0000950170-24-125362 | 10-Q | XBRL Viewer

Property and Equipment , Net

9 Months Ended

Sep. 30, 2024

Property, Plant and Equipment [Abstract]

6. Property and Equipment, Net

Property and equipment, net, as of September 30, 2024 and December 31, 2023 was comprised as follows (in thousands):


	Estimated Useful Life (in Years)	September 30, 2024			December 31, 2023
Laboratory equipment	5	$	11,682		$	11,187
Furniture and office equipment	4		1,068			481
Computer equipment	3		248			241
Leasehold improvements	Shorter of useful life or remaining lease term		25,767			3,356
Construction in progress			223			8,242
Total property and equipment, gross			38,988			23,507
Less: accumulated depreciation			(9,877	)		(7,842	)
Total property and equipment, net		$	29,111		$	15,665

As of September 30, 2024 and December 31, 2023, the Company had construction in progress of $0.2 million and $8.2 million, respectively, predominately related to laboratory equipment received but not yet installed and capitalizable costs related to the Company’s new corporate headquarters.

Depreciation expense for the nine months ended September 30, 2024 and 2023 was $2.3 million and $2.6 million, respectively.

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2024
Accounting Policies [Abstract]
Basis of Presentation and Consolidation	Basis of Presentation and Consolidation The accompanying consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”). These consolidated financial statements have been prepared on the going concern basis of accounting, which assumes continuity of operations, realization of assets and satisfaction of liabilities in the ordinary course of business. The consolidated financial statements include the accounts of Korro Bio, Inc. and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation
Unaudited Interim Condensed Consolidated Financial Information	Unaudited Interim Condensed Consolidated Financial Information The accompanying condensed consolidated financial statements are unaudited. The financial data and other information contained in the notes hereto as of September 30, 2024 and for the three and nine month periods ended September 30, 2024 and 2023 are also unaudited. The condensed consolidated balance sheet data as of December 31, 2023 was derived from the Company's audited consolidated financial statements included in the Company's Annual Report on Form 10-K for the year ended December 31, 2023 (the “2023 Form 10-K”). The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited annual consolidated financial statements, and in the opinion of management, reflect all adjustments, which include any normal recurring adjustments necessary for the fair presentation of the Company's interim period results. These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements as of and for the year ended December 31,2023, and the notes thereto, included in the Company's 2023 Form 10-K. The results for the three and nine month periods ended September 30, 2024 are not necessarily indicative of results to be expected for the year ended December 31, 2024, or any other interim periods, or any future year or period.
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies The significant accounting policies used in preparation of the condensed consolidated financial statements are described in the Company's audited consolidated financial statements as of the year end December 31, 2023, and the notes thereto, which are included in the 2023 Form 10-K. There have been no material changes to the significant accounting policies previously disclosed in the 2023 Form 10-K.
Segment Information	Segment Information Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision-maker in deciding how to allocate resources and assess performance. The Company and the Company’s chief operating decision maker, the Company’s chief executive officer, views the Company’s operations and manages its business as a single operating segment. The Company operates only in the United States.
Use of Estimates	Use of Estimates The preparation of the Company’s consolidated financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of expenses during the reporting period. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to the fair value of the common stock prior to the effective date of the Merger; the fair value of the contingent value rights ("CVR") liability and the incremental borrowing rate for determining lease liabilities and right-of-use assets. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it has concluded to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates as there are changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results may differ materially from those estimates or assumptions.
Recent Accounting Pronouncements - Yet to be Adopted	Recent Accounting Pronouncements—Yet to be Adopted Other accounting standards that have been issued or proposed by the Financial Accounting Standards Board or other standards-setting bodies that do not require adoption until a future date are not expected to have a material impact on the Company’s consolidated financial statements upon adoption. In November 2023, the ASU 2023-07, Segment Reporting (Topic 280), Improvements to Reportable Segment Disclosures, which is intended to provide enhanced segment disclosures. The standard will require disclosures about significant segment expenses and other segment items and identifying the Chief Operating Decision Maker and how they use the reported segment profitability measures to assess segment performance and allocate resources. These enhanced disclosures are required for all public entities on an interim and annual basis, even if they have only a single reportable segment. The standard is effective for years beginning after December 15, 2023, and interim periods within annual periods beginning after December 15, 2024. Early adoption is permitted. The Company is evaluating this standard to determine if adoption will have a material impact on the Company's consolidated financial statements.

- Definition

Disclosure of accounting policy for segment reporting.

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+ Details

Income Taxes - Schedule of Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Deferred taxes:
Total provision for income taxes	$ (9)	$ 0	$ 38	$ 27

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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+ Details

Net Loss per Share - Computation of Diluted Net Loss per Share Attributable to Common Stockholders (Details) - Legacy Korro [Member] - shares	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Antidilutive securities excluded from computation of earnings per share	1,290,431	5,474,807
Outstanding Warrant [Member]
Antidilutive securities excluded from computation of earnings per share	8,049	8,049
Unvested Restricted Stock Units [Member]
Antidilutive securities excluded from computation of earnings per share	0	209
Outstanding Stock Options [Member]
Antidilutive securities excluded from computation of earnings per share	1,282,382	611,310
Series Seed Preferred Stock [Member]
Antidilutive securities excluded from computation of earnings per share	0	684,739
Series A Convertible Preferred Stock [Member]
Antidilutive securities excluded from computation of earnings per share	0	2,029,666
Series B-1 Preferred Stock [Member]
Antidilutive securities excluded from computation of earnings per share	0	1,104,178
Series B-2 Preferred Stock [Member]
Antidilutive securities excluded from computation of earnings per share	0	1,036,656

Condensed Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2024	Jun. 30, 2024
Other comprehensive income, net of tax of	$ 0	$ 0

Commitments and Contingencies

9 Months Ended

Sep. 30, 2024

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

12. Commitments and Contingencies

Leases

The Company had an operating lease at One Kendall Square, Cambridge, Massachusetts where it occupied 22,561 square feet of laboratory and office space (the “OKS Facility”) pursuant to a lease agreement that expired September 30, 2024 (after being extended from December 31, 2023 pursuant an October 20, 2023 lease amendment). The Company also had an operating sublease agreement at Cummings Park in Woburn, Massachusetts where it occupied 18,148 square feet of laboratory and office space (the “Cummings Park Sublease”), which expired on July 31, 2024.

The Company has an operating lease for 50,453 square feet of office and laboratory space at 60 First Street, Cambridge, Massachusetts (the “60 First Street Lease”). In May 2023, the Company obtained control over the space and the Company recognized the operating lease right-of-use asset and the operating lease liability of $26.8 million on the commencement date of the lease. The total rental payments over the 11 year lease are expected to be $62.1 million, including rent credits and other lease incentives per the terms of the lease. Specifically, the 60 First Street Lease provides the Company with a tenant improvement allowance of $13.1 million. The Company utilized $9.8 million of the $13.1 million tenant improvement allowance as of September 30, 2024. The lease has remaining term of approximately 10 years. The Company has an option to extend the lease for an additional period of five years with the rent during the option period being the then fair market rent.

Future minimum lease payments for 60 First Street Lease, net of $3.3 million expected to be received and intended to be used related to the remaining tenant improvement allowance and rent credits associated with the 60 First Street Lease, as of September 30, 2024 were as follows (in thousands):


	As of September 30, 2024
2024	$	(1,776	)
2025		6,247
2026		7,341
2027		7,557
Thereafter		52,498
Total Future Minimum Leases Payments		71,867
Less: Interest		(30,082	)
Present Value of Operating Lease Liabilities	$	41,785

As of September 30, 2024, the weighted average remaining lease term was 9.6 years and the weighted average incremental borrowing rate used to determine the operating lease liability was 11.2%.

The Company combines the lease and non-lease components of fixed costs in its lease arrangements as a single lease component. Variable costs, such as utilities and maintenance costs, are not included in the measurement of right-of-use assets and lease liabilities, but rather are expensed when the event determining the amount of variable consideration to be paid occurs.

The following table summarizes the effect of lease costs in the Company’s condensed consolidated statement of operations and comprehensive loss of its operating leases (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
Operating lease costs	$	1,939	$	1,892	$	6,197	$	3,794
Variable lease costs		471		253		1,295		742
Short-term lease costs		257		182		919		541
Total lease costs	$	2,667	$	2,327	$	8,411	$	5,077

Legal Contingencies

The Company accrues a liability for legal contingencies when it believes that it is both probable that a liability has been incurred and that the Company can reasonably estimate the amount of the loss. The Company reviews these accruals and adjusts them to reflect ongoing negotiations, settlements, rulings, advice of legal counsel and other relevant information. To the extent new information is obtained and the views on the probable outcomes of claims, suits, assessments, investigations or legal proceedings change, changes in the Company’s accrued liabilities would be recorded in the period in which such determination is made.

In addition, in accordance with the relevant authoritative guidance, for any matters in which the likelihood of material loss is at least reasonably possible, the Company will provide disclosure of the possible loss or range of loss. If a reasonable estimate cannot be made, however, the Company will provide disclosure to that effect. The Company expenses legal costs as they are incurred.

