Korro Bio’s shares plunged 81% after Phase I/IIa REWRITE data missed projections for its RNA editing oligonucleotide KRRO‑110 in alpha‑1 antitrypsin deficiency (AATD). The trial showed functional M‑AAT production but did not reach the protective AAT thresholds seen with competitor programs. The company announced a strategic restructuring cutting roughly 34% of staff to extend its cash runway into H2 2027 and will pivot to a GalNAc‑conjugated construct planned for 2027 clinic entry. The move highlights how early clinical shortfalls can trigger rapid operational retrenchment and reshaped development plans in small biotechs.