** Shares of Viridian Therapeutics VRDN.O rise 14.5% to $20.5 premarket

** Co late on Friday said U.S. FDA approved its drug to treat patients with thyroid eye disease

** The approval for the drug, Lumvoa, is supported by data to treat both active and chronic forms of the disease

** Viridian told Reuters that it expected to price Lumvoa at parity with existing approved IGF-1R therapy on a course-of-therapy basis

** Expects to file for U.S. approval of its subcutaneous version of treatment in early 2027

** RBC Capital Markets says, "We view Lumvoa's approval as a transformative milestone for VRDN as their first FDA-approved medicine transitions the company from clinical-stage to commercial-stage"

** As of last close, stock down 42.5% YTD