Korro Bio, Inc.

Previous wording

Since inception, we have incurred significant operating losses. Our net loss was $67.2 million and $62.4 million for the nine months ended September 30, 2025 and 2024, respectively. As of September 30, 2025, we had an accumulated deficit of $333.8 million. We have financed our operations primarily through private placements of our convertible preferred stock and more recently, common stock in our November 2023 and April 2024 private placements. Substantially all of our losses have resulted from expenses incurred in connection with our research and development and from general and administrative costs associated with our operations. We expect to continue to incur significant expenses, increasing operating losses, and negative operating cash flows for the foreseeable future. The net losses we incur may fluctuate significantly from quarter to quarter. We anticipate that our expenses will increase substantially if and as we:

Current wording

Since inception, we have incurred significant operating losses. Our net loss was $19.6 million and $23.4 million for the three months ended March 31, 2026 and 2025, respectively. As of March 31, 2026, we had an accumulated deficit of $403.5 million. We have financed our operations primarily through private placements of our convertible preferred stock and common stock, and sales under our ATM offering program. Substantially all of our losses have resulted from expenses incurred in connection with our research and development and from general and administrative costs associated with our operations, and recently, a $30.9 million impairment charge in the fourth quarter of 2025 related to our operating lease right-of-use asset and fixed assets. We expect to continue to incur significant expenses, increasing operating losses, and negative operating cash flows for the foreseeable future. The net losses we incur may fluctuate significantly from quarter to quarter. We anticipate that our expenses will increase substantially if and as we:

Previous wording

continue current research programs and preclinical and clinical development of any product candidates we may identify;

Current wording

continue current research programs and preclinical and clinical development of any lead candidates or development candidates we may identify;

Previous wording

seek to identify additional research programs and product candidates;

Current wording

seek to identify additional research programs and lead candidates, and nominate development candidates;

Previous wording

We expect that it will be many years, if ever, before we have an RNA editing product ready for commercialization. To become and remain profitable, we must develop and, either directly or through collaborators, eventually commercialize a product or products with market potential. This will require us to be successful in a range of challenging activities, including identifying product candidates, completing preclinical studies and clinical trials of product candidates, obtaining marketing approval for these product candidates, manufacturing, marketing and selling those products for which we may obtain marketing approval and satisfying any post-marketing requirements. We may never succeed in these activities and, even if we are, may never generate revenues that are significant or large enough to achieve profitability.

Current wording

We expect that it will be many years, if ever, before we have an RNA editing product ready for commercialization. To become and remain profitable, we must develop and, either directly or through collaborators, eventually commercialize a product or products with market potential. This will require us to be successful in a range of challenging activities, including identifying lead candidates, completing preclinical studies and clinical trials of development candidates, obtaining marketing approval for these development candidates, manufacturing, marketing and selling those products for which we may obtain marketing approval and satisfying any post-marketing requirements. We may never succeed in these activities and, even if we are, may never generate revenues that are significant or large enough to achieve profitability.

Previous wording

We did not reach projected levels of protein in patients in our Phase 1/2a REWRITE clinical trial of KRRO-110 for AATD and our other programs are in early stages of development. Because of the numerous risks and uncertainties associated with developing oligonucleotide product candidates and the risks associated with conducting clinical trials, we are unable to predict the extent of any future losses or when we will become profitable, if at all. If we do achieve profitability, we may not be able to sustain or increase profitability on a quarterly or annual basis. Our failure to become and remain profitable would decrease the value of our company and could impair our ability to raise capital, maintain our research and development efforts, expand business or continue our operations. A decline in our value could also cause you to lose all or part of your investment.

Current wording

In November 2025, we announced that we did not reach projected levels of protein in patients in our Phase 1/2a REWRITE clinical trial of KRRO-110 for AATD (which we subsequently terminated), and our other programs are in early stages of development. In addition, we undertook workforce reductions in May 2025 and November 2025, and in the fourth quarter of 2025, as a result of identified indicators of impairment for our long-lived assets, primarily including our operating lease right-of-use, or ROU, asset, and property and equipment, we recognized a non-cash, long-lived asset impairment charge of $30.9 million. Because of the numerous risks and uncertainties associated with developing lead candidates and development candidates, and the risks associated with conducting preclinical studies and clinical trials, we are unable to predict the extent of any future losses or when we will become profitable, if at all. If we do achieve profitability, we may not be able to sustain or increase profitability on a quarterly or annual basis. Our failure to become and remain profitable would decrease the value of our company and could impair our ability to raise capital, maintain our research and development efforts, expand business or continue our operations. A decline in our value could also cause you to lose all or part of your investment. Further, we may not even experience the expected benefits of our May 2025 and November 2025 workforce reductions or our decision to discontinue clinical development of KRRO-110. Further, the long-lived asset impairment charges recognized may affect how investors, analysts, and counterparties assess our financial position and prospects, potentially making it more difficult or expensive to raise capital or enter into collaborations on favorable terms.

