CAMBRIDGE, Mass. — Korro Bio, Inc. (Korro), a clinical-stage biopharmaceutical company focused on developing a new class of genetic medicines based on editing RNA for both rare and highly prevalent diseases, announced today that it has been granted orphan drug designation by the European Medicines Agency (EMA) Committee, who adopted a positive opinion on KRRO-110, Korro’s investigational medicine for the treatment of Alpha-1 Antitrypsin Deficiency (AATD).
“The EMA orphan drug designation for KRRO-110 is a significant milestone for Korro and highlights an urgent need to bring innovative solutions to people with AATD seeking new, disease-modifying therapies,” said Kemi Olugemo, MD, Chief Medical Officer at Korro. “Backed by encouraging preclinical data, KRRO-110 has best-in-class potential for the treatment of AATD. This designation represents an important step toward bringing KRRO-110 to European patients.”
In March 2025, KRRO-110 received orphan drug designation from the U.S. Food and Drug Administration for the treatment of AATD. KRRO-110 is currently being evaluated in the Phase 1/2a REWRITE clinical study for AATD, and an interim readout is expected in the second half of 2025.
The EMA grants orphan designation status to medicines intended for the treatment, prevention or diagnosis of life-threatening or chronically debilitating diseases affecting fewer than 5 in 10,000 people in the European Union, and the medicine must be of significant benefit to patients. Orphan drug designation provides companies with various development incentives, including protocol assistance, reduced regulatory fees, and market exclusivity once the medicine is approved.
About REWRITE
REWRITE is a Phase 1/2a two-part single and multiple dose-escalating clinical study that will evaluate the safety and tolerability of KRRO-110 in up to 64 participants, including healthy adults and clinically stable AATD patients with the PiZZ genotype. Secondary and exploratory endpoints include pharmacokinetic and pharmacodynamic parameters that will guide optimal dose selection for later stage studies. Interim data from Part 1 (single ascending doses in healthy volunteers and individuals with AATD) is expected in the second half of 2025, and completion of the study is anticipated in 2026. For additional information about the REWRITE study, visit ClinicalTrials.gov (NCT06677307).
About Alpha-1 Antitrypsin Deficiency (AATD) and KRRO-110
AATD is a genetic disorder most commonly caused by a single missense mutation (G-to-A) in the SERPINA1 gene. Affected adults experience pulmonary emphysema and/or hepatic cirrhosis, as well as end organ manifestations. KRRO-110 is the first RNA editing oligonucleotide product candidate from Korro’s proprietary RNA editing platform, Oligonucleotide Promoted Editing of RNA (OPERA®). KRRO-110, a potential best-in-class compound based on preclinical data, is designed to co-opt an endogenous enzyme, Adenosine Deaminase Acting on RNA (ADAR), to edit the “A” variant on SERPINA1 RNA, repair an amino acid codon, and restore secretion of normal AAT protein. This repair of the endogenous protein has the potential to clear protein aggregates from within liver cells to create a potentially clinically differentiated benefit for liver function and to preserve lung function by providing an adequate amount of normal AAT protein.
About Korro
Korro is a clinical-stage biopharmaceutical company focused on developing a new class of genetic medicines based on editing RNA for both rare and highly prevalent diseases. Korro is generating a portfolio of differentiated programs that are designed to harness the body’s natural RNA editing process, enabling a precise yet transient single base edit. By editing RNA instead of DNA, Korro is expanding the reach of genetic medicines by delivering additional precision and tunability, which has the potential for increased specificity and improved long-term tolerability. Using an oligonucleotide-based approach, Korro expects to bring its medicines to patients by leveraging its proprietary platform with precedented delivery modalities, manufacturing know-how, and established regulatory pathways of approved oligonucleotide drugs. Korro is based in Cambridge, Massachusetts. For more information, visit korrobio.com.
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Korro Bio Contact Information
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