Bull case
Mereo BioPharma Group is viewed favorably because alvelestat has shown compelling clinical signals, including a 48% reduction in the percentage of patients with moderate/severe exacerbations and a 36% decline in annualized exacerbation rate across ATLANTa and ASTRAEUS by 16wk, while its orphan status and estimated 50,000 North American and 60,000 European severe AATD patient pool highlight meaningful commercial upside. The Sentynl option agreement externally validates the asset and could deliver $40M in cash, up to $435M in milestones, and double-digit U.S. royalties, while also helping fund a Phase III study that management expects to align with the FDA ahead of an early 2027 initiation. Setrusumab adds another late-stage rare-disease catalyst, with ORBIT data showing reduced disease severity and improved pain/comfort and sports/activity in pediatric and teen patients, strengthening the company’s broader pipeline optionality.