Korro Bio, Inc.
For the period ended Mar 31, 2026. Filed May 7, 2026.
View on SEC.govAbout this filing
A company's report for each of its first three quarters. The financial statements are not audited. It shows how the business has moved since the last annual report, and what management says changed.
Mar 31, 2026 · Filed May 7, 2026
What changed in Management’s Discussion and Analysis?
Read the current filingPrevious report: 10-Q
Period ended 2025-09-30; filed 2025-11-12.
0001193125-25-277572
Item 2. Management’s Discussion and Analysis of Financial Condition and Results of OperationsCurrent report: 10-Q
Period ended 2026-03-31; filed 2026-05-07.
0001193125-26-210303
Item 2. 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 123 previous paragraphs and 107 current paragraphs.
51 unchanged; 40 reworded; 14 added; 29 removed; 3 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 (14)
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 single nucleotide variants, or 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 urea cycle disorders, or UCD, and hepatic encephalopathy, or HE. KRRO-121 is a GalNAc-conjugated RNA editing oligonucleotide for the potential treatment of hyperammonemia in patients with UCDs of any mutational background as well as patients with HE. Utilizing our proprietary OPERA platform, KRRO-121 is designed to generate a stabilized, de novo glutamine synthetase, or GS, protein, a critical enzyme involved in ammonia clearance. This synthetic rescue approach is designed to augment ammonia clearance in hyperammonemia-driven diseases such as UCDs and HE. Our preclinical data support the potential for KRRO-121 to be a pan-UCD treatment that may control ammonia levels, along with the potential to enable diet liberalization, reduce dependence on nitrogen scavengers, and lower the risk of hyperammonemic crises. KRRO-121 also has the potential to enhance ammonia control in HE patients, which may reduce the risk of recurrent HE episodes. KRRO-121 may offer infrequent subcutaneous dosing, which, if confirmed in clinical studies, could offer significant improvement over current treatments that require multiple daily doses. KRRO-121 has the potential to be a differentiated, first-in-class, disease-modifying therapy for both UCD and HE. We anticipate a regulatory filing to enable commencement of a first-in-human trial in the second half of 2026.
Current report
We are also advancing early-stage research and development programs highlighted by a GalNac-conjugated oligonucleotide for AATD. We are on track to announce our AATD development candidate in second quarter of 2026 and plan to nominate a development candidate for a third GalNAc-conjugated program in the second half of 2026.
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 offering expenses of approximately $0.1 million.
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, or a PIPE, (i) an aggregate of 4,501,928 shares of our common stock at a purchase price of $11.11 per share and (ii) pre-funded warrants to acquire an aggregate 3,148,836 shares of our common stock (at an exercise price of $0.001 per share) at a purchase price of $11.109 per pre-funded warrant. The PIPE, which closed March 10, 2026, resulted in gross cash proceeds of approximately $85.0 million, before deducting placement agent fees and offering expenses of approximately $4.7 million. No pre-funded warrants have been exercised as of March 31, 2026.
Current report
a $5.4 million decrease in KRRO-110 external expenses primarily due to the termination of the Phase 1/2a REWRITE clinical trial during the first quarter of 2026; and
Current report
a $2.5 million decrease in personnel-related expenses, primarily due to a decrease in headcount resulting from the May and November 2025 workforce reductions; and
Current report
a $0.9 million decrease in facilities expenses primarily due to a decrease in depreciation expense attributable to the impairment charge recorded during the fourth quarter of 2025;
Current report
offset by a $3.3 million increase in KRRO-121 external expenses, primarily due to an increase in preclinical and manufacturing costs.
Current report
General and administrative expenses were $7.5 million for the three months ended March 31, 2026, compared to $7.8 million for the three months ended March 31, 2025. The decrease was primarily due to a decrease in facilities expenses and information technology expenses, partially offset by an increase in personnel expenses mainly due to increased stock-based compensation costs.
Current report
In March 2026, we closed a PIPE selling (i) an aggregate of 4,501,928 shares of our common stock at a purchase price of $11.11 per share and (ii) pre-funded warrants to acquire an aggregate 3,148,836 shares of our common stock (at an exercise price of $0.001 per share) at a purchase price of $11.109 per pre-funded warrant, which resulted in gross cash proceeds of approximately $85.0 million, before deducting placement agent fees and offering expenses of approximately $4.7 million.
