Korro Bio, Inc.
For the period ended Sep 30, 2026. Filed Nov 5, 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.
Sep 30, 2026 · Filed Nov 5, 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-Q
Period ended 2026-06-30; filed 2026-08-06.
0001193125-26-336707
Item 2. Management’s Discussion and Analysis of Financial Condition and Results of OperationsCurrent report: 10-Q
Period ended 2026-09-30; filed 2026-11-05.
0001193125-26-448550
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 124 previous paragraphs and 135 current paragraphs.
76 unchanged; 39 reworded; 16 added; 6 removed; 3 previous and 4 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 (16)
Current report
Program Updates and Other Recent Developments
Current report
KRRO-121
Current report
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. In preclinical studies, KRRO-121 stabilized GS protein in human induced pluripotent stem cell, or iPSC, -derived hepatocytes deficient in ornithine transcarbamylase, or OTC, and we observed similar results in iPSC-derived hepatocytes deficient in argininosuccinate synthetase 1, or ASS1. In mouse models of OTC deficiency and carbamoyl phosphate synthetase 1, or CPS-1, deficiency subjected to an ammonia challenge, a mouse-optimized surrogate oligonucleotide reduced plasma ammonia levels following the challenge relative to vehicle control. In a mouse model of argininosuccinate lyase, or ASL, deficiency, treatment with the mouse-optimized surrogate oligonucleotide increased median survival from 18 days to 23 days compared to vehicle. Results of preclinical studies may not be predictive of results in humans. Whether KRRO-121 will control ammonia levels, enable diet liberalization, reduce dependence on nitrogen scavengers or lower the risk of hyperammonemic crises in patients with UCDs, or enhance ammonia control or reduce the risk of recurrent HE episodes in patients with HE, has not been established and will depend on the results of clinical trials. KRRO-121 may permit infrequent subcutaneous dosing; however, its dosing regimen has not been established in clinical studies.
Current report
KRRO-121 is being evaluated in ANCHOR (AssessmeNt of Control of Hyperammonemia through Oligonucleotide-based RNA editing), our global, two-part Phase 1/2 clinical trial program evaluating the safety, tolerability, pharmacokinetics, or PK, and clinical activity of KRRO-121. Part 1 of ANCHOR consists of a Phase 1 single ascending dose, or SAD, study, to be followed by a Phase 1 multiple ascending dose, or MAD, study, of KRRO-121 and placebo in healthy volunteers to evaluate safety, tolerability and PK in up to 50 participants. The SAD portion is designed to enroll up to 30 healthy volunteers across up to five cohorts, and the MAD portion is designed to evaluate selected doses of KRRO-121 in up to 20 healthy volunteers across two cohorts. Both the SAD and MAD portions are placebo-controlled. Part 2 of ANCHOR is designed as an open-label Phase 2 multiple dose study in participants with UCDs who are on stable background standard of care to assess safety, tolerability, PK and clinical activity. The initiation, design and endpoints of Part 2 are subject to regulatory review and clearance to proceed.
Current report
In September 2026, we initiated Part 1 of ANCHOR and dosed the first cohort of healthy volunteers in the SAD portion with a single dose of KRRO-121 or placebo. We announced the dosing of the first cohort in October 2026. ANCHOR does not include patients with HE, and we have not initiated a clinical trial of KRRO-121 in patients with HE. Dosing of UCD patients in Part 2 of ANCHOR is expected to start in the first half of 2027, subject to regulatory clearance to proceed, with an interim clinical readout expected in the second half of 2027.
Current report
In August 2026, we announced that the European Commission granted orphan drug designation to KRRO-121 for the treatment of UCDs, and in August 2026, the U.S. Food and Drug Administration, or FDA, granted rare pediatric disease designation to KRRO-121 for the treatment of UCDs.
Current report
KRRO-111
Current report
In October 2026, we announced additional preclinical data for KRRO-111. In a repeat-dose study in NSG-PiZ mice in which KRRO-111 was administered subcutaneously once weekly, SERPINA1 mRNA editing reached 96%, with M-AAT comprising 93% of total circulating AAT and total AAT concentrations reaching 172 µM (approximately six-fold relative to vehicle) at day 57. In a repeat-dose study in immunocompetent C57BL/6-PiZ mice in which KRRO-111 was administered subcutaneously once weekly, KRRO-111 resulted in robust, dose-dependent correction of SERPINA1 mRNA and M-AAT. KRRO-111 also reduced whole liver Z-AAT levels by up to 95% relative to vehicle control at day 57, as measured by liquid chromatography tandem mass spectrometry. By simultaneously increasing circulating M-AAT protein and decreasing pathogenic Z-AAT aggregates in the lung, KRRO-111 has the potential to be the best-in-class agent, improving both lung and liver manifestations of AATD. Results of preclinical studies may not be predictive of results in humans, and these potential effects of KRRO-111 have not been evaluated in humans. Regulatory submission for KRRO-111 is expected in the first half of 2027.