Previous wording

Our ability to generate revenue from product sales and achieve profitability depends on our ability, alone or with collaborative partners, to successfully complete the development of, and obtain the regulatory approvals necessary to commercialize, product candidates we may identify for development. We do not anticipate generating revenues from product sales for many years, if ever. Our ability to generate future revenues from product sales depends heavily on our, or our collaborators’, ability to successfully:

Current wording

Our ability to generate revenue from product sales and achieve profitability depends on our ability, alone or with collaborative partners, to successfully complete the development of, and obtain the regulatory approvals necessary to commercialize, candidates we may identify for development. We do not anticipate generating revenues from product sales for many years, if ever. Our ability to generate future revenues from product sales depends heavily on our, or our collaborators’, ability to successfully:

Previous wording

identify product candidates and successfully complete research and development of such product candidates;

Current wording

identify lead candidates and successfully complete research and development of such lead candidates;

Previous wording

seek and obtain regulatory and marketing approvals for any product candidates for which we complete clinical trials;

Current wording

seek and obtain regulatory and marketing approvals for any development candidates for which we complete clinical trials;

Previous wording

launch and commercialize any product candidates for which we may obtain regulatory and marketing approval by establishing a sales force, marketing and distribution infrastructure, or alternatively, collaborating with a commercialization partner;

Current wording

launch and commercialize any development candidates for which we may obtain regulatory and marketing approval by establishing a sales force, marketing and distribution infrastructure, or alternatively, collaborating with a commercialization partner;

Previous wording

qualify for adequate coverage and reimbursement by government and third-party payors for any product candidates for which we may obtain regulatory and marketing approval;

Current wording

qualify for adequate coverage and reimbursement by government and third-party payors for any development candidates for which we may obtain regulatory and marketing approval;

Previous wording

Our expenses could increase beyond expectations if we are required by the FDA, the EMA, HREC, TGA, HDEC or other regulatory authorities to perform clinical and other studies in addition to those that we currently anticipate. Even if one or more of the product candidates we may develop are approved for commercial sale, we anticipate incurring significant costs associated with commercializing any approved product candidate. Additionally, such products may become subject to unfavorable pricing regulations, third-party reimbursement practices or healthcare reform initiatives. Even if we are able to generate revenues from the sale of any approved product candidates, we may not become profitable and may need to obtain additional funding to continue operations.

Current wording

Our expenses could increase beyond expectations if we are required by the FDA, the EMA, HREC, or TGA, or other regulatory authorities to perform clinical and other studies in addition to those that we currently anticipate. Even if one or more of the candidates we may develop are approved for commercial sale, we anticipate incurring significant costs associated with commercializing any approved development candidate. Additionally, such products may become subject to unfavorable pricing regulations, third-party reimbursement practices or healthcare reform initiatives. Even if we are able to generate revenues from the sale of any approved development candidates, we may not become profitable and may need to obtain additional funding to continue operations.

Previous wording

Because we have limited financial and managerial resources, we have prioritized our research programs and lead optimization efforts in specific indications among many potential options. Specifically, our initial development programs target liver and central nervous systems indications, amongst others. As a result of this prioritization, we may forego or delay pursuit of opportunities with other product candidates or for other indications that later prove to have greater clinical or commercial potential and we may need to reprioritize our focus in the future. Our resource allocation decisions may cause us to fail to capitalize on viable commercial products or profitable market opportunities. For example, KRRO-110, which used an LNP delivery system, did not reach projected levels of protein in patients in our Phase 1/2a REWRITE clinical trial for AATD and we are now pivoting to a GalNAc delivery system for AATD. Our spending on current and future research and development programs and product candidates for specific indications may not yield any commercially viable products.

Current wording

We expect our expenses to continue to increase in connection with our ongoing activities, particularly as we identify, continue the research and development of, initiate preclinical studies and clinical trials of, and seek marketing approval for, our lead candidates and development candidates. Because we have limited financial and managerial resources, we have prioritized our research programs and oligonucleotide optimization efforts in specific indications among many potential options. Specifically, our initial development programs target liver and central nervous systems indications, amongst others. As a result of this prioritization, we may forego or delay pursuit of opportunities with other lead candidates or development candidates or for other indications that later prove to have greater clinical or commercial potential and we may need to reprioritize our focus in the future. Our resource allocation decisions may cause us to fail to capitalize on viable commercial products or profitable market opportunities. For example, KRRO-110, which used an LNP delivery system, did not reach projected levels of protein in patients in our now terminated Phase 1/2a REWRITE clinical trial for AATD and we have since transitioned to a GalNAc-conjugated delivery system for our AATD program. Our spending on current and future research and development programs, lead candidates, and development candidates for specific indications may not yield any commercially viable products.

