0001193125-23-277196 | 10-Q | XBRL Viewer

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Stock-Based Compensation - Summary of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 1,247	$ 3,041	$ 6,080	$ 8,084
Research and Development Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	40	1,742	1,856	4,722
General and Administrative Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 1,207	$ 1,299	$ 4,224	$ 3,362

Summary of Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2023

Summary Of Significant Accounting Policies [Abstract]

Basis of Presentation

The financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”).

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make judgments, assumptions, and estimates that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of financial statements, and the reported amounts of income and expense during the reporting period. The most significant estimates relate to the determination of the fair value of stock option grants and estimates related to the amount of prepaid and accrued research and development expenses as of the balance sheet date. Management evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors, including the current economic environment, and makes adjustments when the facts and circumstances dictate. These estimates are based on information available as of the date of the financial statements; therefore, actual results could differ from those estimates.

Cash and Cash Equivalents

The Company considers all highly liquid investments with an original maturity of three months or less at the date of purchase to be cash equivalents. As of September 30, 2023 and December 31, 2022, cash and cash equivalents consisted primarily of checking and savings deposits, money market fund holdings, and commercial paper.

Marketable Securities

The Company classifies its marketable securities as

available-for-sale

securities, which are carried at their fair value based on the quoted market prices of the securities. Unrealized gains and losses are reported as accumulated other comprehensive loss, a separate component of stockholders’ deficit. Realized gains and losses on

available-for-sale

securities are included in net loss in the period earned or incurred.

Property and Equipment

Property and equipment are stated at cost less accumulated depreciation. Depreciation expense is recognized using the straight-line method over the estimated useful life of each asset. Equipment and furniture and fixtures are depreciated over five or seven year lives. Leasehold improvements are amortized over the shorter of the lease term or the five-year estimated useful life of the asset. Computer equipment and computer software are depreciated over three years. Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is included in loss from operations. Expenditures for repairs and maintenance are expensed as in

rred.

Impairment of Long-Lived Assets

The Company evaluates its long-lived assets, which consist primarily of property and equipment, for impairment whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to the future undiscounted net cash flows expected to be generated by the asset. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the asset exceeds the fair value of the asset. During the three and nine months ended September 30, 2023, the Company recorded

non-cash

impairment charges of $0.2 million and $3.6 million, respectively. For additional disclosures regarding the $

3.6

million

non-cash

impairment charge and accompanying analysis, refer to Note 7. During the year three and nine months ended September 30, 2022, the company recorded

non-cash

impairment charges of

$0.2

million.

Concentration of Credit Risk

Financial instruments that potentially subject the Company to significant concentration of credit risk consist primarily of cash and cash equivalents. The Company’s investment policy includes guidelines regarding the quality of the financial institutions and financial instruments and defines allowable investments that it believes minimizes the exposure to concentration of credit risk. The Company may invest in money market funds (minimum of $1 billion in assets), U.S. Treasury securities, corporate debt, bank debt, U.S. government-related agency securities, other sovereign debt, municipal debt and commercial paper. These deposits may exceed federally insured limits. The Company has not experienced any losses historically in these accounts and believes that it is not exposed to significant credit risk as its deposits are held at financial institutions that management believes to be of high credit quality.

On March 10, 2023, Silicon Valley Bank (“SVB”) was closed by the California Department of Financial Protection and Innovation, and the Federal Deposit Insurance Corporation (“FDIC”) was appointed as receiver. On March 27, 2023, SVB was acquired by First-Citizen BancShares, Inc (“First-Citizen”). Similarly, on May 1, 2023, First Republic Bank (“FRB”) was closed by the California Department of Financial Protection and Innovation and the FDIC was appointed as receiver. JPMorgan Chase Bank, National Association (N.A.) acquired all of FRB’s deposit accounts and substantially all of its assets. The Company historically did not and currently does not have banking relationships with SVB or FRB.

Fair Value of Financial Instruments

Fair value is defined as the price that the Company would receive to sell an investment in a timely transaction or pay to transfer a liability in a timely transaction with an independent buyer in the principal market, or in the absence of a principal market, the most advantageous market for the investment or liability. A framework is used for measuring fair value utilizing a three-tier hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 investments) and the lowest priority to unobservable inputs (Level 3 investments).

The three levels of the fair value hierarchy are as follows:

•

Level

1 inputs:

Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities;

•

Level

2 inputs:

Quoted prices in markets that are not considered to be active or financial instrument valuations for which all significant inputs are observable, either directly or indirectly; and

•

Level

3 inputs

: Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable.

Financial instruments are categorized in their entirety based on the lowest level of input that is significant to the fair value measurement. The assessment of the significance of a particular input to the fair value measurement requires judgment and considers factors specific to the investment.

The Company’s money market funds and marketable securities are carried at fair value determined according to the fair value hierarchy described above (Level 1 and Level 2, respectively).

Research and Development Expenses

Research and development expenses include (i) employee-related expenses, including salaries, benefits, travel and stock-based compensation expense; (ii) external research and development expenses incurred under arrangements with third parties, such as contract research organization agreements, investigational sites, and consultants; (iii) the cost of acquiring, developing, and manufacturing clinical study materials; (iv) costs associated with preclinical and clinical activities and regulatory operations; (v) costs incurred in development of intellectual property; and (vi) an allocated portion of facilities and other infrastructure costs associated with research and development activities. Costs incurred in connection with research and development activities are expensed as incurred.

The Company enters into consulting, research, and other agreements with commercial entities, researchers, universities, and others for the provision of goods and services. Such arrangements are generally cancelable upon reasonable notice and payment of costs incurred. Costs are considered incurred based on an evaluation of the progress to completion of specific tasks under each contract using information and data provided by the respective vendors, including the Company’s clinical sites. These costs consist of direct and indirect costs associated with specific projects, as well as fees paid to various entities that perform certain research on behalf of the Company. Depending upon the timing of payments to the service providers, the Company recognizes prepaid expenses or accrued expenses related to these costs. These accrued or prepaid expenses are based on management’s estimates of the work performed under service agreements, milestones achieved, and experience with similar contracts. The Company monitors each of these factors and adjusts estimates accordingly.

Stock-Based Compensation

The Company measures all stock options and other stock-based awards granted to employees, nonemployees, and directors based on the fair value on the date of the grant and recognizes stock-based compensation expense of those awards over the requisite service period, which is generally the vesting period of the respective award. Generally, the Company issues stock option, restricted stock unit, and stock appreciation right awards with only service-based vesting conditions and records the expense for these awards using the straight-line method. The Company’s policy is to account for forfeitures when they occur.

The Company classifies stock-based compensation expense in its statement of operations in the same manner in which the award recipient’s payroll costs are classified or in which the award recipients’ service payments are classified.

The fair value of each stock option grant is estimated on the date of grant using the Black-Scholes option-pricing model. The Company recently completed its IPO and lacks company-specific historical and implied volatility information. Therefore, it estimates its expected stock volatility based on the historical volatility of a publicly traded set of peer companies and expects to continue to do so until it has adequate historical data regarding the volatility of its own traded stock price. The expected term of the Company’s stock options has been determined utilizing the “simplified” method for awards that qualify as “plain-vanilla” options. The expected term of stock options granted to

non-employees

is equal to the contractual term of the option award. The risk-free interest rate is determined by reference to the US Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Expected dividend yield is zero because

the Company has never paid cash dividends on common stock and did not expect to pay any cash dividends prior to completion of the Merger.

Prior to the Company’s IPO, the Company considered the estimated fair value of the common stock as of the measurement date in determining the exercise price for options granted. The estimated fair value of the common stock was determined at each grant date based upon a variety of factors, including the illiquid nature of the common stock,

arm’s-length

sales of the Company’s capital stock (including convertible preferred stock), the effect of the rights and preferences of the preferred shareholders, and the prospects of a liquidity event. Among other factors are the Company’s financial position and historical financial performance, forecasted future operations of the Company, an evaluation or benchmark of the Company’s competition, and the current business climate in the marketplace. Significant changes to the key assumptions underlying the factors used could result in different fair values of common stock at each valuation date. The fair value for options granted since the Company’s IPO are based on the closing stock price on grant date.

Income Taxes

The Company accounts for income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the financial statements or in the Company’s tax returns. Deferred tax assets and liabilities are determined on the basis of the differences between the financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. The Company assesses the likelihood that its deferred tax assets will be recovered from future taxable income and, to the extent it believes, based upon the weight of available evidence, that it is more likely than not that all or a portion of the deferred tax assets will not be realized, a valuation allowance is established through a charge to income tax expense. Potential for recovery of deferred tax assets is evaluated by estimating the future taxable profits expected and considering prudent and feasible tax planning strategies.

The Company accounts for uncertainty in income taxes recognized in the financial statements by applying a

two-step

process to determine the amount of tax benefit to be recognized. First, the tax position must be evaluated to determine the likelihood that it will be sustained upon external examination by the taxing authorities. If the tax position is deemed more likely than not to be sustained, the tax position is then assessed to determine the amount of benefit to recognize in the financial statements. The amount of the benefit that may be recognized is the largest amount that has a greater than 50% likelihood of being realized upon ultimate settlement. The provision for income taxes includes the effects of any resulting tax reserves, or unrecognized tax benefits, that are considered appropriate as well as the related net interest and penalties.

The Company provides reserves for potential payments of tax to various tax authorities related to uncertain tax positions. These reserves are based on a determination of whether and how much of a tax benefit taken by the Company in its tax filings or positions is more likely than not to be realized following resolution of any potential contingencies present related to the tax benefit. Potential interest and penalties associated with such uncertain tax positions are recorded as a component of income tax expense. The Company had no significant uncertain tax positions as of September 30, 2023 and December 31, 2022.

Basic and Diluted Net Loss Per Share

The Company calculates basic and diluted net loss per share using the

two-class

method. The

two-class

method requires income available to common stock as if all income for the period had been distributed. Accordingly, basic net loss per share is computed by dividing the net loss by the weighted average number of common shares outstanding during the period, without consideration of potential dilutive securities. Diluted net loss per share is computed by dividing the net loss by the sum of the weighted average number of common shares outstanding during the period plus the dilutive effects of potentially dilutive securities outstanding during the period. Potentially dilutive securities include vested and unexercised stock options, restricted stock issued upon early exercise of stock options, convertible preferred shares and contingent stock liabilities. The dilutive effect of stock options and contingent stock liabilities are computed using the treasury stock method and the dilutive effect of convertible preferred shares is calculated using the

if-converted

method. The Company has generated a net loss for all periods presented, therefore diluted net loss per share is the same as basic net loss per share since the inclusion of potentially dilutive securities would be anti-dilutive.

Segments

Operating segments are defined as components of an entity for which separate financial information is made available and is regularly evaluated by the chief operating decision maker (“CODM”) in making decisions regarding resource allocation and assessing performance. The Company’s CODM is the chief executive officer and operations are managed as a single segment for the purposes of assessing performance and making operating decisions.

Comprehensive Loss

Comprehensive loss represents net loss for the period plus the results of certain other changes in stockholders’ equity. The Company’s comprehensive loss included unrealized gains related to marketable securities for the nine months ended September 30, 2023 and 2022.

Recently Issued Accounting Pronouncements

In February 2016, the FASB issued ASU

No. 2016-02,

Leases (Topic 842), and subsequently has issued additional guidance (collectively, “ASC 842”), which requires companies to generally recognize operating and financing lease liabilities and corresponding

right-of-use

assets on the balance sheet. The Company adopted ASC 842 on January 1, 2022 using the modified retrospective approach, with no restatement of prior periods. Upon adoption, the Company elected the package of transitional practical expedients which allowed the Company to carry forward prior conclusions related to whether any expired or existing contracts are or contain leases, the lease classification for any expired or existing leases and initial direct costs for existing leases. In addition, the Company made an accounting policy election to not apply the recognition requirements in the leasing standards to short-term leases, which is a lease that at commencement date has a lease term of 12 months or less and does not contain a purchase option that it is reasonably certain to exercise.

As a result of the adoption of the new leasing standards, on January 1, 2022, the Company recorded

right-of-use

assets of $3.4 million and operating lease liabilities of $3.5

million. The adoption did not have a material impact on the statement of operations or the statement of cash flows.

