-limiting toxicities.

Albumin and LDL sparing is a relevant point of differentiation in the class. Earlier FcRn-targeting antibodies, including batoclimab, have been associated with reductions in albumin and elevations in LDL cholesterol, effects that have shaped how long patients can stay on therapy.⁶

“Today's VRDN-008 data exceeded expectations and demonstrates a potentially transformative FcRn-inhibitor profile,” said Steve Mahoney, president and CEO of Viridian.¹

In a prior head-to-head study in nonhuman primates, a single high dose of VRDN-008 showed a longer half-life and more sustained IgG reduction than efgartigimod, the company reported in its third-quarter update.³

Wearable delivery and a direct-to-registrational path

Viridian plans to deliver VRDN-008 using enFuse, a hands-free, on-body injector developed by Enable Injections that operates with a single button press and is designed for at-home self-administration.¹ The company holds exclusive global rights to the device for FcRn-targeted therapies.¹

The company intends to begin at least 1 registrational trial in 2027, starting with MG in mid-2027, pending regulatory feedback.¹ The planned multi-arm, placebo-controlled study would test every-4-week and every-8-week dosing arms against placebo, a design Viridian says supports a direct-to-registrational development path.¹ Beyond MG, the company plans to pursue VRDN-008 in multiple other autoantibody-mediated autoimmune diseases.¹

“We are excited for VRDN-008 to anchor a new chapter for Viridian, extending our impact beyond our foundation of thyroid eye disease to a broader range of autoimmune diseases,” Mahoney said.¹

Why it matters for eye care

Although VRDN-008 is not being developed as an ophthalmic therapy, its lead indication sits squarely within the scope of neuro-ophthalmology. MG has ocular signs in roughly 75% of cases, and those signs—ptosis and diplopia—are the first manifestations in the large majority of patients, Julie Falardeau, MD, of the Casey Eye Institute, has noted in Ophthalmology Times.⁴ That makes the ophthalmologist frequently the first clinician to evaluate a patient whose disease may later generalize.⁴

FcRn inhibition has also been explored directly in TED. Because the thyrotropin receptor autoantibodies that drive orbital disease are IgG, lowering circulating IgG offers a mechanistic rationale; batoclimab produced proof-of-concept reductions in these antibodies in early TED trials.⁶ Fatemeh Rajaii, MD, PhD, of the Wilmer Eye Institute, Johns Hopkins, identified anti-FcRn agents as one of 3 main mechanistic classes under investigation in TED, alongside IGF-1 receptor and IL-6 receptor blockade.⁵ Viridian has not announced plans to study VRDN-008 in TED.¹

The broader Viridian pipeline

The FcRn update follows a busy year for Viridian in TED. The FDA approved veligrotug-vvze in June 2026 with a label covering both active and chronic disease regardless of activity or duration.⁷ The company's subcutaneous IGF-1R antagonist elegrobart met its primary end points in both the REVEAL-1 trial in active TED and the REVEAL-2 trial in chronic TED, and a biologics license application is expected in the first quarter of 2027.^8–10 At AAO 2026, Michael T. Yen, MD, of Baylor College of Medicine, told Ophthalmology Times that an at-home subcutaneous option could ease treatment burden while complementing, rather than replacing, intravenous therapy.⁹ Viridian also expects to begin a phase 1 trial of VRDN-292, a thyroid-stimulating hormone receptor inhibitor, in patients with Graves disease in the fourth quarter of 2026.³

Limitations and next steps

The phase 1 data are pharmacokinetic and pharmacodynamic findings from a small cohort of healthy volunteers, and IgG reduction is a surrogate rather than a clinical outcome. Whether the depth and duration of suppression seen here will translate into durable disease control in MG or other autoimmune conditions—including improvement in ocular signs—will depend on results from controlled patient trials. Full data have not yet been published in a peer-reviewed journal.

References

1. Viridian Therapeutics announces positive VRDN-008 phase 1 results supporting potential best-in-class profile with every-8-week subcutaneous dosing. News release. Viridian Therapeutics. November 9, 2026. Accessed November 9, 2026. https://www.viridiantherapeutics.com/press-release/viridian-therapeutics-announces-positive-vrdn-008-phase-1-results-supporting-potential-best-in-class-profile-with-every-8-week-subcutaneous-dosing/

2. Viridian reports positive phase 1 results for VRDN-008. TipRanks. November 9, 2026. Accessed November 9, 2026. https://www.tipranks.com/news/company-announcements/viridian-reports-positive-phase-1-results-for-vrdn-008

3. Viridian Therapeutics reports third quarter 2026 financial results and highlights recent business progress. News release. Viridian Therapeutics. November 4, 2026. Accessed November 9, 2026. https://www.biopharmawatch.com/news/VRDN/viridian-therapeutics-q3-2026-results

4. Ptosis: a sign of myasthenia gravis. Ophthalmology Times. Accessed November 9, 2026. https://www.ophthalmologytimes.com/view/ptosis-sign-myasthenia-gravis

5. AAO 2024: Therapies offering hope for patients diagnosed with TED. Ophthalmology Times. October 20, 2024. Accessed November 9, 2026. https://www.ophthalmologytimes.com/view/aao-2024-therapies-offering-hope-for-patients-diagnosed-with-ted

6. Kahaly GJ, Dolman PJ, Wolf J, et al. Proof-of-concept and randomized, placebo-controlled trials of an FcRn inhibitor, batoclimab, for thyroid eye disease. J Clin Endocrinol Metab. 2023;108(12):3122-3134. doi:10.1210/clinem/dgad381

7. Lumvoa gains US FDA approval for thyroid eye disease with class-first broad label. Ophthalmology Times. June 27, 2026. Accessed November 9, 2026. https://www.ophthalmologytimes.com/view/lumvoa-gains-us-fda-approval-for-thyroid-eye-disease-with-class-first-broad-label

8. Phase 3 trial: positive topline results for elegrobart for the treatment of TED. Ophthalmology Times. May 9, 2026. Accessed November 9, 2026. https://www.ophthalmologytimes.com/view/phase-3-trial-positive-topline-results-for-elegrobart-for-the-treatment-of-ted

9. AAO 2026: How subcutaneous elegrobart could change TED care. Ophthalmology Times. October 14, 2026. Accessed November 9, 2026. https://www.ophthalmologytimes.com/view/aao-2026-subcutaneous-elegrobart-could-change-ted-care

10. Phase 3 topline REVEAL-1 results for elegrobart for TED. Ophthalmology Times. March 31, 2026. Accessed November 9, 2026. https://www.ophthalmologytimes.com/view/phase-3-topline-reveal-1-results-for-elegrobart-for-ted