UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2025 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from _____________________ to _____________________ Commission File Number: 001-39062 Korro Bio, Inc. (Exact name of registrant as specified in its charter) De ...

Exhibit 99.1 Korro Reports Third Quarter Financial Results, Provides Updates on KRRO-110 in Alpha-1 Antitrypsin Deficiency and Additional Pipeline Programs CAMBRIDGE, Mass., November 12, 2025 (GLOBE NEWSWIRE) -- Korro Bio, Inc. (Korro) (Nasdaq: KRRO), a clinical-stage biopharmaceutical company focused on developing a new class of genetic medicines based on editing RNA for both rare and highly prevalent diseases, today provided a program update for its Phase 1/2a REWRITE clinical trial of KRRO-110 in AATD, r ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2025 ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from _____________________ to _____________________ Commission File Number: 001-39062 Korro Bio, Inc. (Exact name of registrant as specified in its charter) Delaware 4 ...

Exhibit 99.1 Korro Reports Second Quarter 2025 Financial Results and Provides Business Updates CAMBRIDGE, Mass., August 12, 2025 (GLOBE NEWSWIRE) -- Korro Bio, Inc. (Korro) (Nasdaq: KRRO), a clinical-stage biopharmaceutical company focused on developing a new class of genetic medicines based on editing RNA for both rare and highly prevalent diseases, today reported financial results for the second quarter of 2025 and provided a business update. Ram Aiyar, Ph.D., CEO and President of Korro, said, "Throughout ...

PART I. FINANCIAL INFORMATION [Item 1. Financial Statements (Unaudited)](index=6&type=section&id=Item%201.%20Financial%20Statements%20(Unaudited)) The company reported a net loss of **$23.4 million** for Q1 2025, driven by higher R&D expenses, while recognizing its first **$2.6 million** collaboration revenue and maintaining sufficient cash for at least **12 months** [Condensed Consolidated Balance Sheets](index=6&type=section&id=Condensed%20Consolidated%20Balance%20Sheets) Total assets decreased to **$202.2 million** as of **March 31, 2025**, primarily due to reduced marketable securities and net loss, impacting stockholders' equity Condensed Consolidated Balance Sheet Highlights (in thousands) | Account | March 31, 2025 | December 31, 2024 | | :--- | :--- | :--- | | **Assets** | | | | Cash and cash equivalents | $64,144 | $55,643 | | Total marketable securities | $74,848 | $107,411 | | Total current assets | $121,235 | $131,532 | | Total assets | $202,207 | $226,240 | | **Liabilities & Stockholders' Equity** | | | | Total current liabilities | $12,881 | $14,960 | | Total liabilities | $63,250 | $65,825 | | Total stockholders' equity | $138,957 | $160,415 | | Total liabilities and stockholders' equity | $202,207 | $226,240 | [Condensed Consolidated Statements of Operations and Comprehensive Loss](index=7&type=section&id=Condensed%20Consolidated%20Statements%20of%20Operations%20and%20Comprehensive%20Loss) For Q1 2025, the company reported its first **$2.6 million** collaboration revenue, but increased operating expenses, primarily R&D, led to a widened net loss of **$23.4 million** Statement of Operations Summary (in thousands, except per share data) | Metric | Q1 2025 | Q1 2024 | | :--- | :--- | :--- | | Collaboration revenue | $2,550 | $0 | | Research and development expenses | $19,739 | $13,572 | | General and administrative expenses | $7,831 | $7,881 | | Loss from operations | ($25,020) | ($21,453) | | Net loss | ($23,387) | ($19,557) | | Net loss per share, basic and diluted | ($2.49) | ($2.44) | [Condensed Consolidated Statements of Cash Flows](index=9&type=section&id=Condensed%20Consolidated%20Statements%20of%20Cash%20Flows) Net cash used in operating activities was **$24.5 million** in Q1 2025, offset by **$32.8 million** from investing activities, resulting in an **$8.5 million** net increase in cash Cash Flow Summary (in thousands) | Activity | Three Months Ended March 31, 2025 | Three Months Ended March 31, 2024 | | :--- | :--- | :--- | | Net cash used in operating activities | ($24,452) | ($21,891) | | Net cash provided by (used in) investing activities | $32,781 | ($5,611) | | Net cash provided by financing activities | $172 | $139 | | **Net increase (decrease) in cash** | **$8,501** | **($27,363)** | [Notes to Unaudited Condensed Consolidated Financial Statements](index=10&type=section&id=Notes%20to%20Unaudited%20Condensed%20Consolidated%20Financial%20Statements) Key notes confirm **$139.0 million** in cash is sufficient for **12 months**, detail a **$70.0 million** PIPE offering, **$2.6 million** Novo Nordisk revenue, and a **20%** workforce reduction with **$1.2 million** restructuring charges - The company expects its cash, cash equivalents, and marketable securities of **$139.0 million** as of **March 31, 2025**, to fund operations for at least **12 months** from the financial statement issuance date[31](index=31&type=chunk) - In April 2024, the company raised gross proceeds of approximately **$70.0 million** through a private placement (PIPE) of its common stock[54](index=54&type=chunk) - The company recognized **$2.6 million** in collaboration revenue during **Q1 2025** from its agreement with **Novo Nordisk**, with revenue recognition expected to continue through **Q1 2027**[68](index=68&type=chunk) - On **May 7, 2025**, the company initiated a workforce reduction of approximately **20%**, expecting to incur one-time restructuring charges of about **$1.2 million**[86](index=86&type=chunk) [Item 2. Management's Discussion and Analysis of Financial Condition and Results of Operations](index=23&type=section&id=Item%202.%20Management%27s%20Discussion%20and%20Analysis%20of%20Financial%20Condition%20and%20Results%20of%20Operations) Management discusses the company's focus on RNA editing with lead program **KRRO-110** in Phase 1/2a trials, a **$23.4 million** net loss for Q1 2025, and a **$139.0 million** cash position expected to fund operations into **2027**, alongside a **20%** workforce reduction [Overview](index=23&type=section&id=Overview) Korro Bio, a clinical-stage biopharmaceutical company, has its lead candidate **KRRO-110** in a **Phase 1/2a** clinical trial (REWRITE) with interim data expected in H2 2025, and initiated a **20%** workforce reduction in May 2025 - The company's lead program, **KRRO-110** for **AATD**, is in a **Phase 1/2a** clinical trial (**REWRITE**), with interim data from healthy volunteers and **AATD** patients expected in the second half of **2025**[91](index=91&type=chunk) - In **May 2025**, the company announced a strategic plan to streamline operations, including a workforce reduction of approximately **20%**[92](index=92&type=chunk) - The **FDA** has granted **Orphan Drug Designation** to **KRRO-110** for the treatment of **AATD** in **March 2025**[91](index=91&type=chunk) [Results of Operations](index=28&type=section&id=Results%20of%20Operations) Q1 2025 saw the company's first **$2.6 million** collaboration revenue, but R&D expenses increased by **$6.1 million** to **$19.7 million**, primarily due to **KRRO-110** clinical trial costs and a **$1.5 million** milestone payment Comparison of Results of Operations (in thousands) | Line Item | Q1 2025 | Q1 2024 | Change | | :--- | :--- | :--- | :--- | | Collaboration Revenue | $2,550 | $0 | $2,550 | | Research and Development | $19,739 | $13,572 | $6,167 | | General and Administrative | $7,831 | $7,881 | ($50) | | **Net Loss** | **($23,387)** | **($19,557)** | **($3,830)** | - The increase in R&D expenses was mainly due to a **$3.9 million** rise in **KRRO-110** external costs, which included a **$2.4 million** increase in clinical trial activities and a **$1.5 million** development milestone payment to **Genevant**[110](index=110&type=chunk) [Liquidity and Capital Resources](index=29&type=section&id=Liquidity%20and%20Capital%20Resources) As of **March 31, 2025**, the company held **$139.0 million** in cash, expected to fund operations into **2027**, and has an active **$100.0 million** **ATM** equity offering program with no shares sold - As of **March 31, 2025**, the company had cash, cash equivalents and marketable securities of **$139.0 million**[114](index=114&type=chunk) - The company expects its current cash position to be sufficient to fund operating expenses and capital expenditure requirements into **2027**[117](index=117&type=chunk) - The company has an active at-the-market (**ATM**) equity offering program for up to **$100.0 million**, but had not sold any shares under the program as of **March 31, 2025**[116](index=116&type=chunk) [Item 3. Quantitative and Qualitative Disclosures About Market Risk](index=33&type=section&id=Item%203.