On June 3, 2021 and June 22, 2021, purported stockholders of Frequency filed putative class action lawsuits in the U.S. District Court for the District of Massachusetts against Frequency and Frequency’s Chief Executive Officer, President, and Director, David Lucchino. On March 21, 2022, the two lawsuits were consolidated into a single lawsuit, Quinones et al. v. Frequency Therapeutics, Inc. et al. and on May 16, 2022, Frequency’s Chief Development Officer, Dr. Carl Le Bel, was added as a defendant. The plaintiffs alleged violations of Sections 10(b), 20(a) and Rule 10b5 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), due to allegedly false and misleading statements and omissions about Frequency’s Phase 2a clinical trial (FX-322-202) for its product candidate FX-322 in Frequency’s public disclosures between October 29, 2020 and March 22, 2021. The lawsuit sought, among other things, damages in connection with Frequency’s allegedly artificially inflated stock price between October 29, 2020 and March 22, 2021 as a result of those allegedly false and misleading statements and omissions, as well as interest, attorneys’ fees and costs. On March 29, 2023, Frequency’s motion to dismiss was granted and the lawsuit was dismissed in its entirety. On April 27, 2023, plaintiff filed a notice of appeal to the United States Court of Appeals for the First Circuit from the order dismissing the lawsuit. On August 2, 2023, plaintiff-appellant submitted its opening brief to the First Circuit. Frequency filed its opposition brief on October 27, 2023, and plaintiff-appellant filed its reply brief on December 14, 2023. The First Circuit heard oral argument on January 8, 2024. On July 2, 2024, the First Circuit issued an opinion and judgment affirming dismissal of the lawsuit in its entirety. On July 18, 2024, plaintiff filed a motion in the U.S. District Court for the District of Massachusetts requesting that the court vacate its prior order and judgment dismissing the plaintiff’s lawsuit. The Company filed an opposition to that motion on August 8, 2024, and on November 1, 2024 the U.S. District Court for the District of Massachusetts denied the plaintiff's request that the court vacate its prior order and judgment dismissing the plaintiff’s lawsuit. At this stage of the case, the Company is not able to estimate a range of possible loss. Because an estimate of the possible loss or range of loss cannot be made at this time, no accruals have been recorded as of September 30, 2024.

Indemnifications

The Company indemnifies each of its officers and directors for certain events or occurrences, subject to certain limits, while the officer or director is or was serving at the Company’s request in such capacity, as permitted under Delaware law and in accordance with the Company’s amended and restated certificate of incorporation and bylaws. The term of the indemnification period lasts as long as an officer or director may be subject to any proceeding arising out of acts or omissions of such officer or director in such capacity.

The maximum amount of potential future indemnification is unlimited; however, the Company currently holds director and officer liability insurance. This insurance allows the transfer of risk associated with the Company’s exposure and may enable the Company to recover a portion of any future amounts paid. The Company believes that the fair value of these potential indemnification obligations is minimal. Accordingly, the Company has not recognized any liabilities relating to these obligations for any period presented.

Collaboration Agreements (Additional Information) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 13, 2024	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	Oct. 31, 2024
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and Development Expense, Total		$ 15,964	$ 14,008	$ 46,674	$ 41,828
Reimbursements with in Research and Development Expense		2,700	$ 3,500	2,700	3,500
Genevant Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and Development Expense, Total				300	$ 500	$ 2,500
Revenue recognized commercialization milestone payments to receive				57,000
Genevant Agreement [Member] \| Development Milestone [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Development Milestone Payment		$ 1,000		1,000
Genevant Agreement [Member] \| Maximum [Member] \| Phase 3 Clinical Trial [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone payment				13,500
Genevant Agreement [Member] \| Maximum [Member] \| Phase2b Clinical Trial [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone payment				$ 27,000
Novo Nordisk Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contract with Customer, Liability, Revenue Recognized	$ 530,000
Milestone payment	115,000
Reimbursements with in Research and Development Expense							$ 29,500
Upfront Non-Refundable Fee	10,000
Commercial Milestone Payments	140,000
Upfront Non Refundable Payment							$ 10,000
Novo Nordisk Agreement [Member] \| Second Research Program [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone payment	115,000
Upfront Non-Refundable Fee	10,000
Commercial Milestone Payments	$ 140,000

The Company and Liquidity (Additional Information) (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2024	Dec. 31, 2023	Nov. 03, 2023
Date of incorporation	Nov. 30, 2014
Common stock, shares issued	9,318,356	8,016,516
Exchange Ratio	4.9688%
Cash ,cash equivalents and marketable securities	$ 169,100
Accumulated deficit	245,387	$ 183,005
MS APA Asset [Member]
Initial Consideration Amount	500
MS APA Asset [Member] \| Minimum [Member]
Future Milestone Payments	700
MS APA Asset [Member] \| Maximum [Member]
Future Milestone Payments	$ 17,500
Common Stock [Member] \| Legacy Korro [Member]
Ownership	91.00%
Common Stock [Member] \| Legacy Korro [Member] \| Accredited Investors [Member]
Common stock, shares issued			42,176,255
Common Stock, Value, Subscriptions			$ 117,300
Sale of Stock, Price Per Share			$ 2.78
Common Stock [Member] \| Frequency [Member]
Common stock, shares issued	8,623,645		7,848,776
Ownership	9.00%
Preferred Stock [Member]
Exchange Ratio	4.9688%
Preferred Stock [Member] \| Legacy Korro [Member]
Exchange Ratio			4.9688%

Preferred Stock

9 Months Ended

Sep. 30, 2024

Class of Stock Disclosures [Abstract]

Preferred Stock

9. Preferred Stock

As of September 30, 2024, the Company was authorized to issue up to 10,000,000 shares of preferred stock at a par value of $0.001 with no preferred stock shares issued or outstanding.

Pursuant to the terms of the Merger Agreement, immediately prior to closing of the Merger, each share of Legacy Korro's Preferred Stock issued and outstanding immediately prior to the Closing of the Merger was converted into shares of Legacy Korro’s common stock, and then exchanged in the Merger for shares of the Company's common stock using an exchange ratio of 0.049688. The conversion was approved by greater than 66% of the then-outstanding shares of Preferred Stock, voting as a single class on an as-converted to common stock basis.

Investments - Schedule of Fair Value of Cash Equivalents and Short-Term Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Cash and Cash Equivalents [Line Items]
Amortized Cost	$ 105,291
Fair Value	$ 105,905	$ 0

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(6))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
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-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479130/326-30-45-1

+ Details

Restricted Cash

9 Months Ended

Sep. 30, 2024

Cash and Cash Equivalents [Abstract]

Restricted Cash

5. Restricted Cash

As of September 30, 2024, the Company maintained current restricted cash of $1.8 million and non-current restricted cash of $3.4 million. As of December 31, 2023, the Company maintained current restricted cash of $3.6 million and non-current restricted cash of $3.4 million. All restricted cash amounts are comprised solely of letters of credit required pursuant to the Company’s facility leases.

The following table provides a reconciliation of cash, cash equivalents and restricted cash as of September 30, 2024 and December 31, 2023 that sums to the total of the same amounts shown in the consolidated statements of cash flows (in thousands):


	September 30, 2024		December 31, 2023
Cash and cash equivalents	$	63,207	$	166,150
Restricted cash		5,174		6,969
Cash, cash equivalents and restricted cash	$	68,381	$	173,119

Stock-based Compensation - Summary of Stock Option Activity (Details) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2024 USD ($) $ / shares shares	Dec. 31, 2023 USD ($) $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of shares Options , Beginning balance \| shares	1,323,151
Number of shares Options , Granted \| shares	214,107
Number of shares Options, Exercised \| shares	(52,765)
Number of shares Options, Forfeited \| shares	(149,953)
Number of shares Options, Cancelled \| shares	(52,158)
Number of shares Options, Ending balance \| shares	1,282,382	1,323,151
Exercisable at September 30, 2024 \| shares	508,595
Weighted average exercise price, Beginning balance \| $ / shares	$ 23.49
Weighted average exercise price, Granted \| $ / shares	46.78
Weighted average exercise price, Exercised \| $ / shares	18.92
Weighted average exercise price, Forfeited \| $ / shares	18.26
Weighted- Average Exercise Price Cancelled \| $ / shares	116.61
Weighted average exercise price, Ending balance \| $ / shares	24.39	$ 23.49
Weighted average exercise price, Options Exercisable at September 30, 2024 \| $ / shares	$ 22.9
Weighted average remaining contractual term (in years), Outstanding	8 years 2 months 12 days	8 years 4 months 24 days
Weighted average remaining contractual term (in years), Options exercisable as of September 30, 2024	6 years 8 months 12 days
Aggregate intrinsic value, Outstanding as of December 31, 2023 \| $	$ 36,310
Aggregate intrinsic value, Outstanding as of September 30, 2024 \| $	18,095	$ 36,310
Aggregate intrinsic value, Options exercisable as of Exercisable at September 30, 2024 \| $	$ 8,795

Common Stock (Tables)

9 Months Ended

Sep. 30, 2024

Equity [Abstract]

Schedule of Number of Shares Reserved for Future Issuance

As of September 30, 2024 and December 31, 2023, the Company had reserved for future issuance the following number of shares of common stock:


	September 30, 2024		December 31, 2023
Exercises of outstanding stock options		1,282,382		1,323,151
Exercise of outstanding warrant		8,049		8,049
Future issuances under 2023 Stock Incentive Plan		644,524		255,694
Future issuances under 2023 ESPP Plan		168,667		88,502
Total reserved for future issuance		2,103,622		1,675,396

Restricted Cash (Tables)

9 Months Ended

Sep. 30, 2024

Cash and Cash Equivalents [Abstract]

Schedule of Reconciliation of Cash, Cash Equivalents and Restricted Cash


	September 30, 2024		December 31, 2023
Cash and cash equivalents	$	63,207	$	166,150
Restricted cash		5,174		6,969
Cash, cash equivalents and restricted cash	$	68,381	$	173,119

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Sep. 30, 2024 shares
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	During the three months ended September 30, 2024, the following officers (as defined in Rule 16a-1(f) under the Exchange Act) adopted contracts, instructions or written plans for the purchase or sale of our securities that were intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) under the Exchange Act (each, a “Rule 10b5-1 plan”): On July 19, 2024, Vineet Agarwal, our Chief Financial Officer, adopted a Rule 10b5-1 plan providing for the potential sale of up to 11,872 shares of our common stock issuable upon the exercise of stock options; this plan is scheduled to expire on January 6, 2025. On August 8, 2024, Todd Chappell, our Chief Operating Officer, adopted a Rule 10b5-1 plan providing for the potential sale of up to 2,284 shares of our common stock issuable upon the exercise of stock options; this plan is scheduled to expire on February 3, 2025. On June 13, 2024, Steve Colletti, our former Chief Scientific Officer, adopted a Rule 10b5-1 plan providing for the potential sale of up to 6,257 shares of our common stock issuable upon the exercise of stock options; this plan would have expired on December 9, 2024 per its terms had it not been terminated on August 5, 2024 following his departure from our company. During the three months ended September 30, 2024, none of our other officers or directors informed us that they adopted, modified or terminated a Rule 10b5-1 plan or a trading plan not intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) under the Exchange Act.
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false
Rule 10b51Arrangement Modified	false
Non Rule 10b51Arrangement Modified	false
Vineet Agarwal [Member]
Trading Arrangements, by Individual
Name	Vineet Agarwal
Title	Chief Financial Officer
Rule 10b5-1 Arrangement Adopted	true
Non-Rule 10b5-1 Arrangement Adopted	false
Adoption Date	July 19, 2024
Expiration Date	January 6, 2025
Arrangement Duration	171 days
Aggregate Available	11,872
Todd Chappell [Member]
Trading Arrangements, by Individual
Name	Todd Chappell
Title	Chief Operating Officer
Rule 10b5-1 Arrangement Adopted	true
Non-Rule 10b5-1 Arrangement Adopted	false
Adoption Date	August 8, 2024
Expiration Date	February 3, 2025
Arrangement Duration	179 days
Aggregate Available	2,284
Steve Colletti (Member)
Trading Arrangements, by Individual
Name	Steve Colletti,
Title	former Chief Scientific Officer
Rule 10b5-1 Arrangement Adopted	true
Non-Rule 10b5-1 Arrangement Adopted	false
Adoption Date	June 13, 2024
Expiration Date	December 9, 2024
Arrangement Duration	179 days
Aggregate Available	6,257