Stock-Based Compensation - Summary of RSU Activity (Details) - Restricted Stock Units	9 Months Ended
	Sep. 30, 2023 $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Outstanding, Number of Restricted Stock Units / Stock Appreciation Rights \| shares	114,461
Granted, Number of Restricted Stock Units \| shares	141,900
Vested, Number of Restricted Stock Units \| shares	(76,482)
Forfeited, Number of Restricted Stock Units \| shares	(119,271)
Other, Number of Restricted Stock Units \| shares	(130)
Outstanding, Number of Restricted Stock Units / Stock Appreciation Rights \| shares	60,478
Outstanding, Weighted - Average Exercise Price per SAR \| $ / shares	$ 67.64
Granted, Weighted-Average Grant Date Fair Value \| $ / shares	17.3
Vested, Weighted-Average Grant Date Fair Value \| $ / shares	38.95
Forfeited, Weighted-Average Grant Date Fair Value \| $ / shares	38.92
Other, Weighted-Average Grant Date Fair Value \| $ / shares	55.1
Outstanding, Weighted - Average Exercise Price per SAR \| $ / shares	$ 42.39

Subsequent Events - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	Oct. 19, 2023	Oct. 06, 2023	Oct. 04, 2023	Sep. 30, 2023	Dec. 31, 2022
Subsequent Event [Line Items]
Common stock, shares issued				4,282,848	4,162,942
Stockholders' equity, reverse stock split	1-for-10
Common stock value				$ 0	$ 0
Common stock, shares outstanding				4,282,848	4,162,942
Subsequent Event
Subsequent Event [Line Items]
Payment of lease termination fees			$ 700
Payment of lease termination fees in cash			600
Payment of lease termination fees in non-cash			$ 100
Share based payment award purchase price of common stock percent in shares	55.00%
Share based payment award purchase price of common stock percent in cash	45.00%
Common stock, shares issued	176,835
Aggregate cash amount	$ 2,800
Subsequent Event \| Nonconsolidated Investees, Other
Subsequent Event [Line Items]
Percentage of ownership of common stock	21.90%
Subsequent Event \| ImmunoFree, Inc.
Subsequent Event [Line Items]
Payments for fees		$ 4,000
Subsequent Event \| Tourmaline
Subsequent Event [Line Items]
Common stock, dividends, per share, cash paid	$ 15.118
Special cash dividend	$ 64,700
Special cash dividend expects to declare	$ 67,500
Common stock, shares issued	20,336,741
Stockholders' equity, reverse stock split	1-for-10
Common stock value	$ 75,000
Common stock conversion basis	one
Common stock, shares outstanding	20,336,741
Common stock exchange ratio	0.7977
Stock Issued During Period, Shares, Acquisitions	15,877,090
Payments of Merger Related Costs, Financing Activities	$ 6,200
Subsequent Event \| Tourmaline \| Nonconsolidated Investees, Other
Subsequent Event [Line Items]
Percentage of ownership of common stock	78.10%

Restructuring Costs

9 Months Ended

Sep. 30, 2023

Restructuring and Related Activities [Abstract]

Restructuring Costs

8. Restructuring Costs

In February 2023, after a review of the Company’s business, programs, resources and capabilities, including anticipated costs and timelines, the Company announced the decision to discontinue its

FREEDOM-1

and

FREEDOM-2

clinical trials and to conduct a comprehensive review of strategic alternatives.

The Company announced a restructuring plan that resulted in the Initial Reduction in Force and the April Reduction in Force, which were substantially completed as of September 30, 2023. During the three and nine months ended September 30, 2023, the Company recorded restructuring costs of $0.1 million and $7.5 million, respectively, related to severance, employee termination, and retention costs.

Restructuring costs also included impairment expense of zero and $3.4 million for the three and nine months ended September 30, 2023, respectively (see Note 7).

The Company’s restructuring liability, which is included in accrued compensation and benefit costs (see Note 9), consisted of the following

(in thousands)


	Employee-Related Costs
	Three months ended September 30, 2023			Nine months ended September 30, 2023

Accrued restructuring balance at beginning of period	$	3,262		$	—
Expenses incurred		89			7,535
Payments		(1,993	)		(6,177	)

Accrued restructuring balance at September 30, 2023	$	1,358		$	1,358

Asset Sale - Additional Information (Details) - USD ($) $ in Thousands			3 Months Ended	9 Months Ended
	Sep. 29, 2023	Jul. 07, 2023	Sep. 30, 2023	Sep. 30, 2023	Sep. 30, 2022
Asset Retirement Obligation [Line Items]
Asset retirement obligation, liabilities settled		$ 200
Proceeds from sale of productive assets				$ 650	$ 0
Gain on Disposition of Assets			$ 538	$ 538	$ 0
ImmunoFree, Inc. \| Asset Purchase Agreement
Asset Retirement Obligation [Line Items]
Sale of clincial data and intellectual property		$ 500
New York Blood Center, Inc. \| Asset Purchase Agreement
Asset Retirement Obligation [Line Items]
Proceeds from sale of productive assets	$ 1,500

Net Loss Per Share Attributable to Common Stockholders - Summary of Potential Dilutive Securities Excluded From Calculation of Net Loss Per Share Due to Anti-dilutive Effect (Details) - shares	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive securities excluded from calculation of net loss per share due to anti-dilutive effect	599,659	759,791
Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive securities excluded from calculation of net loss per share due to anti-dilutive effect	533,900	623,298
Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive securities excluded from calculation of net loss per share due to anti-dilutive effect	60,478	112,701
Restricted Stock Related to Early Exercise of Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive securities excluded from calculation of net loss per share due to anti-dilutive effect	5,281	23,792
Stock Appreciation Rights
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive securities excluded from calculation of net loss per share due to anti-dilutive effect	100,000

Property and Equipment, Net and Assets Held for Sale

9 Months Ended

Sep. 30, 2023

Property, Plant and Equipment [Abstract]

Property and Equipment, Net and Assets Held for Sale

7. Property and Equipment, Net and Assets Held for Sale

Property and equipment, net consisted of the following

(in thousands)


	September 30,		December 31,
	2023		2022

Equipment	$	—	$	6,562
Leasehold improvements		—		1,191
Computer equipment		—		859
Furniture and fixtures		—		674
Construction in progress		—		242

Total property and equipment		—		9,528
Less accumulated depreciation		—		(4,180	)

Property and equipment, net	$	—	$	5,348

Depreciation expense was immaterial and $

0.5 million for the three and nine months ended September 30, 2023, respectively, and $0.4 and $1.0 million for the three and nine months ended September 30, 2022, respectively.

The Company reviewed the cumulative impact of its announcements in February, March and April of 2023 to discontinue its

FREEDOM-1

and

FREEDOM-2

clinical trials and initiate a reduction in force of 33% of its employees, pause enrollment in its

FREEDOM-3

clinical trial and initiate a second reduction in force of 95% of its remaining employees, respectively, on the carrying value of certain of its long-lived assets. The analysis resulted in the Company determining a triggering event had occurred in relation to the long-lived assets used primarily in the Company’s CMC operations The Company obtained third-party quotes to assess the current fair value of these assets and determine if an impairment had occurred. The value determined from these quotes was $2.0 million, resulting in the Company recording a

non-cash

impairment expense of $2.7 million for the assets, during the period ended March 31, 2023.

In April 2023, the Company committed to a plan to sell it

long-lived assets used primarily in its CMC operations. The assets held for sale were reported at the lower of the carrying amount or fair value, less costs to sell. In May 2023, the Company evaluated the fair value, less costs to sell, of its assets held for sale in connection with a potential sale and determined that an impairment had occurred. The Company recorded a

non-cash

impairment expense of $0.5 million, during the period ended June 30, 2023. The Company completed the sale of its long-lived assets used primarily in its CMC operations in September 2023 (see Note 5).

In June 2023, the Company reviewed the impact of the ImmunoFree APA on the carrying value of certain long-lived assets (see Note 5). The analysis resulted in the Company determining a triggering event had occurred in relation to computer equipment. The Company determined the assets had no carrying value and recorded a

non-cash

impairment charge of $0.2 million, during the period ended June 30, 2023.

In September 2023, the Company committed to a plan to sell its remaining long-lived assets of primarily office furniture and computer equipment and therefore classified such assets as held for sale on the accompanying balance sheet as of September 30, 2023 (see Note 15). The assets held for sale were reported at the lower of the carrying amount or fair value, less costs to sell. The Company obtained third-party quotes to assess the current fair value of these assets and determine if an impairment had occurred. The value determined from these quotes was immaterial, resulting in the Company recording a

non-cash

impairment expense

of $0.2 million for the assets during the period ended September 30, 2023.

Nature of Business and Liquidity	9 Months Ended
Nature of Business and Liquidity	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business and Liquidity	1. Nature of Business and Liquidity Talaris Therapeutics, Inc. (“Talaris”) was a cell therapy company focused on developing an innovative method of allogeneic hematopoietic stem cell transplantation (“allo-HSCT”) to transform the standard of care in solid organ transplantation, certain severe autoimmune diseases and certain severe blood, immune and metabolic disorders. Talaris’ lead product candidate was FCR001. On October 19, 2023, Talaris completed its previously announced merger transaction in accordance with the terms and conditions of the Agreement and Plan of Merger, dated as of June 22, 2023 (the “Merger Agreement”), by and among Talaris, Tourmaline Sub, Inc. (formerly known as Tourmaline Bio, Inc., “Legacy Tourmaline”) and Terrain Merger Sub, Inc., a direct wholly owned subsidiary of Talaris (“Merger Sub”), pursuant to which Merger Sub merged with and into Legacy Tourmaline, with Legacy Tourmaline surviving as a direct wholly owned subsidiary of Talaris and the surviving corporation of the merger (the “Merger”). On October 19, 2023, in connection with and prior to the completion of the Merger, Talaris effected a 1-for-10 reverse stock split of its common stock (the “Reverse Stock Split”). Upon the completion of the Merger, Legacy Tourmaline changed its name from “Tourmaline Bio, Inc.” to “Tourmaline Sub, Inc.”, and Talaris changed its name from “Talaris Therapeutics, Inc.” to “Tourmaline Bio, Inc.” (the “Company”). The Merger and the Reverse Stock Split are further described below in Note 15. Subsequent Events . Following the completion of the Merger, the business conducted by the Company became primarily the business conducted by Legacy Tourmaline, which is a late-stage clinical biotechnology company developing transformative medicines that dramatically improve the lives of patients with life-altering immune diseases. The Company’s lead product candidate is TOUR006, a fully human monoclonal antibody that selectively binds to interleukin-6, a key proinflammatory cytokine involved in the pathogenesis of many autoimmune and inflammatory disorders. Founded on September 17, 2021, the Company is headquartered in New York City. Prior to the Merger, in February 2023, Talaris announced the discontinuation of its FREEDOM-1 and FREEDOM-2 clinical trials evaluating FCR001’s ability to induce durable tolerance in living donor kidney transplant recipients. This decision was primarily attributable to the pace of enrollment and the associated timeline to critical milestones. Talaris also announced a restructuring plan that resulted in the reduction in its workforce by 33 % (the “Initial Reduction in Force”) and a comprehensive review of strategic alternatives focused on maximizing shareholder value, including, but not limited to, a reverse merger and/or a divestiture of its cell therapy chemistry, manufacturing and controls (“CMC”) capabilities. In March 2023, pending the outcome of its review of strategic alternatives, Talaris voluntarily paused enrollment in the FREEDOM-3 Phase 2 clinical trial evaluating FCR001’s ability to induce tolerance in diffuse systemic scleroderma, a severe autoimmune disease, while continuing to evaluate patients for potential future enrollment. In April 2023, Talaris’ Board of Directors approved, and Talaris announced, a further reduction in force (the “April Reduction in Force”) that resulted in the termination of approximately 80 additional employees, or approximately 95 % of its remaining workforce. The April Reduction in Force was substantially completed in the second quarter of 2023. In June 2023, following a comprehensive review of strategic alternatives, Talaris entered into the Merger Agreement with Legacy Tourmaline (see Note 15). In July 2023, Talaris entered into an asset purchase agreement with ImmunoFree, Inc. (“ImmunoFree”), pursuant to which it sold certain clinical data and intellectual property related to FCR001 for approximately $2.2 million, including a combination of cash consideration, reimbursement of certain expenses and assumption of all current and future clinical wind-down liabilities (see Note 5). In September 2023, Talaris sold certain long-lived assets primarily used in its CMC operations (see Note 5). On October 19, 2023, Talaris completed the Merger with Legacy Tourmaline pursuant to the Merger Agreement as described in Note 15. Subsequent Events . The Reverse Stock Split has been retroactively applied to the accompanying financial statements and notes to the financial statements (see Note 15). In connection with the Merger, a special dividend of $64.7 million was paid to eligible pre-Merger Talaris stockholders (see Note 15). The financial information included in the accompanying interim financial statements is that of Talaris prior to the Merger because the Merger was consummated after the period covered by these financial statements. Unless the context indicates otherwise, the term “Company” as used hereinafter refers to (i) Talaris Therapeutics, Inc., for periods prior to the effectiveness of the Merger, and (ii) Tourmaline Bio, Inc. (as a combined company) for periods following the effectiveness of the Merger. Liquidity The accompanying interim financial statements have been prepared assuming that the Company will continue as a going concern. Management has evaluated whether there are conditions and events that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date the financial statements are issued. Since its inception, the Company has incurred net losses and negative cash flows from operations. During the nine months ended September 30, 2023 and the year ended December 31, 2022, the Company incurred a net loss of $44.3 million and $73.9 million, respectively, and used $39.1 million and $60.9 million in cash for operations, respectively. In addition, as of September 30, 2023, the Company had an accumulated deficit of $209.0 million. The Company expects to continue to generate operating losses and negative cash flows for the foreseeable future. The Company currently expects its post-merger cash, cash equivalents, and marketable securities of $ 218.2 million will be sufficient to fund its operating expenses and capital requirements for more than twelve months from the date the financial statements are available to be issued.