Removed paragraphs (29)
Previous report
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.
Previous report
The versatility of RNA editing combined with our RNA platform broadens the therapeutic target space significantly. While our approach can be used to repair pathogenic single nucleotide variants, or SNVs, 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 KRRO-121, our recently announced product candidate targeting the liver via GalNAc, initially to treat patients with urea cycle disorders, or UCD, and the potential to expand into patients with hepatic encephalopathy, or HE. 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
We have investigated KRRO-110 as a treatment for AATD where, using our proprietary RNA editing approach, we aimed to repair a pathogenic variant on RNA. KRRO-110 did not reach projected levels of functional protein following a single administration as of the data cutoff date, and we are now pivoting to GalNAc delivery for AATD and expect to nominate a development candidate in 2025. In January 2025, we announced dosing of the first participants in our REWRITE clinical program investigating KRRO-110 as a treatment for AATD. The REWRITE clinical trial is a two-part single and multiple-dose escalating study evaluating the safety and tolerability of KRRO-110, including healthy adults and clinically stable AATD patients with the PiZZ genotype. We have completed all six planned single ascending dose, or SAD, healthy volunteer, or HV, cohorts. Each HV cohort consisted of six participants, with four receiving active drug and two receiving placebo. Doses of KRRO-110 tested in the HVs (n=24) include 0.04, 0.1, 0.2, 0.4, 0.8 and 1.2 mg/kg, with the primary objective to evaluate safety and tolerability. KRRO-110 is currently being evaluated in two AATD patient cohorts at 0.6 mg/kg (n=3) and 0.8 mg/kg (n=4), with seven patients dosed. The AATD patient cohorts are open label with up to four patients in each cohort. There are currently no plans to complete additional SAD patient cohorts for KRRO-110. We are evaluating the totality of the clinical data to evaluate the next steps, if any, for KRRO-110 in the multiple-ascending dose, or MAD, portion of the REWRITE clinical trial. Key findings of the REWRITE clinical trial include:
Previous report
KRRO-110 Safety Observations (as of the November 6, 2025 Data Cutoff Date):
Previous report
No dose-limiting toxicities or treatment emergent serious adverse events observed.
Previous report
Mild-to-moderate infusion-related reactions, or IRRs, observed in two healthy volunteers at the highest dose of 1.2 mg/kg, two AATD patients at 0.6 mg/kg, and two AATD patients at 0.8 mg/kg.
Previous report
All IRRs resolved within 24 hours post KRRO-110 dosing; intervention was limited to antipyretics and antihistamines.
Previous report
KRRO-110 safety profile is consistent with Lipid Nanoparticle, or LNP, infusion-related class effects.
Previous report
KRRO-110 Pharmacodynamic and Pharmacokinetic Observations (as of the November 6, 2025 Data Cutoff Date):
Previous report
Across five AATD patients in the two SAD cohorts evaluable with turbidimetry, the greatest peak total AAT protein was approximately 10 µM and the greatest increase of total AAT protein from baseline was approximately 3 µM. The total AAT protein levels following single-dose administration did not reach the protective threshold of 11 µM.
Previous report
In three of the AATD patients dosed with 0.8 mg/kg evaluable with LC/MS, functional M-AAT protein was observed in each of the patients following administration of KRRO-110. The greatest increase of M-AAT protein from baseline observed at any time point was approximately 2 µM. Functional M-AAT protein lasted up to four weeks for the first patient evaluable with LC/MS, consistent with durability of editing and endogenous M-AAT protein half-life.
Previous report
Pharmacokinetic, or PK, differences in the components of KRRO-110 in plasma were observed between HV and AATD patients, with apparent faster disassociation of KRRO-110, suggesting variability of this formulation in AATD patients compared to HV following a single dose.
Previous report
No evidence of bystander editing observed to date, suggesting high specificity, based on LC/MS data on M-AAT and Z-AAT.
Previous report
KRRO-110 Regulatory Milestones Validate OPERA Platform Potential:
Previous report
First-ever RNA editing technology to receive investigational new drug application, or IND, clearance by the U.S. Food and Drug Administration, or FDA, to our knowledge.
Previous report
Fast Track designation granted by the FDA.
