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10/8/25 , 3:42 PM Table of Contents 20 - F UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 FORM 20 - F ( Mark One ) REGISTRATION STATEMENT PURSUANT TO SECTION 12 ( b ) OR ( g ) OF THE SECURITIES EXCHANGE ACT OF 1934 OR ☑ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31 , 2021 OR TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to OR SHELL COMPANY REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of event requiring this shell company report Commission file number : 001-38452 MEREO BIOPHARMA GROUP PLC ( Exact name of Registrant as specified in its charter ) England and Wales ( Jurisdiction of incorporation or organization ) One Cavendish Place 4th Floor London , W1G 0QF United Kingdom Tel : + 44-333-023-7300 ( Address of principal executive offices ) Charles Sermon , General Counsel Tel : + 44-333-023-7300 Email : cs@mereobiopharma.com 1 Cavendish Place 4th Floor London , W1G 0QF United Kingdom ( Name , Telephone , E - mail and / or Facsimile number and Address of Company Contact Person ) Securities registered or to be registered pursuant to Section 12 ( b ) of the Act : Title of each class Trading Symbol https://www.sec.gov/Archives/edgar/data/1719714/000119312522091822/d237872d20f.htm Name of each exchange on which registered 1/240