WALTHAM, Mass.–Viridian Therapeutics has reported positive Phase 1 clinical trial results for its experimental autoimmune disease treatment VRDN-008, demonstrating sustained reductions in immunoglobulin G (IgG) levels for up to eight weeks following subcutaneous administration.
The biotechnology company said the findings support the potential for VRDN-008 to be administered once every eight weeks, a dosing schedule that could reduce treatment frequency for patients with certain autoimmune diseases.
Viridian plans to advance the drug into pivotal clinical development in 2027, beginning with a registrational trial in myasthenia gravis (MG) in mid-2027, subject to regulatory feedback.
VRDN-008 is an investigational, half-life-extended neonatal Fc receptor (FcRn) inhibitor licensed from Paragon Therapeutics. The treatment is designed to reduce circulating IgG antibodies, including harmful autoantibodies involved in several autoimmune disorders.
The Phase 1 trial evaluated the drug in healthy volunteers who received two subcutaneous doses, one at the beginning of the study and another at week four.
According to Viridian, VRDN-008 produced a peak IgG reduction of 74%, with suppression sustained through eight weeks after dosing. The drug also demonstrated a half-life of 15 to 18 days, approximately six times longer than first-generation Fc fragments.
The company reported that VRDN-008 was generally well tolerated, with no serious adverse events or dose-limiting toxicities observed during the trial. The treatment also maintained albumin and low-density lipoprotein (LDL) levels, suggesting a differentiated safety profile.
“Today’s VRDN-008 data exceeded expectations and demonstrates a potentially transformative FcRn-inhibitor profile. Based on these data, we believe VRDN-008 dosed subcutaneously every 8 weeks can deliver deep and sustained IgG reductions and could provide patients a potential best-in-class option for extended disease control and convenience. We view this as a major clinical advancement for patients living with autoantibody-mediated autoimmune diseases,” said Steve Mahoney, President and Chief Executive Officer of Viridian.
The company intends to use Enable Injections’ enFuse wearable drug delivery system for subcutaneous administration of VRDN-008. The hands-free, on-body injector is designed to allow patients to administer medication at home with the push of a button.
Viridian secured exclusive global rights to the enFuse system for FcRn-targeted therapies in January 2023. The technology is already used with several FDA-approved medications and is being evaluated for additional therapies.
The planned myasthenia gravis trial will evaluate VRDN-008 in a placebo-controlled, multi-arm study comparing two dosing schedules. One treatment group will receive the drug every four weeks, while another will receive it every eight weeks.
Viridian said the study is intended to support a direct path toward a potential Biologics License Application (BLA), depending on clinical outcomes and regulatory discussions.
“We plan to advance VRDN-008 rapidly into registrational development starting with MG in mid-2027, pending feedback from regulatory authorities. Our team has a proven track record of execution, and we plan to quickly generate pivotal clinical data to support a potential rapid path to BLA. Beyond MG, there are multiple autoantibody-mediated autoimmune diseases where we believe that we can develop VRDN-008, including several that are clinically validated for FcRn inhibition, each representing addressable multi-billion-dollar market opportunities. 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.”
Myasthenia gravis is a chronic autoimmune neuromuscular disorder in which antibodies interfere with communication between nerves and muscles, causing muscle weakness and fatigue. FcRn inhibitors are designed to lower levels of circulating IgG antibodies that contribute to the disease.
Beyond myasthenia gravis, Viridian plans to investigate VRDN-008 across additional autoantibody-mediated autoimmune conditions, expanding its development pipeline beyond thyroid eye disease.
Although the Phase 1 findings demonstrated sustained IgG suppression in healthy volunteers, further clinical studies will be required to determine whether the treatment can provide comparable benefits, establish its safety and effectiveness in patients, and support regulatory approval.
