Collaboration Agreements	6 Months Ended
Jun. 30, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaboration Agreements	11. Collaboration Agreements Genevant Agreement In March 2023, Legacy Korro entered into a collaboration and license agreement (the “Genevant Agreement”) with Genevant Sciences GmbH (“Genevant”). Key financial terms under the Genevant Agreement are as follows: • The Company made a $2.5 million payment to Genevant in March 2023 upon execution of the Genevant Agreement and recorded the payment within research and development expense in the consolidated statement of operations and comprehensive loss for the year ended December 31, 2023. • The Company will reimburse Genevant for certain out-of-pocket and full-time equivalent costs incurred as a result of research and development activities performed under the Genevant Agreement. • Genevant is entitled to receive payments from the Company upon the achievement of certain milestones, including potential clinical milestone payments of up to $13.5 million, potential regulatory and development milestone payments of up to $27.0 million, and potential commercial milestone payments up to an aggregate total of $57.0 million. • Genevant is eligible to receive royalties at percentage rates in the mid-single-digits, based on future annual net sales of licensed products within the scope of the Genevant Agreement. As of December 31, 2024, one development milestone of $1.0 million had been achieved. In January 2025, the Company announced dosing of the first participants in its Phase 1/2a REWRITE clinical program investigating KRRO-110 as a treatment for AATD, which triggered the second payment of a $1.5 million development milestone. The Company recorded $1.8 million and $2.6 million within research and development expense in the condensed consolidated statement of operations and comprehensive loss during the six months ended June 30, 2025 and 2024, respectively, related to the Genevant Agreement. The Company recorded $0.1 million and $1.6 million within research and development expense in the condensed consolidated statement of operations and comprehensive loss during the three months ended June 30, 2025 and 2024, respectively, related to the Genevant Agreement. Novo Nordisk Agreement On September 13, 2024, the Company entered into a research collaboration and license agreement with Novo Nordisk A/S (“Novo Nordisk”), pursuant to which the Company granted Novo Nordisk an exclusive worldwide license under certain intellectual property rights to research, develop, manufacture, commercialize or otherwise exploit certain licensed compounds and licensed products for an initial target in the cardiometabolic field and for a second target (to be nominated by Novo Nordisk within a specified time period as set forth in the agreement). Under the agreement, the Company is responsible for certain research and development activities with respect to licensed compounds and licensed products directed against the initial target and the second target (if nominated by Novo Nordisk), and the Company is eligible to receive cost reimbursement from Novo Nordisk for the Company's performance of such research and development activities under the agreement with respect to such target(s). Novo Nordisk may undertake subsequent worldwide development, manufacturing, marketing and commercialization of the licensed products directed against the initial target and the second target (if applicable). For additional information relating to the terms of such agreement, see Note 13 in the audited consolidated financial statements included in the 2024 10-K. In October 2024, the Company received an upfront nonrefundable payment of $10.0 million from Novo Nordisk related to the first product candidate, or program target. The Company is entitled to an additional upfront nonrefundable payment from Novo Nordisk upon the selection of the second program target as well as related cost reimbursements. The Company assessed this arrangement in accordance with Accounting Standards Codification Topic 606, Revenue from Contracts with Customers, and concluded that the contract counterparty, Novo Nordisk, is a customer. The Company determined that the research services and the exclusive licenses granted under the collaboration agreement for the initial target are not distinct and, therefore, the Company accounts for the research services and exclusive licenses as a single performance obligation. Additionally, the Company concluded that Novo Nordisk’s option to select a second target does not give rise to a material right or performance obligation until the additional target is selected due to the additional services being priced at standalone selling price. The Company recognizes revenue related to the combined license and research services performance obligation over time using the input method. Under the input method, the extent of progress towards completion is measured based on the ratio of costs incurred to date to the total estimated costs at completion of the performance obligation, which the Company believes best measures its progress towards satisfying the combined performance obligation. A cost-based input method of revenue recognition requires management to make estimates of costs to complete the performance obligation. In making such estimates, judgment is required to evaluate assumptions related to cost estimates. As of June 30, 2025, the total transaction price was determined to be $39.9 million based on the $10.0 million upfront nonrefundable payment and $29.9 million of estimated research services for the first program target. During the six months ended June 30, 2025 and 2024, the Company recognized total collaboration revenue of $4.0 million and $0.0 million, respectively. During the three months ended June 30, 2025 and 2024, the Company recognized total collaboration revenue of $1.5 million and $0.0 million, respectively. The Company is expected to recognize revenue through the first quarter of 2027. The Company had $3.9 million of current deferred revenue and $4.5 million of noncurrent deferred revenue as of June 30, 2025, based on the period the services are expected to be performed and/or related costs to be incurred. The Company had $1.1 million of current accounts receivable as of June 30, 2025. The Company will assess the probability of receiving payments from achieving the research and development and regulatory milestones and include the payment in the transaction price when they are deemed probable. Royalties and commercial sale milestones will be recognized when the subsequent sales occur based on the sales or usage-based royalty exception.