%20Quantitative%20and%20Qualitative%20Disclosures%20About%20Market%20Risk) The company's primary market risk is interest rate sensitivity on its **$139.0 million** in cash and marketable securities, though a **10%** change is not expected to have a material effect - The company's main market risk is interest rate sensitivity on its **$139.0 million** in cash, cash equivalents, and marketable securities[131](index=131&type=chunk) - Management believes a hypothetical **10%** change in market interest rates would not materially affect the fair market value of its cash or cash equivalents[131](index=131&type=chunk) [Item 4. Controls and Procedures](index=33&type=section&id=Item%204.%20Controls%20and%20Procedures) Management concluded the company's disclosure controls and procedures were effective as of **March 31, 2025**, with no material changes to internal control over financial reporting during the quarter - The **CEO** and **CFO** concluded that the company's disclosure controls and procedures were effective as of **March 31, 2025**[134](index=134&type=chunk) - No material changes to internal control over financial reporting occurred during the most recently completed fiscal quarter[135](index=135&type=chunk) PART II. OTHER INFORMATION [Item 1. Legal Proceedings](index=34&type=section&id=Item%201.%20Legal%20Proceedings) The company is not currently party to any material legal proceedings and does not expect any current matters to have a material adverse effect - As of the date of the report, the company is not party to any claim or litigation that is reasonably expected to have a material adverse effect on its business[137](index=137&type=chunk) [Item 1A. Risk Factors](index=34&type=section&id=Item%201A.%20Risk%20Factors) The company faces significant risks including a history of losses, need for future funding, high development risks for novel RNA editing technology, extensive regulatory oversight, intense competition, reliance on third parties, intellectual property uncertainties, and general business risks like stock price volatility [Risks Related to Our Business](index=34&type=section&id=Risks%20Related%20to%20Our%20Business) The company has incurred significant losses, with an accumulated deficit of **$290.0 million** as of **March 31, 2025**, expects future losses, requires substantial additional funding, and early preclinical results are not predictive of clinical success - The company has incurred significant losses since inception, with an accumulated deficit of **$290.0 million** as of **March 31, 2025**, and expects to incur losses for the foreseeable future[139](index=139&type=chunk) - The company will need substantial additional funding and may be forced to delay, reduce, or eliminate research programs if unable to raise capital[145](index=145&type=chunk) - The company has dosed very few participants in its **Phase 1/2a REWRITE** clinical trial of **KRRO-110** and has not completed any clinical trials for its RNA editing approaches, making early favorable results not predictive of future outcomes[148](index=148&type=chunk) [Risks Related to Discovery, Development and Commercialization](index=41&type=section&id=Risks%20Related%20to%20Discovery%2C%20Development%20and%20Commercialization) Success hinges on novel, unproven RNA editing technology with risks of product failure, unforeseen side effects, complex manufacturing, and intense competition from larger pharmaceutical companies - RNA editing is a novel technology with limited clinical validation for human therapeutic use, and the company's approaches are unproven and may never lead to marketable products[166](index=166&type=chunk) - The manufacturing process for oligonucleotides is complex and presents risks in production, scaling, and quality control, which could delay or hinder development[182](index=182&type=chunk) - The company faces intense competition from large pharmaceutical and biotechnology companies with greater financial, technical, and human resources[199](index=199&type=chunk) [Risks Related to Regulatory, Legal, and Clinical Trials](index=59&type=section&id=Risks%20Related%20to%20Regulatory%2C%20Legal%2C%20and%20Clinical%20Trials) Developing oligonucleotides presents increased regulatory uncertainty due to limited agency experience, potential for non-meaningful clinical endpoints, and extensive post-marketing requirements for any approved products - Developing oligonucleotides, a new class of drugs, presents increased risk as the **FDA** and other regulators have limited experience, which may lead to a complex, uncertain, and lengthy review process[211](index=211&type=chunk) - There is a risk that regulatory authorities may not consider the endpoints of the company's clinical trials to provide clinically meaningful results, which could hinder approval[217](index=217&type=chunk) - Any approved product will be subject to extensive post-marketing regulatory requirements, and failure to comply could result in penalties, restrictions, or withdrawal from the market[229](index=229&type=chunk) [Risks Related to Our Third Party Relationships](index=78&type=section&id=Risks%20Related%20to%20Our%20Third%20Party%20Relationships) The company heavily relies on third parties for clinical trials, manufacturing, and commercialization, risking delays or harm if these partners do not perform satisfactorily or meet deadlines - The company relies on third parties like **CROs** to conduct clinical trials and may be harmed if these parties do not perform satisfactorily or meet deadlines[268](index=268&type=chunk) - The success of the collaboration with **Novo Nordisk** and any future partnerships depends heavily on the efforts and resources of the collaborators, which are outside the company's direct control[270](index=270&type=chunk)[272](index=272&type=chunk) - Reliance on third-party manufacturers (**CMOs**) for the supply of product candidates entails risks related to quality, timing, regulatory compliance (**cGMP**), and supply chain interruptions[277](index=277&type=chunk) [Risks Related to Our Personnel, Operations and Growth](index=85&type=section&id=Risks%20Related%20to%20Our%20Personnel%2C%20Operations%20and%20Growth) The company is highly dependent on senior management and key scientific personnel, and expected operational expansion will strain resources, potentially disrupting operations, especially after the recent workforce reduction - The company is highly dependent on its senior management and key scientific staff, and the loss of any key members could delay R&D programs[286](index=286&type=chunk) - The company expects to expand its operations, and any inability to manage this growth could disrupt operations and delay business plans. The **May 2025** workforce reduction may make recruiting and retention more challenging[287](index=287&type=chunk) [Risks Related to Intellectual Property](index=87&type=section&id=Risks%20Related%20to%20Intellectual%20Property) Success depends on obtaining and protecting intellectual property rights, facing risks of patent challenges, infringement lawsuits, changes in patent law, and inadequate trade secret protection - The company's success depends on its ability to obtain and maintain patent protection for its product candidates and platform technology, but the patent process is expensive, time-consuming, and uncertain[289](index=289&type=chunk)[291](index=291&type=chunk) - Third-party claims of intellectual property infringement could prevent or delay product development and commercialization, and defending against such claims would be expensive and divert resources[312](index=312&type=chunk)[313](index=313&type=chunk) - Changes in **U.S.