Property and Equipment, Net - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 38,988	$ 23,507
Less: accumulated depreciation	(9,877)	(7,842)
Total property and equipment, net	29,111	15,665
Laboratory equipment
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 11,682	$ 11,187
Estimated Useful Life (in Years)	5 years	5 years
Furniture and office equipment
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 1,068	$ 481
Estimated Useful Life (in Years)	4 years	4 years
Computer equipment
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 248	$ 241
Estimated Useful Life (in Years)	3 years	3 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 25,767	$ 3,356
Property, Plant and Equipment, Dispositions	Shorter of useful life or remaining lease term	Shorter of useful life or remaining lease term
Construction in progress
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 223	$ 8,242

Subsequent Events (Additional Information) (Details) - shares	Sep. 30, 2024	Dec. 31, 2023
Subsequent Event [Line Items]
Common Stock, Shares, Issued	9,318,356	8,016,516

Basis of Presentation and Summary of Significant Accounting Policies - Schedule of Financial Statement Affected by Adoption of ASC (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets	$ 24,018	$ 27,150
Operating lease liabilities, current portion	$ 0	$ 1,991

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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+ Details

Restricted Cash - Schedule of Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents	$ 63,207	$ 166,150
Restricted cash	5,174	6,969
Cash, cash equivalents and restricted cash	$ 68,381	$ 173,119

Property and Equipment, Net (Tables)

9 Months Ended

Sep. 30, 2024

Property, Plant and Equipment [Abstract]

Schedule of Property and Equipment

Property and equipment, net, as of September 30, 2024 and December 31, 2023 was comprised as follows (in thousands):


	Estimated Useful Life (in Years)	September 30, 2024			December 31, 2023
Laboratory equipment	5	$	11,682		$	11,187
Furniture and office equipment	4		1,068			481
Computer equipment	3		248			241
Leasehold improvements	Shorter of useful life or remaining lease term		25,767			3,356
Construction in progress			223			8,242
Total property and equipment, gross			38,988			23,507
Less: accumulated depreciation			(9,877	)		(7,842	)
Total property and equipment, net		$	29,111		$	15,665

Fair Value Measurements

9 Months Ended

Sep. 30, 2024

Fair Value Disclosures [Abstract]

Fair Value Measurements

3. Fair Value Measurements

The Company measures the fair value of money market funds based on quoted prices in active markets for identical securities. Marketable securities include U.S. treasury bills and U.S. government agency securities that are valued either based on recent trades of securities in inactive markets or based on quoted market prices of similar instruments and other significant inputs derived from or corroborated by observable market data.

The carrying amounts reflected in the consolidated balance sheets for cash, prepaid expenses and other current assets, accounts payable and accrued expenses approximate their fair values, due to their short-term nature.

Assets and liabilities measured at fair value on a recurring basis as of September 30, 2024 were as follows (in thousands):


	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Financial assets
Cash equivalents:
Money market funds	$	62,743	$	62,743	$	—	$	—
Marketable securities
U.S. treasury bills		48,729		—		48,729		—
U.S. government agency securities		57,176		—		57,176		—
MS APA asset		1,276		—		—		1,276
Total financial assets	$	169,924	$	62,743	$	105,905	$	1,276

Financial liabilities
CVR liability	$	1,276	$	—	$	—	$	1,276
Total financial liabilities	$	1,276	$	—	$	—	$	1,276

Assets and liabilities measured at fair value on a recurring basis as of December 31, 2023 were as follows (in thousands):


	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Financial assets:
Money market funds, included in cash and cash equivalents	$	158,706	$	158,706	$	—	$	—
MS APA asset		1,448		—		—		1,448
Total financial assets	$	160,154	$	158,706	$	—	$	1,448

Financial liabilities:
CVR liability	$	1,448	$	—	$	—	$	1,448
Total financial liabilities	$	1,448	$	—	$	—	$	1,448

As noted previously in Note 1, at the effective time of the Transaction, the Company entered into the CVR Agreement providing for the payment of certain contingent cash payments equal to the net amount of proceeds actually received by the Company or its subsidiaries after the end of each fiscal quarter following the first anniversary of the closing of the Transaction related to the disposition of assets related to Frequency’s former multiple sclerosis programs, with the time periods and subject to deductions as provided therein. The Company concluded that the CVR is a derivative liability and is accounted for at fair value, which was $1.3 million as of September 30, 2024 and $1.4 million as of December 31, 2023, of which $0.6 million and $0.4 million is included in

accrued expenses and other current liabilities and the remaining $0.7 million and $1.0 million in other non-current liabilities in the consolidated balance sheet as of September 30, 2024 and December 31, 2023, respectively. Concurrently, the Company entered into the MS APA with Progentos, whereby Progentos acquired the rights, title and interest in certain assets related to the Company’s MS program. The MS APA included initial consideration of $0.5 million in proceeds that were settled through net cash at the Merger closing and will be entitled to future milestone payments of up to $17.5 million as well as a $0.7 million payment in the event of Progentos closing of an equity financing at or above a specified amount. The equity financing milestone was triggered in the second quarter of 2024 and the related milestone payment of $0.7 million was received from Progentos and distributed to the CVR holders. The Company concluded that the MS APA is a derivative asset and is accounted for at fair value, which was $1.3 million as of September 30, 2024 and $1.4 million as of December 31, 2023, respectively, of which $0.6 million and $0.4 million is included in prepaid and other current assets and the remaining $0.7 million and $1.0 million in other long-term assets in the consolidated balance sheet as of September 30, 2024 and December 31, 2023, respectively.

The fair value of the CVR liability and the MS APA are based on significant unobservable inputs, which represent Level 3 measurements within the fair value hierarchy. In determining the fair value of the CVR liability and the MS APA asset, the Company used the income approach, primarily discounted cash flow models. The discounted cash flow models require the use of significant judgment, estimates and assumptions, including the probability of technical and regulatory success, and discount rates. For the nine months ended September 30, 2024, the aggregate change in fair value of the CVR liability and MS APA asset was $0.1 million. For the year ended December 31, 2023, the aggregate change in fair value of the CVR liability and MS APA asset was $0.1 million.

There were no changes in valuation techniques, nor were there any transfers among the fair value hierarchy levels during the nine months ended September 30, 2024 or during the year ended December 31, 2023.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

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+ Details

Stock-based Compensation (Tables)

9 Months Ended

Sep. 30, 2024

Share-Based Payment Arrangement [Abstract]

Summary of Stock-based Compensation Expense

Total stock-based compensation expense recognized in the consolidated statements of operations and comprehensive loss for the three and the nine months ended September 30, 2024 and 2023 was as follows (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
Research and development	$	418	$	157	$	1,031	$	403
General and administrative		855		247		2,074		751
Total stock-based compensation expense	$	1,273	$	404	$	3,105	$	1,154

Summary of Stock Option Weighted-Average Assumptions

The fair value of stock options granted during the nine months ended September 30, 2024 and 2023 was calculated on the date of grant using the following weighted-average assumptions:


	Nine Months Ended September 30,
	2024			2023
Risk-free interest rate		4.1	%		3.6	%
Expected dividend yield		—	%		—	%
Expected term (in years)		6.0			6.0
Expected volatility		74.6	%		69.5	%

Summary of Stock Option Activity

The following table summarizes changes in stock option activity during the nine months ended September 30, 2024 (in thousands, except per share amounts):


	Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value
Outstanding at December 31, 2023		1,323,151		$	23.49		8.4	$	36,310
Granted		214,107		$	46.78
Exercised		(52,765	)	$	18.92
Forfeited		(149,953	)	$	18.26
Cancelled		(52,158	)	$	116.61
Outstanding as of September 30, 2024		1,282,382		$	24.39		8.2	$	18,095
Exercisable at September 30, 2024		508,595		$	22.90		6.7	$	8,795

Common Stock (Additional Information) (Details) - USD ($) $ / shares in Units, $ in Thousands		9 Months Ended
	Apr. 17, 2024	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Common stock, shares authorized		200,000,000		200,000,000
Common stock, par value		$ 0.001		$ 0.001
Common stock shares issued and sold		9,318,356		8,016,516
Gross proceeds		$ 67,384	$ 0
Private Placement PIPE [Member]
Placement agent fees offering expenses	$ 2,600
Common Stock [Member] \| Private Placement PIPE [Member]
Common stock shares issued and sold	1,249,283
Gross proceeds	$ 70,000
Korros [Member]
Dividends Declared		$ 0
Korros [Member] \| Common Stock [Member]
Common stock, shares authorized		200,000,000
Common stock, par value		$ 0.001

401(k) Savings Plan (Additional Information) (Details) - USD ($) $ in Millions		9 Months Ended
	Apr. 01, 2022	Sep. 30, 2024	Sep. 30, 2023
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	3.00%
Defined Contribution Plan, Cost		$ 0.5	$ 0.4
Maximum [Member]
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	100.00%

401(k) Savings Plan

9 Months Ended

Sep. 30, 2024

Retirement Benefits [Abstract]

401(k) Savings Plan

13. 401(k) Savings Plan

The Company has a defined-contribution savings plan under Section 401(k) of the IRC (the “401(k) Plan”). The 401(k) Plan covers all employees who meet defined minimum age and service requirements and allows participants to defer a portion of their annual compensation, subject to statutory limitations. Beginning on April 1, 2022, the Company matches 100% of an employee’s 401(k) contributions up to a maximum of 3% of the participant’s salary, subject to employer match limitations under the IRC. As such, the Company made $0.5 million and $0.4 million of matching contributions to the 401(k) Plan during the nine months ended September 30, 2024 and September 30, 2023, respectively.

