The Company and Basis of Presentation	6 Months Ended
Jun. 30, 2023
Organization Consolidation And Presentation Of Financial Statements [Abstract]
The Company and Basis of Presentation	1. The Company and Basis of Presentation Aeglea BioTherapeutics, Inc. (“Aeglea” or the “Company”) is a preclinical stage biotechnology company focused on developing next generation therapeutics for patients living with inflammatory bowel disease. The Company was formed as a Limited Liability Company ("LLC") in Delaware on December 16, 2013 under the name Aeglea BioTherapeutics Holdings, LLC and was converted from a Delaware LLC to a Delaware corporation on March 10, 2015. The Company operates in one segment and has its principal offices in Waltham, Massachusetts. On April 12, 2023, based on the review of the inconclusive interim results from our Phase 1/2 clinical trial of pegtarviliase for the treatment of Classical Homocystinuria and other business considerations, the Company announced that it had initiated a process to explore strategic alternatives to maximize stockholder value and engaged an independent exclusive financial advisor to support this process. As a result, in April 2023, the Company implemented a restructuring plan resulting in an approximate 83% reduction of the Company’s existing headcount. On June 22, 2023, the Company acquired, in accordance with the terms of the Agreement and Plan of Merger (the "Acquisition Agreement"), the assets of Spyre Therapeutics, Inc ("Spyre"), as disclosed in Note 7 and 8, a privately held biotechnology company advancing a pipeline of antibody therapeutics with the potential to transform the treatment of inflammatory bowel disease through a research and development option agreement ("Paragon Agreement") with Paragon Therapeutics ("Paragon"). The transaction was structured as a stock-for-stock transaction pursuant to which all of Spyre's outstanding equity interests were exchanged based on a fixed exchange ratio of 13.73622 to 1 for consideration from Aeglea of 12,945,385 shares of common stock and 364,887 shares of Series A non-voting convertible preferred stock, par value of $0.0001 per share ("Series A Preferred Stock") (convertible on a 1,000 to 1 basis) in addition to the assumption of outstanding and unexercised stock options to purchase 68,365 shares of common stock from the Amended and Restated Spyre 2023 Equity Incentive Plan (the "Asset Acquisition"). The Aeglea common stock and Aeglea Series A Preferred Stock related to the Asset Acquisition were issued to the Spyre stockholders on July 7, 2023. For additional information, see Note 7 and 8. In connection with the Asset Acquisition, on June 26, 2023, the Company completed a private placement of shares of Series A Preferred Stock (the “PIPE”) to a group of investors (the “Investors”). The Company sold an aggregate of 721,452 shares of Series A Preferred Stock (the “PIPE Securities”) for an aggregate purchase price of approximately $210.0 million before deducting approximately $12.7 million placement agent and other offering expenses. For additional information, see Note 8. In connection with the Asset Acquisition, a non-transferable contingent value right ("CVR") was distributed to Aeglea stockholders of record as of the close of business on July 3, 2023 (the "Legacy Stockholders"), but was not distributed to the holders of shares of common stock or Series A Preferred Stock issued to the former stockholders of Spyre or Investors in the Transactions. Holders of the CVRs will be entitled to receive cash payments from proceeds received by Aeglea for a three-year period, if any, related to the disposition or monetization of its legacy assets for a period of one-year following the closing of the Asset Acquisition. For additional information see Note 3. Liquidity As of June 30, 2023, the Company had accumulated deficit of $661.1 million, and cash and cash equivalents of $235.4 million, which includes proceeds from the PIPE. The Company has not generated any product revenues and has not achieved profitable operations. There is no assurance that profitable operations will ever be achieved, and, if achieved, could be sustained on a continuing basis. In addition, development activities, clinical and nonclinical testing, and commercialization of the Company’s product candidates will require significant additional financing before a commercial drug can be produced and marketed. The Company is subject to a number of risks similar to other life science companies, including, but not limited to, risks related to the successful discovery, development, and commercialization of product candidates, raising additional capital, development of competing drugs and therapies, protection of proprietary technology and market acceptance of the Company’s product candidates. As a result of these and other factors and the related uncertainties, there can be no assurance of the Company’s future success. In April 2023, the Board of Directors approved a restructuring of the Company’s workforce pursuant to which the Company’s workforce was reduced by approximately 83%, retaining approximately 10 employees. Additionally, the Company announced interim results from its ongoing Phase 1/2 clinical trial of pegtarviliase for the treatment of classical homocystinuria. Following a review of the interim results and other business considerations, the Company explored strategic alternatives with the goal of maximizing stockholder value, including possible business combinations and/or a divestiture of the Company’s clinical programs. On June 22, 2023, the Company acquired, in accordance with the terms of the Acquisition Agreement, the net assets of Spyre, as disclosed in Note 7 and 8. Additionally, the Company completed the PIPE. In accordance with ASC 205-40, Going Concern, the Company has evaluated whether there are conditions and events, considered in the aggregate, 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. If our stockholders do not timely approve the conversion of our Series A Preferred Stock, then the holders of our Series A Preferred Stock may be entitled to require us to settle their shares of Series A Preferred Stock for cash at a price per share equal to the fair value of the Series A Preferred Stock, as described in our Certificate of Designation relating to the Series A Preferred Stock (see Note 9). The cash redemption is not in our control and raises substantial doubt about our ability to continue as a going concern. The accompanying condensed consolidated financial statements assume the Company will continue as a going concern through the realization of assets and satisfaction of liabilities and commitments in the ordinary course of business. Unaudited Interim Financial Information The interim condensed consolidated financial statements included in this document are unaudited. The unaudited interim financial statements have been prepared on the same basis as the annual financial statements and reflect, in the opinion of management, all adjustments of a normal and recurring nature that are necessary for a fair statement of the Company’s financial position as of June 30, 2023, and its results of operations for the three and six months ended June 30, 2023 and 2022, changes in convertible preferred stock and stockholders’ (deficit) equity for the three and six months ended June 30, 2023 and 2022, and cash flows for the six months ended June 30, 2023 and 2022. The results of operations for the three and six months ended June 30, 2023, are not necessarily indicative of the results to be expected for the year ending December 31, 2023 or for any other future annual or interim period. The December 31, 2022 balance sheet was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the United States (“U.S. GAAP”). These financial statements should be read in conjunction with the audited financial statements included in the Company’s Form 10-K for the year ended December 31, 2022 (the "Annual Report") as filed with the Securities and Exchange Commission ("SEC").