** and international patent law could diminish the value of patents, impairing the ability to protect the company's technology and product candidates[342](index=342&type=chunk)[343](index=343&type=chunk) - The company relies on trade secrets and confidentiality agreements, which may be breached or may not provide adequate protection, potentially harming its competitive position[348](index=348&type=chunk)[349](index=349&type=chunk) [General Risk Factors](index=109&type=section&id=General%20Risk%20Factors) The company's stock price is highly volatile, executive officers and directors hold significant voting power, and the ability to use **NOL** carryforwards may be limited by ownership changes - The company's common stock price is highly volatile and subject to substantial fluctuations due to clinical trial results, competitor announcements, and general market conditions[367](index=367&type=chunk) - Executive officers, directors, and principal stockholders beneficially own approximately **71%** of the outstanding common stock, giving them significant influence over stockholder matters[384](index=384&type=chunk) - The company's ability to use its net operating loss (**NOL**) carryforwards of **$352.3 million** (federal) and **$319.7 million** (state) may be limited due to ownership changes under **Section 382** of the Code[390](index=390&type=chunk)[391](index=391&type=chunk) [Item 2. Unregistered Sales of Equity Securities and Use of Proceeds](index=70&type=section&id=Item%202.%20Unregistered%20Sales%20of%20Equity%20Securities%20and%20Use%20of%20Proceeds) This item is not applicable for the reporting period - Not applicable[395](index=395&type=chunk) [Item 3. Defaults Upon Senior Securities](index=70&type=section&id=Item%203.%20Defaults%20Upon%20Senior%20Securities) This item is not applicable for the reporting period - Not applicable[396](index=396&type=chunk) [Item 4. Mine Safety Disclosures](index=70&type=section&id=Item%204.%20Mine%20Safety%20Disclosures) This item is not applicable for the reporting period - Not applicable[397](index=397&type=chunk) [Item 5. Other Information](index=70&type=section&id=Item%205.%20Other%20Information) During Q1 2025, no officers or directors adopted or terminated a **Rule 10b5-1** trading plan or a non-**Rule 10b5-1** trading arrangement - No officers or directors adopted or terminated a **Rule 10b5-1** trading plan during the three months ended **March 31, 2025**[398](index=398&type=chunk) [Item 6. Exhibits](index=71&type=section&id=Item%206.%20Exhibits) The report lists several filed exhibits, including corporate governance documents, an employment agreement for **Loïc Vincent**, and required **CEO/CFO** certifications - Filed exhibits include corporate governance documents, an employment agreement for **Loïc Vincent** effective **March 31, 2025**, and required **CEO/CFO** certifications[400](index=400&type=chunk) Signatures - The quarterly report was duly signed on **May 7, 2025**, by **Ram Aiyar**, President and Chief Executive Officer, and **Vineet Agarwal**, Chief Financial Officer[406](index=406&type=chunk)

Executive Summary & Company Overview [Introduction and Strategic Highlights](index=1&type=section&id=Introduction%20and%20Strategic%20Highlights) Korro Bio reported Q1 2025 results, highlighting progress on KRRO-110 interim data in H2 2025 and its 3-2-1 strategy through 2027 - Korro Bio is a clinical-stage biopharmaceutical company focused on developing a new class of genetic medicines based on editing RNA for both rare and highly prevalent diseases[3](index=3&type=chunk) - The company remains on track to report interim data from its Phase 1/2a REWRITE clinical trial of KRRO-110 in the second half of 2025[4](index=4&type=chunk) - Korro is focused on executing its '3-2-1 strategy' through 2027, aiming to develop novel genetic medicines[4](index=4&type=chunk) [Operational Streamlining and Workforce Reduction](index=1&type=section&id=Operational%20Streamlining%20and%20Workforce%20Reduction) Korro is streamlining operations and reducing its workforce by **20%** to advance key programs, incurring approximately **$1.2 million** in one-time charges - Korro is streamlining operations and reducing its workforce by approximately **20%** to advance programs to key value inflection points[5](index=5&type=chunk) - The company estimates one-time restructuring charges of approximately **$1.2 million**, primarily for employee severance, benefits, and related termination costs, with the majority expected in Q2 2025[5](index=5&type=chunk) - The streamlining is considered essential for long-term success, prioritizing KRRO-110 development and focused investments in the OPERA platform[5](index=5&type=chunk) Pipeline and Business Updates [KRRO-110 Clinical Trial Progress](index=1&type=section&id=KRRO-110%20Clinical%20Trial%20Progress) The KRRO-110 REWRITE clinical trial for AATD is expanding globally, with interim data expected in H2 2025 and trial completion in 2026 - Korro received regulatory approval to expand the REWRITE clinical trial in New Zealand and is progressing enrollment, site activation, and expansion into other geographies, including the United States[6](index=6&type=chunk)[8](index=8&type=chunk) - An interim readout from the Phase 1/2a REWRITE clinical trial of KRRO-110 for AATD is on track for the second half of 2025[7](index=7&type=chunk)[8](index=8&type=chunk)[12](index=12&type=chunk) - Completion of the REWRITE clinical trial is expected in 2026[5](index=5&type=chunk)[8](index=8&type=chunk)[12](index=12&type=chunk) [Strategic Initiatives and Collaborations](index=2&type=section&id=Strategic%20Initiatives%20and%20Collaborations) Korro is executing its 3-2-1 strategy to establish clinical programs and advancing two preclinical programs with Novo Nordisk for cardiometabolic diseases - Korro continues to execute its **3-2-1 strategy**, aiming to establish three clinical-stage development programs targeting two tissue types by leveraging its OPERA™ platform[12](index=12&type=chunk) - The collaboration with Novo Nordisk is progressing, with Korro working to advance up to two programs through preclinical development for cardiometabolic diseases[5](index=5&type=chunk)[12](index=12&type=chunk) - Korro's CNS programs are also continuing to progress[12](index=12&type=chunk) [Leadership Team Enhancements](index=2&type=section&id=Leadership%20Team%20Enhancements) Korro strengthened its leadership team with the appointments of Loïc Vincent, Ph.D., as CSO, and GaoZhong Zhu, Ph.D., as SVP of CMC - Loïc Vincent, Ph.D., was appointed Chief Scientific Officer, bringing over 20 years of experience in drug discovery and translational research[12](index=12&type=chunk) - GaoZhong Zhu, Ph.D., was appointed Senior Vice President of Chemistry, Manufacturing and Controls, with over 25 years of industrial experience in CMC strategies[12](index=12&type=chunk) [Anticipated Upcoming Milestones](index=2&type=section&id=Anticipated%20Upcoming%20Milestones) Key milestones include KRRO-110 interim data in H2 2025, a second development candidate nomination by year-end, and continued Novo Nordisk