Previous wording

In addition, if we obtain marketing approval for any product candidates we may develop, we expect to incur significant commercialization expenses related to product sales, marketing, manufacturing and distribution to the extent that such sales, marketing, manufacturing and distribution are not the responsibility of a collaborator. Furthermore, we expect to continue to incur additional costs associated with operating as a public company. Accordingly, we will need to obtain substantial additional funding in connection with our continuing operations. If we are unable to raise capital when needed or on attractive terms, we would be forced to delay, reduce or eliminate our research and product development programs or future commercialization efforts.

Current wording

In addition, if we obtain marketing approval for any candidates we may develop, we expect to incur significant commercialization expenses related to product sales, marketing, manufacturing and distribution to the extent that such sales, marketing, manufacturing and distribution are not the responsibility of a collaborator. Furthermore, we expect to continue to incur additional costs associated with operating as a public company. Accordingly, we will need to obtain substantial additional funding in connection with our continuing operations. If we are unable to raise capital when needed or on attractive terms, we would be forced to delay, reduce or eliminate our research and product development programs or future commercialization efforts.

Previous wording

As of September 30, 2025, our cash, cash equivalents and marketable securities were $102.5 million, excluding restricted cash, or $105.9 million, including restricted cash. We believe our existing cash, cash equivalents and marketable securities will be sufficient to fund our operating expenses and capital expenditure requirements through several value-creating milestones and into the second half of 2027. However, our operating plan may change as a result of factors currently unknown, and expectations regarding our cash runway and ability to reach data inflection points are based on numerous assumptions that may prove to be untrue. As a result, we may be required to raise capital sooner than anticipated and our exposure to certain contingent liabilities and contractual obligations may be greater than anticipated. Our future capital requirements will depend on many other factors, including those discussed in the risk factor entitled“We have incurred significant losses since inception. We expect to incur losses for the foreseeable future and may never achieve or maintain profitability.”

Current wording

As of March 31, 2026, our cash, cash equivalents and marketable securities were $157.1 million, excluding restricted cash, or $160.5 million, including restricted cash. We believe our existing cash, cash equivalents and marketable securities will be sufficient to fund our operating expenses and capital expenditure requirements through several value-creating milestones and into the second half of 2028. However, our operating plan may change as a result of factors currently unknown, and expectations regarding our cash runway and ability to reach data inflection points are based on numerous assumptions that may prove to be untrue. As a result, we may be required to raise capital sooner than anticipated and our exposure to certain contingent liabilities and contractual obligations may be greater than anticipated. Our future capital requirements will depend on many other factors, including those discussed in the risk factor entitled“We have incurred significant losses since inception. We expect to incur losses for the foreseeable future and may never achieve or maintain profitability.”

Previous wording

Any additional fundraising efforts may divert our management from their day-to-day activities, which may adversely affect our ability to develop and commercialize any product candidates we may develop. We cannot be certain that additional funding will be available on acceptable terms or at all. Although we have an effective shelf registration statement and an at-the-market offering program, we have not sold any shares under the program and we have no committed source of additional capital. If we are unable to raise additional capital in sufficient amounts or on terms acceptable to us, we may have to significantly delay, scale back or discontinue the development or commercialization of any product candidates or other research and development initiatives. We could be required to seek collaborators for potential product candidates earlier than we would otherwise plan or on terms that are less favorable than might otherwise be available. We could also be required to relinquish or license our rights to product candidates on unfavorable terms in certain markets where we otherwise would seek to pursue development or commercialization ourselves.

Current wording

Any additional fundraising efforts may divert our management from their day-to-day activities, which may adversely affect our ability to develop and commercialize any development candidates. We cannot be certain that additional funding will be available on acceptable terms or at all. Although we have an effective shelf registration statement and an at-the-market offering program, we have not sold any shares under the program and we have no committed source of additional capital. If we are unable to raise additional capital in sufficient amounts or on terms acceptable to us, we may have to significantly delay, scale back or discontinue the development or commercialization of any development candidates or other research and development initiatives. We could be required to seek collaborators for potential lead candidates earlier than we would otherwise plan or on terms that are less favorable than might otherwise be available. We could also be required to relinquish or license our rights to lead candidates on unfavorable terms in certain markets where we otherwise would seek to pursue development or commercialization ourselves.

Previous wording

We did not reach projected levels of protein in patients in our Phase 1/2a REWRITE clinical trial of KRRO-110 for AATD and are pivoting to GalNAc delivery for AATD, and may experience delays in developing a potential treatment for AATD. We have not completed any clinical trials nor reported any clinical trial results for any of our proposed delivery methods or RNA editing approaches. Any favorable results we may have from our earlier preclinical studies may not be predictive of results that may be observed in later preclinical studies or clinical trials.