Common Stock

9 Months Ended

Sep. 30, 2023

Stockholders' Equity Note [Abstract]

Common Stock

11. Common Stock

Common Stock

On April 30, 2021, the Company’s stockholders approved the third amended and restated certificate of incorporation of the Company, which included the authorization of 10,000,000 shares of undesignated preferred stock with a par value of $0.0001, authorization of 140,000,000 shares of voting common stock and 10,000,000 shares of

non-voting

common stock. As of September 30, 2023, no undesignated preferred stock was outstanding.

Common Stock Reserved

The number of shares of common stock that have been reserved for outstanding stock-based awards granted and stock-based awards available for grant under the Company’s 2021 Stock Option and Incentive Plan (the “2021 Plan”) and the 2018 Equity Incentive Plan (the “2018 Plan”) and shares reserved for issuance under the Company’s 2021 Employee Stock Purchase Plan (the “2021 ESPP”) are as follows:


	September 30,		December 31,
	2023		2022

Restricted stock related to early exercise of common stock options		5,281		15,815
Restricted stock units outstanding		60,478		114,461
Outstanding common stock options		533,900		626,373
Outstanding stock appreciation rights		100,000		—
Shares reserved for issuance under equity incentive plans		227,602		75,843
Shares reserved for issuance under the 2021 Employee Stock Purchase Plan		158,109		116,644

Total		1,085,370		949,136

- 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//1943274/2147481062/946-235-50-2

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//1943274/2147481062/946-235-50-2

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//1943274/2147481004/946-505-50-6

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)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 16
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-16

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

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

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

+ Details

Nature of Business and Liquidity - Additional Information (Details) $ in Thousands			1 Months Ended		3 Months Ended						9 Months Ended		12 Months Ended
	Oct. 19, 2023 USD ($)	Jul. 31, 2023 USD ($)	Apr. 30, 2023 Employee	Feb. 28, 2023	Sep. 30, 2023 USD ($)	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Sep. 30, 2022 USD ($)	Jun. 30, 2022 USD ($)	Mar. 31, 2022 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Initial reduction in workforce percentage				33.00%
Net loss					$ 7,015	$ 14,738	$ 22,497	$ 19,011	$ 18,096	$ 18,259	$ 44,250	$ 55,366	$ 73,900
Cash used for operation											39,102	$ 46,987	60,900
Accumulated deficit					(208,991)						(208,991)		$ (164,741)
Marketable securities					$ 218,200						$ 218,200
Number of termination of additional employees \| Employee			80
Percentage of remaining workforce			95.00%
Stockholders' equity, reverse stock split	1-for-10
Special Dividend Paid [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Payments of Dividends	$ 64,700
Asset Purchase Agreement [Member] \| ImmunoFree, Inc [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Proceeds From Sale Of Intangible Assets		$ 2,200

Asset Sale	9 Months Ended
Asset Sale	Sep. 30, 2023
Asset Retirement Obligation Disclosure [Abstract]
Asset Sale	5. Asset Sales On July 7, 2023, the Company entered into an asset purchase agreement with ImmunoFree, Inc. (the “ImmunoFree APA”), effective July 1, 2023. Pursuant to the terms of the ImmunoFree APA, the Company sold certain clinical data and intellectual property related to FCR001 for cash consideration of $ 0.5 million, reimbursement of $0.2 million for certain expenses and assumption of all current and future clinical wind-down liabilities. In connection with this agreement, the Company relinquished its rights under the ULRF License Agreement in order to allow ImmunoFree to license such rights to FCR001 from ULRF (see Note 10). The Company recorded a gain on sale of asset of $0.5 million in the accompanying statement of operations and comprehensive loss. On September 29, 2023, the Company entered into an asset purchase agreement with New York Blood Center, Inc. (“NYBC”) (the “NYBC APA”). Pursuant to the terms of the NYBC APA, the Company sold its long-lived assets primarily used in its CMC operations for cash consideration of $1.5 million and assumption of the Company’s lease obligations related to its laboratory space in Louisville, Kentucky and Houston, Texas (see Note 7).

Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Cash flows from operating activities:
Net loss	$ (7,015)	$ (19,011)	$ (44,250)	$ (55,366)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization			494	1,029
Accretion and amortization of marketable securities, net			(3,872)	(621)
Amortization of right-of-use assets			644	580
Stock-based compensation expense			6,081	8,084
Asset impairment			3,614	235
Right-of-use asset impairment			469	0
Gain on asset sales	(538)		(538)	0
Loss on disposal of assets			129	0
Changes in operating assets and liabilities:
Prepaid and other current assets			1,658	(1,634)
Other assets			111	(7)
Accounts payable			(3,626)	(215)
Accrued expenses			635	1,260
Other current liabilities			47	0
Operating lease liability			(682)	(423)
Other liabilities			(16)	91
Net cash used in operating activities			(39,102)	(46,987)	$ (60,900)
Cash flows from investing activities:
Purchases of property and equipment			(541)	(2,774)
Proceeds from asset sales			650	0
Purchases of marketable securities			(85,154)	(140,588)
Maturities of marketable securities			177,303	190,021
Net cash provided by investing activities			92,258	46,659
Cash flows from financing activities:
Proceeds from exercise of stock options			259	105
Payment for repurchase of forfeited restricted stock			(5)	0
Net cash provided by financing activities			257	182
Net increase in cash, cash equivalents and restricted cash			53,413	(146)
Cash and cash equivalents at beginning of period			13,670	18,614	18,614
Cash and cash equivalents at end of period	$ 67,083	$ 18,468	67,083	18,468	$ 13,670
Supplemental disclosure of non-cash investing and financing activities:
Property and equipment additions included in accounts payable and accrued expenses			0	178
Deferred issuance costs included in accounts payable and accrued expenses			0	81
Decrease in right-of-use asset and operating lease liabilities due to remeasurement			1,388	0
Decrease in right-of-use asset and operating lease liabilities due to termination			142	0
Proceeds for asset sales included inother current assets			1,350	0
2021 Employee Stock Purchase Plan
Cash flows from financing activities:
Proceeds from issuance of common stock			$ 3	$ 77

Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2023

Marketable Securities [Abstract]

Summary of Company's Investments

The following table summarizes the Company’s investments

(in thousands)


	September 30, 2023
	Amortized Cost		Unrealized Gain		Unrealized (Loss)			Estimated Fair Value
Commercial paper	$	35,371	$	1	$	(54	)	$	35,318
Government and agency securities		44,685		3		(65	)		44,623

Total	$	80,056	$	4	$	(119	)	$	79,941


	December 31, 2022
	Amortized Cost		Unrealized Gain		Unrealized (Loss)			Estimated Fair Value
Commercial paper	$	119,313	$	19	$	(365	)	$	118,967
Government and agency securities		43,016		—		(368	)		42,648
Corporate debt securities		6,004		—		(7	)		5,997

Total	$	168,333	$	19	$	(740	)	$	167,612

Common Stock - Schedule of Common Stock Reserved (Details) - shares	Sep. 30, 2023	Dec. 31, 2022
Class of Stock [Line Items]
Outstanding common stock options	533,900	626,373
Restricted Stock Units
Class of Stock [Line Items]
Outstanding stock appreciation rights	60,478	114,461
Stock Appreciation Rights
Class of Stock [Line Items]
Outstanding stock appreciation rights	100,000
Common Stock
Class of Stock [Line Items]
Restricted stock related to early exercise of common stock options	5,281	15,815
Outstanding common stock options	533,900	626,373
Total	1,085,370	949,136
Common Stock \| Restricted Stock Units
Class of Stock [Line Items]
Total	60,478	114,461
Common Stock \| Stock Appreciation Rights
Class of Stock [Line Items]
Outstanding stock appreciation rights	100,000
Common Stock \| Equity Incentive Plans
Class of Stock [Line Items]
Shares reserved for issuance	227,602	75,843
Common Stock \| 2021 Employee Stock Purchase Plan
Class of Stock [Line Items]
Shares reserved for issuance	158,109	116,644

Summary of Significant Accounting Policies

9 Months Ended

Sep. 30, 2023

Summary Of Significant Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Basis of Presentation

The financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”).

Use of Estimates

Cash and Cash Equivalents

Marketable Securities

The Company classifies its marketable securities as

available-for-sale

securities are included in net loss in the period earned or incurred.

Property and Equipment

rred.

Impairment of Long-Lived Assets

non-cash

impairment charges of $0.2 million and $3.6 million, respectively. For additional disclosures regarding the $

3.6

million

non-cash

impairment charge and accompanying analysis, refer to Note 7. During the year three and nine months ended September 30, 2022, the company recorded

non-cash

impairment charges of

$0.2

million.

Concentration of Credit Risk

Fair Value of Financial Instruments

The three levels of the fair value hierarchy are as follows:

•

Level

1 inputs:

Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities;

•

Level

2 inputs:

Quoted prices in markets that are not considered to be active or financial instrument valuations for which all significant inputs are observable, either directly or indirectly; and

•

Level

3 inputs

: Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable.

The Company’s money market funds and marketable securities are carried at fair value determined according to the fair value hierarchy described above (Level 1 and Level 2, respectively).

Research and Development Expenses

Stock-Based Compensation

non-employees

the Company has never paid cash dividends on common stock and did not expect to pay any cash dividends prior to completion of the Merger.

arm’s-length

Income Taxes

The Company accounts for uncertainty in income taxes recognized in the financial statements by applying a

two-step

Basic and Diluted Net Loss Per Share

The Company calculates basic and diluted net loss per share using the

two-class

method. The

two-class

if-converted

Segments

Comprehensive Loss

Recently Issued Accounting Pronouncements

In February 2016, the FASB issued ASU

No. 2016-02,

right-of-use

As a result of the adoption of the new leasing standards, on January 1, 2022, the Company recorded

right-of-use

assets of $3.4 million and operating lease liabilities of $3.5

million. The adoption did not have a material impact on the statement of operations or the statement of cash flows.

