Korro Bio Doses First Cohort in Phase 1/2 Trial of KRRO-121 for Hyperammonemia; Shares Rise 3.4%

Korro Bio Inc. (KRRO) said Tuesday it dosed the first cohort in a Phase 1/2 study of KRRO-121, an RNA-editing therapy for hyperammonemia in patients with urea cycle disorders and hepatic encephalopathy. KRRO-121 is a GalNAc-conjugated RNA-editing oligonucleotide designed using the company's OPERA platform. It aims to restore ammonia-to-urea conversion via hepatocellular pathways. Urea cycle disorders are rare congenital defects affecting ureagenesis; ammonia buildup can cause hyperammonemic crises, neurological damage, coma or death. Hepatic encephalopathy from liver cirrhosis can also drive ammonia accumulation. The global Phase 1/2 ANCHOR trial is enrolling healthy participants in Australia. Phase 1 Part 1 includes up to 30 participants in five single-ascending-dose cohorts and up to 20 subjects in two multiple-ascending-dose cohorts. Phase 2 Part 2 will test multiple doses to assess safety, tolerability, pharmacokinetics and clinical activity. Both portions are placebo-controlled. KRRO closed Tuesday at $9.97, up 3.42%.