Current wording

We did not reach projected levels of protein in patients in our now terminated Phase 1/2a REWRITE clinical trial of KRRO-110 for AATD and have transitioned to GalNAc-conjugated delivery for our AATD program, and may experience delays in developing a potential treatment for AATD. We have not completed any clinical trials nor reported any clinical trial results for any of our proposed delivery methods or RNA editing approaches. Any favorable results we may have from our earlier preclinical studies may not be predictive of results that may be observed in later preclinical studies or clinical trials.

Previous wording

The scientific evidence to support the feasibility of developing product candidates using our proprietary RNA editing technology is both preliminary and limited. We dosed very few participants in our Phase 1/2a REWRITE clinical trial of KRRO-110 for AATD. Although we observed functional protein in AATD patients following a single administration of KRRO-110, we did not reach projected levels of protein in patients as of the data cut off date. We have not completed any clinical trials for any of our proposed delivery methods or RNA editing approaches, and we are now pivoting from LNP to GalNAc delivery for AATD. Accordingly, we may experience delays in developing a potential treatment for AATD. In the future, we may use other delivery modalities to deliver our other product candidates. While LNPs have been validated clinically to deliver oligonucleotides, such as siRNA, they have not been clinically proven to deliver oligonucleotides for RNA editing, such as KRRO-110 and our other product candidates.

Current wording

The scientific evidence to support the feasibility of developing development candidates using our proprietary RNA editing technology is both preliminary and limited. We dosed very few participants in our now terminated Phase 1/2a REWRITE clinical trial of KRRO-110 for AATD. Although we observed functional protein in AATD patients following a single administration of KRRO-110, we did not reach projected levels of protein in patients as of the data cut off date. We have not completed any clinical trials for any of our proposed delivery methods or RNA editing approaches, and we have transitioned from LNP to GalNAc-conjugated delivery for our AATD program. Accordingly, we may experience delays in developing a potential treatment for AATD. In the future, we may use other delivery modalities to deliver our other lead candidates. While LNPs have been validated clinically to deliver oligonucleotides, such as siRNA, they were not clinically proven to deliver oligonucleotides for RNA editing, such as KRRO-110 and our other lead candidates. Similarly, while GalNAc-conjugated delivery has been validated in multiple FDA-approved oligonucleotide therapeutics, there are no FDA-approved GalNAc-conjugated RNA editing oligonucleotide therapeutics. Both of our most advanced programs, KRRO-121 and our AATD program, utilize GalNAc-conjugated delivery. If GalNAc-conjugated delivery fails to effectively deliver our RNA editing oligonucleotides, multiple programs in our pipeline could be adversely affected.

Previous wording

In addition, our proprietary RNA editing technology itself may lead to other issues, such as inability to deliver the desired efficacy or safety-related consequences as it is tested in clinical trials. We have not generated any clinical trial results to date. The design of a clinical trial can determine whether its results will support approval of a product candidate and flaws in the design of a clinical trial may not become apparent until the clinical trial is well advanced. Furthermore, preclinical and clinical data are often susceptible to varying interpretations and analyses, and many companies that have believed their product candidates performed satisfactorily in preclinical studies and clinical trials have nonetheless failed to obtain marketing approval of their product candidates. Many product candidates that initially showed promise in early stage testing for treating a variety of diseases have later been found to lack efficacy or to cause side effects that prevented further clinical development of the product candidates. Accordingly, any favorable results we may have from our earlier preclinical studies may not be predictive of results that may be observed in further preclinical studies or clinical trials.

Current wording

In addition, our proprietary RNA editing technology itself may lead to other issues, such as inability to deliver the desired efficacy or safety-related consequences as it is tested in clinical trials. The design of a clinical trial can determine whether its results will support approval of a development candidate and flaws in the design of a clinical trial may not become apparent until the clinical trial is well advanced. Furthermore, preclinical and clinical data are often susceptible to varying interpretations and analyses, and many companies that have believed their development candidates performed satisfactorily in preclinical studies and clinical trials have nonetheless failed to obtain marketing approval of their development candidates. Many lead candidates that initially showed promise in early stage testing for treating a variety of diseases have later been found to lack efficacy or to cause side effects that prevented further clinical development. Accordingly, any favorable results we may have from our earlier preclinical studies may not be predictive of results that may be observed in further preclinical studies or clinical trials.

Previous wording

If preclinical studies or clinical trials of any product candidates we may identify and develop fail to demonstrate safety and efficacy to the satisfaction of regulatory authorities or do not otherwise produce positive results, we may incur additional costs or experience delays in completing, or ultimately be unable to complete, the development and commercialization of such product candidates.

Current wording

If preclinical studies or clinical trials of any lead candidate or development candidate we may identify fail to demonstrate safety and efficacy to the satisfaction of regulatory authorities or do not otherwise produce positive results, we may incur additional costs or experience delays in completing, or ultimately be unable to complete, the development and commercialization of such development candidate.

