Mereo BioPharma Announces Listing Transfer to Nasdaq Capital Market London

Mereo BioPharma Announces Listing Transfer to Nasdaq Capital Market

London, May 5, 2023 - Mereo BioPharma Group plc (NASDAQ: MREO) ( Mereo or the Company ), a clinical-stage

biopharmaceutical company focused on rare diseases, today announced that it has received approval from Listing Qualifications Department of the Nasdaq Stock Market ( Nasdaq ) to transfer the listing of its American Depositary Shares

( ADSs ) from the Nasdaq Global Market to the Nasdaq Capital Market. This transfer became effective at the opening of business on May 3, 2023.

The Nasdaq Global Market and the Nasdaq Capital Market are each market tiers of Nasdaq and the Nasdaq Capital Market is a continuous trading market that

operates in the same manner as the Nasdaq Global Market. Therefore, the Company s ADSs continue to trade under the ticker symbol MREO and are not affected by this change to the listing. The approval by Nasdaq was based upon the

Company meeting the applicable market value of publicly held shares requirement for continued listing and all other applicable requirements for initial listing on the Capital Market, except for the bid price requirement.

In connection with the transfer to the Nasdaq Capital Market, the Company became eligible for an additional 180-day

period (or until October 30, 2023) to regain compliance with the requirement set forth in Nasdaq Listing Rule 5450(a)(1) that the bid price of the Company s ADSs meet or exceed $1.00 per ADS for at least ten consecutive business days. As

of May 5, 2023, the closing bid price of the Company s ADSs had exceeded the $1.00 minimum per ADS for 10 consecutive business days and as a result, the Company believes that it has regained compliance with the relevant listing rule. The

Company will provide a further update on its compliance upon receipt of a formal written notification from Nasdaq.

About Mereo BioPharma

Mereo BioPharma is a biopharmaceutical company focused on the development of innovative therapeutics for rare diseases. The Company has developed a robust

portfolio of clinical stage product candidates. The Company has two rare disease product candidates, setrusumab for the treatment of osteogenesis imperfecta (OI) and alvelestat for the treatment of severe alpha-1-antitrypsin deficiency-associated lung disease (AATD-LD) and Bronchiolitis Obliterans Syndrome (BOS). The Company s partner, Ultragenyx Pharmaceutical,

Inc., has initiated a pivotal Phase 2/3 pediatric study in young adults (5-25 years old) for setrusumab in OI and expects to initiate a study in pediatric patients (<5 years old) in the first half of 2023.

The partnership with Ultragenyx includes potential milestone payments of up to $254 million and royalties to Mereo on commercial sales in Ultragenyx territories. Mereo has retained EU and UK commercial rights and will pay Ultragenyx royalties

on commercial sales in those territories. Alvelestat has received U.S. Orphan Drug Designation for the treatment of AATD, Fast Track designation from the FDA, and positive data were reported from a Phase 2 proof-of-concept study in North America, Europe and the UK. In addition to the rare disease programs, Mereo has two oncology product candidates in clinical development. Etigilimab (anti-TIGIT) has completed

enrollment in a Phase 1b/2 basket study evaluating its safety and efficacy in combination with an anti-PD-1 in a range of tumor types including three rare tumors and

three gynecological carcinomas - cervical, ovarian, and endometrial; Navicixizumab, for the treatment of late line ovarian cancer, has completed a Phase 1 study and has been partnered with OncXerna Therapeutics, Inc. in a global licensing agreement

that includes payments of up to $300 million in milestones and royalties.

Forward-Looking Statements

This press release contains forward-looking statements. All statements other than statements of historical fact contained in this press release are

forward-looking statements within the meaning of Section 27A of the United States Securities Act of 1933, as amended (the Securities Act ), and Section 21E of the United States Securities Exchange Act of 1934, as amended (the

Exchange Act ). Forward-looking statements usually relate to future events and anticipated revenues, earnings, cash flows or other aspects of our operations or operating results. Forward-looking statements are often identified by the

words believe, expect, anticipate, plan, intend, foresee, should, would, could, may, estimate, outlook

and similar expressions, including the negative thereof. The absence of these words, however, does not mean that the statements are not forward-looking. These forward-looking statements are based on the Company s current expectations, beliefs

and assumptions concerning future developments and business conditions and their potential effect on the Company. While management believes that these forward-looking statements are reasonable as and when made, there can be no assurance that future

developments affecting the Company will be those that it anticipates. All of the Company s forward-looking statements involve known and unknown risks and uncertainties some of which are significant or beyond its control and assumptions that

could cause actual results to differ materially from the Company s historical experience and its present expectations or projections. Such risks and uncertainties include, among others, the uncertainties inherent in the clinical development

process; the Company s reliance on third parties to conduct and provide funding for its clinical trials; the Company s dependence on enrollment of patients in its clinical trials; and the Company s dependence on its key executives.

You should carefully consider the foregoing factors and the other risks and uncertainties that affect the Company s business, including those described in the Risk Factors section of its latest Annual Report on Form 20-F, reports on Form 6-K and other documents furnished or filed from time to time by the Company with the Securities and Exchange Commission. The Company wishes to caution

you not to place undue reliance on any forward-looking statements, which speak only as of the date hereof. The Company undertakes no obligation to publicly update or revise any of our forward-looking statements after the date they are made, whether

as a result of new information, future events or otherwise, except to the extent required by law.