Korro Bio, Inc.
For the period ended Dec 31, 2025. Filed Mar 12, 2026.
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A company's yearly report to the SEC, with audited financial statements. It is the fullest account a company gives of its business, its finances and the risks it sees.
FY2025 · Filed Mar 12, 2026
KRRO$14.75+0.1%Stored close · as of Nov 6, 2026
What changed in Management’s Discussion and Analysis?
Read the current filingPrevious report: 10-K
Period ended 2024-12-31; filed 2025-03-18.
0000950170-25-040759
Item 7. Management’s Discussion and Analysis of Financial Condition and Results of OperationsCurrent report: 10-K
Period ended 2025-12-31; filed 2026-03-12.
0001193125-26-104156
Item 7. Management’s Discussion and Analysis of Financial Condition and Results of OperationsThe baseline is this issuer’s latest earlier reporting period of the same form that was filed before the current report. A previous 10-Q is a different quarter, not a year-over-year comparison. Amendments are excluded.
Compared 99 previous paragraphs and 121 current paragraphs.
54 unchanged; 33 reworded; 32 added; 12 removed; 0 previous and 2 current paragraphs rearranged.
Tables are not compared: 4 previous and 4 current tables excluded. Dates, whitespace, punctuation and numbering changes are ignored; changes to financial figures remain significant.
A changed paragraph is not evidence that risk increased or decreased. An unchanged paragraph does not establish that risk stayed the same.
Added paragraphs (32)
Current report
The versatility of RNA editing combined with our OPERA platform broadens the therapeutic target space significantly. The advent of large-scale genome sequencing has progressively revealed causal genetic variation underlying several human diseases, both rare and highly prevalent. Genetic mutations, including SNVs implicated in disease have been found to be diverse in nature and can affect the function of genes and their associated downstream biochemical pathways. Data correlating DNA to RNA to disease phenotype have demonstrated that SNVs lead to a loss-of-function or a gain-of-function of the gene. In addition, the majority of SNVs implicated in complex diseases are due to modulation of gene function. By editing RNA to mimic a SNV, we believe we will be able to address unmet patient need by transiently modifying gene expression and the resultant protein function.
Current report
We continue to make meaningful advancements across our programs, including KRRO-121 as a potential first-in-class treatment for hyperammonemia that has the potential to address substantial unmet need in patients with poor ammonia control, including those with UCD and HE. KRRO-121 is an RNA-editing oligonucleotide conjugated with GalNAc in development for the potential treatment of UCDs of any mutational background in adults and adolescents. Utilizing our proprietary platform, we designed KRRO-121 to edit the GLUL transcript (the gene for the GS protein), to generate a stabilized, de novo variant of GS with enhanced ammonia clearance capacity. This synthetic rescue approach creates a compensating protein rather than repairing the underlying urea cycle defect. By editing GS mRNA to create a de novo protein with a single amino acid change that prevents glutamine-induced proteasomal degradation, we aim to maintain consistent ammonia clearance capacity irrespective of the specific enzyme deficiency in patients with UCD and to reduce ammonia levels in patients with HE. We anticipate a regulatory filing to enable commencement of a first-in-human trial in the second half of 2026.
Current report
In November 2025, we announced that KRRO-110 did not reach projected levels of functional protein following a single administration and pivoted to GalNAc delivery for patients with AATD with development candidate nomination expected in the second quarter of 2026. We are developing a next-generation GalNAc-conjugated RNA editing oligonucleotide for the treatment of AATD that has the potential to be disease-modifying and provide a differentiated therapeutic option.
Current report
In May 2025, we announced a strategic plan to streamline our operations, including a reduction in workforce by 19%, or 21 positions. In November 2025, we implemented a strategic restructuring to extend cash runway, including a further workforce reduction of approximately 34%. Please see Note 16 to our audited consolidated financial statements included elsewhere in this Annual Report on Form 10-K.
Current report
Recent Developments
Current report
At-the-Market Offering Program
Current report
In January 2026, we issued 501,861 shares of common stock under our December 2024 at-the-market sales agreement for gross proceeds of $5.1 million, before deducting estimated offering expenses.
Current report
March 2026 Private Placement
Current report
On March 9, 2026, we entered into a subscription agreement with certain new and existing accredited investors to issue and sell in a private placement an aggregate of 4,501,928 shares of our common stock at a purchase price of $11.11 per share and pre-funded warrants to purchase up to an aggregate of 3,148,836 shares of our common stock (at an exercise price of $0.001 per share) at a price of $11.109 per pre-funded warrant. The private placement, which closed March 10, 2026, resulted in gross proceeds of approximately $85.0 million before deducting placement agent fees and estimated offering expenses.
Current report
November 2025, we agreed to a 12 month pause on such collaboration with Novo Nordisk, and accordingly, we do not expect to recognize any material collaboration revenue under such agreement during the 12-month hold period.
Current report
Long-lived Asset Impairment Charges
Current report
We determined that indicators of impairment existed during the fourth quarter of 2025 and, as a result, our long-lived assets were reviewed for impairment. We assessed the recoverability of our single enterprise-wide asset group and determined that the assets were not fully recoverable when compared to the future undiscounted cash flows from the asset group. As a result, we estimated the fair value of the asset group, which resulted in a non-cash, long-lived asset impairment charge of $30.9 million in 2025. See Note 3 for further discussion of the impairment analysis.