Previous wording

Before obtaining marketing approval from regulatory authorities for the sale of any product candidates we may identify and develop, we must complete preclinical development and then conduct extensive clinical trials to demonstrate the safety and efficacy in humans. Clinical testing is expensive, difficult to design and implement, can take many years to complete, and the outcome is uncertain. A failure of one or more clinical trials can occur at any stage of product candidate development. The outcome of preclinical testing and early clinical trials may not be predictive of the success of later clinical trials, and interim results of a clinical trial do not necessarily predict final results.

Current wording

Before obtaining marketing approval from regulatory authorities for the sale of any development candidates we may identify and develop, we must complete preclinical development and then conduct extensive clinical trials to demonstrate safety and efficacy in humans. Clinical testing is expensive, difficult to design and implement, can take many years to complete, and the outcome is uncertain. A failure of one or more clinical trials can occur at any stage of development. The outcome of preclinical testing and early clinical trials may not be predictive of the success of later clinical trials, and interim results of a clinical trial do not necessarily predict final results.

Previous wording

Moreover, preclinical and clinical data are often susceptible to varying interpretations and analyses. Many companies that have believed their product candidates performed satisfactorily in preclinical studies and clinical trials have nonetheless failed, preventing marketing approval of their product candidates. For example, despite our preclinical data, we did not reach projected levels of protein in AATD patients in our REWRITE Phase 1/2a clinical trial.

Current wording

Moreover, preclinical and clinical data are often susceptible to varying interpretations and analyses. Many companies that have believed their lead candidates or development candidates performed satisfactorily in preclinical studies and clinical trials have nonetheless failed, preventing marketing approval of their development candidates. For example, despite our preclinical data, we did not reach projected levels of protein in AATD patients in our REWRITE Phase 1/2a clinical trial.

Previous wording

We and our collaborators, if any, may experience numerous unforeseen events during, or as a result of, clinical trials that could delay or prevent our ability to receive marketing approval or commercialize any product candidates we may identify and develop, including:

Current wording

We and our collaborators, if any, may experience numerous unforeseen events during, or as a result of, clinical trials that could delay or prevent our ability to receive marketing approval or commercialize any development candidates we may identify and develop, including:

Previous wording

clinical trials of any product candidates we may develop may produce negative or inconclusive results, and we may decide, or regulators may require us, to conduct additional clinical trials or abandon product development or research programs;

Current wording

clinical trials of any development candidates we may develop may produce negative or inconclusive results, and we may decide, or regulators may require us, to conduct additional clinical trials or abandon product development or research programs;

Previous wording

the number of patients required for clinical trials of any product candidates we may develop may be larger than we anticipate; enrollment of suitable participants in these clinical trials may be delayed or slower than we anticipate; or patients may drop out of these clinical trials at a higher rate than we anticipate;

Current wording

the number of patients required for clinical trials may be larger than we anticipate; enrollment of suitable participants in these clinical trials, which may be particularly challenging for some of the rare genetically defined diseases such as UCD, may be delayed or slower than we anticipate; or patients may drop out of these clinical trials at a higher rate than we anticipate;

Previous wording

regulators, IRBs, or independent ethics committees may require that we or our investigators suspend or terminate clinical research or clinical trials of any product candidates we may develop for various reasons, including noncompliance with regulatory requirements, a finding of undesirable side effects or other unexpected characteristics, or that the participants are being exposed to unacceptable health risks or after an inspection of our clinical trial operations or trial sites;

Current wording

regulators, IRBs, or independent ethics committees may require that we or our investigators suspend or terminate clinical research or clinical trials of any development candidates we may develop for various reasons, including noncompliance with regulatory requirements, a finding of undesirable side effects or other unexpected characteristics, or that the participants are being exposed to unacceptable health risks or after an inspection of our clinical trial operations or trial sites;

Previous wording

the cost of clinical trials of any product candidates we may develop may be greater than we anticipate;

Current wording

the cost of clinical trials of any development candidates may be greater than we anticipate;

Previous wording

the supply or quality of any product candidates we may develop or other materials necessary to conduct clinical trials of any product candidates we may develop may be insufficient or inadequate, including as a result of delays in the testing, validation, manufacturing, and delivery of any product candidates we may develop to the clinical sites by us or by third parties with whom we have contracted to perform certain of those functions;

Current wording

the supply or quality of any development candidates or other materials necessary to conduct clinical trials of any development candidates may be insufficient or inadequate, including as a result of delays in the testing, validation, manufacturing, and delivery of any development candidates to the clinical sites by us or by third parties with whom we have contracted to perform certain of those functions;

Previous wording

occurrence of serious adverse events associated with any product candidates we may develop that are viewed to outweigh their potential benefits;

Current wording

occurrence of serious adverse events associated with any development candidates that are viewed to outweigh their potential benefits;