Condensed Consolidated Balance Sheets (unaudited) (Parenthetical) - $ / shares	Sep. 30, 2024	Dec. 31, 2023
Statement [Table]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	9,318,356	8,016,516
Common stock, shares outstanding	9,318,356	8,016,516

- Definition

Disclosure of information about statement of comprehensive income, income, other comprehensive income, financial position, cash flows, and shareholders' equity.

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+ Details

Stock-based Compensation - Summary of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock-based compensation	$ 1,273	$ 404	$ 3,105	$ 1,154
Research and Development Expense [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock-based compensation	418	157	1,031	403
General and Administrative Expense [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock-based compensation	$ 855	$ 247	$ 2,074	$ 751

- Definition

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+ Details

Condensed Consolidated Statements of Operations and Comprehensive Loss (unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Operating expenses:
Research and development	$ 15,964	$ 14,008	$ 46,674	$ 41,828
General and administrative	7,328	5,140	22,196	15,813
Total operating expenses	23,292	19,148	68,870	57,641
Loss from operations	(23,292)	(19,148)	(68,870)	(57,641)
Other income:
Other income, net	2,284	656	6,526	1,922
Total other income, net	2,284	656	6,526	1,922
Loss before provision for income taxes	(21,008)	(18,492)	(62,344)	(55,719)
Provision for income taxes	9	0	(38)	(27)
Net loss	(20,999)	(18,492)	(62,382)	(55,746)
Other comprehensive income
Unrealized gain on available-for-sale marketable securities	593	0	614	5
Foreign currency translation adjustments, net	(40)	0	(40)	0
Comprehensive loss	$ (20,446)	$ (18,492)	$ (61,808)	$ (55,741)
Net loss per share, basic	$ (2.26)	$ (65.08)	$ (7.11)	$ (200.94)
Net loss per share, diluted	$ (2.26)	$ (65.08)	$ (7.11)	$ (200.94)
Weighted-average shares used in computing net loss per share, basic	9,303,218	284,156	8,771,743	277,433
Weighted-average shares used in computing net loss per share, diluted	9,303,218	284,156	8,771,743	277,433

Common Stock - Schedule of Number of Shares Reserved for Future Issuance (Details) - shares	Sep. 30, 2024	Dec. 31, 2023
Common stock shares issued and sold	9,318,356	8,016,516
Total reserved for future issuance	2,103,622	1,675,396
Exercises of outstanding Shares	9,318,356	8,016,516
2023 Stock Incentive Plan
Common stock shares issued and sold	644,524	255,694
Employee Stock Purchase Plan
Common stock shares issued and sold	168,667	88,502
Outstanding Warrant [Member]
Exercises of outstanding Shares	8,049	8,049
Stock Options
Exercises of outstanding Shares	1,282,382	1,323,151

Commitments and Contingencies (Tables)

9 Months Ended

Sep. 30, 2024

Commitments and Contingencies Disclosure [Abstract]

Schedule of Future Minimum Rental Payments


	As of September 30, 2024
2024	$	(1,776	)
2025		6,247
2026		7,341
2027		7,557
Thereafter		52,498
Total Future Minimum Leases Payments		71,867
Less: Interest		(30,082	)
Present Value of Operating Lease Liabilities	$	41,785

Schedule of Lease Costs

The following table summarizes the effect of lease costs in the Company’s condensed consolidated statement of operations and comprehensive loss of its operating leases (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
Operating lease costs	$	1,939	$	1,892	$	6,197	$	3,794
Variable lease costs		471		253		1,295		742
Short-term lease costs		257		182		919		541
Total lease costs	$	2,667	$	2,327	$	8,411	$	5,077

Fair Value Measurements - Schedule of Financial Assets Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	$ 105,905	$ 0
Fair Value Measurements Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	169,924	160,154
Total financial liabilities	1,276	1,448
Fair Value, Inputs, Level 1 [Member] \| Fair Value Measurements Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	62,743	158,706
Total financial liabilities	0	0
Fair Value, Inputs, Level 2 [Member] \| Fair Value Measurements Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	105,905	0
Total financial liabilities	0	0
Fair Value, Inputs, Level 3 [Member] \| Fair Value Measurements Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	1,276	1,448
Total financial liabilities	1,276	1,448
Money Market Funds [Member] \| Fair Value Measurements Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	62,743	158,706
Money Market Funds [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value Measurements Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	62,743	158,706
Money Market Funds [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value Measurements Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0	0
Money Market Funds [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value Measurements Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0	0
MS APA Asset [Member] \| Fair Value Measurements Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	1,276	1,448
MS APA Asset [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value Measurements Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0	0
MS APA Asset [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value Measurements Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0	0
MS APA Asset [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value Measurements Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	1,276	1,448
U.S. treasury bills [Member] \| Fair Value Measurements Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	48,729
U.S. treasury bills [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value Measurements Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0
U.S. treasury bills [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value Measurements Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	48,729
U.S. treasury bills [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value Measurements Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0
U.S. Government Agency Securities [Member] \| Fair Value Measurements Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	57,176
U.S. Government Agency Securities [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value Measurements Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0
U.S. Government Agency Securities [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value Measurements Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	57,176
U.S. Government Agency Securities [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value Measurements Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0
CVR liability [Member] \| Fair Value Measurements Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial liabilities	1,276	1,448
CVR liability [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value Measurements Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial liabilities		0
CVR liability [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value Measurements Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial liabilities		0
CVR liability [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value Measurements Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial liabilities	$ 1,276	$ 1,448

Stock-based Compensation (Additional Information) (Details) - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Weighted-average grant date fair value of stock options granted	$ 31.99	$ 13.87
Exercises in Period, Intrinsic Value	$ 1.4	$ 0.2
Total unrecognized stock-based compensation expense relating to unvested stock options	$ 12.0
Unrecognized unvested stock options, weighted-average period	3 years

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2024	Nov. 07, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Amendment Flag	false
Document Period End Date	Sep. 30, 2024
Document Fiscal Year Focus	2024
Current Fiscal Year End Date	--12-31
Document Fiscal Period Focus	Q3
Entity File Number	001-39062
Entity Registrant Name	Korro Bio, Inc.
Entity Central Index Key	0001703647
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	47-2324450
Entity Address, Address Line One	60 First Street
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	true
Entity Address, Address Line Two	2nd Floor
Entity Address, Address Line Three	Suite 250
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02141
City Area Code	617
Local Phone Number	468-1999
Title of 12(b) Security	Common Stock, par value $0.001 per share
Trading Symbol	KRRO
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Document Transition Report	false
Entity Small Business	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		9,368,262

Collaboration Agreements

9 Months Ended

Sep. 30, 2024

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Collaboration Agreements

11. Collaboration Agreements

Genevant Agreement

In March 2023, Legacy Korro entered into a collaboration and license agreement (the “Genevant Agreement”) with Genevant Sciences GmbH (“Genevant”). Key financial terms under the Genevant Agreement are as follows:

•

The Company made a $2.5 million payment to Genevant in March 2023 upon execution of the Genevant Agreement and recorded the payment within research and development expense in the consolidated statement of operations for the year ended December 31, 2023.

•

The Company will reimburse Genevant for certain out-of-pocket and full-time equivalent costs incurred as a result of research and development activities performed under the Genevant Agreement.

•

Genevant is entitled to receive payments from the Company upon the achievement of certain milestones, including potential clinical milestone payments of up to $13.5 million, potential regulatory and development milestone payments of up to $27.0 million, and potential commercial milestone payments up to an aggregate total of $57.0 million.

•

Genevant is eligible to receive royalties at percentage rates in the mid-single-digits, based on future annual net sales of licensed products within the scope of the Genevant Agreement.

As of September 30, 2024, one development milestone of $1.0 million has been achieved and the Company has recorded $2.7 million and $3.5 million within research and development expense in the condensed consolidated statement of operations during the nine months ended September 30, 2024 and 2023, respectively. The Company has recorded $0.3 million and $0.5 million within research and development expense in the condensed consolidated statement of operations during the three months ended September 30, 2024 and 2023, respectively.

Novo Nordisk Agreement

On September 13, 2024, the Company entered into a research collaboration and license agreement with Novo Nordisk A/S (“Novo Nordisk”), pursuant to which the Company granted Novo Nordisk an exclusive worldwide license under certain intellectual property rights to research, develop, manufacture, commercialize or otherwise exploit certain licensed compounds and licensed products for an initial target in the cardiometabolic field and for a second target (to be nominated by Novo Nordisk within a specified time period as set forth in the agreement).

Under the agreement, the Company has the potential to receive up to a total of $530.0 million plus tiered royalties and cost reimbursement for the Company's performance of research and development activities for two programs. Novo Nordisk agreed to pay the Company an upfront non-refundable fee of $10.0 million for the research program with respect to the initial target, and the Company is eligible to receive an additional $10.0 million upfront non-refundable fee for a second research program with respect to the second target (if nominated by Novo Nordisk). The Company is eligible to receive research and development and regulatory milestone payments of up to $115.0 million for the initial target and up to an additional $115.0 million for the second target (if applicable). The Company is eligible to receive commercial milestone payments of up to $140.0 million for the initial target and up to an additional $140.0 million for the second target (if applicable). In addition, Novo Nordisk agreed to pay the Company royalties for each potential licensed product developed under the agreement that are an escalating tiered, mid-single digit percentage of the annual net sales of such licensed product.