partnership progress - Interim readout from Phase 1/2a REWRITE clinical trial of KRRO-110 for AATD expected in the second half of 2025[12](index=12&type=chunk) - Korro expects to nominate a development candidate by the end of 2025 for its rare metabolic disorder program targeting the liver (GalNAc) with subcutaneous delivery[7](index=7&type=chunk)[12](index=12&type=chunk) - Progress partnership with Novo Nordisk in cardiometabolic diseases with high prevalence[12](index=12&type=chunk) First Quarter 2025 Financial Results [Cash Position](index=2&type=section&id=Cash%20Position) Korro's cash, cash equivalents, and marketable securities decreased to **$139.0 million** in Q1 2025, projected to fund operations into 2027 Cash, Cash Equivalents and Marketable Securities | Date | Amount (in millions) | | :--- | :--- | | March 31, 2025 | $139.0 | | December 31, 2024 | $163.1 | | **Change** | **($24.1)** | - Korro expects its cash, cash equivalents, and marketable securities as of March 31, 2025, will fund operating expenses and capital expenditure requirements into 2027[5](index=5&type=chunk)[7](index=7&type=chunk)[10](index=10&type=chunk) [Collaboration Revenue](index=2&type=section&id=Collaboration%20Revenue) Collaboration revenue significantly increased to **$2.6 million** in Q1 2025, primarily due to the Novo Nordisk agreement Collaboration Revenue (Three Months Ended March 31) | Year | Amount (in thousands) | | :--- | :--- | | 2025 | $2,550 | | 2024 | $0 | | **Change** | **+$2,550** | - The increase in collaboration revenue was due to revenue earned in the first quarter of 2025 from the agreement with Novo Nordisk[11](index=11&type=chunk) [Operating Expenses](index=3&type=section&id=Operating%20Expenses) Total operating expenses increased to **$27.6 million** in Q1 2025, driven by higher R&D expenses, with G&A remaining stable Total Operating Expenses (Three Months Ended March 31) | Year | Amount (in thousands) | | :--- | :--- | | 2025 | $27,570 | | 2024 | $21,453 | | **Change** | **+$6,117** | [Research and Development (R&D) Expenses](index=3&type=section&id=Research%20and%20Development%20(R%26D)%20Expenses) R&D expenses increased to **$19.7 million** in Q1 2025, primarily due to higher KRRO-110 external R&D, personnel, and pre-development candidate expenses R&D Expenses (Three Months Ended March 31) | Year | Amount (in thousands) | | :--- | :--- | | 2025 | $19,739 | | 2024 | $13,572 | | **Change** | **+$6,167** | - The increase in R&D expenses was primarily driven by increases in KRRO-110 external research and development expenses, personnel expenses, and other research and pre-development candidate expenses[13](index=13&type=chunk) [General and Administration (G&A) Expenses](index=3&type=section&id=General%20and%20Administration%20(G%26A)%20Expenses) G&A expenses slightly decreased to **$7.8 million** in Q1 2025, mainly due to lower professional service and facilities fees G&A Expenses (Three Months Ended March 31) | Year | Amount (in thousands) | | :--- | :--- | | 2025 | $7,831 | | 2024 | $7,881 | | **Change** | **-$50** | - The minor decrease in G&A expenses was primarily driven by a **$0.1 million** decrease in professional service fees and facilities expenses, partially offset by an increase in personnel expenses[14](index=14&type=chunk) [Net Loss](index=3&type=section&id=Net%20Loss) Korro's net loss widened to **$23.4 million** in Q1 2025, compared to **$19.6 million** in Q1 2024, reflecting increased operating expenses Net Loss (Three Months Ended March 31) | Year | Amount (in thousands) | | :--- | :--- | | 2025 | $(23,387) | | 2024 | $(19,557) | | **Change** | **-($3,830)** | Net Loss Per Share and Weighted-Average Shares | Metric | 2025 | 2024 | | :--- | :--- | :--- | | Net loss per share, basic and diluted | $(2.49) | $(2.44) | | Weighted-average shares used in computing net loss per share, basic and diluted | 9,384,266 | 8,019,626 | [Balance Sheet Highlights](index=7&type=section&id=Balance%20Sheet%20Highlights) Korro's total assets decreased to **$202.2 million** as of March 31, 2025, with total liabilities and stockholders' equity also decreasing Selected Condensed Consolidated Balance Sheet Data (in thousands) | Metric | March 31, 2025 | December 31, 2024 | Change | | :--- | :--- | :--- | :--- | | Cash, cash equivalents and marketable securities | $138,992 | $163,054 | $(24,062) | | Working capital | $108,354 | $116,572 | $(8,218) | | Total assets | $202,207 | $226,240 | $(24,033) | | Total liabilities | $63,250 | $65,825 | $(2,575) | | Total stockholders' equity | $138,957 | $160,415 | $(21,458) | Product and Company Information [About REWRITE Clinical Trial](index=3&type=section&id=About%20REWRITE%20Clinical%20Trial) The REWRITE clinical trial is a two-part, dose-escalating study for KRRO-110 in up to 64 participants, with interim data expected in H2 2025 - REWRITE is a two-part single and multiple dose-escalating study evaluating the safety and tolerability of KRRO-110[16](index=16&type=chunk) - The study will enroll up to **64 participants**, including healthy adults and clinically stable AATD patients with the PiZZ genotype[16](index=16&type=chunk) - Interim data from Part 1 (single ascending doses) is expected in the second half of 2025, and completion of the study is anticipated in 2026[16](index=16&type=chunk) [About AATD and KRRO-110](index=3&type=section&id=About%20AATD%20and%20KRRO-110) AATD is a genetic disorder caused by a SERPINA1 gene mutation; KRRO-110 aims to repair SERPINA1 RNA to restore AAT protein secretion - AATD is a genetic disorder most commonly caused by a single missense mutation (G-to-A) in the SERPINA1 gene, leading to pulmonary emphysema and/or hepatic cirrhosis[17](index=17&type=chunk) - KRRO-110 is the first RNA editing oligonucleotide product candidate from Korro's proprietary OPERA™ platform[17](index=17&type=chunk) - KRRO-110 is designed to co-opt the ADAR enzyme to edit the 'A' variant on SERPINA1 RNA, repair an amino acid codon, and restore secretion of normal AAT protein, with potential to clear liver protein aggregates and preserve lung function[17](index=17&type=chunk) [About Korro Bio](index=3&type=section&id=About%20Korro%20Bio) Korro Bio is a clinical-stage biopharmaceutical company developing RNA editing genetic medicines for various diseases using its proprietary OPERA™ platform - Korro is a clinical-stage biopharmaceutical company developing genetic medicines based on editing RNA for rare and highly prevalent diseases[18](index=18&type=chunk) - The company's proprietary OPERA™ platform harnesses the body's natural RNA editing process for precise yet transient single-base edits[18](index=18&type=chunk) - By editing RNA instead of DNA, Korro aims to deliver increased precision, tunability, specificity, and improved long-term tolerability[18](index=18&type=chunk) Additional Information [Investor Relations](index=4&type=section&id=Investor%20Relations) Korro will use its IR website, LinkedIn, and X (Twitter) as official channels for disclosing material nonpublic information and Regulation FD compliance - Korro intends to use its Investor Relations website, LinkedIn, and X (Twitter) for disclosing material nonpublic information and complying with Regulation FD[19](index=19&type=chunk) - Investors should monitor these channels in addition to press releases, SEC filings, public conference calls, presentations, and webcasts[19](index=19&type=chunk) [Forward-Looking Statements](index=4&type=section&id=Forward-Looking%20Statements) This press release contains forward-looking statements about future expectations, subject to inherent uncertainties and risks that may cause actual results to differ - The press release contains forward-looking statements regarding future expectations, hopes, beliefs, intentions, or strategies of Korro[20](index=20&type=chunk) - Examples include