Previous wording

If we or our collaborators are required to conduct additional clinical trials or other testing of any product candidates we may develop beyond those that we currently contemplate, if we or our collaborators are unable to successfully complete clinical trials or other testing of any product candidates we may develop, or if the results of these trials or tests are not positive or are only modestly positive or if there are safety concerns, we or our collaborators may:

Current wording

If we or our collaborators are required to conduct additional clinical trials or other testing of any development candidates beyond those that we currently contemplate, if we or our collaborators are unable to successfully complete clinical trials or other testing of any development candidates, or if the results of these trials or tests are not positive or are only modestly positive or if there are safety concerns, we or our collaborators may:

Previous wording

be delayed in obtaining marketing approval for any such product candidates we may develop or not obtain marketing approval at all;

Current wording

be delayed in obtaining marketing approval for any such development candidates or not obtain marketing approval at all;

Previous wording

Product development costs will also increase if we or our collaborators experience delays in clinical trials or other testing or in obtaining marketing approvals. We do not know whether any clinical trials will begin as planned, will need to be restructured, or will be completed on schedule, or at all. Significant clinical trial delays also could shorten any periods during which we may have the exclusive right to commercialize any product candidates we may develop, could allow our competitors to bring products to market before we do, and could impair our ability to successfully commercialize any product candidates we may develop, any of which may harm our business, financial condition, results of operations and prospects.

Current wording

Product development costs will also increase if we or our collaborators experience delays in clinical trials or other testing or in obtaining marketing approvals. We do not know whether any clinical trials will begin as planned, will need to be restructured, or will be completed on schedule, or at all. Significant clinical trial delays also could shorten any periods during which we may have the exclusive right to commercialize any development candidates we may develop, could allow our competitors to bring products to market before we do, and could impair our ability to successfully commercialize any development candidates we may develop, any of which may harm our business, financial condition, results of operations, and prospects.

Previous wording

Clinical trials of a new product candidate require the enrollment of a sufficient number of patients, including patients who are suffering from the disease the product candidate is intended to treat and who meet other eligibility criteria. Rates of patient enrollment are affected by many factors, including the stage and severity of disease, the nature and requirements of the protocol, the proximity of patients to clinical sites, the availability of effective treatments for the relevant disease, and the eligibility criteria for the clinical trial, possible adverse effects from treatments, the existence of competing clinical trials, the involvement of patient advocacy groups, the availability of new or alternative treatments, lack of efficacy, personnel issues and ease of participation in our clinical trials, among others. Clinical trials can also be impacted by other events unrelated to our business, such as the Russian invasion of Ukraine, recent turmoil in the Middle East or other geopolitical events or global pandemics (such as what occurred during the COVID-19 pandemic), or imposition of tariffs that impact the supply chain, or even disruptions due to the ongoing U.S. government shutdown or any future shutdown. In April 2025, the United States imposed tariffs on imports on its trading partners, including, without limitation, Canada, Mexico, the EU and China, and tariff policy (and trading partners subject to such tariffs) have continued to evolve. Historically, tariffs have led to increased costs, political and trade tensions, which negatively affect global supply chains. These types of events can disrupt clinical trial sites and delay patient enrollment, all of which would have a negative impact on our business and ability to obtain regulatory approval. Delays or difficulties in patient enrollment or difficulties retaining trial participants, including as a result of the availability of existing or other investigational treatments, can result in increased costs, longer development times or termination of a clinical trial.

Current wording

Clinical trials of a new development candidate require the enrollment of a sufficient number of patients, including patients who are suffering from the disease the development candidate is intended to treat and who meet other eligibility criteria. Rates of patient enrollment are affected by many factors, including the stage and severity of disease, the nature and requirements of the protocol, the proximity of patients to clinical sites, the availability of effective treatments for the relevant disease, and the eligibility criteria for the clinical trial, possible adverse effects from treatments, the existence of competing clinical trials, the involvement of patient advocacy groups, the availability of new or alternative treatments, lack of efficacy, personnel issues and ease of participation in our clinical trials, among others. Clinical trials can also be impacted by other events unrelated to our business, such as geopolitical events and unrest, such as recent hostilities involving Iran, global pandemics (e.g., COVID-19), or economic uncertainty, including imposition of tariffs that impact the supply chain, or disruptions due to government shutdowns, which can impact regulatory reviews. In April 2025, the United States imposed tariffs on imports on its trading partners and tariff policy (and trading partners subject to such tariffs) has continued to evolve. Historically, tariffs have led to increased costs, political and trade tensions, which negatively affect global supply chains. These types of events can disrupt clinical trial sites and delay patient enrollment, all of which would have a negative impact on our business and ability to obtain regulatory approval. Delays or difficulties in patient enrollment or difficulties retaining trial participants, including as a result of the availability of existing or other investigational treatments, can result in increased costs, longer development times or termination of a clinical trial.

