Mereo BioPharma Group plc announced regulatory feedback following recent end-of-Phase 2 meetings with the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA) related to its alvelestat program for the treatment of alpha-1-antitrypsin deficiency-associated lung disease (AATD-LD). Based on clear recommendations from the FDA and the EMA, the Company is designing a single, global, Phase 3 study evaluating the 240 mg dose of alvelestat versus placebo in patients with AATD-LD to support applications for full marketing approvals in both the United States (U.S.) and European Union (EU). The Company's proposed Phase 3 study has two independent primary endpoints, i) a Patient-Reported Outcome (PRO), as guided by the FDA, and ii) lung density measured by CT scan, as guided by the EMA.

In line with previous guidance by the Company, Mereo is exploring potential partnerships to fund the Phase 3 study, and believes that this clear path forward will support these efforts. The association of desmosine reduction with lung density measured by CT scan was demonstrated in published clinical data in AATD. Both the FDA and EMA recognize the challenges associated with development of new therapeutics for AATD-LD.

Consistent with an openness to supporting the advancement of therapeutic development in this space, the EMA has indicated that for the primary endpoint of lung density measured by CT scan., it would accept a more relaxed Type 1 error (i.e., p<0.1) for a potential full approval that is not contingent on the outcome of a confirmatory study. Mereo also believes that this proposed study, if successful, will support more productive initial reimbursement discussions with payors following potential regulatory approvals. 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 recently 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.