Previous report
Orphan Drug Designation granted by both the FDA and European Medicines Agency.
Previous report
We recently nominated our second development candidate, KRRO-121, for the potential treatment of UCD and HE. KRRO-121 is a GalNAc-conjugated oligonucleotide that will be administered subcutaneously to create de novo protein variants and designed to stabilize a critical enzyme involved in reducing ammonia levels. We plan to submit a regulatory filing of first-in-human trial for KRRO-121 in the second half of 2026. We are also prioritizing other high-potential GalNAc-conjugated programs targeting the liver, including an AATD program and programs for subcutaneous delivery in cardiometabolic indications. We plan to nominate a development candidate for our GalNAc-conjugated AATD program in 2026.
Previous report
In May 2025, we announced a strategic plan to streamline our operations, including a reduction in workforce by 19%, or 21 positions. Please refer to Note 16 in the condensed consolidated financial statements included in this Quarterly Report.
Previous report
In November 2025, we implemented a strategic restructuring to extend cash runway, including a further workforce reduction of approximately 34%. We estimate that we will incur one-time restructuring charges of approximately $2.4 million including employee severance, benefits and related termination costs, the majority of which we expect to recognize during the three months ended December 31, 2025.
Previous report
a $2.0 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 continued to progress; and
Previous report
offset by a $0.9 million increase in personnel-related expenses, primarily due to the expansion of our clinical development function.
Previous report
Research and development expenses were $54.6 million for the nine months ended September 30, 2025, compared to $46.7 million for the nine months ended September 30, 2024. The increase was primarily due to the following:
Previous report
a $4.3 million increase in personnel-related expenses, primarily due to an increase in headcount prior to the May 2025 workforce reduction, the expansion of our clinical development function and one-time severance charges related to the May 2025 workforce reduction;
Previous report
a $2.7 million increase in other research and pre-development candidate expenses as we furthered development of KRRO-121; and
Previous report
a $1.3 million increase in KRRO-110 external expenses, primarily to an increase in clinical trial expenses in 2025 for the Phase 1/2a REWRITE clinical trial, partially offset by a reduction in non clinical costs, and a $0.5 million net increase in development milestone under our collaboration and license agreement with Genevant Sciences GmbH.
Previous report
General and administrative expenses were $6.5 million for the three months ended September 30, 2025, compared to $7.3 million for the three months ended September 30, 2024. The decrease was primarily due to a $0.7 million decrease in professional services expenses.
Previous report
General and administrative expenses were $22.0 million for the nine months ended September 30, 2025, compared to $22.2 million for the nine months ended September 30, 2024. The decrease was primarily due to a $1.8 million decrease in professional services expenses, offset by a $1.9 million increase in personnel-related expenses, which was mainly attributable to an increase in stock-based compensation costs and severance costs related to the May 2025 workforce reduction.
Previous report
Comparison of the Nine Months Ended September 30, 2025 and 2024
Reworded paragraphs (40)
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 drugs. 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 a biopharmaceutical company leveraging a novel oligonucleotide promoted editing of RNA, or OPERA, platform to develop a new class of genetic medicines for rare and highly prevalent diseases. OPERA provides precise, tissue-directed delivery of oligonucleotides that modify the targeted native mRNA transcript to repair or form a de-novo protein with enhanced functionality. The platform combines a suite of capabilities consisting of sophisticated knowledge of transcription biology through ADAR proteins (Adenosine Deaminases Acting on RNA), machine learning optimization of oligonucleotides, linker chemistry expertise, along with use of a highly targeted tissue-specific delivery methodology. As such, the OPERA platform has enabled us to generate and advance a portfolio of differentiated programs that are designed to harness the body’s natural RNA editing process, providing precise yet transient single base edits to produce therapeutic proteins with augmented activity versus its endogenous counterpart. 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 OPERA platform with precedented delivery modalities, including N-acetylgalactosamine, or GalNAc, conjugated for 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, $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 $501.0 million of aggregate gross proceeds from sales of our equity securities.