timing of data readouts, trial completion, execution of the 3-2-1 strategy, timing of second development candidate nomination, cash runway, KRRO-110's potential, and benefits of workforce reduction and Novo Nordisk collaboration[20](index=20&type=chunk) - Forward-looking statements are based on current expectations and assumptions that are inherently uncertain, and actual results may differ materially due to various factors and risks outlined in SEC filings[20](index=20&type=chunk) [Contact Information](index=5&type=section&id=Contact%20Information) Contact details are provided for investor and media inquiries - Investor & Media Contact: IR@korrobio.com[21](index=21&type=chunk) Financial Statements [Condensed Consolidated Statements of Operations and Comprehensive Loss](index=6&type=section&id=Condensed%20Consolidated%20Statements%20of%20Operations%20and%20Comprehensive%20Loss) This section presents unaudited condensed consolidated statements of operations and comprehensive loss for Q1 2025 and 2024, detailing revenue, expenses, and net loss Condensed Consolidated Statements of Operations and Comprehensive Loss (in thousands, except share and per share amounts) | | Three Months Ended March 31, 2025 | Three Months Ended March 31, 2024 | | :--- | :--- | :--- | | Collaboration revenue | $2,550 | $— | | Research and development | $19,739 | $13,572 | | General and administrative | $7,831 | $7,881 | | Total operating expenses | $27,570 | $21,453 | | Loss from operations | $(25,020) | $(21,453) | | Other income, net | $1,633 | $1,913 | | Loss before provision for income taxes | $(23,387) | $(19,540) | | Provision for income taxes | $— | $(17) | | Net loss | $(23,387) | $(19,557) | | Other comprehensive income (loss): | | | | Unrealized gain on available-for-sale investments | $(3) | $— | | Foreign currency translation adjustments, net | $(1) | $— | | Comprehensive loss | $(23,391) | $(19,557) | | Net loss per share, basic and diluted | $(2.49) | $(2.44) | | Weighted-average shares used in computing net loss per share, basic and diluted | 9,384,266 | 8,019,626 | [Selected Condensed Consolidated Balance Sheet Data](index=7&type=section&id=Selected%20Condensed%20Consolidated%20Balance%20Sheet%20Data) This section provides selected unaudited condensed consolidated balance sheet data as of March 31, 2025, and December 31, 2024 Selected Condensed Consolidated Balance Sheet Data (in thousands) | | March 31, 2025 | December 31, 2024 | | :--- | :--- | :--- | | Cash, cash equivalents and marketable securities | $138,992 | $163,054 | | Working capital | $108,354 | $116,572 | | Total assets | $202,207 | $226,240 | | Total liabilities | $63,250 | $65,825 | | Total stockholders' equity | $138,957 | $160,415 |

[Executive Summary and Business Highlights](index=1&type=section&id=executive_summary_and_business_highlights) [Introduction and CEO Commentary](index=1&type=section&id=introduction_and_ceo_commentary) The company reported 2024 results and business updates, highlighting key achievements and strategic goals for its RNA editing platform - Korro Bio is a clinical-stage biopharmaceutical company focused on developing genetic medicines based on RNA editing for rare and prevalent diseases[2](index=2&type=chunk)[17](index=17&type=chunk) - Key objectives for 2024 included initiating the **Phase 1/2a REWRITE clinical study** of KRRO-110, announcing a collaboration with Novo Nordisk, and advancing multiple product candidates[3](index=3&type=chunk) - KRRO-110 is anticipated to demonstrate **best-in-class potential** with interim data readout of REWRITE in H2 2025[4](index=4&type=chunk) - The company plans to announce its second development candidate by the end of 2025 and aims for **three clinical-stage development candidates** by the end of 2027[4](index=4&type=chunk) [Key Achievements and Strategic Outlook](index=1&type=section&id=key_achievements_and_strategic_outlook) The company advanced its lead candidate KRRO-110, secured key designations, and maintained a strong financial position - Completed dosing of the first two cohorts in the **Phase 1/2a REWRITE Clinical Study** of KRRO-110 for AATD, with interim readout expected in H2 2025[6](index=6&type=chunk)[7](index=7&type=chunk) - KRRO-110 received **U.S. FDA Orphan Drug Designation** for AATD treatment[6](index=6&type=chunk)[7](index=7&type=chunk)[8](index=8&type=chunk) - Ended 2024 with **$163.1 million** in cash, cash equivalents, and marketable securities, providing a cash runway into H2 2026[6](index=6&type=chunk)[9](index=9&type=chunk) - Executing a **'3-2-1 strategy'** to establish three clinical-stage development programs by the end of 2027[6](index=6&type=chunk)[12](index=12&type=chunk) [Pipeline and Business Updates](index=1&type=section&id=pipeline_and_business_updates) [KRRO-110 Clinical Development for AATD](index=1&type=section&id=krro_110_clinical_development_for_aatd) The company's lead candidate, KRRO-110, progressed in its Phase 1/2a study and received Orphan Drug Designation [REWRITE Clinical Study Progress](index=1&type=section&id=rewrite_clinical_study_progress) The REWRITE study completed dosing for its initial cohorts with no serious adverse events, targeting an interim readout in H2 2025 - Completed dosing of the first two single ascending dose cohorts in healthy adult volunteers in **Phase 1/2a REWRITE clinical study** of KRRO-110[6](index=6&type=chunk)[7](index=7&type=chunk) - **No serious adverse events** observed through completion of dosing of the first two cohorts[7](index=7&type=chunk) - Interim readout from Phase 1/2a REWRITE clinical study of KRRO-110 for AATD expected in the **second half of 2025**, and study completion expected in 2026[6](index=6&type=chunk)[7](index=7&type=chunk)[12](index=12&type=chunk) [Orphan Drug Designation](index=1&type=section&id=orphan_drug_designation) KRRO-110 received Orphan Drug Designation from the U.S. FDA, providing key development incentives for treating AATD - KRRO-110 granted **Orphan Drug Designation** by the U.S. FDA for the treatment of AATD[6](index=6&type=chunk)[7](index=7&type=chunk) - Orphan Drug designation provides various development incentives, including **tax credits**, user fee exemptions, and potential **market exclusivity** following FDA approval[8](index=8&type=chunk) [Strategic Pipeline and Corporate Development](index=1&type=section&id=strategic_pipeline_and_corporate_development) The company is executing its '3-2-1 strategy' to expand its pipeline while advancing collaborations and strengthening its leadership team [3-2-1 Strategy and Future Candidates](index=1&type=section&id=3_2_1_strategy_and_future_candidates) The '3-2-1 strategy' aims for three clinical programs by 2027, with a second development candidate nomination expected by the end of 2025 - Executing **3-2-1 strategy** through end of 2027 with the goal of establishing three clinical-stage development programs, targeting two tissue types with a single RNA-editing platform[6](index=6&type=chunk)[12](index=12&type=chunk) - **Second development candidate** expected to be announced in 2025[6](index=6&type=chunk) - Korro expects to nominate a development candidate for its rare metabolic disorder program targeting the liver by the **end of 2025**[12](index=12&type=chunk) [Collaborations and Leadership Enhancements](index=1&type=section&id=collaborations_and_leadership_enhancements) The collaboration with Novo Nordisk is progressing, and the company has strengthened its leadership with key appointments - Collaboration with **Novo Nordisk** continues to progress, leveraging Korro's OPERA platform for up to two disease targets[12](index=12&type=chunk) - Strengthened leadership team with the formation of **Clinical Advisory Board** and key additions to board and management team[6](index=6&type=chunk)[12](index=12&type=chunk) - GaoZhong Zhu, Ph.D. joined