Korro Bio Highlights Data for its Lead Program in Alpha-1 Antitrypsin Deficiency (AATD) and Progress Across its RNA Editing Portfolio

• KRRO-110 has a potentially best-in-class profile with secretion of ~50µM functional AAT protein after a single dose in a preclinical mouse model
• Evidence of greater than 40% editing of SERPINA1 RNA in non-human primates (NHPs) further supports the potential translation of KRRO-110 in humans
• Demonstrated greater than 50% editing using GalNAc conjugates in the liver in a preclinical mouse model
• Generated a de novo protein variant in NHPs, further highlighting the potential power of our RNA editing approach

CAMBRIDGE, Mass., Jan. 18, 2024 (GLOBE NEWSWIRE) -- Korro Bio, Inc. (Korro) (Nasdaq: KRRO), a biopharmaceutical company focused on developing a new class of genetic medicines for both rare and highly prevalent diseases, presented new data for KRRO-110 and reported progress across its RNA editing portfolio at the J.P. Morgan Healthcare Conference on January 9, 2024.

“KRRO-110 data showed the highest levels of corrected protein in a human transgenic PiZ mouse model, supporting a potentially best-in-class therapeutic for AATD patients,” said Chief Executive Officer and President, Ram Aiyar, Ph.D. “Beyond AATD, our ability to generate de novo mutations to activate a biological pathway is uncharted in the field of RNA editing. The progress we have made across our platform and pipeline underscores our commitment to bringing differentiated therapeutic options to patients with significant unmet medical needs.”

Pipeline updates

KRRO-110

As announced on December 7, 2023, Korro selected KRRO-110 as its first development candidate for the potential treatment of AATD, an inherited genetic disorder caused by single nucleotide variants (SNVs) in the SERPINA1 gene. AATD can lead to severe progressive lung disease, including emphysema and chronic obstructive pulmonary disease (COPD), and severe liver disease leading to inflammation, cirrhosis, and fibrosis. Preclinical data to date for KRRO-110 demonstrated:

• High specificity with no bystander effects in MZ human primary hepatocytes
• Intravenous administration at 2 mg/kg resulted in secretion of ~50µM functional AAT as early as 7 days post-single dose in a human transgenic PiZ mouse model
• Increase in AAT protein and the inhibition of elastase activity were sustained through week 9 when dosed every 2 weeks, demonstrating durability in mice
• Greater than 40% editing in NHPs utilizing an earlier generation oligonucleotide designed to edit a surrogate SERPINA1 RNA target site

Preclinical development of KRRO-110 is ongoing in preparation for a regulatory filing expected in the second half of 2024, with a potential interim clinical readout in the second half of 2025.