Exhibit 99.1 Mereo BioPharma Reports Full Year 2022 Financial Results and Recent Highlights — London, March 28, 2023 - Mereo BioPharma Group plc (NASDAQ: MREO) (“Mereo” or the “Company”), a clinical-stage biopharmaceutical company focused on rare diseases, today announced its financial results for the year ended December 31, 2022 and provided an update on recent corporate highlights. “In 2022, we made important progress in the ongoing advancement of our core rare disease programs. The data from our Phase 2 ...