Organization and Basis of Presentation	12 Months Ended
Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	1. Organization and Basis of Presentation Organization Calithera Biosciences, Inc., or the Company, was incorporated in the State of Delaware on March 9, 2010. Until recently, the Company was a fully-integrated, clinical stage precision oncology biopharmaceutical company. On January 9, 2023, the Company announced, after extensive consideration of potential strategic alternatives, the Company’s Board of Directors unanimously approved the dissolution and liquidation of the Company pursuant to a plan of complete liquidation and dissolution, or the Plan of Dissolution, subject to stockholder approval. In connection with the Plan of Dissolution, the Company began discontinuing all clinical programs and commenced reducing its workforce, which includes the planned termination of most employees by the end of the first quarter, and began the wind-up of its operations. The Company is seeking to sell all of its clinical assets and programs. The Plan of Dissolution has not been brought to a vote of or approved by the Company’s stockholders. The Company’s principal operations are based in South San Francisco, California, and it operates in one segment. Presentation The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries, Calithera Biosciences UK Limited and Calithera Biosciences Ireland Limited. All significant intercompany accounts and transactions have been eliminated from the consolidated financial statements. The Company's Ability to Continue as a Going Concern As of December 31, 2022, the Company had cash and cash equivalents of $25.5 million. The Company has incurred losses since inception and to date has financed its operations primarily through the sale of shares of its capital stock and payments from the Company’s collaboration and licensing agreements. As of December 31, 2022, the Company had an accumulated deficit of $512.6 million. During the year ended December 31, 2022, the Company incurred a loss from continuing operations of $39.7 million and used $43.6 million of cash in operations. The Company expects to continue to generate operating losses and negative operating cash flows for the foreseeable future, including through the execution of the Plan of Dissolution if approved by the Company’s stockholders. In accordance with Accounting Standards Codification, or ASC, 205-40, Going Concern, the Company evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about its ability to continue as a going concern within one year after the date that these consolidated financial statements are issued on March 30, 2023. The Company has determined that its cash and cash equivalents as of December 31, 2022 would be insufficient to fund its operations for a period of at least twelve months from the date of these financial statements which raises substantial doubt regarding the Company’s ability to continue as a going concern. As of December 31, 2022, the Company, including its Board of Directors, continued to evaluate potential strategic alternatives to fund and develop the Company’s programs. On January 9, 2023, the Company announced that the Company’s Board of Directors unanimously approved the Plan of Dissolution. As the Company continued to evaluate potential strategic alternatives as of December 31, 2022 and as the Plan of Dissolution was not approved by the Company’s Board of Directors as of December 31, 2022 and has not yet been brought to a vote of or approved by the Company’s stockholders, the Company concluded that the liquidation basis of accounting should not be applied as of the balance sheet date. Accordingly, the accompanying financial statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the ordinary course of business. The financial statements do not include any adjustments relating to the recoverability and classification of recorded asset amounts or the amounts and classification of liabilities that might result from the outcome of the uncertainties described above. Certain Effects of the Reverse Stock Split The Company's stockholders approved a reverse stock split of the Company's common stock on June 1, 2022, which became effective on June 14, 2022, or the Reverse Stock Split. On that date, every 20 issued and outstanding shares of the Company's common stock automatically converted into one outstanding share of common stock. As a result of the Reverse Stock Split, the number of the outstanding shares of common stock decreased from 97,300,826 (pre-split) shares to 4,865,036 (post-split) shares. In addition, by reducing the number of outstanding shares, the Company's loss per share in all prior periods increased by a factor of 20. The Reverse Stock Split affected all shares of common stock outstanding immediately prior to the effective time of the Reverse Stock Split, as well as the number of shares of common stock available for issuance under the Company's equity incentive plans and employee stock purchase plan. In addition, the Reverse Stock Split effected a reduction in the number of shares of common stock issuable upon the conversion of shares of Series A convertible preferred stock, or the Series A preferred stock, and upon the exercise of the stock options and warrants outstanding immediately prior to the effectiveness of the Reverse Stock Split. The reverse stock split affected all holders of common stock uniformly, and did not affect any stockholder's percentage of ownership interest. The par value of the Company's common stock remained unchanged at $0.0001 per share and the number of authorized shares of common stock remained the same after the Reverse Stock Split. As the par value per share of the Company's common stock remained unchanged at $0.0001 per share, the change in the common stock recorded at par value has been reclassified to additional paid-in-capital on a retroactive basis. All references to shares of common stock and per share data for all periods presented in the accompanying financial statements and notes thereto have been adjusted to reflect the reverse stock split on a retroactive basis.