Current report
Collaboration with Novo Nordisk
Current report
In September 2024, we entered into a research collaboration and license agreement, or the collaboration and license agreement, with Novo Nordisk A/S, or Novo Nordisk, which we amended in November 2025 to pause the agreement for 12 months. We completed the wind-down of our research and development activities under the agreement in the first quarter of 2026. Novo Nordisk did not exercise its right to substitute the collaboration target during the hold period. We did not recognize collaboration revenue under the collaboration and license agreement during the three months ended September 30, 2026. On November 3, 2026, after the end of the quarter, we received written notice from Novo Nordisk of its election to terminate the collaboration and license agreement for convenience. The termination will be effective on February 1, 2027. For additional information, see Note 11, Collaboration Agreement and Note 17 Subsequent Events, in the condensed consolidated financial statements included in this Quarterly Report.
Current report
Research and development expenses were $12.1 million for the three months ended September 30, 2026, compared to $13.8 million for the three months ended September 30, 2025. The decrease was primarily due to the following:
Current report
a $0.6 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
Research and development expenses were $38.6 million for the nine months ended September 30, 2026, compared to $53.7 million for the nine months ended September 30, 2025. The decrease was primarily due to the following:
Current report
General and administrative expenses were $20.4 million for the nine months ended September 30, 2026, compared to $21.6 million for the nine months ended September 30, 2025. The decrease was primarily due to the following:
Current report
a $0.6 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; and
Current report
Comparison of the Nine Months Ended September 30, 2026 and 2025
Removed paragraphs (6)
Previous report
Research and development expenses were $13.6 million for the three months ended June 30, 2026, compared to $20.1 million for the three months ended June 30, 2025. The decrease was primarily due to the following:
Previous report
a $0.7 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;
Previous report
Research and development expenses were $26.5 million for the six months ended June 30, 2026, compared to $39.9 million for the six months ended June 30, 2025. The decrease was primarily due to the following:
Previous report
a $1.6 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;
Previous report
General and administrative expenses were $14.0 million for the six months ended June 30, 2026, compared to $15.1 million for the six months ended June 30, 2025. The decrease was primarily due to the following:
Previous report
Comparison of the Six Months Ended June 30, 2026 and 2025
Reworded paragraphs (39)
Previous 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 RNA-editing oligonucleotides, or REOs, 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 REOs, 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 REO-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.
Current wording
We are a clinical-stage 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 RNA-editing oligonucleotides, or REOs, that modify the targeted native mRNA transcript to repair or form ade 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 REOs, 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 REO-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 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
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 REO 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 obviate the need for a functional urea cycle and instead generate a stabilized, de novo glutamine synthetase, or GS, protein, a critical enzyme in an alternate pathway 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. In August 2026, we announced the European Medicines Agency, or EMA, granted orphan drug designation for KRRO-121 for patients with UCDs. We remain on track to commence a first-in-human trial for KRRO-121 in the second half of 2026.
Current wording
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, as well as KRRO-111, our proprietary GalNAc-conjugated REO in development for the treatment of AATD.
Previous wording
We have incurred significant operating losses since inception. Our net losses were $38.5 million and $49.2 million for the six months ended June 30, 2026 and 2025, respectively. We had an accumulated deficit of $422.4 million as of June 30, 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.
Current wording
We have incurred significant operating losses since inception. Our net losses were $56.1 million and $67.2 million for the nine months ended September 30, 2026 and 2025, respectively. We had an accumulated deficit of $439.9 million as of September 30, 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 are also advancing our other early-stage research and development programs. In May 2026, we announced KRRO-111, our development candidate for the potential treatment of AATD. KRRO-111 is a proprietary GalNAc-conjugated REO that is delivered subcutaneously to the liver cells, where it is engineered to co-opt the hepatocytes’ endogenous ADAR enzyme and repair a pathogenic SNV on alpha-1 antitrypsin, or AAT, mRNA to restore production of normal AAT protein. This therapeutic profile and titratable dosing position KRRO-111 as a potential best-in-class candidate. In preclinical studies, KRRO-111 demonstrated best-in-class RNA editing where over 90% of the AAT transcripts in the liver cells have been corrected, translating into approximately 90% M-AAT protein. In a repeat-dose study, KRRO-111 was administered to PiZZ mice with a loading phase followed by dosing once every two weeks. KRRO-111 demonstrated a reduction of non-inclusion Z-AAT by approximately 95% and a reduction in pre-existing aggregates by approximately 62% at day 28 with RNA editing in a mouse model of AATD. Pre-existing aggregates were progressively cleared, with inclusion-associated Z-AAT significantly reduced by approximately 62% at day 28, consistent with autophagic clearance of accumulated protein following successful editing. By simultaneously increasing circulating M-AAT protein and decreasing pathogenic Z-AAT aggregates in the lung, KRRO-111 has the potential to be the best-in-disease agent, improving both lung and liver manifestations of the disease. We also expect to nominate a development candidate for a third GalNAc-conjugated program in the second half of 2026.
