Lexeo Therapeutics, Inc.

Previous wording

We are a clinical stage genetic medicine company dedicated to reshaping heart health by applying pioneering science to fundamentally change how cardiovascular diseases are treated. We are advancing a portfolio of therapeutic candidates that take aim at the underlying genetic causes of conditions, including FA cardiomyopathy, PKP2 arrhythmogenic cardiomyopathy, and other devastating diseases with high unmet need.

Current wording

We are a clinical stage genetic medicine company dedicated to reshaping heart health by applying pioneering science to fundamentally change how cardiovascular diseases are treated. We are advancing a portfolio of therapeutic candidates that take aim at the underlying genetic causes of conditions, including FA cardiomyopathy, plakophilin-2, or PKP2, arrhythmogenic cardiomyopathy, or ACM, and other devastating diseases with high unmet need.

Previous wording

Our most advanced cardiovascular product candidate, LX2006 for the treatment of FA cardiomyopathy, is currently being evaluated in SUNRISE-FA, our ongoing Phase 1/2 clinical trial and in a Cornell investigator-initiated trial. In July 2024, we provided an interim clinical update, which included baseline characteristics from the 11 treated participants across the two studies and data from the 8 participants who had reached at least 6-months of follow-up as of that time. These data showed improvements in key cardiac biomarkers including left ventricular mass index, lateral wall thickness, and high-sensitivity troponin I. Additionally, in November 2024 we reported that we observed an increase in frataxin protein expression in the hearts of four patients that had undergone cardiac biopsies (cohort 1 (n=1), cohort 2 (n=3)) as measured by LCMS and immunohistochemistry. LX2006 has been generally well-tolerated across both trials to date. One year after dosing, one participant with multiple comorbidities and a history of flu-like symptoms presented with Grade 2 asymptomatic myocarditis. Six weeks later, a biopsy was negative for myocarditis and the participant remains asymptomatic. In November 2024 we announced alignment with the FDA on key elements of a registrational development plan for LX2006, including an accelerated approval pathway with left ventricular mass index and frataxin protein expression as co-primary registrational endpoints. In February 2025, we reached further alignment with FDA that the frataxin protein expression co-primary endpoint would be evaluated for any increase from baseline in frataxin positive area as measured by immunohistochemistry as opposed to any specific numerical threshold. We expect to provide a further interim data update in mid-2025.

Current wording

LX2006 for the treatment of FA cardiomyopathy

Previous wording

Our second most advanced cardiovascular product candidate, LX2020 for the treatment of ACM caused by mutations in the PKP2 gene, referred to as PKP2-ACM, is currently being evaluated in HEROIC-PKP2, an ongoing Phase 1/2 clinical trial. To date, six participants have been enrolled in this trial: three in cohort 1 and three in cohort 2. We have obtained post-treatment cardiac biopsies from two participants in cohort 1; the third cohort 1 participant elected to not undergo the post-treatment biopsy procedure. In these two participants with post-treatment samples, we have observed an increase in PKP2 protein expression in the heart quantified using western blot assay showing a 71% and 115% increase in PKP2 protein expression versus pre-treatment baseline. In addition, the first participant to reach 6 months post-treatment experienced a 67% reduction in PVCs from baseline and normalization of QRS duration. Across all participants dosed, LX2020 has been generally well-tolerated with no treatment-related serious adverse events to date. We expect to provide an interim data readout focused on clinical efficacy biomarkers in the second half of 2025.

Current wording

Our second most advanced cardiovascular product candidate, LX2020 for the treatment of arrhythmogenic cardiomyopathy, or ACM, caused by mutations in the PKP2 gene, referred to as PKP2-ACM, is currently being evaluated in HEROIC-PKP2, an ongoing Phase 1/2 clinical trial.