Subject to the terms of the agreement, the Company granted Novo Nordisk an exclusive, worldwide, royalty-bearing license, with the right to grant sublicenses, to use certain technology controlled by the Company for the purpose of researching, developing, manufacturing, commercializing or otherwise exploiting certain licensed compounds and licensed products that contain such licensed compounds, for all uses and indications, including prophylactic, diagnostic, therapeutic, curative, management, mitigation and preventative uses. During the term of the agreement and a two-year post-termination period and on a per target basis, the Company will not be permitted to research, develop, manufacture, commercialize, or otherwise exploit outside of the collaboration, any product targeting such target.

Under the agreement, the Company is responsible for certain research and development activities with respect to licensed compounds and licensed products directed against the initial target and the second target (if nominated by Novo Nordisk), and the Company is eligible to receive cost reimbursement from Novo Nordisk for its performance of such research and development activities under the agreement with respect to such target(s). Novo Nordisk may undertake subsequent worldwide development, manufacturing, marketing and commercialization of the licensed products directed against the initial target and the second target (if applicable).

Unless earlier terminated, the agreement has a term that continues, on a per licensed product and per country basis, until the later of (i) the expiration of the last valid patent claim controlled or invented by us that covers the composition of matter of such licensed product’s licensed compound in such country, and (ii) 10 years after the first reimbursed sale of such licensed product in such country. Novo Nordisk has the right to terminate the agreement without cause in its entirety or on a per research program or per licensed product basis. The agreement may also be terminated by either party based on an uncured material breach by the other party or the bankruptcy of the other party. Upon termination of the agreement due to Novo Nordisk’s actions, the license granted by the Company to Novo Nordisk to develop, manufacture, commercialize or otherwise exploit the licensed compounds and licensed products will automatically terminate with respect to the terminated research program or terminated licensed product, as applicable. Upon termination of the agreement due to the Company's actions, Novo Nordisk may choose to either have the license granted by the Company to Novo Nordisk to develop, manufacture, commercialize or otherwise exploit the licensed compounds and licensed products terminate or continue with respect to the terminated research program or terminated licensed product.

In October 2024, the Company received an upfront nonrefundable payment of $10.0 million from Novo Nordisk and expected to receive approximately $29.5 million in cost reimbursement through 2026 to fund the related research and development activities related to the first product candidate, or program target. The Company is entitled to an additional upfront nonrefundable payment from Novo Nordisk upon the selection of the second program target as well as related cost reimbursements.

Accrued Expenses and Other Current Liabilities

9 Months Ended

Sep. 30, 2024

Payables and Accruals [Abstract]

Accrued Expenses and Other Current Liabilities

7. Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities as of September 30, 2024 and December 31, 2023 were comprised as follows (in thousands):


	September 30, 2024		December 31, 2023
Employee compensation and benefits	$	3,063	$	7,896
External research and development services		1,287		1,255
CVR liability, current		558		395
Professional fees		365		219
Other operating expenses		186		447
Total accrued expenses and other current liabilities	$	5,459	$	10,212

Net Loss per Share

9 Months Ended

Sep. 30, 2024

Earnings Per Share [Abstract]

Net Loss per Share

14. Net Loss per Share

The following common stock equivalents have been excluded from the calculation of diluted net loss per share because their effect would be anti-dilutive:


	Nine Months Ended September 30,
	2024		2023
Legacy Korro Series Seed Preferred Stock		—		684,739
Legacy Korro Series A Preferred Stock		—		2,029,666
Legacy Korro Series B-1 Preferred Stock		—		1,104,178
Legacy Korro Series B-2 Preferred Stock		—		1,036,656
Unvested Legacy Korro restricted common stock		—		209
Outstanding Legacy Korro stock options		1,282,382		611,310
Outstanding Legacy Korro warrant		8,049		8,049
Total		1,290,431		5,474,807

Commitments and Contingencies - Schedule of Future Minimum Rental Payments (Details) $ in Thousands	Sep. 30, 2024 USD ($)
Lessee, Lease, Description [Line Items]
2024	$ (1,776)
2025	6,247
2026	7,341
2027	7,557
Thereafter	52,498
Total Future Minimum Leases Payments	71,867
Less: Interest	(30,082)
Present Value of Operating Lease Liabilities	$ 41,785

Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Operating Activities:
Net loss	$ (62,382)	$ (55,746)
Adjustments to reconcile net loss to net cash used in operating activities:
Non-cash lease expense	3,131	2,376
Stock-based compensation expense	3,105	1,154
Depreciation expense	2,312	2,645
Net amortization of premiums and discounts on marketable securities	(1,159)	(80)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(893)	(14)
Accounts payable	(736)	309
Accrued expenses and other current liabilities	(4,765)	1,730
Operating lease liabilities	8,578	1,313
Other non-current assets	230	137
Net cash used in operating activities	(52,579)	(46,176)
Investing Activities:
Purchases of marketable securities	(118,132)	0
Proceeds from maturities of marketable securities	14,000	19,000
Purchases of property and equipment	(16,450)	(6,181)
Net cash (used in) provided by investing activities	(120,582)	12,819
Financing Activities:
Proceeds from PIPE financing, net of issuance costs	67,384	0
Proceeds from exercises of stock options	1,039	349
Other financing activities, net	0	(2,634)
Net cash provided by financing activities	68,423	43,173
Effect of exchange rate changes on cash, cash equivalents and restricted cash	2	0
Net (decrease) increase in cash, cash equivalents and restricted cash	(104,738)	9,816
Cash, cash equivalents and restricted cash, beginning of period	173,119	41,477
Cash, cash equivalents and restricted cash, end of period	68,381	51,293
Non-cash investing and financing activities:
Property and equipment capitalized under tenant improvement allowance	7,583	2,138
Purchases of property and equipment in accounts payable and accrued expenses	1,401	167
Financing costs in accounts payable and accrued expenses	0	965
Operating lease liabilities arising from right-of-use assets	0	26,777
Supplemental cash flow information:
Cash paid for income taxes	47	27
Cash paid for operating lease liabilities	2,083	2,244
Series B-2 Preferred Stock [Member]
Financing Activities:
Proceeds from Series B-2 convertible preferred stock, net of issuance costs	$ 0	$ 45,458

Preferred Stock (Additional Information) (Details) - $ / shares	Sep. 30, 2024	Dec. 31, 2023	Nov. 03, 2023
Class of Stock [Line Items]
Preferred stock, shares issued	0	0
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, par value	$ 0.001	$ 0.001
Preferred Stock share Outstanding	0	0
Preferred Stock, Convertible, Conversion Ratio	4.9688%
Preferred Stock [Member]
Class of Stock [Line Items]
Percentage of outstanding shares of Preferred Stock	66.00%
Preferred Stock, Convertible, Conversion Ratio	4.9688%
Legacy Korro [Member] \| Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, Convertible, Conversion Ratio			4.9688%

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
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-Paragraph 13
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-14

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-18

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
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-Name Accounting Standards Codification
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-URI https://asc.fasb.org/1943274/2147481112/505-10-50-2

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
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-Section S99
-Paragraph 1
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-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-Section S99
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Commitments and Contingencies - Schedule of Lease Costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Operating lease costs	$ 1,939	$ 1,892	$ 6,197	$ 3,794
Variable lease costs	471	253	1,295	742
Short-term lease costs	257	182	919	541
Total lease costs	$ 2,667	$ 2,327	$ 8,411	$ 5,077

Property and Equipment, Net (Additional Information) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 2,312	$ 2,645

Reverse Merger (Additional Information) (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Business Combination, Asset Acquisition, and Joint Venture Formation [Abstract]
Cash and cash equivalents	$ 63,207	$ 166,150

Net Loss per Share (Tables)

9 Months Ended

Sep. 30, 2024

Earnings Per Share [Abstract]

Computation of Diluted Net Loss per Share

The following common stock equivalents have been excluded from the calculation of diluted net loss per share because their effect would be anti-dilutive:


	Nine Months Ended September 30,
	2024		2023
Legacy Korro Series Seed Preferred Stock		—		684,739
Legacy Korro Series A Preferred Stock		—		2,029,666
Legacy Korro Series B-1 Preferred Stock		—		1,104,178
Legacy Korro Series B-2 Preferred Stock		—		1,036,656
Unvested Legacy Korro restricted common stock		—		209
Outstanding Legacy Korro stock options		1,282,382		611,310
Outstanding Legacy Korro warrant		8,049		8,049
Total		1,290,431		5,474,807

Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 63,207	$ 166,150
Short-term marketable securities	73,790	0
Accounts receivable	10,000	0
Restricted cash	1,768	3,563
Prepaid expenses and other current assets	4,018	3,015
Total current assets	152,783	172,728
Property and equipment, net	29,111	15,665
Operating lease right-of-use assets	24,018	27,150
Restricted cash, net of current portion	3,406	3,406
Long-term marketable securities	32,115	0
Other non-current assets	2,110	2,714
Total assets	243,543	221,663
Current liabilities:
Accounts payable	5,950	7,280
Accrued expenses and other current liabilities	5,459	10,212
Operating lease liabilities, current portion	0	1,991
Deferred revenue, current portion	2,201	0
Total current liabilities	13,610	19,483
Operating lease liabilities, net of current portion	41,785	31,216
Deferred revenue, net of current portion	7,799	0
Other non-current liabilities	717	1,053
Total liabilities	63,911	51,752
Commitments and contingencies (Note 12)
Stockholders' equity
Preferred stock, $0.001 par value; 10,000,000 shares authorized at September 30, 2024 and December 31, 2023; no shares issued and outstanding at September 30, 2024 and December 31, 2023	0	0
Common stock, $0.001 par value; 200,000,000 shares authorized at September 30, 2024 and December 31, 2023; 9,318,356 shares and 8,016,516 shares issued and outstanding at September 30, 2024 and December 31, 2023, respectively	9	8
Additional paid-in capital	424,436	352,908
Accumulated other comprehensive income	574	0
Accumulated deficit	(245,387)	(183,005)
Total stockholders' equity	179,632	169,911
Total liabilities and stockholders' equity	$ 243,543	$ 221,663

Restricted Cash (Additional Information) (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Cash and Cash Equivalents [Abstract]
Restricted Cash, Current	$ 1,768	$ 3,563
Restricted Cash, Noncurrent	$ 3,400	$ 3,400