Previous wording

The gene editing field and RNA editing in particular is relatively new and is evolving rapidly. We are very early in our development efforts and may not be successful in identifying and developing product candidates. It will be many years before we or our collaborators commercialize a product candidate or generate any revenues, if ever. Additionally, other genetic medicine technologies may be discovered that provide significant advantages over RNA editing, which could materially harm our business.

Current wording

The gene editing field and RNA editing in particular is relatively new and is evolving rapidly. We are very early in our development efforts and may not be successful in identifying and developing any candidates. It will be many years before we or our collaborators commercialize a development candidate or generate any revenues, if ever. Additionally, other genetic medicine technologies may be discovered that provide significant advantages over RNA editing, which could materially harm our business.

Previous wording

The success of our business depends primarily upon our ability to identify, develop and commercialize product candidates. We are very early in our development efforts and have focused our research and development efforts to date on developing OPERA, our RNA editing platform, and identifying our initial targeted disease indications. We only recently announced our second development candidate, KRRO-121. Although we believe we can demonstrate many of the key advantages of RNA editing, because we are very early in our development efforts, we are not yet certain of the results we may achieve, which may be important for registration and commercialization of our products. Such uncertainties include, but are not limited to, the level of editing efficiency needed in a target tissue type to achieve a clinical benefit, and associated safety of our edits in humans. We have also not yet shown that preclinical editing activity can result in clinically important effects, nor that the data generated by our preclinical studies can translate into positive results in clinical trials.

Current wording

The success of our business depends primarily upon our ability to identify, develop and commercialize development candidates. We are very early in our development efforts and have focused our research and development efforts to date on developing OPERA, our RNA editing platform, and identifying our initial targeted disease indications. We currently only have one nominated development candidate in our pipeline, KRRO-121, as we terminated further development of KRRO-110 after it failed to reach projected levels of protein in our first in-human clinical trial. Although we believe we can demonstrate many of the key advantages of RNA editing, because we are very early in our development efforts, we are not yet certain of the results we may achieve, which may be important for registration and commercialization of any candidates we successfully develop. Such uncertainties include, but are not limited to, the level of editing efficiency needed in a target tissue type to achieve a clinical benefit, and associated safety of our edits in humans. We have also not yet shown that preclinical editing activity can result in clinically important effects, nor that the data generated by our preclinical studies can translate into positive results in clinical trials.

Previous wording

We only have one product candidate, KRRO-110, in a Phase 1/2a clinical trial and currently have no plans to complete additional SAD patient cohorts for KRRO-110 as KRRO-110 did not reach projected levels of protein in AATD patients who were evaluable as of the November 6, 2025 data cutoff date. All of our other product development programs are still in the research or preclinical stage of development. Our research methodology may be unsuccessful in identifying product candidates, our product candidates may be shown to have harmful side effects in preclinicalin vitro experiments or animal model studies, they may not show promising signals of therapeutic effect in such experiments or studies or they may have other characteristics that may make the product candidates impractical to manufacture, unmarketable, or unlikely to receive marketing approval.

Current wording

All of our product development programs are still in the research or preclinical stage of development. Our research methodology may be unsuccessful in identifying lead candidates, our development candidates may be shown to have harmful side effects in preclinicalin vitro experiments or animal model studies, they may not show promising signals of therapeutic effect in such experiments or studies or they may have other characteristics that may make the development candidates impractical to manufacture, unmarketable, or unlikely to receive marketing approval.

Previous wording

The pharmacological properties ascribed to the product candidates we are testing in preclinical studies may not be positively demonstrated in clinical trials in patients, and they may interact with human biological systems in unforeseen, ineffective or harmful ways. If our product candidates prove to be ineffective, unsafe or commercially unviable, OPERA and our pipeline would have little, if any, value, which would substantially harm our business, financial condition, results of operations and prospects. In addition, our approach, which focuses on using oligonucleotides for drug development, as opposed to multiple or other, more advanced proven technologies, and new products and technologies that may enter the market, may expose us to additional financial risks and make it more difficult to raise additional capital if we are not successful in developing one or more product candidates that receive regulatory approval. Our ability to generate product revenue, which we do not expect will occur for many years, if ever, will depend heavily on the successful development and eventual commercialization of any product candidates we may discover, which may never occur. We currently generate no revenue from sales of any product, and we may never be able to develop or commercialize a marketable product.

