Viridian Therapeutics announced on Mar. 31 that its investigational antibody, elegrobart, met the primary goal of reducing abnormal bulging of the eyes in a late-stage study for thyroid eye disease but did not meet investor expectations.
The outcome is significant because it may affect Viridian's chances of bringing the first subcutaneous treatment for this condition to market. The company's stock dropped nearly 33% to $18.53 per share following the announcement.
Analysts from Truist Securities described the data as encouraging and highlighted that subcutaneous dosing could help commercialize the drug. William Blair analysts said, “these results not only support potential regulatory approvals” but also “support a compelling commercial profile and significant market opportunity” if approved.
In the Phase 3 REVEAL-1 trial, two dosing schedules were tested: every four weeks and every eight weeks. The monthly group had a response rate of 54%, while those treated every eight weeks had a response rate of 63%. The placebo group saw an 18% response rate. However, William Blair noted that placebo-adjusted responder rates fell below what investors anticipated: "While there are several factors that may contribute to this weaker placebo-adjusted delta," such as a strong placebo response, "the fact remains that the headline proptosis responder rate does not fully live up to expectations," William Blair added.
Although elegrobart achieved one key secondary endpoint by showing greater mean reduction in proptosis compared to placebo, it did not outperform placebo on clinical activity scores (CAS). This result prevented further statistical testing on other secondary outcomes due to study design rules. Still, Viridian reported some numerical advantages for diplopia resolution and proptosis improvement with less frequent dosing.
Truist called elegrobart’s safety profile “clean,” describing all adverse events as non-serious and mild; hearing-related issues included tinnitus but no hearing loss was observed. Analysts said they believe this safety profile will support future regulatory submissions.
Viridian stated it expects another pivotal readout later in the year and plans to submit a biologics license application in early 2027.