Fair Value Measurements (Additional Information) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Tranfer of assets among fair value hierarchy levels	$ 0	$ 0
Prepaid Expense and Other Assets, Current	4,018	3,015
Other non-current liabilities	$ 717	1,053
MS APA Asset [Member]
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Liabilities
Derivative Liability	$ 1,300	1,400
Other current liabilities	600	400
Initial Consideration Amount	$ 500
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Assets
Derivative Asset	$ 1,300	1,400
Other Assets, Current	700	1,000
Prepaid Expense and Other Assets, Current	600	400
Other non-current liabilities	700	1,000
Maximum [Member] \| MS APA Asset [Member]
Future Milestone Payments	17,500
Minimum [Member] \| MS APA Asset [Member]
Future Milestone Payments	700
Fair Value, Inputs, Level 3 [Member] \| MS APA Asset [Member]
Change in fair value of CVR liability	$ 100	$ 100

Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Payables and Accruals [Abstract]
Employee compensation and benefits	$ 3,063	$ 7,896
External research and development services	1,287	1,255
CVR liability, current	558	395
Professional fees	365	219
Other operating expenses	186	447
Total accrued expenses and other current liabilities	$ 5,459	$ 10,212

Marketable Securities

9 Months Ended

Sep. 30, 2024

Marketable Securities [Abstract]

Marketable Securities

4. Marketable Securities

Marketable securities were comprised as follows (in thousands):


	Maturities	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value

U.S. treasury bills	Within 1 year	$	48,649	$	80	$	—	$	48,729
U.S. government agency securities	Within 1 year		24,911		150		—		25,061
U.S. government agency securities	Between 1 to 2 years		31,731		384		—		32,115
Total		$	105,291	$	614	$	—	$	105,905

The amortized cost of available-for-sale securities is adjusted for amortization of premiums and accretion of discounts to maturity. There were no realized gains or losses on available-for-sale securities for the periods presented. None of the investments were in an unrealized loss position for greater than 12 months as of September 30, 2024. The unrealized losses on the Company's available-for-sale securities were caused by the impact of central bank and market interest rates on the investments held. The Company does not intend to sell the investments, and it is not more likely than not that the Company will be required to sell the investments before recovery of their amortized cost bases. After analyzing the securities in an unrealized loss position, the portion of these losses that relates to changes in credit quality is insignificant. The Company did not record an allowance for credit losses as of September 30, 2024. Furthermore, the Company does not believe that these securities expose the Company to undue market risk or counterparty credit risk.

The Company did not hold any available-for-sale securities as of December 31, 2023.

Stock-based Compensation - Summary of Stock Option Weighted-Average Assumptions (Details)	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Share-Based Payment Arrangement [Abstract]
Risk-free interest rate	4.10%	3.60%
Expected dividend yield	0.00%	0.00%
Expected term (in years)	6 years	6 years
Expected volatility	74.60%	69.50%

Commitments and Contingencies (Additional Information) (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2024 USD ($) ft²	Dec. 31, 2023 USD ($)	May 31, 2023 USD ($)
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets	$ 24,018	$ 27,150
Operating lease liability	41,785
Lease rental payments	$ 71,867
Weighted average remaining lease term	9 years 7 months 6 days
Weighted average remaining lease discount rate	11.20%
OKS Facility [Member]
Lessee, Lease, Description [Line Items]
Lease area of land \| ft²	22,561
Lease expiration date	Oct. 20, 2023
Cummings Park Sublease [Member]
Lessee, Lease, Description [Line Items]
Lease area of land \| ft²	18,148
Lease expiration date	Jul. 31, 2024
60 First Street Lease [Member]
Lessee, Lease, Description [Line Items]
Lease remaining terms	10 years
Lease area of land \| ft²	50,453
Operating lease liability			$ 26,800
Lease rental payments			62,100
Lessee, Operating Lease, Remaining Lease Term	10 years
Tenant improvement allowance	$ 13,100		$ 13,100
Tenant improvement allowance utilized	9,800
Future minimum lease payments receivable	$ 3,300

Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2024

Marketable Securities [Abstract]

Summary of Marketable securities

Marketable securities were comprised as follows (in thousands):


	Maturities	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value

U.S. treasury bills	Within 1 year	$	48,649	$	80	$	—	$	48,729
U.S. government agency securities	Within 1 year		24,911		150		—		25,061
U.S. government agency securities	Between 1 to 2 years		31,731		384		—		32,115
Total		$	105,291	$	614	$	—	$	105,905

Marketable Securities - Summary of Marketable Securities (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Marketable Securities [Line Items]
AmortizedCost	$ 105,291
Unrealized Gains	614
Unrealized Losses	0
Fair Value	105,905	$ 0
U.S. treasury bills [Member] \| Within 1 year [Member]
Marketable Securities [Line Items]
AmortizedCost	48,649
Unrealized Gains	80
Unrealized Losses	0
Fair Value	48,729
U.S. government agency securities [Member] \| Within 1 year [Member]
Marketable Securities [Line Items]
AmortizedCost	24,911
Unrealized Gains	150
Unrealized Losses	0
Fair Value	25,061
U.S. government agency securities [Member] \| Between 1 to 2 years [Member]
Marketable Securities [Line Items]
AmortizedCost	31,731
Unrealized Gains	384
Unrealized Losses	0
Fair Value	$ 32,115

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

+ Details

Marketable Securities (Additional Information) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Marketable Securities [Abstract]
Realized gains or losses	$ 0
Unrealized loss position for greater than 12 months	0
Allowance for credit losses	0
Available for sale securities	$ 105,905	$ 0

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

+ Details

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ (20,999)	$ (21,826)	$ (19,557)	$ (18,492)	$ (17,649)	$ (19,605)	$ (62,382)	$ (55,746)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-6

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
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-Name Accounting Standards Codification
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-URI https://asc.fasb.org/1943274/2147483443/250-10-50-9

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Publisher FASB
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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-Section 45
-Paragraph 1A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482790/220-10-45-1A

Reference 36: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1B
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482790/220-10-45-1B

Reference 37: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(22))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478524/942-220-S99-1

+ Details

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2024

Fair Value Disclosures [Abstract]

Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis

Assets and liabilities measured at fair value on a recurring basis as of September 30, 2024 were as follows (in thousands):


	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Financial assets
Cash equivalents:
Money market funds	$	62,743	$	62,743	$	—	$	—
Marketable securities
U.S. treasury bills		48,729		—		48,729		—
U.S. government agency securities		57,176		—		57,176		—
MS APA asset		1,276		—		—		1,276
Total financial assets	$	169,924	$	62,743	$	105,905	$	1,276

Financial liabilities
CVR liability	$	1,276	$	—	$	—	$	1,276
Total financial liabilities	$	1,276	$	—	$	—	$	1,276

Assets and liabilities measured at fair value on a recurring basis as of December 31, 2023 were as follows (in thousands):


	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Financial assets:
Money market funds, included in cash and cash equivalents	$	158,706	$	158,706	$	—	$	—
MS APA asset		1,448		—		—		1,448
Total financial assets	$	160,154	$	158,706	$	—	$	1,448

Financial liabilities:
CVR liability	$	1,448	$	—	$	—	$	1,448
Total financial liabilities	$	1,448	$	—	$	—	$	1,448

Stock-based Compensation

9 Months Ended

Sep. 30, 2024

Share-Based Payment Arrangement [Abstract]

Stock-based Compensation

10. Stock-based Compensation

The Company grants stock-based awards under its 2023 Stock Option and Incentive Plan (the "2023 Plan"), which was approved by the Company’s stockholders in November 2023 and became effective in November 2023 in connection with completion of the Merger. The Company also has outstanding stock option awards under the "Legacy Korro 2019 Plan", the Frequency 2014 Stock Incentive Plan (the "2014 Plan"), the 2019 Incentive Award Plan (the "Frequency 2019 Plan"), but is no longer granting awards under these plans. The Company also has the option to grant awards under the 2023 Employee Stock Purchase Plan (the "2023 ESPP"), which was approved by the Company’s stockholders in November 2023 and became effective in November 2023 in connection with completion of the Merger.

Stock-based Compensation Expense


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
Research and development	$	418	$	157	$	1,031	$	403
General and administrative		855		247		2,074		751
Total stock-based compensation expense	$	1,273	$	404	$	3,105	$	1,154

Stock Option Activity

The fair value of stock options granted during the nine months ended September 30, 2024 and 2023 was calculated on the date of grant using the following weighted-average assumptions:


	Nine Months Ended September 30,
	2024			2023
Risk-free interest rate		4.1	%		3.6	%
Expected dividend yield		—	%		—	%
Expected term (in years)		6.0			6.0
Expected volatility		74.6	%		69.5	%

Using the Black-Scholes option pricing model, the weighted-average grant date fair value of stock options granted during the nine months ended September 30, 2024 and 2023 was $31.99 and $13.87 per share, respectively.

The following table summarizes changes in stock option activity during the nine months ended September 30, 2024 (in thousands, except per share amounts):


	Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value
Outstanding at December 31, 2023		1,323,151		$	23.49		8.4	$	36,310
Granted		214,107		$	46.78
Exercised		(52,765	)	$	18.92
Forfeited		(149,953	)	$	18.26
Cancelled		(52,158	)	$	116.61
Outstanding as of September 30, 2024		1,282,382		$	24.39		8.2	$	18,095
Exercisable at September 30, 2024		508,595		$	22.90		6.7	$	8,795

The aggregate intrinsic value of options is calculated as the difference between the exercise price of the stock options and the fair value of the Company’s common stock for those stock options that had exercise prices lower than the fair value of the common stock as of the end of the period. The aggregate intrinsic value of stock options exercised during the nine months ended September 30, 2024 and 2023 was $1.4 million and $0.2 million, respectively.

As of September 30, 2024, there was unrecognized stock-based compensation expense related to unvested stock options of $12.0 million, which the Company expects to recognize over a weighted-average period of approximately 3.0 years.