Current wording
KRRO-111 is a proprietary GalNAc-conjugated REO in development for the potential treatment of AATD. KRRO-111 is delivered subcutaneously to the liver cells, where it is engineered to co-opt the hepatocytes’ endogenous ADAR enzyme and repair a pathogenic SNV on alpha-1 antitrypsin, or AAT, mRNA to restore production of the normal M variant of AAT, or M-AAT, protein while reducing synthesis of the mutant Z variant of AAT, or Z-AAT. This therapeutic profile and titratable dosing position KRRO-111 as a potential best-in-class candidate. In preclinical studies, KRRO-111, to our knowledge, demonstrated best-in-class RNA editing where over 90% of the AAT transcripts in the liver cells have been corrected, translating into approximately 90% M-AAT protein. In a repeat-dose study, KRRO-111 was administered to PiZZ mice with a loading phase followed by dosing once every two weeks. KRRO-111 demonstrated a reduction of non-inclusion Z-AAT by approximately 95% and a reduction in pre-existing aggregates by approximately 62% at day 28 with RNA editing in a mouse model of AATD. Pre-existing aggregates were progressively cleared, with inclusion-associated Z-AAT significantly reduced by approximately 62% at day 28, consistent with autophagic clearance of accumulated protein following successful editing.
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 six months ended June 30, 2026 and 2025, we recognized $0.0 million and $4.0 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.
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 nine months ended September 30, 2026 and 2025, we recognized $0.0 million and $5.1 million of collaboration revenue, respectively, which is related to our research collaboration and license agreement with Novo Nordisk. On November 3, 2026, Novo Nordisk delivered written notice of its election to terminate the collaboration agreement in its entirety for convenience. Accordingly, we expect to recognize the remaining deferred revenue under the agreement of approximately $7.8 million in the fourth quarter of 2026.
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 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 being terminated effective February 1, 2027, see Note 11, Collaboration Agreements, in the condensed consolidated financial statements included in this Quarterly Report.
Previous wording
Comparison of the Three and Six Months Ended June 30, 2026 and 2025
Current wording
Comparison of the Three and Nine Months Ended September 30, 2026 and 2025
Previous wording
The following table summarizes our results of operations for the three and six months ended June 30, 2026 and 2025:
Current wording
The following table summarizes our results of operations for the three and nine months ended September 30, 2026 and 2025:
Previous wording
During the three months ended June 30, 2026 and 2025, we recognized $0.0 million and $1.5 million, respectively, of collaboration revenue from our research collaboration and license agreement with Novo Nordisk. During the six months ended June 30, 2026 and 2025, we recognized $0.0 million and $4.0 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.
Current wording
During the three months ended September 30, 2026 and 2025, we recognized $0.0 million and $1.1 million, respectively, of collaboration revenue from our research collaboration and license agreement with Novo Nordisk. During the nine months ended September 30, 2026 and 2025, we recognized $0.0 million and $5.1 million, respectively, of collaboration revenue from our research collaboration and license agreement with Novo Nordisk. On November 3, 2026, Novo Nordisk delivered written notice of its election to terminate the collaboration agreement in its entirety for convenience. Accordingly, we expect to recognize the remaining deferred revenue under the agreement of approximately $7.8 million in the fourth quarter of 2026.