The Company and Basis of Presentation

6 Months Ended

Jun. 30, 2023

Organization Consolidation And Presentation Of Financial Statements [Abstract]

1. The Company and Basis of Presentation

Aeglea BioTherapeutics, Inc. (“Aeglea” or the “Company”) is a preclinical stage biotechnology company focused on developing next generation therapeutics for patients living with inflammatory bowel disease. The Company was formed as a Limited Liability Company ("LLC") in Delaware on December 16, 2013 under the name Aeglea BioTherapeutics Holdings, LLC and was converted from a Delaware LLC to a Delaware corporation on March 10, 2015. The Company operates in one segment and has its principal offices in Waltham, Massachusetts.

On April 12, 2023, based on the review of the inconclusive interim results from our Phase 1/2 clinical trial of pegtarviliase for the treatment of Classical Homocystinuria and other business considerations, the Company announced that it had initiated a process to explore strategic alternatives to maximize stockholder value and engaged an independent exclusive financial advisor to support this process. As a result, in April 2023, the Company implemented a restructuring plan resulting in an approximate 83% reduction of the Company’s existing headcount.

On June 22, 2023, the Company acquired, in accordance with the terms of the Agreement and Plan of Merger (the "Acquisition Agreement"), the assets of Spyre Therapeutics, Inc ("Spyre"), as disclosed in Note 7 and 8, a privately held biotechnology company advancing a pipeline of antibody therapeutics with the potential to transform the treatment of inflammatory bowel disease through a research and development option agreement ("Paragon Agreement") with Paragon Therapeutics ("Paragon"). The transaction was structured as a stock-for-stock transaction pursuant to which all of Spyre's outstanding equity interests were exchanged based on a fixed exchange ratio of 13.73622 to 1 for consideration from Aeglea of 12,945,385 shares of common stock and 364,887 shares of Series A non-voting convertible preferred stock, par value of $0.0001 per share ("Series A Preferred Stock") (convertible on a 1,000 to 1 basis) in addition to the assumption of outstanding and unexercised stock options to purchase 68,365 shares of common stock from the Amended and Restated Spyre 2023 Equity Incentive Plan (the "Asset Acquisition"). The Aeglea common stock and Aeglea Series A Preferred Stock related to the Asset Acquisition were issued to the Spyre stockholders on July 7, 2023. For additional information, see Note 7 and 8.