Accrued Expenses and Other Current Liabilities (Tables)

9 Months Ended

Sep. 30, 2024

Payables and Accruals [Abstract]

Schedule of Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities as of September 30, 2024 and December 31, 2023 were comprised as follows (in thousands):


	September 30, 2024		December 31, 2023
Employee compensation and benefits	$	3,063	$	7,896
External research and development services		1,287		1,255
CVR liability, current		558		395
Professional fees		365		219
Other operating expenses		186		447
Total accrued expenses and other current liabilities	$	5,459	$	10,212

Condensed Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (unaudited) - USD ($) $ in Thousands	Total	Series Seed Convertible Preferred Stock [Member]	Series A Convertible Preferred Stock [Member]	Series B-1 Convertible Preferred Stock [Member]	Series B-2 Convertible Preferred Stock [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]
Temporary equity, beginning balance (in share) at Dec. 31, 2022		684,739	2,029,666	1,104,178	223,417
Temporary equity, beginning balance at Dec. 31, 2022		$ 15,924	$ 77,736	$ 57,703	$ 12,500
Beginning balance (in share) at Dec. 31, 2022						268,399
Beginning balance at Dec. 31, 2022	$ (99,031)						$ 2,807	$ (5)	$ (101,833)
Issuance of common stock for services rendered (in share)						292
Issuance of common stock for services rendered	6						6
Exercises of stock options (in shares)						4,332
Exercises of stock options	51						51
Vesting of restricted common stock (in share)						1,437
Stock-based compensation expense	343						343
Issuance of Series B-2 convertible preferred stock, net of issuance costs (in share)					813,239
Issuance of Series B-2 convertible preferred stock, net of issuance costs					$ 45,458
Other comprehensive income	5							5
Net Income (Loss)	(19,605)								(19,605)
Ending balance (in share) at Mar. 31, 2023						274,460
Ending balance at Mar. 31, 2023	(118,231)						3,207		(121,438)
Temporary equity, ending balance (in share) at Mar. 31, 2023		684,739	2,029,666	1,104,178	1,036,656
Temporary equity, ending balance at Mar. 31, 2023		$ 15,924	$ 77,736	$ 57,703	$ 57,958
Temporary equity, beginning balance (in share) at Dec. 31, 2022		684,739	2,029,666	1,104,178	223,417
Temporary equity, beginning balance at Dec. 31, 2022		$ 15,924	$ 77,736	$ 57,703	$ 12,500
Beginning balance (in share) at Dec. 31, 2022						268,399
Beginning balance at Dec. 31, 2022	(99,031)						2,807	(5)	(101,833)
Net Income (Loss)	(55,746)
Ending balance (in share) at Sep. 30, 2023						298,153
Ending balance at Sep. 30, 2023	(153,257)						4,322		(157,579)
Temporary equity, ending balance (in share) at Sep. 30, 2023		684,739	2,029,666	1,104,178	1,036,656
Temporary equity, ending balance at Sep. 30, 2023		$ 15,924	$ 77,736	$ 57,703	$ 57,958
Temporary equity, beginning balance (in share) at Mar. 31, 2023		684,739	2,029,666	1,104,178	1,036,656
Temporary equity, beginning balance at Mar. 31, 2023		$ 15,924	$ 77,736	$ 57,703	$ 57,958
Beginning balance (in share) at Mar. 31, 2023						274,460
Beginning balance at Mar. 31, 2023	(118,231)						3,207		(121,438)
Exercises of stock options (in shares)						5,347
Exercises of stock options	82						82
Vesting of restricted common stock (in share)						628
Stock-based compensation expense	401						401
Net Income (Loss)	(17,649)								(17,649)
Ending balance (in share) at Jun. 30, 2023						280,435
Ending balance at Jun. 30, 2023	(135,397)						3,690		(139,087)
Temporary equity, ending balance (in share) at Jun. 30, 2023		684,739	2,029,666	1,104,178	1,036,656
Temporary equity, ending balance at Jun. 30, 2023		$ 15,924	$ 77,736	$ 57,703	$ 57,958
Exercises of stock options (in shares)						17,090
Exercises of stock options	228						228
Vesting of restricted common stock (in share)						628
Stock-based compensation expense	404						404
Net Income (Loss)	(18,492)								(18,492)
Ending balance (in share) at Sep. 30, 2023						298,153
Ending balance at Sep. 30, 2023	$ (153,257)						4,322		(157,579)
Temporary equity, ending balance (in share) at Sep. 30, 2023		684,739	2,029,666	1,104,178	1,036,656
Temporary equity, ending balance at Sep. 30, 2023		$ 15,924	$ 77,736	$ 57,703	$ 57,958
Temporary equity, beginning balance (in share) at Dec. 31, 2023		0	0	0	0
Temporary equity, beginning balance at Dec. 31, 2023		$ 0	$ 0	$ 0	$ 0
Beginning balance (in share) at Dec. 31, 2023	8,016,516					8,016,516
Beginning balance at Dec. 31, 2023	$ 169,911					$ 8	352,908	0	(183,005)
Exercises of stock options (in shares)						5,947
Exercises of stock options	139						139
Stock-based compensation expense	865						865
Net Income (Loss)	(19,557)								(19,557)
Ending balance (in share) at Mar. 31, 2024						8,022,463
Ending balance at Mar. 31, 2024	$ 151,358					$ 8	353,912	0	(202,562)
Temporary equity, beginning balance (in share) at Dec. 31, 2023		0	0	0	0
Temporary equity, beginning balance at Dec. 31, 2023		$ 0	$ 0	$ 0	$ 0
Beginning balance (in share) at Dec. 31, 2023	8,016,516					8,016,516
Beginning balance at Dec. 31, 2023	$ 169,911					$ 8	352,908	0	(183,005)
Exercises of stock options (in shares)	52,765
Net Income (Loss)	$ (62,382)
Ending balance (in share) at Sep. 30, 2024	9,318,356					9,318,356
Ending balance at Sep. 30, 2024	$ 179,632					$ 9	424,436	574
Beginning balance (in share) at Mar. 31, 2024						8,022,463
Beginning balance at Mar. 31, 2024	151,358					$ 8	353,912	0	(202,562)
Exercises of stock options (in shares)						8,191
Exercises of stock options	172						172
Stock-based compensation expense	967						967
Issuance of common stock for cash in PIPE financing (in share)						1,249,283
Issuance of common stock for cash in PIPE financing	67,385					$ 1	67,384
Other comprehensive income	21							21
Net Income (Loss)	(21,826)								(21,826)
Ending balance (in share) at Jun. 30, 2024						9,279,937
Ending balance at Jun. 30, 2024	198,077					$ 9	422,435	21	(224,388)
Exercises of stock options (in shares)						38,419
Exercises of stock options	728						728
Stock-based compensation expense	1,273						1,273
Other comprehensive income	553							553
Net Income (Loss)	$ (20,999)								$ (20,999)
Ending balance (in share) at Sep. 30, 2024	9,318,356					9,318,356
Ending balance at Sep. 30, 2024	$ 179,632					$ 9	$ 424,436	$ 574

The Company and Liquidity

9 Months Ended

Sep. 30, 2024

Organization, Consolidation and Presentation of Financial Statements [Abstract]

The Company and Liquidity

1. The Company and Liquidity

Nature of Business

Korro Bio, Inc. (together with its subsidiaries, the “Company”) is a biopharmaceutical company with a mission to discover, develop and commercialize a new class of genetic medicines based on editing RNA, enabling the treatment of both rare and highly prevalent diseases. The Company was incorporated in November 2014 as a Delaware corporation. The Company's principal offices are in Cambridge, Massachusetts.

Risks and Uncertainties

The Company is subject to risks common to companies in the biotechnology industry including, but not limited to, new technological innovations, protection of proprietary technology, dependence on key personnel, compliance with government regulations and the need to obtain additional financing. Product candidates currently under development will require significant additional research and development efforts, including extensive pre-clinical and clinical testing and regulatory approval, prior to commercialization. These efforts will require significant amounts of additional capital, adequate personnel infrastructure and extensive compliance-reporting capabilities. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will realize revenue from product sales.

Reverse Merger with Legacy Korro

On July 14, 2023, Frequency Merger Sub, Inc. (“Merger Sub”) a Delaware corporation, a wholly-owned subsidiary of Frequency Therapeutics, Inc. (“Frequency”), a Delaware corporation and Korro Bio Ops, Inc (“Legacy Korro”), a Delaware corporation, entered into an Agreement and Plan of Merger (the “Merger Agreement”). The merger was completed on November 3, 2023 (the “Merger” or the "Transaction"). In accordance with the Merger Agreement, the Merger Sub merged with and into Legacy Korro, with Legacy Korro surviving as a wholly-owned subsidiary of the Company. In connection with the completion of the Merger, the Company changed its name from Frequency Therapeutics, Inc. to Korro Bio, Inc. On November 6, 2023, the combined company’s common stock began trading on The Nasdaq Capital Market under the ticker symbol “KRRO”.

Except as otherwise indicated, references herein to the “Company,” or the “combined company”, refer to Korro Bio, Inc. on a post-merger basis, and the term “Legacy Korro” refers to the business of privately held Korro Bio Ops, Inc., (formerly known as Korro Bio, Inc.), prior to completion of the Merger. References to Frequency refer to Frequency Therapeutics, Inc. prior to completion of the Merger.

Concurrently with the execution and delivery of the Merger Agreement, Legacy Korro entered into a subscription agreement with a number of accredited investors. Immediately prior to consummation of the Merger, Legacy Korro issued and sold an aggregate of 42,176,255 shares of its common stock at a purchase price of approximately $2.78 per share, for an aggregate purchase price of approximately $117.3 million (the “Pre-Closing Financing”). Shares of Legacy Korro common stock issued pursuant to the Pre-Closing Financing were converted into shares of the Company’s common stock based on an exchange ratio (as defined below).

Pursuant to the terms of the Merger Agreement, immediately prior to the effective time of the Merger, each share of Legacy Korro preferred stock was converted into a share of Legacy Korro common stock, and then exchanged in the Merger for shares of Frequency common stock using an exchange ratio of 0.049688 (the “Exchange Ratio”).