Previous wording
The following table summarizes our research and development expenses for the three and six months ended June 30, 2026 and 2025:
Current wording
The following table summarizes our research and development expenses for the three and nine months ended September 30, 2026 and 2025:
Previous wording
a $6.1 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 wording
a $3.6 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
Previous wording
a $1.3 million decrease in personnel-related expenses, primarily due to a decrease in headcount resulting from the May and November 2025 workforce reductions, partially offset by an increase in stock-based compensation costs; and
Current wording
a $0.8 million decrease in personnel-related expenses, primarily due to a decrease in headcount resulting from the May and November 2025 workforce reductions, partially offset by an increase in stock-based compensation costs; and
Previous wording
offset by a $4.9 million increase in KRRO-121 external expenses, primarily due to an increase in preclinical and manufacturing costs; and
Current wording
offset by a $1.9 million increase in KRRO-121 external expenses, primarily due to an increase in preclinical, manufacturing, and clinical costs for the Phase 1/2 ANCHOR clinical trial; and
Previous wording
offset by a $1.7 million increase in KRRO-111 external expenses, primarily due to an increase in preclinical and manufacturing costs; and
Current wording
a $1.1 million increase in KRRO-111 external expenses, primarily due to an increase in preclinical and manufacturing costs; and
Previous wording
a $11.5 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 wording
a $15.1 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
Previous wording
a $3.8 million decrease in personnel-related expenses, primarily due to a decrease in headcount resulting from the May and November 2025 workforce reductions, partially offset by an increase in stock-based compensation costs; and
Current wording
a $4.6 million decrease in personnel-related expenses, primarily due to a decrease in headcount resulting from the May and November 2025 workforce reductions, partially offset by an increase in stock-based compensation costs; and
Previous wording
a $1.7 million decrease in other research and pre-development candidate expenses primarily due to a decrease in lab supplies and consumables; and
Current wording
a $3.2 million decrease in other research and pre-development candidate expenses primarily due to a decrease in lab supplies and consumables; and
Previous wording
a $1.6 million increase in KRRO-121 external expenses, primarily due to an increase in preclinical and manufacturing costs.
Current wording
offset by a $6.7 million increase in KRRO-121 external expenses, primarily due to an increase in preclinical, manufacturing, and clinical costs for the Phase 1/2 ANCHOR clinical trial; and
Previous wording
a $2.2 million increase in KRRO-111 external expenses, primarily due to an increase in preclinical and manufacturing costs.
Current wording
a $3.3 million increase in KRRO-111 external expenses, primarily due to an increase in preclinical and manufacturing costs.
Previous wording
The following table summarizes our general and administrative expenses for the three and six months ended June 30, 2026 and 2025:
Current wording
The following table summarizes our general and administrative expenses for the three and nine months ended September 30, 2026 and 2025:
Previous wording
General and administrative expenses were $6.5 million for the three months ended June 30, 2026, compared to $7.3 million for the three months ended June 30, 2025. The decrease was primarily due to the following:
Current wording
General and administrative expenses were $6.4 million for the three months ended September 30, 2026, compared to $6.5 million for the three months ended September 30, 2025. The decrease was primarily due to the following:
Previous wording
a $0.5 million decrease in other expenses, primarily due to a decrease in information technology expenses; and
Current wording
a $0.4 million decrease in other expenses, primarily due to a decrease in information technology expenses; and
Previous wording
offset by a $0.3 million increase in personnel expenses mainly due to increased stock-based compensation costs, partially offset by a decrease in headcount resulting from the May and November 2025 workforce reductions.
Current wording
offset by a $0.3 million increase in personnel expenses mainly due to increased stock-based compensation costs, partially offset by a decrease in headcount resulting from the May and November 2025 workforce reductions; and
Previous wording
a $0.8 million decrease in other expenses, primarily due to a decrease in information technology expenses; and
Current wording
a $1.1 million decrease in other expenses, primarily due to a decrease in information technology expenses; and
Previous wording
a $0.2 million decrease in professional services;
Current wording
a $0.1 million decrease in professional services;
Previous wording
offset by a $0.1 million increase in personnel expenses mainly due to increased stock-based compensation costs, partially offset by a decrease in headcount resulting from the May and November 2025 workforce reductions.
Current wording
offset by a $0.6 million increase in personnel expenses mainly due to increased stock-based compensation costs, partially offset by a decrease in headcount resulting from the May and November 2025 workforce reductions.
Previous wording
Restructuring charges for the three and six months ended June 30, 2025 consisted of $1.2 million of employee termination benefits related to our workforce reduction in May 2025. During the year ended December 31, 2025, all activities related to our May 2025 workforce reduction were completed. We did not incur any restructuring charges for the three and six months ended June 30, 2026.
Current wording
Restructuring charges for the nine months ended September 30, 2025 consisted of $1.2 million of employee termination benefits related to our workforce reduction in May 2025. We did not incur any restructuring charges for the three months ended September 30, 2025. During the year ended December 31, 2025, all activities related to our May 2025 workforce reduction were completed. We did not incur any restructuring charges for the three and nine months ended September 30, 2026.
