** Shares of some biotech companies rise premarket as head of U.S. health regulator's vaccines and biologics unit Vinay Prasad set to leave the agency in April

** "We believe his departure will lead to a much more favorable regulatory environment for certain companies such as Regenxbio RGNX.O" - Clear Street

** Shares of UniQure UQ1.F, Disc Medicine IRON.O, Capricor Therapeutics CAPR.O and Regenxbio climb between 1.5% and 35% in trading before the bell

** "Overall, we believe Dr. Prasad's departure is likely a tailwind for the biotech sector, particularly in cases of regulatory flexibility for companies developing novel therapies for rare diseases, but we would caution against celebrating before a replacement is disclosed" - William Blair

** Truist analysts said while they expect his departure to be viewed positively by industry stakeholders, the overall outlook remains far from clear until it becomes clear who will lead the unit

** Up to last close, RGNX down 39.9%, QURE down 40.3%, IRON down 22.9% and CAPR down 3.3% YTD

(Reporting by Sneha S K)

((Sneha.SK@thomsonreuters.com;))