Korro Bio, Inc.

What they do

Korro Bio uses its OPERA platform to engineer oligonucleotides that co-opt the body's endogenous ADAR enzyme to make a precise adenosine-to-inosine edit on RNA, aiming to repair or activate protein function rather than permanently edit DNA. The company uses GalNAc-conjugated delivery for subcutaneous administration to liver cells and has nominated development candidates including KRRO-121 for hyperammonemia and KRRO-111 for alpha-1 antitrypsin deficiency. It has no approved products.

Revenue drivers

• Collaboration and license revenue — Revenue was $6.4 million in 2025 and $2.3 million in 2024, with no revenue in the first half of 2026; historically this line reflects collaboration or grant-related payments rather than product sales.
• Product sales — Korro has no approved products and reported no product revenue in any period shown.
• Government or grant funding — The filings show no material government grant revenue line, and 2025 revenue of $6.4 million is not broken out by source in the excerpts.

Recent performance

Second quarter 2026 revenue was zero, following zero in the first quarter and $1.3 million in the fourth quarter of 2025. Full-year 2025 revenue was $6.4 million against a net loss of $117.3 million, and operating cash use was $78.6 million. At June 30, 2026, Korro reported $24.9 million in cash and equivalents on the balance sheet, while the earnings release cited $137.9 million in cash, cash equivalents and marketable securities. Total assets were $163.4 million and total liabilities $60.2 million at June 30, 2026.

Strategy

Korro is prioritizing clinical execution on KRRO-121 for hyperammonemia, with a first-in-human trial targeted for the second half of 2026, and on KRRO-111 for AATD following its nomination as a development candidate. Management said it expects to add a third GalNAc-conjugated program in 2026 and continues to refine OPERA oligonucleotide chemistry to improve editing potency. The company states its cash resources are sufficient to reach value inflection points for multiple programs, including clinical data, with runway into the second half of 2028. It is also presenting preclinical data at scientific meetings including ASGCT.

Risks

• No approved products or product revenue — Korro has never generated product revenue and depends on clinical success of programs such as KRRO-121 and KRRO-111.
• Early and limited RNA editing evidence — The 10-K states the scientific evidence supporting feasibility of RNA editing candidates is preliminary and limited, and regulators have not established definitive development guidelines for RNA editing therapies.
• Cash burn and financing need — Operating cash use was $78.6 million in 2025 and the company reported $24.9 million of cash and equivalents at June 30, 2026, requiring additional capital despite stated runway into the second half of 2028.
• Clinical and regulatory timing risk — The first-in-human trial for KRRO-121 is targeted for the second half of 2026 and depends on obtaining regulatory approvals.

Outlook

Management says KRRO-121 remains on track to begin first-in-human clinical trials in the second half of 2026 and that it is preparing regulatory approvals for that program. It also expects to nominate a third GalNAc-conjugated program in 2026 and to generate clinical data for KRRO-121 and KRRO-111. The company states its cash resources provide sufficient runway into the second half of 2028 to reach value inflection points for multiple RNA editing programs.