Previous wording

To date, we have funded our operations primarily through proceeds from the sale of shares of our convertible preferred stock and common stock, including our Private Placement, IPO and the subsequent partial exercise of the underwriters’ 30-day option to purchase additional shares of common stock. As of December 31, 2024, we had $128.5 million of cash, cash equivalents, and investments. We have incurred significant operating losses since the commencement of our operations. Our ability to generate product revenue sufficient to achieve profitability will depend heavily on the successful development and eventual commercialization of one or more of our current gene therapy candidates or any future gene therapy candidates. Our net losses for the years ended December 31, 2024 and December 31, 2023 were $98.3 million and $66.4 million, respectively, and our accumulated deficit was $280.2 million at December 31, 2024. We expect to continue to incur significant losses for the foreseeable future as we advance our current and future product candidates through preclinical and clinical development, continue to build our operations and operate as a public company.

Current wording

To date, we have funded our operations primarily through proceeds from the sale of shares of our convertible preferred stock, common stock, and pre-funded warrants and warrants to purchase our common stock, including from our October 2025 Financing Transactions, May 2025 Private Placement, March 2024 Private Placement, IPO and the subsequent partial exercise of the underwriters’ 30-day option to purchase additional shares of common stock. As of December 31, 2025, we had $246.6 million of cash, cash equivalents, and investments in U.S. Treasury securities. We have incurred significant operating losses since the commencement of our operations. Our ability to generate product revenue sufficient to achieve profitability will depend heavily on the successful development and eventual commercialization of one or more of our current gene therapy candidates or any future gene therapy candidates. Our net losses for the years ended December 31, 2025 and December 31, 2024 were $100.0 million and $98.3 million, respectively, and our accumulated deficit was $380.1 million at December 31, 2025. We expect to continue to incur significant losses for the foreseeable future as we advance our current and future product candidates through preclinical and clinical development, continue to build our operations and operate as a public company.

Previous wording

We expense research and development costs as incurred. Nonrefundable advance payments for goods and services that will be used in future research and development activities are expensed when the activity has been performed or when the goods have been received rather than when the payment is made. When third-party service providers’ billing terms do not coincide with our period-end, we are required to make estimates of our obligations to those third parties incurred in a given accounting period and record accruals at the end of the period. We base these estimates on our knowledge of the research and development programs, services performed for the period, past history for related activities and the expected duration of the third-party service contract, where applicable. If timelines or contracts are modified based upon changes in the scope of work to be performed, we modify our estimates of accrued expenses accordingly on a prospective basis; therefore, actual results could differ from our estimates. Upfront payments under license agreements are expensed upon receipt of the license, and annual maintenance fees under license agreements are expensed in the period in which they are incurred. Milestone payments under license agreements are accrued, with a corresponding expense being recognized, in the period in which the milestone is determined to be probable of achievement and the related amount is reasonably estimable.

Current wording

We record research and development costs as expenses when incurred. Nonrefundable advance payments for goods and services that will be used in future research and development activities are expensed when the activity has been performed or when the goods have been received rather than when the payment is made. When third-party service providers’ billing terms do not coincide with our period-end, we are required to make estimates of our obligations to those third parties incurred in a given accounting period and record accruals at the end of the period. We base these estimates on our knowledge of the research and development programs, services performed for the period, past history for related activities and the expected duration of the third-party service contract, where applicable. If timelines or contracts are modified based upon changes in the scope of work to be performed, we modify our estimates of accrued expenses accordingly on a prospective basis; therefore, actual results could differ from our estimates. Upfront payments under license agreements are expensed upon receipt of the license, and annual maintenance fees under license agreements are expensed in the period in which they are incurred. Milestone payments under license agreements are accrued, with a corresponding expense being recognized, in the period in which the milestone is determined to be probable of achievement and the related amount is reasonably estimable.

Previous wording

Other income (expense), net includes net foreign exchange gains and (losses).

Current wording

Other income (expense), net includes foreign exchange gains and (losses).