Previous wording
We have incurred significant operating losses since inception. Our net losses were $67.2 million and $62.4 million for the nine months ended September 30, 2025 and 2024, respectively. We had an accumulated deficit of $333.8 million as of September 30, 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 product candidates 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 $19.6 million and $23.4 million for the three months ended March 31, 2026 and 2025, respectively. We had an accumulated deficit of $403.5 million as of March 31, 2026. 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 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 nine months ended September 30, 2025, we recognized $5.1 million of collaboration revenue, which is related to our September 2024 research collaboration and license agreement with Novo Nordisk. During the nine months ended September 30, 2024, we recognized no collaboration revenue. In November 2025, we agreed to a 12 month pause on such collaboration with Novo Nordisk, accordingly, we do not expect to recognize any material collaboration revenue under such
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 three months ended March 31, 2026 and 2025, we recognized $0.0 million and $2.6 million of collaboration revenue, respectively, which is related to our research collaboration and license agreement with Novo Nordisk. In November 2025, we agreed to a 12-month pause on such 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
For additional information about our revenue recognition policy and our collaboration and license agreement with Novo Nordisk, which is now paused, see Note 11 and Note 17 in the condensed consolidated financial statements included in this Quarterly Report.
Current wording
For additional information about our revenue recognition policy and our collaboration and license agreement with Novo Nordisk, which is now paused, see Note 11 in the condensed consolidated financial statements included in this Quarterly Report.
Previous wording
Research and development expenses consist primarily of costs incurred for our research 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 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
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 development 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 development candidates to pursue and how much funding to direct to each development 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 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, the Human Research Ethics Committee, or HREC, Therapeutic Goods Administration, or TGA, the Health and Disability Ethics Committees, or HDEC, 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 Food and Drug Administration, or FDA, European Medicines Agency, or EMA, the Human Research Ethics Committee, or HREC, Therapeutic Goods Administration, or TGA, the Health and Disability Ethics Committees, or HDEC, 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
Comparison of the Three and Nine Months Ended September 30, 2025 and 2024
Current wording
Comparison of the Three Months Ended March 31, 2026 and 2025
Previous wording
The following table summarizes our results of operations for the three and nine months ended September 30, 2025 and 2024:
Current wording
The following table summarizes our results of operations for the three months ended March 31, 2026 and 2025:
Previous wording
During the three and nine months ended September 30, 2025, we recognized $1.1 million and $5.1 million, respectively, of collaboration revenue from our research collaboration and license agreement with Novo Nordisk. During the three and nine months ended September 30, 2024, we recognized no collaboration revenue. 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.
Current wording
During the three months ended March 31, 2026 and 2025, we recognized $0.0 million and $2.6 million, respectively, of collaboration revenue 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
The following table summarizes our research and development expenses for the three and nine months ended September 30, 2025 and 2024:
Current wording
The following table summarizes our research and development expenses for the three months ended March 31, 2026 and 2025:
Previous wording
Research and development expenses were $13.8 million for the three months ended September 30, 2025, compared to $16.0 million for the three months ended September 30, 2024. The decrease was primarily due to the following:
Current wording
Research and development expenses were $12.9 million for the three months ended March 31, 2026, compared to $19.7 million for the three months ended March 31, 2025. The decrease was primarily due to the following:
Previous wording
a $0.7 million decrease in other research and pre-development candidate expenses;
Current wording
a $1.3 million decrease in other research and pre-development candidate expenses; and
Previous wording
The following table summarizes our general and administrative expenses for the three and nine months ended September 30, 2025 and 2024:
Current wording
The following table summarizes our general and administrative expenses for the three months ended March 31, 2026 and 2025:
Previous wording
Total other income, net was $1.2 million for the three months ended September 30, 2025, compared to $2.3 million for the three months ended September 30, 2024. The decrease of $1.1 million was primarily due to lower interest income generated from a lower cash, cash equivalent and marketable securities balance as of September 30, 2025.
Current wording
Total other income, net was $0.9 million for the three months ended March 31, 2026, compared to $1.6 million for the three months ended March 31, 2025. The decrease of $0.7 million was primarily due to lower interest income generated from a lower cash, cash equivalent and marketable securities balance during the quarter prior to the March 2026 PIPE.
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 September 30, 2025, we had cash, cash equivalents and marketable securities of $102.5 million.
Current 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 $501.0 million of aggregate gross proceeds from sales of our equity securities. As of March 31, 2026, we had cash, cash equivalents and marketable securities of $157.1 million.
Previous wording
Since inception, we have incurred significant operating losses and, as of September 30, 2025, had an accumulated deficit of $333.8 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.