Current report
Restructuring Charges
Current report
In May 2025, we announced a strategic plan to streamline our operations, including a workforce reduction of approximately 20%. In connection with the November 2025 announcement regarding KRRO-110, we further implemented a strategic restructuring to reserve resources and extend cash runway, including a reduction in our workforce. Restructuring charges consist primarily of severance and employee benefits costs incurred in relation to our reductions in force.
Current report
See Note 16 to our audited consolidated financial statements included in this Annual Report on Form 10-K for further discussion of our restructuring charges.
Current report
a $4.8 million increase in KRRO-121 external expenses, primarily due to exploratory and manufacturing costs; and
Current report
a $2.5 million increase in personnel-related expenses, primarily due to the expansion of our clinical development function and stock-based compensation;
Current report
offset by a $3.0 million decrease in KRRO-110 external expenses, primarily due to a reduction in non clinical costs partially offset by an increase in clinical costs for the Phase 1/2a REWRITE clinical trial as it progressed during 2025; and
Current report
General and administrative expenses were $28.2 million for the year December 31, 2025, compared to $30.5 million for the year ended December 31, 2024. The decrease was primarily due to a $2.6 million decrease in professional services expenses, offset by a $1.2 million increase in personnel-related expenses, which was mainly attributable to an increase in stock-based compensation costs.
Current report
Long-lived Asset Impairment Charges
Current report
Long-lived asset non-cash impairment charges for the year ended December 31, 2025 consisted of $15.0 million and $15.9 million of impairment charges on our operating ROU asset and property and equipment, respectively. We did not incur any impairment charges for the year ended December 31, 2024.
Current report
Restructuring Charges
Current report
Restructuring charges for the year ended December 31, 2025 consisted of $3.6 million of employee termination benefits related to our workforce reductions in May and November 2025. During the year ended December 31, 2025, all activities related to our May 2025 workforce reduction were completed. The remaining payments related to our November 2025 workforce reduction are expected to be paid by the third quarter of 2026. We did not incur any restructuring charges for the year ended December 31, 2024.
Current report
Total other income, net was $5.2 million for the year ended December 31, 2025, compared to $8.5 million for the year ended December 31, 2024. The decrease of $3.3 million was primarily due to lower interest income generated from a lower cash, cash equivalent and marketable securities balance in 2025 compared to 2024.
Current report
2026 sales under our at-the-market offering program, and $85.0 million from the March 2026 private placement. As of December 31, 2025, we had cash, cash equivalents and marketable securities of $85.2 million.
Current report
Net cash used in operating activities was $78.6 million for the year ended December 31, 2025, primarily resulted from our net loss of $117.3 million, which was primarily attributable to our research and development activities and our general and administrative expenses, along with changes in our operating assets and liabilities of $4.4 million, offset by $43.1 million of non-cash items, primarily the $30.9 million impairment of long-lived assets.
Current report
Net cash used in operating activities was $60.1 million for the year ended December 31, 2024, primarily resulted from our net loss of $83.6 million, which was primarily attributable to our research and development activities and our general and administrative expenses, along with changes in our operating assets and liabilities of $13.6 million, offset by $9.9 million of non-cash items.
Current report
Net cash provided by financing activities was $0.7 million for the year ended December 31, 2025 and consisted of proceeds from exercises of stock options.
Current report
Long-lived Assets
Current report
We periodically evaluate long-lived assets for impairment when changes in circumstances or the occurrence of certain events indicate the carrying amount of an asset or asset group may not be recoverable. Identifying and assessing whether impairment indicators exist, or if events or changes in circumstances have occurred, including an adverse change in legal factors or in the business climate that could affect the value of the long-lived asset (group); an adverse change in the extent or manner in which the long-lived asset (group) is used or is expected to be used, or in its physical condition; and current or forecasted operating or cash flow losses that demonstrate continuing losses associated with the use of the long-lived asset (group), requires judgment. Additionally, grouping assets requires judgment. Changes in judgment used could materially affect our financial condition and results of operations.
Current report
We determined that indicators of impairment existed during the fourth quarter of 2025 and, as a result, reviewed our long-lived assets for impairment. We assessed the recoverability of our single enterprise-wide asset group and determined that the assets were not fully recoverable when compared to the future undiscounted cash flows from the asset group. As a result, we estimated the fair value of the asset group which resulted in a non-cash, long-lived asset impairment charge of $30.9 million in 2025.
Current report
See Note 3 to our audited consolidated financial statements included in this Annual Report on Form 10-K for further discussion of our impairment analysis.
Removed paragraphs (12)
Previous report
The versatility of RNA editing combined with our OPERA platform broadens the therapeutic target space significantly. While our approach can be used to repair pathogenic single nucleotide variants, or SNVs, as demonstrated by our most advanced clinical-stage program, our AATD product candidate, we can also engineer de novo SNVs and change amino acids on proteins to endow them with desired properties while preserving their broader functional capabilities, as exemplified by three of our other programs (an undisclosed rare metabolic disorder, ALS, and pain). In preclinical studies, we have demonstrated that single RNA changes can disrupt protein-protein interactions, prevent protein aggregation, selectively modulate ion channels and activate kinases. These modification approaches can unlock validated target classes that have historically been difficult to drug, enabling us to pursue a broad range of diseases traditionally out-of-scope for other genetic medicine approaches and current traditional drug modalities.