Previous wording

Interest income is primarily related to interest earned from our investment in a U.S. government money market fund and interest earned from our investments in U.S. Treasury securities, as well as interest earned on interest-bearing demand deposit cash accounts.

Current wording

Interest income is primarily related to interest earned from our investments in U.S. government money market funds and interest earned from our investments in U.S. Treasury securities, as well as interest earned on interest-bearing demand deposit cash accounts and a cash collateral account.

Previous wording

Accretion of discount on investments consists of accretion of discount on our investments in U.S. Treasury securities.

Current wording

Amortization of premium and accretion of discount on investments consists of amortization of premium and accretion of discount on our investments in U.S. Treasury securities.

Previous wording

The net increase of $21.0 million in total research and development expenses for the year ended December 31, 2024 compared to the year ended December 31, 2023 was primarily due to increases in (i) clinical trial costs of $8.7 million excluding an adjustment reducing estimated accrued clinical trial expenses by $2.2 million for our LX1001 program recorded during the year ended December 31, 2024, (ii) employee compensation and stock-based compensation expenses of $8.5 million primarily due to increased headcount and equity awards granted since December 31, 2023, (iii) chemistry, manufacturing and controls, or CMC, expenses of $3.8 million, (iv) net milestone expense of $2.6 million, including a $6.0 million development milestone for our LX2020 program that was achieved and paid to the selling shareholders of Stelios during the year ended December 31, 2024, which was partially offset by a $3.5 million development milestone for our LX2006 program that was achieved and paid to Adverum during the year ended December 31, 2023, (v) quality assurance and program and portfolio management expenses of $1.0 million, and (vi) license fees of $0.7 million primarily related to the Third Cornell License Agreement. These increases were partially offset by decreases in (i) non-clinical and preclinical expenses of $2.5 million primarily related to our early stage cardiovascular and CNS disease programs, and (ii) estimated accrued clinical trial expenses of $2.2 million resulting from an adjustment recorded during the year ended December 31, 2024 for our LX1001 program.

Current wording

The net decrease of $10.3 million in total research and development expenses for the year ended December 31, 2025 compared to the year ended December 31, 2024 was primarily due to decreases in (i) milestone expenses of $6.1 million, consisting primarily of a $6.0 million development milestone for our LX2020 program that was achieved during the third quarter of 2024 and subsequently paid to the selling shareholders of Stelios, (ii) clinical trial costs of $3.2 million excluding an adjustment that reduced estimated accrued clinical trial expenses in 2024 by $2.2 million for our LX1001 program, (iii) employee and stock-based compensation costs of $1.3 million primarily due to decreased headcount, (iv) CMC expenses of $1.2 million, and (v) license fees of $0.6 million related to the Third Cornell License Agreement that were incurred in 2024. These decreases were partially offset by an adjustment that reduced estimated accrued clinical trial expenses in 2024 by $2.2 million for our LX1001 program.

Previous wording

The net increase of $16.3 million in general and administrative expenses for the year ended December 31, 2024 compared to the year ended December 31, 2023 was primarily due to increases in (i) employee compensation and stock-based compensation expenses of $7.3 million primarily due to increased headcount and equity awards granted since December 31, 2023, (ii) third-party legal fees and associated costs of $6.4 million, (iii) third-party audit, tax, investor relations, public relations and other professional service provider fees, as well as insurance expenses, of $1.2 million primarily due to our becoming a publicly traded company in November 2023, (iv) travel, software, office supplies, and dues and subscription expenses of $0.6 million, and (v) capital tax expense of $0.3 million.

Current wording

The net increase of $13.8 million in general and administrative expenses for the year ended December 31, 2025 compared to the year ended December 31, 2024 was primarily due to increases in third-party legal fees and associated costs of $11.7 million, as well as employee compensation costs of $1.9 million primarily due to increased headcount.