Korro as **Senior Vice President of Chemistry, Manufacturing and Controls (CMC) & Technical Operations**[12](index=12&type=chunk) [Full Year 2024 Financial Results](index=2&type=section&id=full_year_2024_financial_results) [Cash Position](index=2&type=section&id=cash_position) The company ended 2024 with $163.1 million in cash and equivalents, sufficient to fund operations into the second half of 2026 | Metric | As of Dec 31, 2024 | As of Dec 31, 2023 | Change | | :-------------------------------- | :------------------- | :------------------- | :----- | | Cash, cash equivalents and marketable securities | $163.1 million | $166.1 million | -$3.0 million | - Cash runway expected into the **second half of 2026**[6](index=6&type=chunk)[9](index=9&type=chunk) [Collaboration Revenue](index=2&type=section&id=collaboration_revenue) The company recognized its first collaboration revenue of $2.3 million in 2024 from its partnership with Novo Nordisk | Metric | Year Ended Dec 31, 2024 | Year Ended Dec 31, 2023 | Change | | :------------------- | :---------------------- | :---------------------- | :----- | | Collaboration revenue | $2.271 million | $0 | +$2.271 million | - Increase due to collaboration revenue earned in the fourth quarter of 2024 from the company's partnership with **Novo Nordisk**[10](index=10&type=chunk) [Operating Expenses](index=2&type=section&id=operating_expenses) Total operating expenses increased to $94.2 million in 2024, driven by higher R&D and G&A costs [Research and Development (R&D) Expenses](index=2&type=section&id=Research%20and%20Development%20(R&D)%20Expenses) R&D expenses rose to $63.6 million in 2024 due to increased costs for the KRRO-110 program, personnel, and facilities | Metric | Year Ended Dec 31, 2024 | Year Ended Dec 31, 2023 | Change | | :------------------- | :---------------------- | :---------------------- | :----- | | R&D expenses | $63.636 million | $57.250 million | +$6.386 million | - Increase driven primarily by increases in **KRRO-110 external research and development expenses**, personnel expenses, and facilities expenses[11](index=11&type=chunk) [General and Administrative (G&A) Expenses](index=3&type=section&id=General%20and%20Administrative%20(G&A)%20Expenses) G&A expenses increased to $30.5 million in 2024, primarily from higher IT, insurance, and professional fees | Metric | Year Ended Dec 31, 2024 | Year Ended Dec 31, 2023 | Change | | :------------------- | :---------------------- | :---------------------- | :----- | | G&A expenses | $30.545 million | $27.284 million | +$3.261 million | - Increase primarily due to increased information technology, insurance and other costs, as well as increased professional fees and facility costs[13](index=13&type=chunk) [Net Loss](index=3&type=section&id=net_loss) The company's net loss slightly increased to $83.6 million for the year ended December 31, 2024 | Metric | Year Ended Dec 31, 2024 | Year Ended Dec 31, 2023 | Change | | :------- | :---------------------- | :---------------------- | :----- | | Net loss | $(83.581) million | $(81.172) million | $(2.409) million | | Metric | Year Ended Dec 31, 2024 | Year Ended Dec 31, 2023 | | :-------------------------------------------------- | :---------------------- | :---------------------- | | Net loss per share, basic and diluted | $(9.37) | $(53.08) | | Weighted-average shares used in computing net loss per share | 8,920,561 | 1,529,321 | [Program and Company Information](index=3&type=section&id=program_and_company_information) [About REWRITE Study](index=3&type=section&id=about_rewrite_study) The REWRITE study evaluates the safety and tolerability of KRRO-110 in healthy adults and AATD patients - REWRITE is a two-part single and multiple dose-escalating study that will evaluate the safety and tolerability of KRRO-110 in up to **64 participants**[15](index=15&type=chunk) - Secondary and exploratory endpoints include **pharmacokinetic and pharmacodynamic parameters** to guide optimal dose selection for later stage studies[15](index=15&type=chunk) - Interim data from Part 1 is expected in the **second half of 2025**, with study completion anticipated in 2026[15](index=15&type=chunk) [About Alpha-1 Antitrypsin Deficiency (AATD) and KRRO-110](index=3&type=section&id=About%20Alpha-1%20Antitrypsin%20Deficiency%20(AATD)%20and%20KRRO-110) AATD is a genetic disorder that KRRO-110 aims to treat by editing RNA to restore normal protein function - AATD is a genetic disorder most commonly caused by a single missense mutation (G-to-A) in the **SERPINA1 gene**, leading to pulmonary emphysema and/or hepatic cirrhosis[16](index=16&type=chunk) - KRRO-110 is the first RNA editing oligonucleotide product candidate from Korro's proprietary **OPERA™ platform**[16](index=16&type=chunk) - KRRO-110 is designed to edit the SERPINA1 RNA to restore secretion of normal AAT protein, potentially clearing liver aggregates and preserving lung function[16](index=16&type=chunk) [About Korro Bio](index=3&type=section&id=about_korro_bio) Korro Bio is a clinical-stage company developing a new class of genetic medicines based on its proprietary OPERA™ RNA editing platform - Korro is a clinical-stage biopharmaceutical company focused on developing a new class of genetic medicines based on **editing RNA** for both rare and highly prevalent diseases[17](index=17&type=chunk) - Korro's proprietary RNA editing platform, **OPERA™**, is designed to harness the body's natural RNA editing process for a precise, transient single base edit[16](index=16&type=chunk)[17](index=17&type=chunk) - By editing RNA instead of DNA, Korro aims to expand the reach of genetic medicines with **increased specificity** and improved long-term tolerability[17](index=17&type=chunk) [Financial Statements](index=5&type=section&id=financial_statements) [Consolidated Statements of Operations and Comprehensive Loss](index=5&type=section&id=consolidated_statements_of_operations_and_comprehensive_loss) The company reported its first collaboration revenue of $2.3 million and a net loss of $83.6 million in 2024 | Metric | Year Ended Dec 31, 2024 (in thousands) | Year Ended Dec 31, 2023 (in thousands) | | :------------------------------------ | :------------------------------------- | :------------------------------------- | | Collaboration revenue | $2,271 | $— | | Research and development | $63,636 | $57,250 | | General and administrative | $30,545 | $27,284 | | Total operating expenses | $94,181 | $84,534 | | Loss from operations | $(91,910) | $(84,534) | | Other income, net | $8,470 | $3,389 | | Net loss | $(83,581) | $(81,172) | | Net loss per share, basic and diluted | $(9.37) | $(53.08) | | Weighted-average shares used in computing net loss per share | 8,920,561 | 1,529,321 | [Selected Condensed Consolidated Balance Sheet Data](index=6&type=section&id=selected_condensed_consolidated_balance_sheet_data) The company's balance sheet shows total assets of $226.2 million and total stockholders' equity of $160.4 million as of year-end 2024 | Metric | As of Dec 31, 2024 (in thousands) | As of Dec 31, 2023 (in thousands) | | :-------------------------------- | :-------------------------------- | :-------------------------------- | | Cash, cash equivalents and investments | $163,054 | $166,150 | | Working capital | $116,572 | $153,245 | | Total assets | $226,240 | $221,663 | | Total liabilities | $65,825 | $51,752 | | Total stockholders' equity | $160,415 | $169,911 | [Legal and Contact Information](index=4&type=section&id=legal_and_contact_information) [Forward-Looking Statements](index=4&type=section&id=forward_looking_statements) This section outlines the inherent risks and uncertainties associated with forward-looking statements contained in the report - Forward-looking statements are based on current expectations and assumptions that are **inherently uncertain**[20](index=20&type=chunk) - Factors that may cause actual results to differ materially include risks of conducting a clinical study, **regulatory oversight**, enrollment risks, and general economic conditions[20](index=20&type=chunk) - Readers should **not place undue reliance** on forward-looking statements in this press release, which speak only as of the date they are made[20](index=20&type=chunk) [Investor & Media Contact](index=4&type=section&id=investor_media_contact) This section provides contact details for investor and media inquiries and lists official disclosure channels - Investor & Media Contact: Tim Palmer, **IR@korrobio.com**[21](index=21&type=chunk) - Korro intends to use its Investor Relations website, LinkedIn, and X (Twitter) as means of disclosing **material nonpublic information**[18](index=18&type=chunk)[19](index=19&type=chunk)