Previous report
Our most advanced program is a development candidate, KRRO-110, which is in clinical development for the treatment of AATD where, using our proprietary RNA editing approach, we are repairing a pathogenic variant on RNA. KRRO-110 has the potential to be disease-modifying and provide a differentiated therapeutic option. In January 2025, we announced dosing of the first participants in our REWRITE clinical program investigating KRRO-110 as a treatment for AATD. REWRITE is a two-part single and multiple dose-escalating Phase 1/2a clinical trial that will evaluate the safety and tolerability of KRRO-110 in up to 64 participants, including healthy adults and clinically stable AATD patients with the PiZZ genotype. Secondary and exploratory endpoints include pharmacokinetic and pharmacodynamic parameters that will guide optimal dose selection for later stage studies. We have completed dosing of the first two single ascending dose cohorts in healthy adult volunteers. We have not observed any serious adverse events as of the date of this annual report on Form 10-K through completion of dosing of the first two cohorts. We continue to progress enrollment, site activation and expansion into other geographies beyond Australia, including the U.S. In March 2025, we announced that the FDA has granted orphan drug designation to KRRO-110 for the treatment of AATD. Interim data from single ascending doses in healthy volunteers and AATD patients is expected in the second half of 2025, and completion of the trial is anticipated in 2026. Based on the preclinical data, we believe KRRO-110 has best-in-class potential for the treatment of AATD. However, KRRO-110 is in early clinical development and there is no guarantee that it will be successful.
Previous report
KRRO-110 external expenses upon its December 2023 development candidate nomination as well as less lab supplies and consumables purchased for research and preclinical activities.
Previous report
General and administrative expenses were $30.5 million for the year ended December 31, 2024, compared to $27.3 million for the year ended December 31, 2023. The increase of $3.3 million was primarily driven a $1.9 million increase in information technology, insurance and other costs, a $1.1 million increase in professional fees, and a $0.5 million increase in facility costs primarily due to the expansion of our mixed-use office spaces and overall support of the growth of our company, partially offset by a $0.3 million decrease in employee related expenses. We incurred $2.5 million of severance cost for Frequency employees related to the November 2023 business combination during year ended December 31, 2023. No comparable costs occurred during year ended December 31, 2024.
Previous report
Total other income, net was $8.5 million for the year ended December 31, 2024, compared to $3.4 million for the year ended December 31, 2023. The increase of $5.1 million was primarily due to an increase of $5.1 million in interest income earned from our cash, cash equivalents and marketable securities driven by interest rates and higher marketable securities balance.
Previous report
Net cash used in operating activities was $60.1 million for the year ended December 31, 2024, which consisted of $83.6 million of net loss, $9.9 million of non-cash adjustments to net loss and an increase of $13.6 million in the net change in operating assets and liabilities. Non-cash adjustments primarily consisted of $3.3 million of amortization of operating lease right of use, or ROU, assets, $4.5 million of stock-based compensation expenses, and $3.6 million of depreciation expenses partially offset by $1.8 million of net amortization of premiums and discounts on marketable securities. The increase in net assets consisted primarily of a $1.7 million and $9.4 million increase in accounts receivable and deferred revenue, respectively, a $11.6 million increase in operating lease liabilities, a $0.7 million increase in prepaid expenses and other current assets, offset by a $4.0 million decrease in accrued expenses and other liabilities and a $1.3 million decrease in accounts payable.
Previous report
Net cash used in operating activities was $67.3 million for the year ended December 31, 2023, which consisted of $81.2 million of net loss, $9.6 million of non-cash adjustments to net loss and an increase of $4.3 million in the net change in operating assets and liabilities. Non-cash adjustments primarily consisted of $3.6 million of depreciation expense, $3.6 million of amortization of operating lease ROU assets, and $2.4 million of stock-based compensation expenses. The increase in net assets consisted primarily of a $3.1 million increase in accounts payable, a $2.0 million increase in other non-current assets, a $1.3 million increase in operating lease liabilities, a $1.3 million increase in accrued expenses and other liabilities, offset by a $0.6 million decrease in prepaid and other current assets.
Previous report
Cash Provided by Investing Activities
Previous report
Net cash provided by financing activities was $187.8 million for the year ended December 31, 2023 and consisted primarily of net proceeds of $45.5 million from the issuance of Legacy Korro’s Series B-2 convertible preferred stock, net proceeds of $117.3 million from the issuance of common stock in a private placement that closed immediately prior to the November 2023 business combination and net proceeds of $24.4 million in connection with the reverse recapitalization.