Collaboration Agreements

6 Months Ended

Jun. 30, 2025

Organization, Consolidation and Presentation of Financial Statements [Abstract]

11. Collaboration Agreements

Genevant Agreement

In March 2023, Legacy Korro entered into a collaboration and license agreement (the “Genevant Agreement”) with Genevant Sciences GmbH (“Genevant”). Key financial terms under the Genevant Agreement are as follows:

•

The Company made a $2.5 million payment to Genevant in March 2023 upon execution of the Genevant Agreement and recorded the payment within research and development expense in the consolidated statement of operations and comprehensive loss for the year ended December 31, 2023.

•

The Company will reimburse Genevant for certain out-of-pocket and full-time equivalent costs incurred as a result of research and development activities performed under the Genevant Agreement.

•

Genevant is entitled to receive payments from the Company upon the achievement of certain milestones, including potential clinical milestone payments of up to $13.5 million, potential regulatory and development milestone payments of up to $27.0 million, and potential commercial milestone payments up to an aggregate total of $57.0 million.

•

Genevant is eligible to receive royalties at percentage rates in the mid-single-digits, based on future annual net sales of licensed products within the scope of the Genevant Agreement.

As of December 31, 2024, one development milestone of $1.0 million had been achieved. In January 2025, the Company announced dosing of the first participants in its Phase 1/2a REWRITE clinical program investigating KRRO-110 as a treatment for AATD, which triggered the second payment of a $1.5 million development milestone. The Company recorded $1.8 million and $2.6 million within research and development expense in the condensed consolidated statement of operations and comprehensive loss during the six months ended June 30, 2025 and 2024, respectively, related to the Genevant Agreement. The Company recorded $0.1 million and $1.6 million within research and development expense in the condensed consolidated statement of operations and comprehensive loss during the three months ended June 30, 2025 and 2024, respectively, related to the Genevant Agreement.

Novo Nordisk Agreement

On September 13, 2024, the Company entered into a research collaboration and license agreement with Novo Nordisk A/S (“Novo Nordisk”), pursuant to which the Company granted Novo Nordisk an exclusive worldwide license under certain intellectual property rights to research, develop, manufacture, commercialize or otherwise exploit certain licensed compounds and licensed products for an initial target in the cardiometabolic field and for a second target (to be nominated by Novo Nordisk within a specified time period as set forth in the agreement). Under the agreement, the Company is responsible for certain research and development activities with respect to licensed compounds and licensed products directed against the initial target and the second target (if nominated by Novo Nordisk), and the Company is eligible to receive cost reimbursement from Novo Nordisk for the Company's performance of such research and development activities under the agreement with respect to such target(s). Novo Nordisk may undertake subsequent worldwide development, manufacturing, marketing and commercialization of the licensed products directed against the initial target and the second target (if applicable). For additional information relating to the terms of such agreement, see Note 13 in the audited consolidated financial statements included in the 2024 10-K.

In October 2024, the Company received an upfront nonrefundable payment of $10.0 million from Novo Nordisk related to the first product candidate, or program target. The Company is entitled to an additional upfront nonrefundable payment from Novo Nordisk upon the selection of the second program target as well as related cost reimbursements.

The Company assessed this arrangement in accordance with Accounting Standards Codification Topic 606, Revenue from Contracts with Customers, and concluded that the contract counterparty, Novo Nordisk, is a customer. The Company determined that the research services and the exclusive licenses granted under the collaboration agreement for the initial target are not distinct and, therefore, the Company accounts for the research services and exclusive licenses as a single performance obligation. Additionally, the Company concluded that Novo Nordisk’s option to select a second target does not give rise to a material right or performance obligation until the additional target is selected due to the additional services being priced at standalone selling price. The Company recognizes revenue related to the combined license and research services performance obligation over time using the input method. Under the input method, the extent of progress towards completion is measured based on the ratio of costs incurred to date to the total estimated costs at completion of the performance obligation, which the Company believes best measures its progress towards satisfying the combined performance obligation. A cost-based input method of revenue recognition requires management to make estimates of costs to complete the performance obligation. In making such estimates, judgment is required to evaluate assumptions related to cost estimates.

As of June 30, 2025, the total transaction price was determined to be $39.9 million based on the $10.0 million upfront nonrefundable payment and $29.9 million of estimated research services for the first program target. During the six months ended June 30, 2025 and 2024, the Company recognized total collaboration revenue of $4.0 million and $0.0 million, respectively. During the three months ended June 30, 2025 and 2024, the Company recognized total collaboration revenue of $1.5 million and $0.0 million, respectively. The Company is expected to recognize revenue through the first quarter of 2027.

The Company had $3.9 million of current deferred revenue and $4.5 million of noncurrent deferred revenue as of June 30, 2025, based on the period the services are expected to be performed and/or related costs to be incurred. The Company had $1.1 million of current accounts receivable as of June 30, 2025.

The Company will assess the probability of receiving payments from achieving the research and development and regulatory milestones and include the payment in the transaction price when they are deemed probable. Royalties and commercial sale milestones will be recognized when the subsequent sales occur based on the sales or usage-based royalty exception.