Marketable Securities - Additional Information (Details)	Sep. 30, 2023 USD ($)
Investments, Debt and Equity Securities [Abstract]
Available-for-sale securities, unrealized loss position	$ 61,100,000
Available-for-sale securities, allowance for credit losses	$ 0

Property and Equipment, Net and Assets Held for Sale - Additional Information (Details) - USD ($) $ in Millions	1 Months Ended		3 Months Ended			9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Sep. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Property, Plant and Equipment [Line Items]
Depreciation expense					$ 0.4	$ 0.5	$ 1.0
Long lived assets fair value from quotes	$ 2.0		$ 2.0			2.0
Non-cash impairment expense		$ 0.5	$ 0.2	$ 2.7	$ 3.6	$ 3.6	$ 0.2
FREEDOM-1 and FREEDOM-2 Clinical Trials
Property, Plant and Equipment [Line Items]
Percentage of reduction in employees						33.00%
FREEDOM-3 Clinical Trial
Property, Plant and Equipment [Line Items]
Percentage of reduction in employees						95.00%
Computer Equipment
Property, Plant and Equipment [Line Items]
Non-cash impairment expense	$ 0.2	$ 0.2

Commitments and Contingencies	9 Months Ended
Commitments and Contingencies	Sep. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	10. Commitments and Contingencies Leases The Company had one active lease agreement for office space as of September 30, 2023. The Company’s former cell processing facility lease was located on the University of Louisville campus in Louisville, Kentucky (the “Louisville Lease”). This lease had a termination date in November 2023, with an option to extend for three additional one-year renewals at the Company’s discretion. In May 2020, the Company added additional office and laboratory space to the Louisville Lease. In March 2023, the Company entered into an amended lease agreement for the Louisville Lease that increased the successive one-year renewal terms from three to five and reduces the written notice period for the successive one-year renewals from six months in advance to three months in advance. The Company reviewed the cumulative impact of its announcements in February, March and April of 2023 on its lease terms. Based on this analysis, the Company determined a triggering event had occurred and it was not reasonably certain to exercise its option to renew the Louisville Lease upon its original termination in November 2023. As a result of this determination, the Company remeasured the associated right-of-use asset and operating lease liability. The Company prospectively modified the estimated useful lives of the existing leasehold improvements. These assets were subject to the non-cash impairment disclosed in Note 7. In September 2023, the Company, NYBC and landlord entered into an assignment, assumption, and amendment of lease and landlord consent agreement (“Louisville Lease Assignment Agreement”). Pursuant to the Louisville Lease Assignment Agreement, the Company assigned its rights and obligations under the Louisville Lease to NYBC effective September 29, 2023. The Company recorded a reduction to the associated right-of-use asset and operating lease liability. There was no impact to the accompanying statement of operations for the three and nine months ended September 30, 2023. In September 2021, the Company entered into a sublease agreement for separate office space in Louisville, Kentucky. This sublease had a termination date in November 2023. In August 2023, the Company entered into an amended sublease agreement, effective August 1, 2023, to terminate the sublease for no cash consideration. The Company recorded a reduction to the associated right-of-use asset and operating lease liability. There was no impact to the accompanying statement of operations for the three and nine months ended September 30, 2023. In July 2021, the Company entered into a lease agreement for laboratory space in Houston, Texas (the “Houston Lease”). The Houston Lease commenced in January 2022. The term of the lease was 36 months from the commencement date, terminating December 2024. In September 2023, the Company, NYBC and landlord entered into an assignment, assumption, and amendment of lease and landlord consent agreement (“Houston Lease Assignment Agreement”). Pursuant to the Houston Lease Assignment Agreement, the Company assigned its rights under the Houston Lease to NYBC effective September 29, 2023. The Company recorded a reduction to the associated right-of-use asset and operating lease liability. The Company recorded a minimal gain on disposal of the right-of-use asset as gain on asset sale in the accompanying statement of operations and comprehensive loss for the three and nine months ended September 30, 2023. Pursuant to the Houston Lease Assignment Agreement, the Company retained its obligations to the Houston Lease as a guarantor. The Company evaluated the conditions of its guarantee as of the balance sheet date and determine the fair value of the guarantee is de-minimus. The Company maintained a lease for office space in Wellesley, Massachusetts (the “Boston Lease”) as of September 30, 2023. The Boston Lease, that had an original termination date in March 2021. In April 2021, the Company entered into an amended lease agreement providing for temporary space from April 2021 until an expansion of the Boston Lease was complete, from which the lease term extends 39 months from the expansion completion date. The expansion was completed in June 2022, resulting in the lease term extending to September 2025. In October 2023, the Company entered into an agreement to terminate the lease (see Note 15). The Company determined a triggering event had occurred in relation to its Boston Lease and recorded a non-cash impairment expense of $0.5 million related to its right-of-use asset during the three and nine months ended September 30, 2023, included in general and administrative expenses in the accompanying statements of operations and comprehensive loss. The future minimum rent payments relating to the Company’s Boston Lease under the terms and conditions existing as of September 30, 2023, were $0.6 million for the year ending December 31, 2023. In October 2023, the Company paid $0.6 million in connection with its termination of the Boston Lease (see Note 15). Subsequent to the October payment on the Boston Lease, the Company has no remaining lease obligations. The Company incurred rent expense of $0.2 million and $0.7 million for the three and nine months ended September 30, 2023, respectively, and $0.3 million and $0.8 million for three and nine months ended September 30, 2022, respectively. Cash paid for amounts included in the measurement of the Company’s operating lease liability was $0.3 million and $0.5 million for the three and nine months ended September 30, 2023, respectively, and $0.2 million and $0.6 million for the three and nine months ended September 30, 2022, respectively. License Agreement In October 2018, the Company entered an amended and restated exclusive license agreement with ULRF related to certain licensed patent rights and know-how related to human facilitating cells for its Facilitated allo-HSCT Therapy approach. Pursuant to the ULRF License Agreement, ULRF granted the Company an exclusive, worldwide license under such patents and a nonexclusive royalty-bearing, worldwide license for such know-how to research, develop, commercialize and manufacture FCR001 and products containing FCR001 in all fields, without limitation. ULRF also granted the Company the right to grant sublicenses in accordance with the ULRF License Agreement. Under the terms of the agreement, the Company is obligated to compensate ULRF three percent of net sales of all licensed products sold, one third of any non-royalty sublicensing income, and up to $1.625 million in regulatory and sales milestones on each licensed product upon the occurrence of specific events as outlined in the license agreement; and annual license maintenance fees. In addition, upon execution of the ULRF License Agreement, the Company granted contingent equity consideration equal to 65,186 shares of common stock to ULRF. Coincident with the completion of the Company’s IPO, the Company issued 48,889 shares of common stock to ULRF and provided a cash payment of approximately $0.3 million in lieu of issuing the remaining 16,297 shares of common stock. The Company incurred $0.1 million in expense in January 2023 related to an annual maintenance fee pursuant to the ULRF License Agreement for the year end ing December 31, 2023. The Company incurred $0.1 million in expense in February 2022 related to an annual maintenance fee pursuant to the license agreement for the year ended December 31, 2022. In connection with the transaction with ImmunoFree, the ULRF License Agreement relating to FCR001 was terminated, conditioned upon the license of Talaris’ rights under the ULRF License Agreement to ImmunoFree. Legal Proceedings At each reporting date, the Company evaluates whether a potential loss amount or a potential range of loss is probable and reasonably estimable under the provisions of the authoritative guidance that addresses accounting for contingencies. The Company expenses the costs related to its legal proceedings as incurred. The Company may be involved in litigation arising in the ordinary course of conducting business. The Company reviews all litigation on an ongoing basis when making accrual and disclosure decisions. The Company, in accordance with current accounting standards for loss contingencies and based upon information currently known by the Company, will establish reserves for litigation when it is probable that a loss associated with a claim or proceeding has been incurred and the amount of the loss or range of loss can be reasonably estimated. When no amount within the range of loss is a better estimate than any other amount, the Company will accrue the minimum amount of the estimable loss. To the extent that such litigation against the Company may have an exposure to a loss in excess of the amount accrued, the Company believes that such excess would not be material to its financial condition, results of operations, or cash flows. In September 2023, the Company received a purported notice of material breach from ImmunoFree (the “ImmunoFree Demand Letter”) alleging that the Company breached a provision of the ImmunoFree APA and that the Company fraudulently induced ImmunoFree to enter into the ImmunoFree APA. In the ImmunoFree Demand Letter, ImmunoFree alleged the Company failed to disclose certain information and costs related to a patient in the FREEDOM-1 Study and demanded that the Company indemnify ImmunoFree for the cost of treatment for this patient. During the three and nine months ended September 30, 2023, the Company recorded an expense of $ 4.0 million related to the ImmunoFree Demand Letter (see Note 15). This expense is included in accrued expenses in the accompanying balance sheets (see Note 9) and general and administrative expenses in the accompanying statements of operations and comprehensive loss. In addition, three individual lawsuits have been filed against Talaris and its directors related to the Merger: Wieder v. Talaris Therapeutics, Inc., et al., No. 1:23-cv-08355 (S.D.N.Y. filed Sept. 21, 2023), Carlisle v. Talaris Therapeutics, Inc., et al., No. 1:23-cv-08520 (S.D.N.Y. filed Sept. 27, 2023), and Roberts v. Talaris Therapeutics, Inc., et al., No. 1:23-cv-01063 (D. Del. filed Sept. 27, 2023) (collectively, the “Stockholder Litigation”). The complaints named Talaris and the Board of Directors of Talaris as defendants. Legacy Tourmaline and its officers and directors were not named as defendants in the complaints. The complaints asserted claims under Section 14(a) and Section 20(a) of the Securities Exchange Act of 1934, as amended, and Rule 14a-19 promulgated thereunder, and generally allege that the proxy statement filed by Talaris on July 20, 2023, and as amended on August 25, 2023 and September 11, 2023 (the “Proxy Statement”), misrepresents and/or omits certain purportedly material information relating to the Merger. The complaints sought a variety of equitable and injunctive relief including, among other things, an injunction enjoining the consummation of the Merger, rescission of the Merger if it is consummated, rescissory damages and costs and attorneys’ fees. Between July 25 and September 20, 2023, six purported stockholders of Talaris sent demand letters regarding the Proxy Statement (the “Demand Letters”). Based on the same core allegations as the Stockholder Litigation, the Demand Letters requested that Talaris disseminate corrective disclosures in an amendment or supplement to the Proxy Statement. On October 10, 2023, Talaris filed a Form 8-K to update and supplement the Proxy Statement with additional disclosures relating to the Merger (the “Supplemental Disclosures”). Thereafter, plaintiffs in the Stockholder Litigation voluntarily dismissed their complaints, and opposing counsel (for the stockholders in the Stockholder Litigation and Demand Letters) requested a mootness fee in connection with the Supplemental Disclosures. The ultimate outcome of any litigation is uncertain and unfavorable outcomes could have a negative impact on the Company’s results of operations and financial condition. Regardless of outcome, litigation can have an adverse impact on the Company due to defense and settlement costs, diversion of management resources, negative publicity and reputational harm, and other factors.