Previous report
Accrued and Prepaid Research and Development Expenses
Previous report
As part of the process of preparing the consolidated financial statements, we are required to estimate our accrued research and development expenses. This process involves reviewing open contracts and purchase orders, communicating with internal personnel and vendors to identify services that have been performed on our behalf and estimating the level of service performed and the associated cost incurred for the service when we have not yet been invoiced or otherwise notified of actual costs. The majority of our service providers require advance payments; however, some providers invoice us in arrears for services performed, on a pre-determined schedule or when contractual milestones are met. We make estimates of our accrued expenses as of each balance sheet date in the consolidated financial statements based on facts and circumstances known to us at that time. We periodically confirm the accuracy of the estimates with the service providers and make adjustments if necessary.
Previous report
We recognize expenses related to preclinical studies, clinical trials and other studies on our estimates of the services performed pursuant to contracts with research institutions and clinical research organizations that conduct and manage preclinical studies, clinical trials and other studies on our behalf. The financial terms of these agreements are subject to negotiation, vary from contract to contract and may result in uneven payment flows. There may be instances in which payments made to our vendors will exceed the level of services provided and result in a prepayment of the expense. In accruing service fees, we estimate the time period over which services will be performed and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from the estimate, we adjust the accrual or prepaid expense accordingly. Although we do not expect our estimates to be materially different from amounts actually incurred, our understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary and may result in reporting amounts that are too high or too low in any particular period. To date, we have not made any material adjustments to our prior estimates of accrued research and development expenses.
Reworded paragraphs (33)
Previous wording
We are a clinical-stage biopharmaceutical company with a mission to discover, develop and commercialize a new class of genetic medicines based on editing RNA, enabling the treatment of both rare and highly prevalent diseases.
Current wording
We are a biopharmaceutical company with a mission to discover, develop and commercialize a new class of genetic medicines based on editing RNA, enabling the treatment of both rare and highly prevalent diseases.
Previous wording
We are generating a portfolio of differentiated programs that are designed to harness the body’s natural RNA editing process to effect a precise yet transient single base edit. By editing RNA instead of DNA, we are expanding the reach of genetic medicines by delivering additional precision and tunability, which has the potential for increased specificity and improved long-term tolerability. Using an oligonucleotide-based approach, we expect to bring our medicines to patients by leveraging our proprietary platform with precedented delivery modalities, manufacturing know-how, and established regulatory pathways of approved oligonucleotide medicines. However, the scientific evidence to support the feasibility of developing product candidates using our RNA editing technology is both preliminary and limited. Moreover, regulators have not yet established any definitive guidelines related to overall development considerations for RNA editing therapies and limited clinical data has been generated to date.
Current wording
We are generating a portfolio of differentiated programs that are designed to harness the body’s natural RNA editing process to effect a precise yet transient change to a single nucleoside (adenosine to an inosine edit). By editing RNA instead of DNA, we are expanding the reach of genetic medicines by delivering additional precision and tunability, which has the potential for increased specificity and improved long-term tolerability. We use an oligonucleotide-based approach and expect to bring our medicines to patients by leveraging our proprietary platform with precedented delivery modalities, including N-acetylgalactosamine, or GalNAc, -conjugated delivery for subcutaneous administration, manufacturing know-how, and established regulatory pathways of approved oligonucleotide medicines. However, the scientific evidence to support the feasibility of developing our development candidates using our RNA editing technology is both preliminary and limited. Moreover, regulators have not yet established any definitive guidelines related to overall development considerations for RNA editing therapies and limited clinical data has been generated to date.
Previous wording
Since inception, we have focused primarily on organizing and staffing our company, business planning, raising capital, securing related intellectual property, and conducting research and development activities for our potential programs and product candidates. Since inception, we have funded our operations primarily through the private placement of our equity securities. To date, we have raised approximately $223.6 million of aggregate gross proceeds from the sale of our convertible preferred stock, and $117.3 million from the sale of shares of common stock issued in a private placement that closed immediately prior to the November 2023 business combination and $70.0 million from the April 2024 private placement of shares of our common stock.
Current wording
Since inception, we have focused primarily on organizing and staffing our company, business planning, raising capital, securing related intellectual property, and conducting research and development activities for our potential programs and development candidates. Since inception, we have funded our operations primarily through the private placement of our equity securities. To date, we have raised approximately $223.6 million of aggregate gross proceeds from the sale of our convertible preferred stock, $117.3 million from the sale of shares of common stock issued in a private placement that closed immediately prior to the November 2023 business combination, $70.0 million from the April 2024 private placement of shares of our common stock, $5.1 million from sales under our at-the-market offering program, and $85.0 million from the March 2026 private placement.
Previous wording
We have incurred significant operating losses since inception. Our net losses were $83.6 million and $81.2 million for the years ended December 31, 2024 and 2023, respectively. We had an accumulated deficit of $266.6 million as of December 31, 2024. We expect to continue to incur significant and increasing expenses and operating losses and negative operating cash flows for the foreseeable future as we continue our research and development efforts, advance product candidates into and through clinical development, and seek regulatory approvals for our pipeline candidates. Our net losses may fluctuate significantly from quarter-to-quarter and year-to-year, depending on the timing of our preclinical studies, initiation and conduct of any clinical trials, and our expenditures on other research and development activities, including the expansion of our pipeline.