Previous wording

We recognized interest income of $7.6 million and $2.9 million for the years ended December 31, 2024 and December 31, 2023, respectively, primarily related to interest earned on our investment in a U.S. government money market fund and our investments in U.S Treasury securities with an increased average invested balance in 2024 primarily due to the net proceeds received from our IPO and the subsequent partial exercise of the underwriters' option to purchase additional shares in November 2023, as well as the net proceeds received from our Private Placement offering in March 2024.

Current wording

We recognized interest income of $6.1 million and $7.6 million for the years ended December 31, 2025 and December 31, 2024, respectively, primarily related to interest earned on our investments in U.S. government money market funds and our investments in U.S Treasury securities, with the decrease primarily due to lower interest rates.

Previous wording

Since our inception, we have not generated any revenue from product sales and have incurred significant operating losses and negative cash flows from our operations. We expect to incur significant expenses and operating losses for the foreseeable future as we advance the clinical development of our product candidates. Since our inception through December 31, 2024, we funded our operations primarily with total net proceeds from sales of our common stock, convertible SAFE Note and convertible equity securities of $377.9 million. As of December 31, 2024 and December 31, 2023, we had cash, cash equivalents, and investments of $128.5 million and $121.5 million, respectively.

Current wording

Since our inception, we have not generated any revenue from product sales and have incurred significant operating losses and negative cash flows from our operations. We expect to incur significant expenses and operating losses for the foreseeable future as we advance the clinical development of our product candidates. Since our inception through December 31, 2025, we funded our operations primarily through proceeds from the sale of shares of our convertible preferred stock, common stock, and pre-funded warrants and warrants to purchase our common stock, including from our October 2025 Financing Transactions, May 2025 Private Placement, March 2024 Private Placement, IPO and the subsequent partial exercise of the underwriters’ 30-day option to purchase additional shares of common stock, with estimated net proceeds since our inception totaling $594.9 million. As of December 31, 2025 and December 31, 2024, we had cash, cash equivalents, and investments in U.S. Treasury Securities of $246.6 million and $128.5 million, respectively.

Previous wording

We believe that our cash, cash equivalents, and investments balances will be sufficient to fund our planned operating expenses and capital expenditure requirements into 2027. Our total future capital requirements will depend on many factors and is subject to the risks and uncertainties set forth in “Item 1A. Risk Factors.”

Current wording

We believe that our cash, cash equivalents, and investments in U.S. Treasury securities balances will be sufficient to fund our planned operating expenses and capital expenditure requirements into 2028. Our total future capital requirements will depend on many factors and are subject to the risks and uncertainties set forth in “Item 1A Risk Factors.”

Previous wording

During the year ended December 31, 2023, net cash used in operating activities consisted primarily of our net loss of $66.4 million, which was partially offset by (i) $3.0 million of stock-based compensation expense, (ii) $1.6 million of amortization of our right-of-use assets for our operating and finance leases, and (iii) $1.5 million of net cash provided by changes in operating assets and liabilities.

Current wording

During the year ended December 31, 2025, net cash used in operating activities consisted primarily of our net loss of $100.0 million, which included an unrealized gain of $3.4 million recorded to other non-operating income upon receipt of our long-term investment in convertible preferred stock, in addition to $9.5 million of net cash used in changes in operating assets and liabilities, which were partially offset by $12.1 million of stock-based compensation expense and $2.1 million of depreciation expense and amortization of operating and finance right-of-use assets.

Previous wording

During the year ended December 31, 2024, net cash used in operating activities consisted primarily of our net loss of $98.3 million, which was partially offset by (i) $12.5 million of stock-based compensation expense, (ii) $2.7 million of net cash provided by changes in operating assets and liabilities, and (iii) $1.7 million of amortization of our right-of-use assets for our operating and finance leases.

Current wording

During the year ended December 31, 2024, net cash used in operating activities consisted primarily of our net loss of $98.3 million, which was partially offset by (i) $12.5 million of stock-based compensation expense, (ii) $2.7 million of net cash provided by changes in operating assets and liabilities, and (iii) $2.0 million of depreciation expense and amortization of operating and finance right-of-use assets.