Stock-Based Compensation - Schedule of Assumptions Used to Determine the Fair Values of Stock Appreciation Rights Granted (Details) - Stock Appreciation Rights - 2021 Employee Stock Purchase Plan	9 Months Ended
	Sep. 30, 2023 $ / shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Fair value of common stock	$ 17.3
Volatility	90.83%
Risk-free interest rate	3.46%
Expected term (years)	4 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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 35
-Paragraph 1D
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480483/718-10-35-1D

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 35
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480483/718-10-35-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
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+ Details

Common Stock - Additional Information (Details) - $ / shares	Sep. 30, 2023	Dec. 31, 2022	Apr. 30, 2021
Class of Stock [Line Items]
Authorization of undesignated preferred stock			10,000,000
Undesignated preferred stock, par value			$ 0.0001
Common stock, shares authorized	140,000,000	140,000,000
Undesignated preferred stock, outstanding	0
Voting Shares
Class of Stock [Line Items]
Common stock, shares authorized			140,000,000
Non-voting Shares
Class of Stock [Line Items]
Common stock, shares authorized	10,000,000	10,000,000	10,000,000

- 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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-Publisher FASB
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Reference 2: http://www.xbrl.org/2003/role/recommendedDisclosureRef
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Accrued Expenses (Tables)

9 Months Ended

Sep. 30, 2023

Accrued Liabilities, Current [Abstract]

Schedule of Accrued Expenses

Accrued expenses consisted of the following

(in thousands)


	September 30,		December 31,
	2023		2022

Compensation and benefit costs	$	1,498	$	3,566
Research and development expenses		418		1,978
Legal settlement		4,000		—
Professional fees, consulting and other		1,372		1,121

Total accrued expenses	$	7,288	$	6,665

Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Beginning balance at Dec. 31, 2021	$ 242,809	$ 0	$ 333,734	$ (90,847)	$ (78)
Beginning balance, shares at Dec. 31, 2021		4,091,304
Issuance of common stock upon exercise of stock options	131		131
Issuance of common stock upon exercise of stock options, shares		11,081
Stock-based compensation expense	2,197		2,197
Net loss	(18,259)			(18,259)
Unrealized gain (loss) on marketable securities	(848)				(848)
Ending balance at Mar. 31, 2022	226,030	$ 0	336,062	(109,106)	(926)
Ending balance, shares at Mar. 31, 2022		4,102,385
Beginning balance at Dec. 31, 2021	242,809	$ 0	333,734	(90,847)	(78)
Beginning balance, shares at Dec. 31, 2021		4,091,304
Net loss	(55,366)
Unrealized gain (loss) on marketable securities	(1,144)
Ending balance at Sep. 30, 2022	194,867	$ 0	342,302	(146,213)	(1,222)
Ending balance, shares at Sep. 30, 2022		4,148,188
Beginning balance at Dec. 31, 2021	242,809	$ 0	333,734	(90,847)	(78)
Beginning balance, shares at Dec. 31, 2021		4,091,304
Net loss	(73,900)
Ending balance at Dec. 31, 2022	$ 180,055	$ 0	345,517	(164,741)	(721)
Ending balance, shares at Dec. 31, 2022	4,162,942	4,162,942
Beginning balance at Mar. 31, 2022	$ 226,030	$ 0	336,062	(109,106)	(926)
Beginning balance, shares at Mar. 31, 2022		4,102,385
Issuance of common stock upon exercise of stock options	102		102
Issuance of common stock upon exercise of stock options, shares		10,185
Issuance of common stock under 2021 employee stock purchase plan	77		77
Issuance of common stock under 2021 employee stock purchase plan, shares		2,016
Stock-based compensation expense	2,846		2,846
Net loss	(18,096)			(18,096)
Unrealized gain (loss) on marketable securities	(217)				(217)
Ending balance at Jun. 30, 2022	210,742	$ 0	339,087	(127,202)	(1,143)
Ending balance, shares at Jun. 30, 2022		4,114,586
Issuance of common stock upon exercise of stock options	174		174
Issuance of common stock upon exercise of stock options, shares		18,164
Vesting of restricted stock units, shares		15,438
Stock-based compensation expense	3,041		3,041
Net loss	(19,011)			(19,011)
Unrealized gain (loss) on marketable securities	(79)				(79)
Ending balance at Sep. 30, 2022	194,867	$ 0	342,302	(146,213)	(1,222)
Ending balance, shares at Sep. 30, 2022		4,148,188
Beginning balance at Dec. 31, 2022	$ 180,055	$ 0	345,517	(164,741)	(721)
Beginning balance, shares at Dec. 31, 2022	4,162,942	4,162,942
Issuance of common stock upon exercise of stock options	$ 92		92
Issuance of common stock upon exercise of stock options, shares		8,778
Vesting of restricted stock units, shares		19,283
Stock-based compensation expense	3,659		3,659
Net loss	(22,497)			(22,497)
Unrealized gain (loss) on marketable securities	422				422
Ending balance at Mar. 31, 2023	161,731	$ 0	349,268	(187,238)	(299)
Ending balance, shares at Mar. 31, 2023		4,191,003
Beginning balance at Dec. 31, 2022	$ 180,055	$ 0	345,517	(164,741)	(721)
Beginning balance, shares at Dec. 31, 2022	4,162,942	4,162,942
Issuance of common stock upon exercise of stock options, shares	27,686
Net loss	$ (44,250)
Unrealized gain (loss) on marketable securities	606
Ending balance at Sep. 30, 2023	$ 142,874	$ 0	351,980	(208,991)	(115)
Ending balance, shares at Sep. 30, 2023	4,282,848	4,277,564
Beginning balance at Mar. 31, 2023	$ 161,731	$ 0	349,268	(187,238)	(299)
Beginning balance, shares at Mar. 31, 2023		4,191,003
Issuance of common stock upon exercise of stock options	177		177
Issuance of common stock upon exercise of stock options, shares		17,975
Vesting of restricted stock units, shares		45,748
Issuance of common stock under 2021 employee stock purchase plan	3		3
Issuance of common stock under 2021 employee stock purchase plan, shares		322
Stock-based compensation expense	1,174		1,174
Net loss	(14,738)			(14,738)
Unrealized gain (loss) on marketable securities	85				85
Ending balance at Jun. 30, 2023	148,432	$ 0	350,622	(201,976)	(214)
Ending balance, shares at Jun. 30, 2023		4,255,048
Issuance of common stock upon exercise of stock options	111		111
Issuance of common stock upon exercise of stock options, shares		10,985
Vesting of restricted stock units, shares		11,531
Stock-based compensation expense	1,247		1,247
Net loss	(7,015)			(7,015)
Unrealized gain (loss) on marketable securities	99				99
Ending balance at Sep. 30, 2023	$ 142,874	$ 0	$ 351,980	$ (208,991)	$ (115)
Ending balance, shares at Sep. 30, 2023	4,282,848	4,277,564

Stock-Based Compensation - Schedule of Assumptions Used to Determine the Fair Values of Stock Options Granted (Details) - $ / shares	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected dividend yield	0.00%
Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected dividend yield	0.00%
Volatility, minimum	90.36%	82.29%
Volatility, maximum	91.64%	88.41%
Risk-free interest rate, minimum	3.46%	1.46%
Risk-free interest rate, maximum	3.98%	3.38%
Stock Option \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	5 years 6 months	5 years 4 months 17 days
Stock Option \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	6 years 3 months	6 years 3 months
Common Stock \| Stock Option \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair value of common stock	$ 17.3	$ 23
Common Stock \| Stock Option \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair value of common stock	$ 25.4	$ 165.6

Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 67,083	$ 13,670
Marketable securities	79,941	167,612
Prepaid and other current assets	4,023	4,331
Total current assets	151,047	185,613
Property and equipment, net	0	5,348
Assets held for sale	14	0
Right-of-use assets	0	2,643
Other assets	0	111
Total assets	151,061	193,715
Current liabilities:
Accounts payable	136	3,887
Accrued expenses	7,288	6,665
Lease liability, current	634	910
Other current liabilities	47	0
Total current liabilities	8,105	11,462
Share repurchase liability	82	208
Other liabilities	0	16
Lease liability, net of current	0	1,974
Total liabilities	8,187	13,660
Commitments and contingencies (Note 9)
Stockholders' equity
Common stock, $0.0001 par value, 140,000,000 shares authorized and 4,282,848 issued and outstanding and 10,000,000 non-voting shares authorized as of September 30, 2023 and 140,000,000 shares authorized and 4,162,942 issued and outstanding and 10,000,000 non-voting shares authorized as of December 31, 2022	0	0
Additional paid-in-capital	351,980	345,517
Accumulated deficit	(208,991)	(164,741)
Accumulated other comprehensive loss	(115)	(721)
Total stockholders' equity	142,874	180,055
Total liabilities and stockholders' equity	$ 151,061	$ 193,715

Fair Value of Financial Assets - Summary of Financial Instruments Measured at Fair Value on Recurring Basis (Details) - Fair Value, Recurring - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Financial assets:
Total financial assets measured at fair value	$ 146,660	$ 179,921
Money Market Funds \| Cash Equivalents
Financial assets:
Total financial assets measured at fair value	66,719	12,309
Marketable Securities
Financial assets:
Total financial assets measured at fair value	79,941	167,612
Level 1
Financial assets:
Total financial assets measured at fair value	74,545	44,027
Level 1 \| Money Market Funds \| Cash Equivalents
Financial assets:
Total financial assets measured at fair value	66,719	12,309
Level 1 \| Marketable Securities
Financial assets:
Total financial assets measured at fair value	7,826	31,718
Level 2
Financial assets:
Total financial assets measured at fair value	72,115	135,894
Level 2 \| Marketable Securities
Financial assets:
Total financial assets measured at fair value	$ 72,115	$ 135,894

Stock-Based Compensation - Summary of SAR Activity (Details) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2023 USD ($) $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Exercisable, Number of Restricted Stock Units / Stock Appreciation Rights \| shares	240,475
Exercisable, Weighted - Average Exercise Price per SAR \| $ / shares	$ 59.13
Exercisable, Weighted-Average Remaining Contractual Life (in years)	7 years 7 months 24 days
Stock Appreciation Rights
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Granted, Number of Stock Appreciation Rights \| shares	100,000
Outstanding, Number of Restricted Stock Units / Stock Appreciation Rights \| shares	100,000
Exercisable, Number of Restricted Stock Units / Stock Appreciation Rights \| shares	33,332
Granted, Weighted - Average Exercise Price per SAR \| $ / shares	$ 17.3
Outstanding, Weighted - Average Exercise Price per SAR \| $ / shares	17.3
Exercisable, Weighted - Average Exercise Price per SAR \| $ / shares	$ 17.3
Outstanding, Weighted-Average Remaining Contractual Life (in years)	9 years 4 months 6 days
Exercisable, Weighted-Average Remaining Contractual Life (in years)	9 years 4 months 6 days
Outstanding, Aggregate intrinsic value \| $	$ 1,080

Defined Contribution Plan - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Defined Contribution Plan Disclosure [Line Items]
Contribution amount	$ 0.1	$ 0.3	$ 0.4
First 3% of Employee Contributions
Defined Contribution Plan Disclosure [Line Items]
Percentage of employee contributions		3.00%
First 3% of Employee Contributions \| Minimum
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan minimum service requirements percentage		100.00%
Next 2% of Employee Contributions
Defined Contribution Plan Disclosure [Line Items]
Percentage of employee contributions		2.00%
Next 2% of Employee Contributions \| Minimum
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan minimum service requirements percentage		50.00%

Stock-Based Compensation - Additional Information (Details) $ in Millions		9 Months Ended	12 Months Ended
	Jan. 01, 2023 shares	Sep. 30, 2023 USD ($) Installment shares	Dec. 31, 2022 shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options outstanding, shares		533,900	626,373
Contractual term of stock option		8 years 7 days	8 years 5 months 4 days
Unrecognized compensation cost \| $		$ 2.5
2021 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Increment in number of shares authorized possible	208,937
Number of shares remained available for future grant		227,602
Percentage of shares issued and outstanding			5.00%
Percentage of fair market value of common stock		100.00%
Stock options vesting period		4 years
2021 Equity Incentive Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Contractual term of stock option		10 years
2018 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options outstanding, shares		694,378
2021 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Increment in number of shares authorized possible	41,787
Percentage Of cumulative number of shares of common stock outstanding			1.00%
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation cost \| $		$ 0.3
Number of installments, vested \| Installment		4
Incremental period of vesting		2 years
Stock Appreciation Rights
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation cost \| $		$ 0.2
Incremental period of vesting		18 months
Stock Appreciation Rights Contractual Term		10 years

Fair Value of Financial Assets

9 Months Ended

Sep. 30, 2023

Fair Value Disclosures [Abstract]

Fair Value of Financial Assets

3. Fair Value of Financial Assets

The following table presents information about the Company’s financial instruments that are measured at fair value on a recurring basis and indicates the fair value hierarchy of the inputs the Company utilized to determine such fair value

(in thousands)


	September 30, 2023
	Total		Level 1		Level 2		Level 3
Financial assets:
Money market funds (cash equivalents)	$	66,719	$	66,719	$	—	$	—
Marketable securities		79,941		7,826		72,115		—

Total financial assets measured at fair value	$	146,660	$	74,545	$	72,115	$	—


	December 31, 2022
	Total		Level 1		Level 2		Level 3
Financial assets:
Money market funds (cash equivalents)	$	12,309	$	12,309	$	—	$	—
Marketable securities		167,612		31,718		135,894		—

Total financial assets measured at fair value	$	179,921	$	44,027	$	135,894	$	—

- 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.