Current wording
We have incurred significant operating losses since inception. Our net losses were $117.3 million and $83.6 million for the years ended December 31, 2025 and 2024, respectively. We had an accumulated deficit of $383.8 million as of December 31, 2025. We expect to continue to incur significant and increasing expenses and operating losses and negative operating cash flows for the foreseeable future as we continue our research and development efforts, advance development candidates into and through clinical development, and seek regulatory approvals for our development candidates. Our net losses may fluctuate significantly from quarter-to-quarter and year-to-year, depending on the timing of our preclinical studies, initiation and conduct of any clinical trials, and our expenditures on other research and development activities, including the expansion of our pipeline.
Previous wording
We do not have any product candidates approved for sale and have not generated any revenue from product sales. We will not generate revenue from product sales unless and until we successfully obtain regulatory approval for our product candidates, if ever, and as appropriate, move pipeline candidates into the clinic and complete clinical development. If we obtain regulatory approval for our product candidates and do not enter into third-party commercialization partnerships, we expect to incur significant expenses related to developing commercialization capabilities to support product sales, marketing, manufacturing and distribution activities. As a result, we will need substantial additional funding to support our continuing operations and pursue our development and growth strategy. Until we can generate significant revenue from product sales, if ever, we expect to finance our operations through a combination of public or private offerings of securities, debt financings or other sources, such as potential collaboration agreements, strategic alliances and licensing arrangements. We may be unable to raise additional funds or enter into such other agreements or arrangements when needed on acceptable terms, or at all. Our failure to raise capital or enter into such agreements as, and when needed, could have a negative effect on our business, results of operations and financial condition.
Current wording
We do not have any development candidates approved for sale and have not generated any revenue from product sales. We will not generate revenue from product sales unless and until we successfully obtain regulatory approval for our development candidates, if ever, and as appropriate, move pipeline candidates into the clinic and complete clinical development. If we obtain regulatory approval for our development candidates and do not enter into third-party commercialization partnerships, we expect to incur significant expenses related to developing commercialization capabilities to support product sales, marketing, manufacturing and distribution activities. As a result, we will need substantial additional funding to support our continuing operations and pursue our development and growth strategy. Until we can generate significant revenue from product sales, if ever, we expect to finance our operations through a combination of public or private offerings of securities, debt financings or other sources, such as potential collaboration agreements, strategic alliances and licensing arrangements. We may be unable to raise additional funds or enter into such other agreements or arrangements when needed on acceptable terms, or at all. Our failure to raise capital or enter into such agreements as, and when needed, could have a negative effect on our business, results of operations and financial condition.
Previous wording
We have not generated any revenue from product sales, and do not expect to generate any revenue from the sale of products in the near future. During the year ended December 31, 2024, we recognized $2.3 million of collaboration revenue, which is related to our research collaboration and license agreement with Novo Nordisk. During the year ended December 31, 2023, we recognized no collaboration revenue.
Current wording
We have not generated any revenue from product sales, and do not expect to generate any revenue from the sale of products in the near future. During the year ended December 31, 2025 and 2024, we recognized $6.4 million and $2.3 million of collaboration revenue, respectively, which is related to our research collaboration and license agreement with Novo Nordisk. In
Previous wording
For additional information about our revenue recognition policy, see Note 2 and Note 13 in the consolidated financial statements included in this Annual Report on Form 10-K.
Current wording
For additional information about our revenue recognition policy, see Note 2 and Note 12 to our audited consolidated financial statements included in this Annual Report on Form 10-K.
Previous wording
Research and development expenses consist primarily of costs incurred for our research and development activities, including our discovery of novel genetic medicines and the development of our product candidates, salaries and benefits, and third-party license fees. We expense research and development costs as incurred, which include:
Current wording
Research and development expenses consist primarily of costs incurred for our research and development activities, including our discovery of novel genetic medicines and the development of our development candidates, salaries and benefits, and third-party license fees. We expense research and development costs as incurred, which include:
Previous wording
A large portion of our research and development expenses have been external expenses, which we track on a program-by-program basis following nomination as a development candidate. Our internal research and development expenses are primarily personnel-related expenses, including stock-based compensation expense and facility expenses, mainly including office rent expenses and depreciation expenses. We do not allocate our internal research and development expenses to specific drug candidate programs as they are deployed across multiple projects under research and development.
Current wording
A large portion of our research and development expenses have been external expenses, which we track on a program-by-program basis following nomination as a development candidate. Our internal research and development expenses are primarily personnel-related expenses, including stock-based compensation expense and facility expenses, mainly including office rent expenses and depreciation expenses. We do not allocate our internal research and development expenses to specific development candidate programs as they are deployed across multiple projects under research and development.