Current wording
Since inception, we have incurred significant operating losses and, as of March 31, 2026, had an accumulated deficit of $403.5 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 September 30, 2025, 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 Cowen 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, or ATM, offerings. In January 2026, we issued 501,861 shares of common stock under the ATM offering program for gross proceeds of $5.1 million, before deducting offering expenses of approximately $0.1 million.
Previous wording
As of September 30, 2025, we had cash, cash equivalents and marketable securities of $102.5 million. We expect that our cash, cash equivalents and marketable securities outstanding as of September 30, 2025 will be sufficient to fund our operating expenses and capital expenditure requirements into the second half of 2027. 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 March 31, 2026, we had cash, cash equivalents and marketable securities of $157.1 million. We expect that our cash, cash equivalents and marketable securities outstanding as of March 31, 2026 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-121, a GalNAc-conjugated candidate for AATD, 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, a GalNAc-conjugated candidate for AATD, and other development candidates we may develop;
Previous wording
the cost of continuing to build our Oligonucleotide Promoted Editing of RNA, or OPERA, platform and discover additional novel genetic medicines;
Current wording
the cost of continuing to build our OPERA platform and discover additional novel genetic medicines;
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, acquires or in-licenses other lead candidates, development candidates and technologies or enters into additional collaborations;
Previous wording
our headcount growth and associated costs when 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
The following table summarizes our cash flows for the nine months ended September 30, 2025 and 2024:
Current wording
The following table summarizes our cash flows for the three months ended March 31, 2026 and 2025:
Previous wording
Net cash used in operating activities was $52.6 million for the nine months ended September 30, 2024, primarily resulted from our net loss of $62.4 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 $2.4 million, offset by $7.4 million of non-cash items.
Current wording
Net cash used in operating activities was $16.1 million for the three months ended March 31, 2026, primarily resulted from our net loss of $19.6 million, which was primarily attributable to our research and development activities and our general and administrative expenses, offset by changes in our operating assets and liabilities of $0.2 million and $3.3 million of non-cash items.
Previous wording
Net cash used in operating activities was $60.9 million for the nine months ended September 30, 2025, primarily resulted from our net loss of $67.2 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 $3.0 million, offset by $9.3 million of non-cash items.
Current wording
Net cash used in operating activities was $24.5 million for the three months ended March 31, 2025, primarily resulted from our net loss of $23.4 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 $3.9 million, offset by $2.8 million of non-cash items.
Previous wording
Net cash used in investing activities was $120.6 million for the nine months ended September 30, 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.
Current wording
Net cash used in investing activities was $32.2 million for the three months ended March 31, 2026 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 investing activities was $29.1 million for the nine months ended September 30, 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.
Current wording
Net cash provided by investing activities was $32.8 million for the three months ended March 31, 2025 and consisted primarily of the proceeds from maturities of marketable securities, offset by and the purchase of property and equipment.
Previous wording
Net cash provided by financing activities was $68.4 million for the nine months ended September 30, 2024 and consisted primarily of net proceeds from the April 2024 private placement.
Current wording
Net cash provided by financing activities was $88.2 million for the three months ended March 31, 2026 and consisted of net proceeds from the March 2026 PIPE, sales of shares under our ATM program, and exercises of stock options.
Previous wording
Net cash provided by financing activities was $0.3 million for the nine months ended September 30, 2025 and consisted of proceeds from exercises of stock options.
Current wording
Net cash provided by financing activities was $0.1 million for the three months ended March 31, 2025 and consisted primarily of proceeds from exercises of stock options.
Rearranged current paragraphs (2)
Current report — wording carried from elsewhere
Comparison of the Three Months Ended March 31, 2026 and 2025
Current report — wording carried from elsewhere
Cash (Used in) Provided by Investing Activities
Rearranged previous paragraphs (3)
Previous report — wording carried elsewhere
agreement during the 12-month hold period.
Previous report — wording carried elsewhere
Total other income, net was $4.2 million for the nine months ended September 30, 2025, compared to $6.5 million for the nine months ended September 30, 2024. The decrease of $2.3 million was primarily due to lower interest income generated from a lower cash, cash equivalent and marketable securities balance as of September 30, 2025.
Previous report — wording carried elsewhere
Cash Provided by (Used in) Investing Activities