+ References + Details

Stock-Based Compensation - Summary of Option Activity (Details) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award, Additional General Disclosures [Abstract]
Options outstanding, beginning balance, shares \| shares	626,373
Granted, shares \| shares	118,450
Exercised, shares \| shares	(27,686)
Cancelled, shares \| shares	(55,348)
Forfeited, shares \| shares	(127,789)
Other, shares \| shares	(100)
Options outstanding, ending balance, shares \| shares	533,900	626,373
Options exercisable, shares \| shares	240,475
Options outstanding, weighted- average exercise price \| $ / shares	$ 69.2
Granted, weighted- average exercise price \| $ / shares	18.56
Exercised, weighted- average exercise price \| $ / shares	9.34
Cancelled, weighted-average exercise price \| $ / shares	84.53
Forfeited, weighted- average exercise price \| $ / shares	69.67
Other, weighted- average exercise price \| $ / shares	59.58
Options outstanding, weighted- average exercise price \| $ / shares	60.2	$ 69.2
Options exercisable, weighted- average exercise price \| $ / shares	$ 59.13
Options outstanding, weighted- average remaining contractual life	8 years 7 days	8 years 5 months 4 days
Exercisable, Weighted-Average Remaining Contractual Life (in years)	7 years 7 months 24 days
Options outstanding, aggregate intrinsic value \| $	$ 1,506	$ 42

Prepaid and Other Current Assets

9 Months Ended

Sep. 30, 2023

Prepaid Expense and Other Assets, Current [Abstract]

Prepaid and Other Current Assets

6. Prepaid and Other Current Assets

Prepaid and other current assets consisted of the following

(in thousands)


	September 30,		December 31,
	2023		2022

Prepaid insurance	$	1,179	$	1,037
Prepaid research and development expenses		—		2,426
Receivable from asset sale		1,350		—
Other current assets		1,494		868

Total prepaid and other current assets	$	4,023	$	4,331

Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2023

Share-Based Payment Arrangement [Abstract]

Schedule of Assumptions Used to Determine the Fair Values of Stock Options Granted

The assumptions used to determine the fair values of stock options granted to employees and directors are presented as follows:


	Nine months ended September 30,
	2023	2022
Fair value of common stock	$17.30 - $25.40	$23.00 - $165.60
Dividend yield	—%	—%
Volatility	90.36% - 91.64%	82.29% - 88.41%
Risk-free interest rate	3.46% - 3.98%	1.46% - 3.38%
Expected term (years)	5.50 - 6.25	5.38 - 6.25

Summary of Option Activity

The Company’s stock option activity regarding employees, directors, and nonemployees is summarized as follows (

in thousands excepts share and per share amounts)


	Shares			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Life (in years)		Aggregate intrinsic value
Options outstanding—December 31, 2022		626,373		$	69.20		8.43	$	42
Granted		118,450			18.56
Exercised		(27,686	)		9.34
Cancelled		(55,348	)		84.53
Forfeited		(127,789	)		69.67
Other		(100	)		59.58

Options outstanding—September 30, 2023		533,900		$	60.20		8.02	$	1,506

Options exercisable—September 30, 2023		240,475		$	59.13		7.65

Summary of Additional Information to Stock Option Activity Involving Employees and Directors

Additional information with regard to stock option activity involving employees and directors is as follows (

in thousands except per share amounts)


	Nine months ended September 30,
	2023		2022
Weighted-average grant-date fair value per option of total options granted	$	13.73	$	60.40
Aggregate intrinsic value of stock options exercised		489		286

Summary of RSU Activity

The following table summarizes the Company’s RSU activity for the three months ended September 30, 2023:


	Number of Restricted Stock Units			Weighted- Average Grant Date Fair Value
Outstanding at December 31, 2022		114,461		$	67.64
Granted		141,900			17.30
Vested		(76,482	)		38.95
Forfeited		(119,271	)		38.92
Other		(130	)		55.10

Outstanding at September 30, 2023		60,478		$	42.39

Schedule of Assumptions Used to Determine the Fair Values of Stock Appreciation Rights Granted

The fair values of stock appreciation rights (“SARs”) are based on the fair market value of the Company’s common stock on the date of grant. Each SAR represents a contingent right to receive shares of the Company’s common stock equal to the increase in fair value from the date of grant upon exercise. In general, SARs vest incrementally over 18 months and have a contractual term of 10 years. The assumptions used to determine the fair values of SARs granted to employees and directors under the 2021 Plan are presented as follows:


	Nine months ended September 30,
	2023
Fair value of common stock	$	17.30
Dividend yield		—	%
Volatility		90.83	%
Risk-free interest rate		3.46	%
Expected term (years)		4.0

Summary of Stock Appreciation Rights Activity

The Company’s SAR grant activity regarding employees is summarized as follows (

in thousands excepts share and per share amounts)


	Number of SARs		Weighted- Average Exercise Price per SAR		Weighted- Average Remaining Contractual Life (in years)		Aggregate intrinsic value
Outstanding—January 1, 2023		—	$	—		—	$	—
Granted		100,000		17.30
Exercised		—		—
Forfeited		—		—

Outstanding—September 30, 2023		100,000	$	17.30		9.35	$	1,080

Exercisable—September 30, 2023		33,332	$	17.30		9.35

Summary of Stock-based Compensation Expense

The Company recorded stock-based compensation expense

regarding

its employees, directors, and nonemployees as follows

(in thousands)


	Three months ended September 30,				Nine months ended September 30,
	2023		2022		2023		2022
Research and development expense	$	40	$	1,742	$	1,856	$	4,722
General and administrative expense		1,207		1,299		4,224		3,362

Total	$	1,247	$	3,041	$	6,080	$	8,084

Restructuring Costs - Schedule of Restructuring Liability (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 89	$ 10,958
Severance and Termination
Restructuring Cost and Reserve [Line Items]
Accrued restructuring balance at beginning of period	3,262
Restructuring costs	89	7,535
Payments	(1,993)	(6,177)
Accrued restructuring balance at June 30, 2023	$ 1,358	$ 1,358

- 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

Stock-Based Compensation

9 Months Ended

Sep. 30, 2023

Share-Based Payment Arrangement [Abstract]

Stock-Based Compensation

12. Stock-Based Compensation

2021

Employee

Stock Purchase Plan

On January 1, 2023, an additional 41,787 shares were added to the 2021 ESPP, representing 1% of total common shares outstanding at December 31, 2022, pursuant to the terms of the plan. The expense incurred under this plan for the nine months ended September 30, 2023 and 2022 was immaterial to the financial statements. The amounts have been included in the total stock-based compensation line items in the accompanying financial statements and disclosures.

Equity Incentive Plans

On January 1, 2023 an additional 208,937 shares were added to the 2021 Plan, representing 5% of total common shares outstanding at December 31, 2022, pursuant to the terms of the plan.

As of September 30, 2023, 227,602 shares remained available for future grant under the 2021 Plan. 694,378 stock-based award units were outstanding under the 2021 Plan and 2018 Plan as of September 30, 2023.

The Company’s 2021 Plan provides for the Company to sell or issue common stock or restricted common stock or to grant incentive stock options or nonqualified stock options for the purchase of common stock, to employees, nonemployees and members of the board of directors of the Company. The 2021 Plan is administered by the board of directors or at the discretion of the board of directors by the compensation committee of the board. The exercise prices, vesting periods, and other restrictions are determined at the discretion of the compensation committee of the board of directors, except that the exercise price per share of stock options may not be less than 100% of the fair market value of the share of common stock on the date of grant and the contractual term of stock option may not be greater than 10 years. Stock options granted to

date

typically vest over four years.

Stock Option Valuation

The assumptions used to determine the fair values of stock options granted to employees and directors are presented as follows:


	Nine months ended September 30,
	2023	2022
Fair value of common stock	$17.30 - $25.40	$23.00 - $165.60
Dividend yield	—%	—%
Volatility	90.36% - 91.64%	82.29% - 88.41%
Risk-free interest rate	3.46% - 3.98%	1.46% - 3.38%
Expected term (years)	5.50 - 6.25	5.38 - 6.25

Summary of Option Activity

The Company’s stock option activity regarding employees, directors, and nonemployees is summarized as follows (

in thousands excepts share and per share amounts)


	Shares			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Life (in years)		Aggregate intrinsic value
Options outstanding—December 31, 2022		626,373		$	69.20		8.43	$	42
Granted		118,450			18.56
Exercised		(27,686	)		9.34
Cancelled		(55,348	)		84.53
Forfeited		(127,789	)		69.67
Other		(100	)		59.58

Options outstanding—September 30, 2023		533,900		$	60.20		8.02	$	1,506

Options exercisable—September 30, 2023		240,475		$	59.13		7.65

Additional information with regard to stock option activity involving employees and directors is as follows (

in thousands except per share amounts)


	Nine months ended September 30,
	2023		2022
Weighted-average grant-date fair value per option of total options granted	$	13.73	$	60.40
Aggregate intrinsic value of stock options exercised		489		286

As of September 30, 2023, total unrecognized compensation cost related to the unvested awards to employees, directors, and nonemployees is $2.5

million, which is expected to be recognized in October 2023 as a result of the Company’s merger (see Note 15).

Summary of Restricted Stock Unit Activity

The fair values of restricted stock units (“RSUs”) are based on the fair market value of the Company’s common stock on the date of grant. Each RSU represents a contingent right to receive one share of the Company’s common stock upon vesting. In general, RSUs vest (i) annually in four equal installments on the grant anniversary or (ii) incrementally over two years. The following table summarizes the Company’s RSU activity for the three months ended September 30, 2023:


	Number of Restricted Stock Units			Weighted- Average Grant Date Fair Value
Outstanding at December 31, 2022		114,461		$	67.64
Granted		141,900			17.30
Vested		(76,482	)		38.95
Forfeited		(119,271	)		38.92
Other		(130	)		55.10

Outstanding at September 30, 2023		60,478		$	42.39

As of September 30, 2023, total unrecognized compensation cost related to the unvested awards to employees is $0.3

million, which is expected to be recognized in October 2023 as a result of the Company’s merger (see Note 15).

Stock Appreciation Rights Valuation


	Nine months ended September 30,
	2023
Fair value of common stock	$	17.30
Dividend yield		—	%
Volatility		90.83	%
Risk-free interest rate		3.46	%
Expected term (years)		4.0

Summary of Stock Appreciation Rights Activity

The Company’s SAR grant activity regarding employees is summarized as follows (

in thousands excepts share and per share amounts)


	Number of SARs		Weighted- Average Exercise Price per SAR		Weighted- Average Remaining Contractual Life (in years)		Aggregate intrinsic value
Outstanding—January 1, 2023		—	$	—		—	$	—
Granted		100,000		17.30
Exercised		—		—
Forfeited		—		—

Outstanding—September 30, 2023		100,000	$	17.30		9.35	$	1,080

Exercisable—September 30, 2023		33,332	$	17.30		9.35

As of September 30, 2023, total unrecognized compensation cost related to unvested awards to employees is $0.2

million, which is expected to be recognized in October 2023 as a result of the Company’s merger (see Note 15).