Previous wording
The successful development of our product candidates is highly uncertain. We plan to substantially increase our research and development expenses for the foreseeable future as we continue the development of our product candidates, conduct discovery and research activities for our preclinical programs, and expands our pipeline. We cannot determine with certainty the timing of initiation, the duration or the completion costs of current or future preclinical studies and clinical trials of our product candidates due to the inherently unpredictable nature of preclinical and clinical development. Clinical and preclinical development timelines, the probability of success and development costs can differ materially from expectations. We anticipate that we will make determinations as to which product candidates to pursue and how much funding to direct to each product candidate on an ongoing basis in response to the results of ongoing and future preclinical studies and clinical trials, regulatory developments and our ongoing assessments as to each product candidate’s commercial potential. Our clinical development costs are expected to increase significantly as we commence clinical trials. We anticipate that our expenses will increase substantially, particularly due to the numerous risks and uncertainties associated with developing product candidates, including the uncertainty of:
Current wording
The successful development of our development candidates is highly uncertain. We plan to substantially increase our research and development expenses for the foreseeable future as we continue the development of our candidates, conduct discovery and research activities for our preclinical programs, and expand our pipeline. We cannot determine with certainty the timing of initiation, the duration or the completion costs of current or future preclinical studies and clinical trials of our development candidates due to the inherently unpredictable nature of preclinical and clinical development. Clinical and preclinical development timelines, the probability of success and development costs can differ materially from expectations. We anticipate that we will make determinations as to which lead candidates and development candidates to pursue and how much funding to direct to each on an ongoing basis in response to the results of ongoing and future preclinical studies and clinical trials, regulatory developments and our ongoing assessments as to each development candidate’s commercial potential. Our clinical development costs are expected to increase significantly as we commence clinical trials. We anticipate that our expenses will increase substantially, particularly due to the numerous risks and uncertainties associated with developing development candidates, including the uncertainty of:
Previous wording
whether our product candidates show safety and efficacy in our clinical trials;
Current wording
whether our development candidates show safety and efficacy in our clinical trials;
Previous wording
obtaining and maintaining patent and trade secret protection and regulatory exclusivity for our product candidates;
Current wording
obtaining and maintaining patent and trade secret protection and regulatory exclusivity for our development candidates;
Previous wording
commercializing product candidates, if and when approved, whether alone or in collaboration with others; and
Current wording
commercializing development candidates, if and when approved, whether alone or in collaboration with others; and
Previous wording
Any changes in the outcome of any of these variables with respect to the development of our product candidates in preclinical and clinical development could mean a significant change in the costs and timing associated with the development of these product candidates. We may never succeed in achieving regulatory approval for any of our product candidates. We may obtain unexpected results from our clinical trials. We may elect to discontinue, delay or modify clinical trials of some product candidates or focus on other product candidates. For example, if the FDA, EMA, HREC, TGA or another regulatory authority were to delay the planned start of clinical trials or require us to conduct clinical trials or other testing beyond those that we currently expect or if we experience significant delays in enrollment in any planned clinical trial, we could be required to expend significant additional financial resources and time on the completion of clinical development of that product candidate.
Current wording
Any changes in the outcome of any of these variables with respect to the development of our development candidates in preclinical and clinical development could mean a significant change in the costs and timing associated with the development of these development candidates. We may never succeed in achieving regulatory approval for any of our development candidates. We may obtain unexpected results from our clinical trials. We may elect to discontinue, delay or modify clinical trials of some development candidates or focus on other development candidates. For example, if the FDA, EMA, HREC, TGA or another regulatory authority were to delay the planned start of clinical trials or require us to conduct clinical trials or other testing beyond those that we currently expect or if we experience significant delays in enrollment in any planned clinical trial, we could be required to expend significant additional financial resources and time on the completion of clinical development of that development candidate.
Previous wording
We anticipate that our general and administrative expenses will increase in the future as we increase our headcount to support our continued research activities and development of our product candidates. We also expect to continue to incur costs associated with being a public company and maintaining controls over financial reporting, including costs of accounting, audit, legal, regulatory, compliance and director and officer insurance costs as well as investor and public relations expenses.
Current wording
We anticipate that our general and administrative expenses will decrease or remain flat in the near future to support our current planned research activities and development of our lead candidates and development candidates at current personnel levels. However, should we grow our operations, we anticipate that such personnel-related expenses would increase. We also expect to continue to incur costs associated with being a public company and maintaining controls over financial reporting, including costs of accounting, audit, legal, regulatory, compliance and director and officer insurance costs as well as investor and public relations expenses.
Previous wording
During the year ended December 31, 2024, we recognized $2.3 million of collaboration revenue from our research collaboration and license agreement with Novo Nordisk. During the year ended December 31, 2023, we recognized no collaboration revenue.
Current wording
During the year ended December 31, 2025 and 2024, we recognized $6.4 million and $2.3 million of collaboration revenue, respectively, from our research collaboration and license agreement with Novo Nordisk. In November 2025, we agreed to a 12 month pause on our collaboration with Novo Nordisk. Accordingly, we do not expect to recognize any material collaboration revenue under such agreement during the 12-month hold period.
