Korro Bio Early Trial Results Fall Short; Stock Hits New Low

Core Insights - Korro Bio, Inc. (NASDAQ:KRRO) is experiencing a significant decline in stock price, down 80% to $6.27, with a trading volume of 6.68 million shares compared to the average of 1.42 million shares [1][8] - The company provided an update on its Phase 1/2a REWRITE clinical trial for KRRO-110, which targets alpha-1 antitrypsin deficiency (AATD) [1][2] - KRRO-110 successfully generated functional M-AAT protein in AATD patients, but the protein levels achieved were below preclinical projections [2][3] Clinical Trial Results - In a study involving five AATD patients, the peak total AAT protein reached approximately 10 µM, with a maximum increase from baseline of about 3 µM [3] - The total AAT protein levels did not meet the protective threshold of 11 µM, although no serious adverse events were reported [3] Strategic Restructuring - The company is implementing a strategic restructuring that includes a workforce reduction of approximately 34% to focus on generating clinical data and advancing liver-targeted programs [4][6] - This restructuring is expected to extend the company's cash runway into the second half of 2027, with cash and marketable securities reported at $102.5 million [6] Future Development Plans - Korro has nominated KRRO-121 as the next development candidate for hyperammonemia, with regulatory filing anticipated in the second half of 2026 [5] - The company amended its collaboration agreement with Novo Nordisk, establishing a 12-month pause to reassess the current research program [5] Analyst Commentary - William Blair downgraded Korro shares from Outperform to Market Perform, citing concerns over the non-competitive clinical profile of KRRO-110 despite the validation of ADAR-mediated editing [7] - The analyst expressed continued interest in Korro's expansion into urea cycle disorders with KRRO-121 but noted the company's shift back to a preclinical stage [7]