Sentynl bets up to $475M in licensing deal for Mereo’s rare lung disease asset alvelestat for AATD-LD on August 12, 2026 AATD-LD alpha-1 antitrypsin deficiency-associated lung disease Alvelestat Drugs, Orphan Fast Track Mereo BioPharma milestone payments Neutrophil Elastase Inhibitors royalties Sentynl upfront payments +