Previous wording
Research and development expenses were $63.6 million for the year ended December 31, 2024, compared to $57.2 million for the year ended December 31, 2023. The increase was primarily due to a $19.3 million increase in KRRO-110 external expenses, which was primarily attributable to higher manufacturing activities in 2024 to produce the clinical drug product and an increase in clinical trial activities in 2024 for the Phase 1/2a REWRITE clinical trial. A portion of the increase was also due to a $3.2 million increase in personnel-related expenses driven by an increase in headcount to support the expansion of our research and clinical development function, and a $2.1 million increase in facility costs due to the expansion of our mixed-use office spaces and overall support of research and development activities. These increases were partially offset by a $18.2 million decrease in other research and pre-development candidates expenses, which was primarily attributable to the breakout of
Current wording
Research and development expenses were $65.6 million for the year ended December 31, 2025, compared to $63.6 million for the year ended December 31, 2024. The increase was primarily due to the following:
Previous wording
Since our inception, we have generated recurring net losses. We have not yet commercialized any product and we do not expect to generate revenue from sales of any products for several years, if at all. Since inception, we have funded our operations primarily through proceeds from the issuance of convertible preferred stock and common stock. To date, we have raised approximately $223.6 million of aggregate gross proceeds from the sale of convertible preferred stock, $117.3 million from the sale of shares of common stock issued in a private placement that closed immediately prior to the November 2023 business combination and $70.0 million from the April 2024 private placement of shares of our common stock. As of December 31, 2024, we had cash, cash equivalents and marketable securities of $163.1 million.
Current wording
Since our inception, we have generated recurring net losses. We have not yet commercialized any products and we do not expect to generate revenue from sales of any products for several years, if at all. Since inception, we have funded our operations primarily through proceeds from the issuance of convertible preferred stock and common stock. To date, we have raised approximately $223.6 million of aggregate gross proceeds from the sale of convertible preferred stock, $117.3 million from the sale of shares of common stock issued in a private placement that closed immediately prior to the November 2023 business combination, $70.0 million from the April 2024 private placement of shares of our common stock, $5.1 million from the January
Previous wording
Since inception, we have incurred significant operating losses and, as of December 31, 2024, had an accumulated deficit of $266.6 million. We expect to continue to incur significant expenses, operating losses, and negative operating cash flows for the foreseeable future. In addition, we have not yet commercialized any product and we do not expect to generate revenue from sales of any products for several years, if at all.
Current wording
Since inception, we have incurred significant operating losses and, as of December 31, 2025, had an accumulated deficit of $383.8 million. We expect to continue to incur significant expenses, operating losses, and negative operating cash flows for the foreseeable future. In addition, we have not yet commercialized any product and we do not expect to generate revenue from sales of any products for several years, if at all.
Previous wording
In December 2024, we entered into a sales agreement with TD Securities (USA) LLC, or TD Cowen, under which we may, from time to time, issue and sell shares of our common stock having aggregate sales proceeds of up to $100.0 million, in a series of one or more at-the-market equity offerings. As of December 31, 2024, we have not sold any shares of common stock under our at-the-market equity offering program.
Current wording
In December 2024, we entered into a sales agreement with TD Securities (USA) LLC, or TD Cowen, under which we may, from time to time, issue and sell shares of our common stock having aggregate sales proceeds of up to $100.0 million, in a series of one or more at-the-market equity offerings. As of December 31, 2025, we had not sold any shares of common stock under our at-the-market equity offering program. In January 2026, we issued 501,861 shares of common stock under the at-the-market offering program for gross proceeds of $5.1 million.
Previous wording
As of December 31, 2024, we had cash, cash equivalents and marketable securities of $163.1 million. We expect that our cash, cash equivalents and marketable securities outstanding as of December 31, 2024, will be sufficient to fund our operating expenses and capital expenditure requirements into the second half of 2026 (including completion of the Phase 1/2a REWRITE clinical trial of KRRO-110 and progress additional product candidates). We have based this estimate on assumptions that may prove to be wrong, and we could expend our capital resources sooner than we expect. We may also pursue additional cash resources through public or private equity, collaborations or debt financings. There is no assurance that we will be successful in obtaining sufficient financing on acceptable terms to continue funding our operations.
Current wording
As of December 31, 2025, we had cash, cash equivalents and marketable securities of $85.2 million. We expect that our cash, cash equivalents and marketable securities outstanding as of December 31, 2025, together with the net proceeds raised under the January at-the-market offering program sales and March 2026 private placement, will be sufficient to fund our operating expenses and capital expenditure requirements into the second half of 2028. We have based this estimate on assumptions that may prove to be wrong, and we could expend our capital resources sooner than we expect. We may also pursue additional cash resources through public or private equity, collaborations or debt financings. There is no assurance that we will be successful in obtaining sufficient financing on acceptable terms to continue funding our operations.
Previous wording
We expect to continue to incur significant expenses, operating losses, and negative operating cash flows for the foreseeable future as we continue our novel genetic medicine discovery efforts, advance our pipeline candidates into the clinic and through clinical trials, seek regulatory approval of our product candidates and pursue commercialization of any approved product candidates. In addition, we expect to continue to incur costs associated with operating as a public company.
Current wording
We expect to continue to incur significant expenses, operating losses, and negative operating cash flows for the foreseeable future as we continue our novel genetic medicine discovery efforts, advance our pipeline candidates into the clinic and through clinical trials, seek regulatory approval of our development candidates and pursue commercialization of any approved development candidates. In addition, we expect to continue to incur costs associated with operating as a public company.
Previous wording
Because of the numerous risks and uncertainties associated with research, development and commercialization of our product candidates, we are unable to estimate the exact amount of our working capital requirements.
