Korro Bio Plummets To A Record Low On A Big Setback In RNA-Editing

Korro Bio (KRRO) stock plummeted Thursday after its RNA-editing drug failed to pass muster in patients with a rare lung and liver disease.

The company hoped to offer a treatment for alpha-1 antitrypsin deficiency, or AATD. In these patients, mutations in a specific gene prevent the body from making the alpha-1 antitrypsin protein. This protein protects the lungs from damage. Patients can also make abnormal forms of the protein. These can build up on the liver, causing scar tissue to form.

Korro said its drug helped patients produce some of the missing protein. But the levels didn't meet the company's bar for effectiveness. Korro Bio used ADAR editing. This takes advantage of a natural process in which enzymes called ADAR make changes to the RNA, the body's messenger system for making proteins.

"Clearly some ADAR editing is taking place, but not in sufficient amounts, and nowhere near what was observed in preclinical studies," Chardan analyst Keay Nakae said in a report.

Korro is abandoning the failed drug, called KRRO-110. It's now pivoting to a new delivery system and working on a new treatment for patients with AATD. That puts the first clinical data out to 2027.

https://www.investors.com/news/technology/korro-bio-stock-rna-editing-adar-editing-aatd-treatment/