PART I. FINANCIAL INFORMATION [Financial Statements (Unaudited)](index=5&type=section&id=Item%201.%20Financial%20Statements%20%28Unaudited%29) Unaudited financial statements show a **$62.4 million** net loss for nine months, with cash decreasing to **$63.2 million** due to investments and operations Condensed Consolidated Balance Sheets Condensed Consolidated Balance Sheet Highlights (in thousands) | Account | September 30, 2024 | December 31, 2023 | | :--- | :--- | :--- | | **Assets** | | | | Cash and cash equivalents | $63,207 | $166,150 | | Marketable securities (Short & Long-term) | $105,905 | $0 | | Total current assets | $152,783 | $172,728 | | Total assets | $243,543 | $221,663 | | **Liabilities & Stockholders' Equity** | | | | Total current liabilities | $13,610 | $19,483 | | Total liabilities | $63,911 | $51,752 | | Accumulated deficit | $(245,387) | $(183,005) | | Total stockholders' equity | $179,632 | $169,911 | Condensed Consolidated Statements of Operations and Comprehensive Loss Statement of Operations Highlights (in thousands, except per share data) | Metric | Nine Months Ended Sep 30, 2024 | Nine Months Ended Sep 30, 2023 | | :--- | :--- | :--- | | Research and development | $46,674 | $41,828 | | General and administrative | $22,196 | $15,813 | | Total operating expenses | $68,870 | $57,641 | | Loss from operations | $(68,870) | $(57,641) | | Net loss | $(62,382) | $(55,746) | | Net loss per share, basic and diluted | $(7.11) | $(200.94) | - The significant difference in **Net loss per share** year-over-year is primarily due to a substantial increase in the weighted-average shares outstanding following the reverse merger and financing activities, from approximately **277,000** to **8.77 million**[17](index=17&type=chunk) Condensed Consolidated Statements of Cash Flows Cash Flow Summary for the Nine Months Ended September 30 (in thousands) | Activity | 2024 | 2023 | | :--- | :--- | :--- | | Net cash used in operating activities | $(52,579) | $(46,176) | | Net cash (used in) provided by investing activities | $(120,582) | $12,819 | | Net cash provided by financing activities | $68,423 | $43,173 | | **Net (decrease) increase in cash, cash equivalents and restricted cash** | **$(104,738)** | **$9,816** | - The significant use of cash in investing activities in 2024 was driven by the purchase of **$118.1 million** in marketable securities. Cash from financing activities in 2024 was primarily from a **$67.4 million** net proceed from a PIPE financing[22](index=22&type=chunk) Notes to Unaudited Condensed Consolidated Financial Statements - The company completed a reverse merger with Frequency Therapeutics, Inc. on **November 3, 2023**, and is now trading under the ticker "**KRRO**". The transaction was accounted for as a reverse recapitalization, with Legacy Korro as the accounting acquirer[26](index=26&type=chunk)[34](index=34&type=chunk) - The company believes its existing cash, cash equivalents, and marketable securities of **$169.1 million** as of **September 30, 2024**, are sufficient to fund operations for at least the next **12 months** from the issuance date of the financial statements[36](index=36&type=chunk) - In **September 2024**, the company entered into a research collaboration and license agreement with Novo Nordisk, receiving a **$10.0 million** upfront payment in **October 2024**. The company is eligible for up to **$530.0 million** in total payments plus royalties across two programs[75](index=75&type=chunk)[76](index=76&type=chunk)[80](index=80&type=chunk) - The company is involved in a putative class action lawsuit inherited from Frequency Therapeutics. The lawsuit was dismissed, and the dismissal was affirmed on appeal. However, the plaintiff filed a motion to vacate the dismissal, which was denied on **November 1, 2024**. The company cannot estimate a range of possible loss[89](index=89&type=chunk) [Management's Discussion and Analysis of Financial Condition and Results of Operations](index=21&type=section&id=Item%202.%20Management's%20Discussion%20and%20Analysis%20of%20Financial%20Condition%20and%20Results%20of%20Operations) Management discusses RNA editing focus, **KRRO-110** entering Phase 1/2 in **Q1 2025**, and **$169.1 million** liquidity funding operations into **H2 2026** Overview and Recent Developments - Korro Bio is a biopharmaceutical company focused on developing a new class of genetic medicines based on editing RNA using its proprietary **OPERA platform**[96](index=96&type=chunk)[98](index=98&type=chunk) - The most advanced program is **KRRO-110** for **Alpha-1 Antitrypsin Deficiency (AATD)**. A regulatory filing for a Phase 1/2 clinical trial was submitted in **November 2024**, with the first participant expected to be dosed in **Q1 2025** and interim data anticipated in **H2 2025**[99](index=99&type=chunk) - In **September 2024**, the company entered a collaboration with **Novo Nordisk** for two cardiometabolic targets, with the potential to receive up to **$530 million** plus royalties and cost reimbursement. An initial **$10 million** upfront fee was received[104](index=104&type=chunk)[105](index=105&type=chunk) Results of Operations Operating Expenses Comparison (in thousands) | Expense Category | Nine Months Ended Sep 30, 2024 | Nine Months Ended Sep 30, 2023 | Change | | :--- | :--- | :--- | :--- | | Research and development | $46,674 | $41,828 | $4,846 | | General and administrative | $22,196 | $15,813 | $6,383 | | **Total operating expenses** | **$68,870** | **$57,641** | **$11,229** | - The **$4.8 million** increase in R&D expenses for the nine-month period was primarily driven by a **$3.7 million** increase in discovery, preclinical, and contract manufacturing costs in preparation for the **KRRO-110** trial, and a **$3.0 million** increase in personnel costs due to higher headcount[118](index=118&type=chunk)[119](index=119&type=chunk) - The **$6.4 million** increase in G&A expenses for the nine-month period was mainly due to a **$2.5 million** increase in employee-related expenses from headcount growth, a **$1.6 million** increase in IT and insurance costs, and a **$1.3 million** increase in professional fees[121](index=121&type=chunk) Liquidity and Capital Resources - As of **September 30, 2024**, the company had **$169.1 million** in cash, cash equivalents, and marketable securities[124](index=124&type=chunk) - The company expects its current cash position to be sufficient to fund operating expenses and capital expenditure requirements into the **second half of 2026**[126](index=126&type=chunk) - Since inception, the company has raised approximately **$223.6 million** from convertible preferred stock, **$117.3 million** from the Pre-Closing Financing, and **$70.0 million** from the April 2024 PIPE[124](index=124&type=chunk) [Quantitative and Qualitative Disclosures About Market Risk](index=30&type=section&id=Item%203.