At the effective time of the Merger, the Company issued (or reserved for issuance upon exercise of options assumed in the Merger) an aggregate of approximately 7,848,776 shares of its common stock to Legacy Korro securityholders (before eliminating fractions), calculated as provided in the Merger Agreement, (the “Exchange”), resulting in approximately 8,623,645 shares of its common stock being issued and outstanding on a fully diluted basis immediately following the effective time of the Merger. This number includes shares of the Company’s common stock that was issued upon vesting and settlement of certain outstanding equity awards at the effective time of the Merger. Immediately following the completion of the Merger, Frequency securityholders prior to the Merger owned approximately 9% of the outstanding shares of common stock on a fully diluted basis and Legacy Korro’s securityholders, including those securityholders who purchased shares in the Pre-Closing Financing, owned approximately 91% of the outstanding shares on a fully diluted basis. The Merger was intended to qualify for federal income tax purposes as a tax-free reorganization under the provisions of Section 368(a) of the Internal Revenue Code of 1986, as amended (the "IRC").

Upon closing of the Merger, the Company assumed the Legacy Korro 2019 Stock Incentive Plan (the “Legacy Korro 2019 Plan”), and each outstanding and unexercised option to purchase Legacy Korro shares at such time, each of which converted into an

option to purchase shares of the Company’s common stock, with necessary adjustments to the number of shares and exercise price to reflect the Exchange Ratio. In addition, upon the closing of the Merger, the Company assumed each outstanding and unexercised warrant to purchase Legacy Korro shares at such time, each of which converted into a warrant to purchase shares of the Company’s common stock, with necessary adjustments to the number of shares and exercise price to reflect the Exchange Ratio.

At the effective time of the Merger, the Company entered into a contingent value rights agreement (the “CVR Agreement”) with Computershare Trust Company, N.A. and Computershare Inc., collectively as rights agent providing for the payment of certain contingent cash payments equal to the net amount (calculated in accordance with GAAP consistently applied) of proceeds actually received by the Company or its subsidiaries after the end of each fiscal quarter following the first anniversary of the closing of the Transaction related to the disposition of assets related to Frequency’s former multiple sclerosis programs, with the time periods and subject to deductions as provided therein. Concurrently, the Company entered into an asset purchase agreement with Progentos Therapeutics (“Progentos”), whereby Progentos acquired the rights, title and interest in certain assets related to Freqeuncy’s MS program ("MS APA"). The MS APA included initial consideration of $0.5 million in proceeds that were settled through net cash at the Merger closing and will be entitled to future milestone payments of up to $17.5 million as well as a $0.7 million payment in the event of Progentos closing of an equity financing at or above a specified amount.

The Merger was accounted for as a reverse recapitalization in accordance with U.S. GAAP. For accounting purposes, Legacy Korro was considered to be acquiring the assets and liabilities of Frequency in the Merger based on the terms of the Merger Agreement and other factors, including: (i) Legacy Korro controlling the majority of outstanding voting shares; (ii) Legacy Korro controlling the Board of Directors; (iii) Legacy Korro’s executive management team became the management of the combined company; and (iv) the pre-combination assets of Frequency were primarily cash and cash equivalents and other non-operating assets. Accordingly, the Merger was treated as the equivalent of Legacy Korro issuing stock to acquire the net assets of Frequency. As a result of Legacy Korro being treated as the accounting acquirer, Legacy Korro’s assets and liabilities were recorded at their pre-combination carrying amounts. Frequency’s assets and liabilities were measured and recognized at their fair values, which approximated their carrying values as of the effective date of the Merger, and combined with the assets, liabilities, and results of operations of Legacy Korro after the consummation of the Merger. As a result, upon consummation the historical financial statements of Legacy Korro became the historical consolidated financial statements of the combined company.

Reverse Stock Split and Exchange Ratio

In connection with, and prior to the completion of, the Merger, Frequency effected a 1-for-50 reverse stock split of its then outstanding common stock (the “Reverse Stock Split”). The par value and the authorized shares of the common stock were not adjusted as a result of the Reverse Stock Split. All issued and outstanding Legacy Korro common stock, convertible preferred stock and options prior to the effective date of the Merger have been retroactively adjusted to reflect the Merger 0.049688 Exchange Ratio, which reflects the impact of the reverse stock split, for all periods presented.

Liquidity and Capital Resources

The Company’s consolidated financial statements have been prepared on the basis of the Company continuing as a going concern. The Company expects that its existing cash, cash equivalents and marketable securities as of September 30, 2024 of $169.1 million will enable the Company to fund its planned operating expense and capital expenditure requirements for at least 12 months from the date of issuance of these consolidated financial statements. The Company has incurred recurring losses and negative cash flows from operations since inception. As of September 30, 2024, the Company had an accumulated deficit of $245.4 million. The Company expects its operating losses and negative operating cash flows to continue into the foreseeable future. The future viability of the Company is dependent on its ability to generate cash from operating activities or to raise additional capital to finance its operations. There can be no assurance that the Company will ever earn revenues or achieve profitability, or if achieved, that the revenues or profitability will be sustained on a continuing basis. In addition, the Company’s preclinical and clinical development activities, manufacturing and commercialization of the Company’s product candidates, if approved, will require significant additional financing. However, if the Company is unable to obtain additional financing, the Company would be forced to delay, reduce or eliminate its research and development programs and/or relinquish valuable rights to its technology and product candidates. There is no assurance that the Company will be successful in obtaining sufficient financing on acceptable terms to continue funding its operations.

Common Stock

9 Months Ended

Sep. 30, 2024

Equity [Abstract]

Common Stock

8. Common Stock

At the closing of the Merger, the shares of Legacy Korro common stock were converted into shares of the Company's common stock based on the exchange ratio determined in the Merger Agreement.

As of September 30, 2024, the Company was authorized to issue 200,000,000 shares of common stock, $0.001 per value per share. Prior to the Merger, the holders of Legacy Korro’s common stock were subject to and qualified by the rights, powers and preferences of the holders of the Preferred Stock. Holders of common stock are entitled to one vote per share. In addition, holders of common stock are entitled to receive dividends, if and when declared by the Company’s Board of Directors. As of September 30, 2024, no dividends had been declared.

As of September 30, 2024 and December 31, 2023, the Company had reserved for future issuance the following number of shares of common stock:


	September 30, 2024		December 31, 2023
Exercises of outstanding stock options		1,282,382		1,323,151
Exercise of outstanding warrant		8,049		8,049
Future issuances under 2023 Stock Incentive Plan		644,524		255,694
Future issuances under 2023 ESPP Plan		168,667		88,502
Total reserved for future issuance		2,103,622		1,675,396

On April 17, 2024, the Company entered into a subscription agreement with certain new and existing accredited investors to issue and sell an aggregate of 1,249,283 shares of its common stock in a private placement ("PIPE") that resulted in gross proceeds of approximately $70.0 million, before deducting placement agent fees and offering expenses of approximately $2.6 million. The PIPE closed on April 22, 2024.

- Definition

The entire disclosure for equity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-14

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477968/946-235-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477968/946-235-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478448/946-505-50-6

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480237/815-40-50-6

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480008/505-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(e)(1))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org/505/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-14

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (c)
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+ Details

Basis of Presentation and Summary of Significant Accounting Policies

9 Months Ended

Sep. 30, 2024

Accounting Policies [Abstract]

Basis of Presentation and Summary of Significant Accounting Policies

2. Basis of Presentation and Summary of Significant Accounting Policies

Basis of Presentation and Consolidation

The accompanying consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”). These consolidated financial statements have been prepared on the going

concern basis of accounting, which assumes continuity of operations, realization of assets and satisfaction of liabilities in the ordinary course of business.

The consolidated financial statements include the accounts of Korro Bio, Inc. and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation.

Unaudited Interim Condensed Consolidated Financial Information

The accompanying condensed consolidated financial statements are unaudited. The financial data and other information contained in the notes hereto as of September 30, 2024 and for the three and nine month periods ended September 30, 2024 and 2023 are also unaudited. The condensed consolidated balance sheet data as of December 31, 2023 was derived from the Company's audited consolidated financial statements included in the Company's Annual Report on Form 10-K for the year ended December 31, 2023 (the “2023 Form 10-K”).

The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited annual consolidated financial statements, and in the opinion of management, reflect all adjustments, which include any normal recurring adjustments necessary for the fair presentation of the Company's interim period results. These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements as of and for the year ended December 31,2023, and the notes thereto, included in the Company's 2023 Form 10-K.

The results for the three and nine month periods ended September 30, 2024 are not necessarily indicative of results to be expected for the year ended December 31, 2024, or any other interim periods, or any future year or period.

Summary of Significant Accounting Policies

The significant accounting policies used in preparation of the condensed consolidated financial statements are described in the Company's audited consolidated financial statements as of the year end December 31, 2023, and the notes thereto, which are included in the 2023 Form 10-K. There have been no material changes to the significant accounting policies previously disclosed in the 2023 Form 10-K.

Segment Information

Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision-maker in deciding how to allocate resources and assess performance. The Company and the Company’s chief operating decision maker, the Company’s chief executive officer, views the Company’s operations and manages its business as a single operating segment. The Company operates only in the United States.

Use of Estimates

The preparation of the Company’s consolidated financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of expenses during the reporting period. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to the fair value of the common stock prior to the effective date of the Merger; the fair value of the contingent value rights ("CVR") liability and the incremental borrowing rate for determining lease liabilities and right-of-use assets. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it has concluded to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates as there are changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results may differ materially from those estimates or assumptions.

Recent Accounting Pronouncements—Yet to be Adopted

Other accounting standards that have been issued or proposed by the Financial Accounting Standards Board or other standards-setting bodies that do not require adoption until a future date are not expected to have a material impact on the Company’s consolidated financial statements upon adoption.

In November 2023, the ASU 2023-07, Segment Reporting (Topic 280), Improvements to Reportable Segment Disclosures, which is intended to provide enhanced segment disclosures. The standard will require disclosures about significant segment expenses and other segment items and identifying the Chief Operating Decision Maker and how they use the reported segment profitability

measures to assess segment performance and allocate resources. These enhanced disclosures are required for all public entities on an interim and annual basis, even if they have only a single reportable segment. The standard is effective for years beginning after December 15, 2023, and interim periods within annual periods beginning after December 15, 2024. Early adoption is permitted. The Company is evaluating this standard to determine if adoption will have a material impact on the Company's consolidated financial statements.