Current wording
Because of the numerous risks and uncertainties associated with research, development and commercialization of our development candidates, we are unable to estimate the exact amount of our working capital requirements.
Previous wording
the scope, progress, results, and costs of discovery, preclinical development, laboratory testing, manufacturing and clinical trials for KRRO-110 and other product candidates we may develop;
Current wording
the scope, progress, results, and costs of discovery, preclinical development, laboratory testing, manufacturing and clinical trials for KRRO-121 and other candidates we may develop;
Previous wording
the extent to which we partner our programs, acquires or in-licenses other product candidates and technologies or enters into additional collaborations;
Current wording
the extent to which we partner our programs, acquire or in-license other lead candidates, development candidates and technologies or enter into additional collaborations;
Previous wording
our headcount growth and associated costs as we expand our research and development efforts;
Current wording
any future headcount growth and associated costs, should we expand our research and development efforts;
Previous wording
the cost of defending potential intellectual property disputes, including patent infringement actions brought by third parties against us or any of our product candidates;
Current wording
the cost of defending potential intellectual property disputes, including patent infringement actions brought by third parties against us or any of our lead candidates or development candidates;
Previous wording
the costs and timing of future commercialization activities, including product manufacturing, marketing, sales and distribution, for any product candidates for which we receive marketing approval;
Current wording
the costs and timing of future commercialization activities, including product manufacturing, marketing, sales and distribution, for any development candidates for which we receive marketing approval;
Previous wording
Until such time, if ever, as we can generate substantial product revenues to support our cost structure, we expect to finance our cash needs through a combination of equity offerings, debt financings, collaborations and other similar arrangements. To the extent that we raise additional capital through the sale of equity or convertible securities, the ownership interest of our stockholders will be or could be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect the rights of our common stockholders. Debt financing and equity financing, if available, may involve agreements that include covenants limiting or restricting our ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends. If we raise funds through collaborations, or other similar arrangements with third parties, we may have to relinquish valuable rights to our technologies, future revenue streams, research programs or product candidates or grant licenses on terms that may not be favorable to us and/or may reduce the value of our common shares. If we are unable to raise additional funds through equity or debt financings when needed, we may be required to delay, limit, reduce or terminate our product research and development or grant rights to develop and market our product candidates even if we would otherwise prefer to develop and market such product candidates ourselves.
Current wording
Until such time, if ever, as we can generate substantial product revenues to support our cost structure, we expect to finance our cash needs through a combination of equity offerings, debt financings, collaborations and other similar arrangements. To the extent that we raise additional capital through the sale of equity or convertible securities, the ownership interest of our stockholders will be or could be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect the rights of our common stockholders. Debt financing and equity financing, if available, may involve agreements that include covenants limiting or restricting our ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends. If we raise funds through collaborations, or other similar arrangements with third parties, we may have to relinquish valuable rights to our technologies, future revenue streams, research programs or development candidates or grant licenses on terms that may not be favorable to us and/or may reduce the value of our common shares. If we are unable to raise additional funds through equity or debt financings when needed, we may be required to delay, limit, reduce or terminate our product research and development or grant rights to develop and market our development candidates even if we would otherwise prefer to develop and market such development candidates ourselves.
Previous wording
Net cash provided by investing activities was $11.2 million for the year ended December 31, 2023 and consisted primarily of $19.0 million proceeds from maturity of marketable securities, offset by $7.8 million of purchase of property and equipment.
Current wording
Net cash provided by investing activities was $44.0 million for the year ended December 31, 2025 and consisted primarily of the proceeds from maturities of marketable securities, offset by purchase of marketable securities and the purchase of property and equipment.
Previous wording
Net cash used in investing activities was $123.3 million for the year ended December 31, 2024 and consisted primarily of $146.3 million of purchase of marketable securities and $17.9 million of purchase of property and equipment, offset by $40.9 million of proceeds from maturities of marketable securities.
Current wording
Net cash used in investing activities was $123.3 million for the year ended December 31, 2024 and consisted primarily of the purchase of marketable securities and the purchase of property and equipment, offset by proceeds from maturities of marketable securities.
Previous wording
Net cash provided by financing activities was $69.4 million for the year ended December 31, 2024 and consisted primarily of net proceeds of $67.4 million from the April 2024 private placement of shares of our common stock.
Current wording
Net cash provided by financing activities was $69.4 million for the year ended December 31, 2024 and consisted of net proceeds from the April 2024 private placement and proceeds from exercises of stock options.
Previous wording
While our significant accounting policies are described in more detail in Note 2 to our audited consolidated financial statements appearing elsewhere in this Annual Report on Form 10-K, we believe that the following accounting policies are those most critical to the judgments and estimates used in the preparation of our consolidated financial statements.
Current wording
While our significant accounting policies are described in more detail in Note 2 to our audited consolidated financial statements appearing elsewhere in this Annual Report on Form 10-K, we believe that the following accounting policy is most critical to the judgments and estimates used in the preparation of our consolidated financial statements.
Rearranged current paragraphs (2)
Current report — wording carried from elsewhere
a $1.5 million decrease in other research and pre-development candidate expenses.
Current report — wording carried from elsewhere
Cash Provided by (Used in) Investing Activities