Previous wording

During the year ended December 31, 2023, net cash provided by financing activities consisted primarily of the net proceeds received from the IPO of $100.3 million, as well as net proceeds received from the issuance of the convertible SAFE Note of $3.9 million, which were partially offset by $0.4 million of principal payments made on equipment finance leases.

Current wording

During the year ended December 31, 2025, net cash provided by financing activities consisted primarily of the net proceeds received from the October 2025 Financing Transactions of $143.9 million, the May 2025 Private Placement of $73.1 million, as well as proceeds received from common stock issuances under the 2023 ESPP (as defined below) of $0.3 million and proceeds received from the exercise of stock options of $0.1 million, which were partially offset by $0.5 million of principal payments made on equipment finance leases.

Previous wording

During the year ended December 31, 2024, net cash provided by financing activities consisted primarily of the net proceeds received from the Private Placement offering of $88.7 million, as well as $0.5 million of proceeds received from the exercise of stock options, which were partially offset by $0.4 million of principal payments made on equipment finance leases.

Current wording

During the year ended December 31, 2024, net cash provided by financing activities consisted primarily of the net proceeds received from the March 2024 Private Placement of $88.7 million, as well as $0.5 million of proceeds received from the exercise of stock options, which were partially offset by $0.4 million of principal payments made on equipment finance leases.

Previous wording

our ability to maintain our relationships with Weill Cornell Medicine, Adverum, The Regents of UCSD, and any other key licensors or collaborators;

Current wording

our ability to maintain our relationships with Cornell University, Adverum, The Regents of UCSD, and any other key licensors or collaborators;

Previous wording

We may be unable to raise additional funds or enter into potential collaborations, strategic partnerships or marketing, distribution, licensing or other similar agreements or arrangements on favorable terms, or at all. To the extent that we raise additional capital through the sale of equity or convertible debt securities, your ownership interest will be diluted. If we fail to raise capital or enter into such agreements or arrangements as, and when, needed, we may have to significantly delay, scale back or discontinue the development or commercialization of our product candidates or grant rights to develop and market product candidates that we would otherwise prefer to develop and market ourselves.

Current wording

We may be unable to raise additional funds or enter into potential collaborations, strategic partnerships or marketing, distribution, licensing or other similar agreements or arrangements on favorable terms, or at all. To the extent that we raise additional capital through the sale of equity or convertible debt securities, your stockholder ownership interest will be diluted. If we fail to raise capital or enter into such agreements or arrangements as, and when, needed, we may have to significantly delay, scale back or discontinue the development or commercialization of our product candidates or grant rights to develop and market product candidates that we would otherwise prefer to develop and market ourselves.

Previous wording

Expected Volatility. Because we did not have any trading history for our shares of common stock prior to the IPO, the expected volatility for stock options granted prior to the IPO was estimated entirely using averages of the historical volatility of our peer group of companies, and the expected stock price volatility was primarily based on the historical volatility of a publicly traded set of peer companies for stock options granted since the IPO, each for a period equal to the expected life of the stock options granted, and we expect to continue to do so until such time as we have adequate historical data regarding the volatility of our own traded stock price. Our peer group of publicly traded companies was chosen based on their similar size, stage in the life cycle or area of specialty.

Current wording

Expected Volatility. The expected stock price volatility is primarily based on the historical volatility of a publicly traded set of peer companies for stock options granted since the IPO, each for a period equal to the expected life of the stock options granted, and we expect to continue to do so until such time as we have adequate historical data regarding the volatility of our own traded stock price. Our peer group of publicly traded companies was chosen based on their similar size, stage in the life cycle or area of specialty.

Previous wording

Fair Value of Common Stock. Since our IPO, the fair value of shares of our common stock is measured by the stock price on the date of grant.

Current wording

Fair Value of Common Stock. The fair value of shares of our common stock is measured by the stock price on the date of grant.