Stock-Based Compensation

The Company recorded stock-based compensation expense

regarding

its employees, directors, and nonemployees as follows

(in thousands)


	Three months ended September 30,				Nine months ended September 30,
	2023		2022		2023		2022
Research and development expense	$	40	$	1,742	$	1,856	$	4,722
General and administrative expense		1,207		1,299		4,224		3,362

Total	$	1,247	$	3,041	$	6,080	$	8,084

Net Loss Per Share Attributable to Common Stockholders (Tables)

9 Months Ended

Sep. 30, 2023

Earnings Per Share [Abstract]

Summary of Computation of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders

The following table summarizes the computation of basic and diluted net loss per share attributable to common stockholders of the Company

(in thousands except share and per share amounts


	Three months ended September 30,						Nine months ended September 30,
	2023			2022			2023			2022
Net loss and net loss attributable to common stockholders	$	(7,015	)	$	(19,011	)	$	(44,250	)	$	(55,366	)
Net loss per share attributable to common stockholders, basic and diluted	$	(1.64	)	$	(4.59	)	$	(10.48	)	$	(13.45	)
Weighted average number of common shares outstanding used in computation of net loss per common share, basic and diluted		4,271,920			4,137,553			4,221,205			4,114,939

Summary of Potential Dilutive Securities Excluded From Calculation of Net Loss Per Share Due to Anti-dilutive Effect

The following potential dilutive securities, presented on an as converted basis, were excluded from the calculation of net loss per share due to their anti-dilutive effect:


	Nine months ended September 30,
	2023		2022
Options to purchase common stock		533,900		623,298
Restricted stock units		60,478		112,701
Restricted stock related to early exercise of options to purchase common stock		5,281		23,792
Stock appreciation rights		100,000		—

		599,659		759,791

Restructuring Costs (Tables)

9 Months Ended

Sep. 30, 2023

Restructuring and Related Activities [Abstract]

Schedule of Restructuring Liability

The Company’s restructuring liability, which is included in accrued compensation and benefit costs (see Note 9), consisted of the following

(in thousands)


	Employee-Related Costs
	Three months ended September 30, 2023			Nine months ended September 30, 2023

Accrued restructuring balance at beginning of period	$	3,262		$	—
Expenses incurred		89			7,535
Payments		(1,993	)		(6,177	)

Accrued restructuring balance at September 30, 2023	$	1,358		$	1,358

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended			9 Months Ended
	Jun. 30, 2023	Sep. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Jan. 01, 2022
Summary Of Significant Accounting Policies [Line Items]
Non-cash impairment expense	$ 500,000	$ 200,000	$ 2,700,000	$ 3,600,000	$ 3,600,000	$ 200,000
Expected dividend yield					0.00%
Right-of-use assets		$ 0			$ 0		$ 2,643,000	$ 3,400,000
Operating lease liability								$ 3,500,000
Leasehold Improvements
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life		5 years			5 years
Property, plant and equipment, useful life		us-gaap:UsefulLifeShorterOfTermOfLeaseOrAssetUtilityMember			us-gaap:UsefulLifeShorterOfTermOfLeaseOrAssetUtilityMember
Computer Equipment and Computer Software
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life		3 years			3 years
Minimum \| Money Market Funds
Summary Of Significant Accounting Policies [Line Items]
Investment in assets		$ 1,000,000,000			$ 1,000,000,000
Minimum \| Equipment and Furniture and Fixtures
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life		5 years			5 years
Maximum \| Equipment and Furniture and Fixtures
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life		7 years			7 years

Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Sep. 30, 2023	Dec. 31, 2022
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	140,000,000	140,000,000
Common stock, shares issued	4,282,848	4,162,942
Common stock, shares outstanding	4,282,848	4,162,942
Non-voting Shares
Common stock, shares authorized	10,000,000	10,000,000

Prepaid and Other Current Assets (Tables)

9 Months Ended

Sep. 30, 2023

Prepaid Expense and Other Assets, Current [Abstract]

Summary of Prepaid and Other Current Assets

Prepaid and other current assets consisted of the following

(in thousands)


	September 30,		December 31,
	2023		2022

Prepaid insurance	$	1,179	$	1,037
Prepaid research and development expenses		—		2,426
Receivable from asset sale		1,350		—
Other current assets		1,494		868

Total prepaid and other current assets	$	4,023	$	4,331

Marketable Securities - Summary of Company's Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Marketable Securities [Line Items]
Amortized Cost	$ 80,056	$ 168,333
Unrealized Gain	4	19
Unrealized (Loss)	(119)	(740)
Estimated Fair Value	79,941	167,612
Commercial paper
Marketable Securities [Line Items]
Amortized Cost	35,371	119,313
Unrealized Gain	1	19
Unrealized (Loss)	(54)	(365)
Estimated Fair Value	35,318	118,967
Corporate debt securities
Marketable Securities [Line Items]
Amortized Cost		43,016
Unrealized (Loss)		(368)
Estimated Fair Value		42,648
Government and agency securities
Marketable Securities [Line Items]
Amortized Cost	44,685	6,004
Unrealized Gain	3
Unrealized (Loss)	(65)	(7)
Estimated Fair Value	$ 44,623	$ 5,997

Subsequent Events	9 Months Ended
Subsequent Events	Sep. 30, 2023
Subsequent Events [Abstract]
Subsequent Events	15. Subsequent Events The Company has evaluated subsequent events through November 14, 2023, the date the financial statements were available to be issued. The Company has concluded no subsequent events have occurred that require disclosure, except for those referenced below. ImmunoFree Demand Letter On October 6, 2023, the Company and ImmunoFree executed a binding settlement agreement (the “Settlement Agreement”) pursuant to which the Company paid ImmunoFree $4.0 million and ImmunoFree and the Company mutually released each other from any and all claims, liabilities and/or losses relating to the ImmunoFree APA, the FREEDOM-1 Study, and the ImmunoFree Demand Letter and the allegations therein. As set forth in the Settlement Agreement, the Company denies any and all liability with respect to this matter, and has resolved it solely to avoid the risks and costs associated with litigating this matter and any risk to the consummation of the Merger Agreement. Lease Termination On October 4, 2023, the Company entered into a lease termination agreement related to its Boston Lease. Pursuant to the terms of the lease termination agreement, the Company agreed to pay a termination fee of $ 0.7 million, consisting of a payment of $0.6 million in cash and $0.1 million non-cash consideration for its security deposit. These amounts are included in lease liability, current and other current assets in the accompanying balance sheets as of September 30, 2023. In connection with the lease termination, the Company sold its remaining long-lived assets held for sale, primarily office furniture and computer equipment. Reverse Stock Split Immediately prior to the effective time of the Merger, the Company effected a 1-for-10 Reverse Stock Split of its shares of common stock. As a result of the Reverse Stock Split, every 10 shares of the Company’s common stock held by a stockholder immediately prior to the Reverse Stock Split were combined and reclassified into one share of the Company’s common stock. No fractional shares were issued in connection with the Reverse Stock Split. Any fractional shares resulting from the Reverse Stock Split were rounded down to the nearest whole number, and each Company stockholder who would otherwise be entitled to a fraction of a share of common stock upon the Reverse Stock Split (after aggregating all fractions of a share to which such stockholder would otherwise be entitled) was entitled to receive a cash payment in lieu thereof at a price equal to the fraction to which the stockholder would otherwise be entitled multiplied by the closing price of the Company’s common stock on October 19, 2023. No fractional shares of Company common stock were issuable to Legacy Tourmaline stockholders pursuant to the Merger, and no certificates or scrip for any such fractional shares were issued, with no cash being paid for any fractional share eliminated by such rounding. Merger Agreement and Financing Transaction On October 19, 2023, the Company completed the Merger with Legacy Tourmaline. In connection with the Merger, the Company declared a special cash dividend to its stockholders on October 6, 2023 (the “Special Dividend”). The Special Dividend was $15.118 per share of Company common stock, payable in cash. The ex-dividend date in respect to the Special Dividend was before market open on October 20, 2023, and only pre-Merger stockholders of record as of October 16, 2023, record date for the Special Dividend , that continued to hold their eligible shares of the Company until market open on October 20, 2023 were entitled to the dividend payment. The Special Dividend was $ 64.7 million ($67.5 million less the Aggregate Cash Amount (as defined in the Merger Agreement)) and was contingent upon closing of the Merger. Subject to the terms of the Merger Agreement, immediately prior to effective time of the Merger, (a) all unexpired and unvested Company stock options, stock appreciation rights, and restricted stock units were accelerated, (b) all outstanding Company restricted stock units and all outstanding and in-the-money Company stock options and stock appreciation rights were settled for consideration equal to (i) 55% of each award’s value in shares of Company common stock and (ii) 45% of each award’s value in cash, and (c) all out-of-the-money outstanding Company stock options and stock appreciation rights were cancelled for no consideration. As a result, the Company issued 176,835 shares of Company common stock and paid an Aggregate Cash Amount (as defined in the Merger Agreement) of $2.8 million to certain pre-Merger holders of Company stock options, stock appreciation rights and restricted stock units. Subject to the terms of the Merger Agreement, immediately prior to the effective time of the Merger, (a) certain new and current investors of Legacy Tourmaline purchased an aggregate of $ 75.0 million of common stock of Legacy Tourmaline (the “Pre-Merger Financing Transaction”) and (b) each share of Legacy Tourmaline’s preferred stock was converted into one share of Legacy Tourmaline’s common stock. At the effective time of the Merger, the Company issued an aggregate of approximately 15,877,090 shares of its common stock to Legacy Tourmaline’s stockholders, based on an exchange ratio of 0.7977 (without giving effect to the Reverse Stock Split) shares of the Company’s common stock for each share of Legacy Tourmaline common stock outstanding immediately prior to the Merger, including those shares of common stock issued upon the conversion of Legacy Tourmaline preferred stock and those shares of Legacy Tourmaline common stock issued in the Pre-Merger Financing Transaction (but excluding shares canceled pursuant to the Merger Agreement and excluding any dissenting shares). The issuance of the shares of the Company’s common stock issued to the former stockholders of Legacy Tourmaline was registered with the Securities and Exchange Commission on the Company’s Registration Statement on Form S-4 (File No. 333-273335), as amended. Immediately following the effective time of the Merger, 20,336,741 shares of the Company’s common stock were issued and outstanding. Company securityholders as of immediately prior to the Merger owned approximately 21.9 % of the outstanding shares of the Company and former Legacy Tourmaline securityholders, including those who purchased shares in the Pre-Merger Financing Transaction, owned approximately 78.1 % of the outstanding shares of the Company. In connection with the Merger, the Company paid an estimated $6.2 million for transaction-related expenses contingent on the Merger, including payments to certain former Talaris employees. The Company is still evaluating the accounting impact of the Merger.

Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Accrued Liabilities, Current [Abstract]
Compensation and benefit costs	$ 1,498	$ 3,566
Research and development expenses	418	1,978
Legal settlement	4,000
Professional fees, consulting and other	1,372	1,121
Total accrued expenses	$ 7,288	$ 6,665

Property and Equipment, Net and Assets Held for Sale (Tables)

9 Months Ended

Sep. 30, 2023

Property, Plant and Equipment [Abstract]

Schedule of Property and Equipment, Net

Property and equipment, net consisted of the following

(in thousands)


	September 30,		December 31,
	2023		2022

Equipment	$	—	$	6,562
Leasehold improvements		—		1,191
Computer equipment		—		859
Furniture and fixtures		—		674
Construction in progress		—		242

Total property and equipment		—		9,528
Less accumulated depreciation		—		(4,180	)

Property and equipment, net	$	—	$	5,348

Accrued Expenses

9 Months Ended

Sep. 30, 2023

Accrued Liabilities, Current [Abstract]

Accrued Expenses

9. Accrued Expenses

Accrued expenses consisted of the following

(in thousands)


	September 30,		December 31,
	2023		2022

Compensation and benefit costs	$	1,498	$	3,566
Research and development expenses		418		1,978
Legal settlement		4,000		—
Professional fees, consulting and other		1,372		1,121

Total accrued expenses	$	7,288	$	6,665

Defined Contribution Plan	9 Months Ended
Defined Contribution Plan	Sep. 30, 2023
Retirement Benefits [Abstract]
Defined Contribution Plan	14. Defined Contribution Plan The Company established a defined contribution savings plan under Section 401(k) of the Internal Revenue Code. This plan covers substantially all employees who meet minimum age and service requirements and allows participants to defer a portion of their annual compensation on a pretax basis. Current Company match contributions to the plan are made to employees who meet minimum service requirements in the amount of 100% of the first 3%, and 50% of the next 2 % of employee contributions, subject to certain limitations. Contributions made by the Company were immaterial and $ 0.3 million for the three and nine months ended September 30, 2023, respectively, and $0.1 million and $0.4 million for the three and nine months ended September 30, 2022, respectively.