%20Quantitative%20and%20Qualitative%20Disclosures%20About%20Market%20Risk) Primary market risk is interest rate fluctuations on **$169.1 million** cash and marketable securities, foreign currency risk is minimal - The company's cash, cash equivalents, and marketable securities totaled **$169.1 million** as of **September 30, 2024**, consisting of bank deposits, money market funds, and U.S. government-backed securities[141](index=141&type=chunk) - The company has determined that its exposure to interest rate risk and foreign currency risk is not material at this time[141](index=141&type=chunk)[142](index=142&type=chunk) [Controls and Procedures](index=30&type=section&id=Item%204.%20Controls%20and%20Procedures) Disclosure controls and procedures were effective as of **September 30, 2024**, with no material changes to internal controls - The CEO and CFO have concluded that the company's disclosure controls and procedures were effective as of **September 30, 2024**[144](index=144&type=chunk) - No changes in internal control over financial reporting occurred during the quarter that materially affected, or are reasonably likely to materially affect, these controls[145](index=145&type=chunk) PART II. OTHER INFORMATION [Legal Proceedings](index=31&type=section&id=Item%201.%20Legal%20Proceedings) Class action lawsuit inherited from Frequency Therapeutics was dismissed, affirmed, and motion to vacate denied on **November 1, 2024** - The company is involved in a putative class action lawsuit, *Quinones et al. v. Frequency Therapeutics, Inc. et al.*, inherited from the merger with Frequency Therapeutics[148](index=148&type=chunk) - The lawsuit was dismissed, the dismissal was affirmed by the First Circuit Court of Appeals on **July 2, 2024**, and a plaintiff's motion to vacate the dismissal was denied on **November 1, 2024**[148](index=148&type=chunk) [Risk Factors](index=31&type=section&id=Item%201A.%20Risk%20Factors) The company faces significant risks including historical losses, funding needs, unproven technology, development uncertainties, and regulatory and IP challenges Risks Related to Financial Position and Need for Capital - The company has a history of significant operating losses (**$245.4 million** accumulated deficit as of **Sep 30, 2024**) and expects to incur losses for the foreseeable future, with no guarantee of ever achieving profitability[150](index=150&type=chunk) - Substantial additional funding will be required to continue R&D programs and potential commercialization. Failure to raise capital when needed could force the company to delay, reduce, or eliminate programs[158](index=158&type=chunk) Risks Related to Discovery, Development and Commercialization - **RNA editing** is a novel technology with limited clinical validation. The company's approaches are unproven and may never lead to marketable products[179](index=179&type=chunk) - All programs are in the research or preclinical stage. Product candidates may fail in development, and any favorable preclinical results may not be predictive of clinical trial outcomes[181](index=181&type=chunk)[200](index=200&type=chunk) - The manufacturing process for oligonucleotides is complex and subject to risks, including process development, scaling-up, and reliance on a limited number of third-party suppliers and CMOs[196](index=196&type=chunk)[192](index=192&type=chunk) Risks Related to Regulatory, Legal, and Clinical Trials - As a new class of drugs, oligonucleotides face a complex and uncertain regulatory review process, as the FDA and other agencies have limited experience and have not established definitive guidelines for **RNA editing therapies**[231](index=231&type=chunk) - There is a risk that regulatory authorities may not consider the proposed clinical trial endpoints to be clinically meaningful, which could delay or prevent approval[236](index=236&type=chunk) - Even if approved, products will be subject to extensive post-marketing regulations, and failure to comply could result in restrictions, withdrawal from the market, or penalties[255](index=255&type=chunk) Risks Related to Third Party Relationships - The company relies on third parties (CROs, CMOs, etc.) to conduct clinical trials and for manufacturing, which reduces control over these activities and may lead to delays or performance issues[292](index=292&type=chunk)[299](index=299&type=chunk) - The success of collaborations, like the one with **Novo Nordisk**, depends heavily on the efforts of partners who have significant discretion over the resources they apply[294](index=294&type=chunk)[296](index=296&type=chunk) Risks Related to Personnel, Operations and Growth - The company is highly dependent on its senior management and scientific staff, and the loss of key personnel could harm the business. There is intense competition for qualified personnel in the biotech industry[310](index=310&type=chunk) - Expected expansion of operations may lead to difficulties in managing growth, potentially straining resources and infrastructure[312](index=312&type=chunk) Risks Related to Intellectual Property - The company's success depends on its ability to obtain and maintain patent protection for its product candidates and platform technology, but the patent position of biotech companies is highly uncertain[314](index=314&type=chunk)[320](index=320&type=chunk) - The company may be subject to lawsuits from third parties claiming intellectual property infringement, which could be expensive, time-consuming, and prevent or delay development efforts[331](index=331&type=chunk)[339](index=339&type=chunk) - Changes in U.S. or international patent law could diminish the value of patents and impair the ability to protect products[368](index=368&type=chunk) [Unregistered Sales of Equity Securities and Use of Proceeds](index=80&type=section&id=Item%202.%20Unregistered%20Sales%20of%20Equity%20Securities%20and%20Use%20of%20Proceeds) This item is not applicable for the reporting period - Not applicable[415](index=415&type=chunk) [Defaults Upon Senior Securities](index=80&type=section&id=Item%203.%20Defaults%20Upon%20Senior%20Securities) This item is not applicable for the reporting period - Not applicable[416](index=416&type=chunk) [Mine Safety Disclosures](index=80&type=section&id=Item%204.%20Mine%20Safety%20Disclosures) This item is not applicable for the reporting period - Not applicable[417](index=417&type=chunk) [Other Information](index=80&type=section&id=Item%205.%20Other%20Information) During **Q3 2024**, officers adopted **Rule 10b5-1** trading plans for potential common stock sales from stock options - During the quarter, CFO Vineet Agarwal, COO Todd Chappell, and former CSO Steve Colletti adopted **Rule 10b5-1** trading plans for the potential sale of shares[418](index=418&type=chunk) [Exhibits](index=81&type=section&id=Item%206.%20Exhibits) This section lists exhibits filed with the Form 10-Q, including the **Novo Nordisk** collaboration agreement and officer certifications - Key exhibits filed include the Research Collaboration and License Agreement with **Novo Nordisk A/S**, dated **September 13, 2024**[420](index=420&type=chunk)

Exhibit 99.1 Korro Reports Third Quarter 2024 Financial Results and Provides Business Updates CAMBRIDGE, Mass., Nov. 12, 2024 (GLOBE NEWSWIRE) -- Korro Bio, Inc. (Korro) (Nasdaq: KRRO), a biopharmaceutical company focused on developing a new class of genetic medicines based on editing RNA for both rare and highly prevalent diseases, today reported financial results for the third quarter of 2024 and provided an update on its recent progress and anticipated milestones. "Korro is delivering across key scientif ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2024 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from _____________________ to _____________________ Commission File Number: 001-39062 Korro Bio, Inc. (Exact name of registrant as specified in its charter) Delawar ...