Previous wording
Total other income, net was $1.3 million for the three months ended June 30, 2026, compared to $1.4 million for the three months ended June 30, 2025. The decrease of $0.1 million was primarily due to fluctuations in foreign currency exchange rates.
Current wording
Total other income, net was $1.2 million for the three months ended September 30, 2026 and 2025.
Previous wording
Total other income, net was $2.2 million for the six months ended June 30, 2026, compared to $3.1 million for the six months ended June 30, 2025. The decrease of $0.9 million was primarily due to lower interest income generated from a lower cash, cash equivalent and marketable securities balance during the year prior to our $85.0 million March 2026 private placement, or the March 2026 PIPE, and fluctuations in foreign currency exchange rates.
Current wording
Total other income, net was $3.4 million for the nine months ended September 30, 2026, compared to $4.2 million for the nine months ended September 30, 2025. The decrease of $0.9 million was primarily due to lower interest income generated from a lower cash, cash equivalents and marketable securities balance during the year prior to our $85.0 million March 2026 private placement, or the March 2026 PIPE, and fluctuations in foreign currency exchange rates.
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 $501.0 million of aggregate gross proceeds from sales of our equity securities. As of June 30, 2026, we had cash, cash equivalents and marketable securities of $137.9 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 September 30, 2026, we had cash, cash equivalents and marketable securities of $124.8 million.
Previous wording
Since inception, we have incurred significant operating losses and, as of June 30, 2026, had an accumulated deficit of $422.4 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 September 30, 2026, had an accumulated deficit of $439.9 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
As of June 30, 2026, we had cash, cash equivalents and marketable securities of $137.9 million. We expect that our cash, cash equivalents and marketable securities outstanding as of June 30, 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.
Current wording
As of September 30, 2026, we had cash, cash equivalents and marketable securities of $124.8 million. We expect that our cash, cash equivalents and marketable securities outstanding as of September 30, 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
The following table summarizes our cash flows for the six months ended June 30, 2026 and 2025:
Current wording
The following table summarizes our cash flows for the nine months ended September 30, 2026 and 2025:
Previous wording
Net cash used in operating activities was $43.7 million for the six months ended June 30, 2025, primarily resulted from our net loss of $49.2 million, which was primarily attributable to our research and development activities and our general and administrative expenses and changes in our operating assets and liabilities of $0.7 million, offset by $6.2 million of non-cash items.
Current wording
Net cash used in operating activities was $46.0 million for the nine months ended September 30, 2026, primarily resulting from our net loss of $56.1 million, which was primarily attributable to our research and development activities and our general and administrative expenses offset by $10.1 million of non-cash items.
Previous wording
Net cash used in operating activities was $33.1 million for the six months ended June 30, 2026, primarily resulted from our net loss of $38.5 million, which was primarily attributable to our research and development activities and our general and administrative expenses and changes in our operating assets and liabilities of $1.2 million, offset by $6.6 million of non-cash items.
Current wording
Net cash used in operating activities was $60.9 million for the nine months ended September 30, 2025, primarily resulting 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.
Previous wording
Net cash used in investing activities was $50.1 million for the six months ended June 30, 2026 and consisted 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 $21.9 million for the nine months ended September 30, 2026 and consisted 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 $21.5 million for the six months ended June 30, 2025 and consisted of the proceeds from maturities of marketable securities, offset by the purchase of marketable securities and the purchase of property and equipment.
Current 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.
Previous wording
Net cash provided by financing activities was $85.3 million for the six months ended June 30, 2026 and consisted of net proceeds from the March 2026 PIPE, sales of shares under our ATM program, and exercises of stock options.
Current wording
Net cash provided by financing activities was $85.3 million for the nine months ended September 30, 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 $0.2 million for the six months ended June 30, 2025 and consisted primarily of proceeds from exercises of stock options.
Current 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.
Rearranged current paragraphs (4)
Current report — wording carried from elsewhere
KRRO-121 is a GalNAc-conjugated REO in development 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 in an alternate pathway involved in ammonia clearance. This synthetic rescue approach is designed to augment ammonia clearance in hyperammonemia-driven diseases such as UCDs and HE.
Current report — wording carried from elsewhere
a $0.3 million increase in other research and pre-development candidate expenses.
Current report — wording carried from elsewhere
a $2.2 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 — wording carried from elsewhere
a $0.1 million increase in professional services.
Rearranged previous paragraphs (3)
Previous report — wording carried elsewhere
a $3.6 million decrease in other research and pre-development candidate expenses primarily due to a decrease in lab supplies and consumables; and
Previous report — wording carried elsewhere
a $0.2 million decrease in professional services; and
Previous report — wording carried elsewhere
a $0.4 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; and