Commitments and Contingencies - Additional Information (Details)		1 Months Ended						3 Months Ended		9 Months Ended
	Jul. 31, 2021	Oct. 31, 2023 USD ($)	Sep. 30, 2023 USD ($) shares	Jan. 31, 2023 USD ($)	Feb. 28, 2022 USD ($)	May 31, 2021 USD ($) shares	Oct. 31, 2018 USD ($) shares	Sep. 30, 2023 USD ($) shares	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) Leaseagreement shares	Sep. 30, 2022 USD ($)	Oct. 19, 2023 shares	Dec. 31, 2022 shares
Loss Contingencies [Line Items]
Number of active lease agreements \| Leaseagreement										1
Lessee, operating lease, existence of option to extend										true
Lease option to extend										three additional one-year
Lease termination date										Nov. 30, 2023
Rent expense								$ 200,000	$ 300,000	$ 700,000	$ 800,000
Common stock issued \| shares			4,282,848					4,282,848		4,282,848			4,162,942
Annual maintenance fee pursuant to license agreement					$ 100,000
Annual maintenance fee pursuant to ULRF license agreement				$ 100,000
Cash paid for measurement of operating lease liability								$ 300,000	$ 200,000	$ 500,000	$ 600,000
Operating leases future minimum rent payments			$ 600,000
Subsequent Event [Member]
Loss Contingencies [Line Items]
Common stock issued \| shares												176,835
ImmunoFree, Inc.
Loss Contingencies [Line Items]
Loss contingency, loss in period								$ 4,000,000		$ 4,000,000
ULRF
Loss Contingencies [Line Items]
Common stock issued \| shares						16,297
ULRF \| IPO
Loss Contingencies [Line Items]
Common stock issued \| shares						48,889
Cash payment for contingent equity settlement						$ 300,000
ULRF License Agreement \| ULRF
Loss Contingencies [Line Items]
Percentage of compensation on net sales of all licensed products sold							3.00%
Compensation on non-royalty sublicensing income										one third
ULRF License Agreement \| ULRF \| Contingent Equity Consideration
Loss Contingencies [Line Items]
Common stock issued \| shares							65,186
ULRF License Agreement \| ULRF \| Maximum
Loss Contingencies [Line Items]
Compensation on regulatory and sales milestones							$ 1,625,000
Massachusetts
Loss Contingencies [Line Items]
Lease termination date										Mar. 31, 2021
Non-cash impairment expense of right-of-use asset										$ 500,000
Houston, Texas
Loss Contingencies [Line Items]
Lease term period	36 months
Termination date	December 2024
M A \| Subsequent Event [Member]
Loss Contingencies [Line Items]
Payment Of Termination Of Lease		$ 600,000
Gain (Loss) on Termination of Lease		$ 600,000

Marketable Securities

9 Months Ended

Sep. 30, 2023

Marketable Securities [Abstract]

Marketable Securities

4. Marketable Securities

The fair value of the Company’s marketable securities as of September 30, 2023 and December 31, 2022 is based on level 1 and level 2 inputs. The Company’s investments consist mainly of U.S. government and agency securities, government-sponsored bond obligations and certain other corporate debt securities. Fair value is determined by taking into consideration valuations obtained from third-party pricing services. The third-party pricing services utilize industry standard valuation models, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include reported trades of and broker/dealer quotes on the same or similar securities; issuer credit spreads; benchmark securities; and other observable inputs. There were no transfers between levels within the hierarchy during the nine months ended September 30, 2023 and the year ended December 31, 2022. The Company has assessed U.S. government treasuries as level 1 and all other marketable securities as level 2 within the fair value hierarchy of ASC 820. The Company classifies its entire investment portfolio as

available-for-sale

as defined in ASC 320, Debt Securities. Securities are carried at fair value with the unrealized gains (losses) reported in other comprehensive loss.

As of September 30, 2023 and December 31, 2022, none of the Company’s investments were determined to be other than temporarily impaired.

The following table summarizes the Company’s investments

(in thousands)


	September 30, 2023
	Amortized Cost		Unrealized Gain		Unrealized (Loss)			Estimated Fair Value
Commercial paper	$	35,371	$	1	$	(54	)	$	35,318
Government and agency securities		44,685		3		(65	)		44,623

Total	$	80,056	$	4	$	(119	)	$	79,941


	December 31, 2022
	Amortized Cost		Unrealized Gain		Unrealized (Loss)			Estimated Fair Value
Commercial paper	$	119,313	$	19	$	(365	)	$	118,967
Government and agency securities		43,016		—		(368	)		42,648
Corporate debt securities		6,004		—		(7	)		5,997

Total	$	168,333	$	19	$	(740	)	$	167,612

The aggregate fair value of

available-for-sale

securities in an unrealized loss position as of September 30, 2023 was $61.1 million. The Company has reviewed its portfolio of

available-for-sale

debt securities and determined that the decline in fair value below cost did not result from credit-loss related factors. As such, no allowance for credit losses

was

recorded as of September 30, 2023.

Prepaid and Other Current Assets - Summary of Prepaid and Other Current Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid insurance	$ 1,179	$ 1,037
Prepaid research and development expenses		2,426
Receivable from asset sale	1,350
Other current assets	1,494	868
Total prepaid and other current assets	$ 4,023	$ 4,331

Net Loss Per Share Attributable to Common Stockholders - Summary of Computation of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended		12 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Earnings Per Share [Abstract]
Net loss and net loss attributable to common stockholders	$ (7,015)	$ (14,738)	$ (22,497)	$ (19,011)	$ (18,096)	$ (18,259)	$ (44,250)	$ (55,366)	$ (73,900)
Net loss per share attributable to common stockholders, basic	$ (1.64)			$ (4.59)			$ (10.48)	$ (13.45)
Net loss per share attributable to common stockholders, diluted	$ (1.64)			$ (4.59)			$ (10.48)	$ (13.45)
Weighted average number of common shares outstanding used in computation of net loss per common share, basic	4,271,920			4,137,553			4,221,205	4,114,939
Weighted average number of common shares outstanding used in computation of net loss per common share, diluted	4,271,920			4,137,553			4,221,205	4,114,939

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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+ Details

Cover Page - shares	9 Months Ended
Cover Page - shares	Sep. 30, 2023	Nov. 10, 2023
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Trading Symbol	TRML
Entity Registrant Name	TOURMALINE BIO, INC.
Entity Central Index Key	0001827506
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Common Stock, Shares Outstanding		20,336,741
Entity Current Reporting Status	Yes
Entity Shell Company	false
Title of 12(b) Security	Common Stock, $0.0001 par value per share
Security Exchange Name	NASDAQ
Document Quarterly Report	true
Document Transition Report	false
Entity Interactive Data Current	Yes
Entity File Number	001-40384
Entity Tax Identification Number	83-2377352
Entity Incorporation, State or Country Code	DE
Entity Address, Address Line One	27 West 24th Street
Entity Address, Address Line Two	Suite 702
Entity Address, City or Town	New York
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10010
City Area Code	646
Local Phone Number	481-9832

Common Stock (Table)

9 Months Ended

Sep. 30, 2023

Stockholders' Equity Note [Abstract]

Schedule of Common Stock Reserved


	September 30,		December 31,
	2023		2022

Restricted stock related to early exercise of common stock options		5,281		15,815
Restricted stock units outstanding		60,478		114,461
Outstanding common stock options		533,900		626,373
Outstanding stock appreciation rights		100,000		—
Shares reserved for issuance under equity incentive plans		227,602		75,843
Shares reserved for issuance under the 2021 Employee Stock Purchase Plan		158,109		116,644

Total		1,085,370		949,136

Property and Equipment, Net and Assets Held for Sale - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 0	$ 9,528
Less accumulated depreciation		(4,180)
Property and equipment, net	$ 0	5,348
Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross		6,562
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross		1,191
Computer Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross		859
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property and equipment, gross		674
Construction in Progress
Property Plant And Equipment [Line Items]
Property and equipment, gross		$ 242

Net Loss Per Share Attributable to Common Stockholders

9 Months Ended

Sep. 30, 2023

Earnings Per Share [Abstract]

Net Loss Per Share Attributable to Common Stockholders

13. Net Loss Per Share Attributable to Common Stockholders

The following table summarizes the computation of basic and diluted net loss per share attributable to common stockholders of the Company

(in thousands except share and per share amounts


	Three months ended September 30,						Nine months ended September 30,
	2023			2022			2023			2022
Net loss and net loss attributable to common stockholders	$	(7,015	)	$	(19,011	)	$	(44,250	)	$	(55,366	)
Net loss per share attributable to common stockholders, basic and diluted	$	(1.64	)	$	(4.59	)	$	(10.48	)	$	(13.45	)
Weighted average number of common shares outstanding used in computation of net loss per common share, basic and diluted		4,271,920			4,137,553			4,221,205			4,114,939

The Company’s potential dilutive securities, which include convertible preferred stock, contingent stock liabilities, restricted stock related to early exercise of common stock options and common stock options, have been excluded from the computation of diluted net loss per share as the effect would be antidilutive. Therefore, the weighted average number of common shares outstanding used to calculate both basic and diluted net loss per share attributable to common stockholders is the same. The following potential dilutive securities, presented on an as converted basis, were excluded from the calculation of net loss per share due to their anti-dilutive effect:


	Nine months ended September 30,
	2023		2022
Options to purchase common stock		533,900		623,298
Restricted stock units		60,478		112,701
Restricted stock related to early exercise of options to purchase common stock		5,281		23,792
Stock appreciation rights		100,000		—

		599,659		759,791

Fair Value of Financial Assets (Tables)

9 Months Ended

Sep. 30, 2023

Fair Value Disclosures [Abstract]

Summary of Financial Instruments Measured at Fair Value on Recurring Basis

(in thousands)


	September 30, 2023
	Total		Level 1		Level 2		Level 3
Financial assets:
Money market funds (cash equivalents)	$	66,719	$	66,719	$	—	$	—
Marketable securities		79,941		7,826		72,115		—

Total financial assets measured at fair value	$	146,660	$	74,545	$	72,115	$	—


	December 31, 2022
	Total		Level 1		Level 2		Level 3
Financial assets:
Money market funds (cash equivalents)	$	12,309	$	12,309	$	—	$	—
Marketable securities		167,612		31,718		135,894		—

Total financial assets measured at fair value	$	179,921	$	44,027	$	135,894	$	—

Restructuring Costs - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 89	$ 10,958
Severance and Termination
Restructuring Cost and Reserve [Line Items]
Restructuring costs	89	7,535
Impairment Expense
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 0	$ 3,400

- 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

Stock-Based Compensation - Summary of Additional Information to Stock Option Activity Involving Employees and Directors (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Additional Disclosures [Abstract]
Weighted-average grant-date fair value per option of total options granted	$ 13.73	$ 60.4
Aggregate intrinsic value of stock options exercised	$ 489	$ 286

Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Operating expenses
Research and development	$ 267	$ 14,981	$ 17,770	$ 42,364
General and administrative	9,114	4,842	21,322	14,288
Restructuring costs	89		10,958
Total operating expenses	9,470	19,823	50,050	56,652
Gain on asset sales	538		538	0
Loss from operations	(8,932)	(19,823)	(49,512)	(56,652)
Interest and other income (expense), net	1,917	812	5,262	1,286
Net loss	(7,015)	(19,011)	(44,250)	(55,366)
Unrealized gain (loss) on marketable securities	99	(79)	606	(1,144)
Total comprehensive loss	(6,916)	(19,090)	(43,644)	(56,510)
Net loss	$ (7,015)	$ (19,011)	$ (44,250)	$ (55,366)
Net loss per common share, basic	$ (1.64)	$ (4.59)	$ (10.48)	$ (13.45)
Net loss per common share, diluted	$ (1.64)	$ (4.59)	$ (10.48)	$ (13.45)
Weighted average number of common shares outstanding used in computation of net loss per common share, basic	4,271,920	4,137,553	4,221,205	4,114,939
Weighted average number of common shares outstanding used in computation of net loss per common share, diluted	4,271,920	4,137,553	4,221,205	4,114,939