In connection with the Asset Acquisition, on June 26, 2023, the Company completed a private placement of shares of Series A Preferred Stock (the “PIPE”) to a group of investors (the “Investors”). The Company sold an aggregate of 721,452 shares of Series A Preferred Stock (the “PIPE Securities”) for an aggregate purchase price of approximately $210.0 million before deducting approximately $12.7 million placement agent and other offering expenses. For additional information, see Note 8.

In connection with the Asset Acquisition, a non-transferable contingent value right ("CVR") was distributed to Aeglea stockholders of record as of the close of business on July 3, 2023 (the "Legacy Stockholders"), but was not distributed to the holders of shares of common stock or Series A Preferred Stock issued to the former stockholders of Spyre or Investors in the Transactions. Holders of the CVRs will be entitled to receive cash payments from proceeds received by Aeglea for a three-year period, if any, related to the disposition or monetization of its legacy assets for a period of one-year following the closing of the Asset Acquisition. For additional information see Note 3.

Liquidity

As of June 30, 2023, the Company had accumulated deficit of $661.1 million, and cash and cash equivalents of $235.4 million, which includes proceeds from the PIPE. The Company has not generated any product revenues and has not achieved profitable operations. There is no assurance that profitable operations will ever be achieved, and, if achieved, could be sustained on a continuing basis. In addition, development activities, clinical and nonclinical testing, and commercialization of the Company’s product candidates will require significant additional financing before a commercial drug can be produced and marketed.

The Company is subject to a number of risks similar to other life science companies, including, but not limited to, risks related to the successful discovery, development, and commercialization of product candidates, raising additional capital, development of competing drugs and therapies, protection of proprietary technology and market acceptance of the Company’s product candidates. As a result of these and other factors and the related uncertainties, there can be no assurance of the Company’s future success.

In April 2023, the Board of Directors approved a restructuring of the Company’s workforce pursuant to which the Company’s workforce was reduced by approximately 83%, retaining approximately 10 employees. Additionally, the Company announced interim results from its ongoing Phase 1/2 clinical trial of pegtarviliase for the treatment of classical homocystinuria. Following a review of the interim results and other business considerations, the Company explored strategic

alternatives with the goal of maximizing stockholder value, including possible business combinations and/or a divestiture of the Company’s clinical programs.

On June 22, 2023, the Company acquired, in accordance with the terms of the Acquisition Agreement, the net assets of Spyre, as disclosed in Note 7 and 8. Additionally, the Company completed the PIPE.

In accordance with ASC 205-40, Going Concern, the Company has evaluated whether there are conditions and events, considered in the aggregate, 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. If our stockholders do not timely approve the conversion of our Series A Preferred Stock, then the holders of our Series A Preferred Stock may be entitled to require us to settle their shares of Series A Preferred Stock for cash at a price per share equal to the fair value of the Series A Preferred Stock, as described in our Certificate of Designation relating to the Series A Preferred Stock (see Note 9). The cash redemption is not in our control and raises substantial doubt about our ability to continue as a going concern. The accompanying condensed consolidated financial statements assume the Company will continue as a going concern through the realization of assets and satisfaction of liabilities and commitments in the ordinary course of business.

Unaudited Interim Financial Information

The interim condensed consolidated financial statements included in this document are unaudited. The unaudited interim financial statements have been prepared on the same basis as the annual financial statements and reflect, in the opinion of management, all adjustments of a normal and recurring nature that are necessary for a fair statement of the Company’s financial position as of June 30, 2023, and its results of operations for the three and six months ended June 30, 2023 and 2022, changes in convertible preferred stock and stockholders’ (deficit) equity for the three and six months ended June 30, 2023 and 2022, and cash flows for the six months ended June 30, 2023 and 2022. The results of operations for the three and six months ended June 30, 2023, are not necessarily indicative of the results to be expected for the year ending December 31, 2023 or for any other future annual or interim period. The December 31, 2022 balance sheet was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the United States (“U.S. GAAP”). These financial statements should be read in conjunction with the audited financial statements included in the Company’s Form 10-K for the year ended December 31, 2022 (the "Annual Report") as filed with the Securities and Exchange Commission ("SEC").