FDA Grants Orphan Drug Status to KRRO-110 for Alpha-1 Antitrypsin Deficiency

On March 14, 2025, Korro Bio, Inc. (Nasdaq: KRRO), a clinical-stage biopharmaceutical firm, announced that the U.S. Food and Drug Administration (FDA) has granted orphan drug designation to its investigational medicine KRRO-110. This designation is for the treatment of Alpha-1 Antitrypsin Deficiency (AATD), a rare condition affecting the liver and lungs. The Chief Medical Officer of Korro, Dr. Kemi Olugemo, emphasized the significance of this milestone, highlighting the urgent need for innovative treatments for AATD patients. KRRO-110 aims to address both liver and lung symptoms associated with the condition, marking a potential breakthrough in therapy.

KRRO-110 is being developed using Korro’s proprietary OPERATM platform and is currently under evaluation in the Phase 1/2a REWRITE clinical study. The initial two single ascending dose cohorts in healthy volunteers have been completed, with interim results anticipated in the latter half of 2025. The FDA's orphan drug designation is pivotal as it provides various incentives for drug development, including tax credits, fee exemptions, and the possibility of market exclusivity post-approval.

The REWRITE study is a comprehensive, two-part trial that assesses the safety and tolerability of KRRO-110 across 64 participants, including both healthy individuals and AATD patients with the PiZZ genotype. It is designed to help determine the optimal dosing for future studies, with interim data from the first part expected later in 2025 and overall study completion projected for 2026.

AATD is a genetic disorder primarily resulting from a single missense mutation in the SERPINA1 gene, leading to conditions such as pulmonary emphysema and liver cirrhosis in affected adults. KRRO-110 is the first RNA editing candidate from Korro’s OPERA™ platform, utilizing RNA editing oligonucleotides. It functions by employing an endogenous enzyme, Adenosine Deaminase Acting on RNA (ADAR), to correct a genetic variant in SERPINA1 RNA, thereby restoring the secretion of normal AAT protein. This correction aims to clear protein aggregates from liver cells, potentially improving liver function and preserving lung health by ensuring adequate AAT protein production.

Korro Bio, based in Cambridge, Massachusetts, is committed to advancing a new class of genetic medicines that utilize RNA editing. This approach offers increased precision and potential improved long-term tolerability compared to traditional DNA editing methods. By focusing on RNA, Korro aims to expand the possibilities of genetic medicine, providing more precise and adjustable treatments.

The company's strategic goal is to leverage its proprietary platform to deliver effective genetic therapies using established oligonucleotide delivery methods. Korro's innovative approach is designed to harness the body's natural RNA editing processes for therapeutic purposes, potentially leading to significant advancements in the treatment of both rare and common diseases.

Korro is actively working on a portfolio of programs and is dedicated to bringing its medicines to patients. With a strong emphasis on regulatory compliance and efficient drug development, Korro is poised to make strides in the biopharmaceutical landscape through its innovative RNA-based therapies.