Current wording

The pharmacological properties ascribed to the lead candidates we are testing in preclinical studies may not be positively demonstrated in clinical trials in patients, and they may interact with human biological systems in unforeseen, ineffective or harmful ways (such as we experienced in our REWRITE Phase 1/2a clinical trial). If our development candidates prove to be ineffective, unsafe or commercially unviable, OPERA and our pipeline would have little, if any, value, which would substantially harm our business, financial condition, results of operations and prospects. In addition, our approach, which focuses on using oligonucleotides for drug development, as opposed to multiple or other, more advanced proven technologies, and new products and technologies that may enter the market, may expose us to additional financial risks and make it more difficult to raise additional capital if we are not successful in developing one or more development candidates that receive regulatory approval. Our ability to generate product revenue, which we do not expect will occur for many years, if ever, will depend heavily on the successful development and eventual commercialization of any development candidates we may discover, which may never occur. We currently generate no revenue from sales of any product, and we may never be able to develop or commercialize a marketable product.

Previous wording

In addition, although we believe OPERA, our RNA editing platform, will position us to expand our portfolio of product candidates beyond the initial product candidates we may develop, we have not yet successfully developed any product candidate and our ability to expand our portfolio may never materialize.

Current wording

In addition, although we believe OPERA, our RNA editing platform, will position us to expand our portfolio of development candidates beyond the initial candidates we may develop, we have not yet successfully developed any candidate and our ability to expand our portfolio may never materialize.

Previous wording

We are focused on developing products based on RNA editing. Although there have been significant advances in the field of gene editing in recent years, RNA editing technologies are new and largely unproven. The technologies that we have developed have not yet been clinically tested, and while limited clinical data has been generated to date, we are not aware of any clinical trials for safety or efficacy having been completed by third parties using RNA editing or similar technologies. The scientific evidence to support the feasibility of developing product candidates based on these technologies is both preliminary and limited. Successful development of product candidates by us will require solving a number of issues, including optimizing the efficiency and specificity of such product candidates, and ensuring the therapeutic selectivity of such product candidates. There can be no assurance we will be successful in solving any or all of these issues.

Current wording

We are focused on developing products based on RNA editing. Although there have been significant advances in the field of gene editing in recent years, RNA editing technologies are new and largely unproven. The technologies that we have developed have not yet completed clinical development. The scientific evidence to support the feasibility of developing development candidates based on these technologies is both preliminary and limited. Successful development of development candidates by us will require solving a number of issues, including optimizing the efficiency and specificity of such development candidates, and ensuring the therapeutic selectivity of such development candidates. There can be no assurance we will be successful in solving any or all of these issues.

Previous wording

We have concentrated our research efforts to date on preclinical work to bring therapeutics to the clinic for our initial indications, and our future success is highly dependent on the successful development of OPERA, our RNA editing platform, as well as cellular delivery methods and therapeutic applications of that technology. While some of the existing, non-RNA editing, gene editing technologies developed by third parties have progressed to clinical trials, they continue to suffer from various limitations, and such limitations may affect our future success. While a number of clinical trials for oligonucleotide products conducted by other companies have not been successful, some have received regulatory approval. The pharmacological properties ascribed to the product candidates we are testing or will test in the future may not be positively demonstrated in clinical trials in patients, and they may interact with human biological systems in unforeseen, ineffective or harmful ways. If our product candidates prove to be ineffective, unsafe or commercially unviable, our OPERA platform and our pipeline would have little, if any, value, which would substantially harm our business, financial condition, results of operations and prospects. We may decide to alter or abandon our initial programs as new data becomes available and we gain experience in developing base editing therapeutics. We cannot be sure that our technologies will yield satisfactory products that are safe and effective, scalable or profitable in our initial indications or any other indication we pursue.

Current wording

We have concentrated our research efforts to date on preclinical work to bring therapeutics to the clinic for our initial indications, and our future success is highly dependent on the successful development of OPERA, our RNA editing platform, as well as cellular delivery methods and therapeutic applications of that technology. While some of the existing, non-RNA editing, gene editing technologies developed by third parties have progressed to clinical trials, they continue to suffer from various limitations, and such limitations may affect our future success. While a number of clinical trials for oligonucleotide products conducted by other companies have not been successful, some have received regulatory approval. The pharmacological properties ascribed to the development candidates we are testing or will test in the future may not be positively demonstrated in clinical trials in patients, and they may interact with human biological systems in unforeseen, ineffective or harmful ways. If our development candidates prove to be ineffective, unsafe or commercially unviable, our OPERA platform and our pipeline would have little, if any, value, which would substantially harm our business, financial condition, results of operations and prospects. We may decide to alter or abandon our initial programs as new data becomes available and we gain experience in developing base editing therapeutics. We cannot be sure that our technologies will yield satisfactory products that are safe and effective, scalable or profitable in our initial indications or any other indication we pursue.

Previous wording

We are very early in our development efforts, and our preclinical studies and clinical trials may not be successful. If we are unable to commercialize our product candidates or experience significant delays in doing so, our business will be materially harmed.

Current wording

We are very early in our development efforts, and our preclinical studies and clinical trials may not be successful. If we are unable to commercialize our development candidates or experience significant delays in doing so, our business will be materially harmed.