Organization and Basis of Presentation

12 Months Ended

Dec. 31, 2022

Organization, Consolidation and Presentation of Financial Statements [Abstract]

1. Organization and Basis of Presentation

Organization

Calithera Biosciences, Inc., or the Company, was incorporated in the State of Delaware on March 9, 2010. Until recently, the Company was a fully-integrated, clinical stage precision oncology biopharmaceutical company. On January 9, 2023, the Company announced, after extensive consideration of potential strategic alternatives, the Company’s Board of Directors unanimously approved the dissolution and liquidation of the Company pursuant to a plan of complete liquidation and dissolution, or the Plan of Dissolution, subject to stockholder approval. In connection with the Plan of Dissolution, the Company began discontinuing all clinical programs and commenced reducing its workforce, which includes the planned termination of most employees by the end of the first quarter, and began the wind-up of its operations. The Company is seeking to sell all of its clinical assets and programs. The Plan of Dissolution has not been brought to a vote of or approved by the Company’s stockholders. The Company’s principal operations are based in South San Francisco, California, and it operates in one segment.

Presentation

The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries, Calithera Biosciences UK Limited and Calithera Biosciences Ireland Limited. All significant intercompany accounts and transactions have been eliminated from the consolidated financial statements.

The Company's Ability to Continue as a Going Concern

As of December 31, 2022, the Company had cash and cash equivalents of $25.5 million. The Company has incurred losses since inception and to date has financed its operations primarily through the sale of shares of its capital stock and payments from the Company’s collaboration and licensing agreements. As of December 31, 2022, the Company had an accumulated deficit of $512.6 million. During the year ended December 31, 2022, the Company incurred a loss from continuing operations of $39.7 million and used $43.6 million of cash in operations. The Company expects to continue to generate operating losses and negative operating cash flows for the foreseeable future, including through the execution of the Plan of Dissolution if approved by the Company’s stockholders.

In accordance with Accounting Standards Codification, or ASC, 205-40, Going Concern, the Company evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about its ability to continue as a going concern within one year after the date that these consolidated financial statements are issued on March 30, 2023. The Company has determined that its cash and cash equivalents as of December 31, 2022 would be insufficient to fund its operations for a period of at least twelve months from the date of these financial statements which raises substantial doubt regarding the Company’s ability to continue as a going concern.

As of December 31, 2022, the Company, including its Board of Directors, continued to evaluate potential strategic alternatives to fund and develop the Company’s programs. On January 9, 2023, the Company announced that the Company’s Board of Directors unanimously approved the Plan of Dissolution. As the Company continued to evaluate potential strategic alternatives as of December 31, 2022 and as the Plan of Dissolution was not approved by the Company’s Board of Directors as of December 31, 2022 and has not yet been brought to a vote of or approved by the Company’s stockholders, the Company concluded that the liquidation basis of accounting should not be applied as of the balance sheet date. Accordingly, the accompanying financial statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the ordinary course of business. The financial statements do not include any adjustments relating to the recoverability and classification of recorded asset amounts or the amounts and classification of liabilities that might result from the outcome of the uncertainties described above.

Certain Effects of the Reverse Stock Split

The Company's stockholders approved a reverse stock split of the Company's common stock on June 1, 2022, which became effective on June 14, 2022, or the Reverse Stock Split. On that date, every 20 issued and outstanding shares of the Company's common stock automatically converted into one outstanding share of common stock. As a result of the Reverse Stock Split, the number of the outstanding shares of common stock decreased from 97,300,826 (pre-split) shares to 4,865,036 (post-split) shares. In addition, by reducing the number of outstanding shares, the Company's loss per share in all prior periods increased by a factor of 20. The Reverse Stock Split affected all shares of common stock outstanding immediately prior to the effective time of the Reverse Stock Split, as well as the number of shares of common stock available for issuance under the Company's equity incentive plans and employee stock purchase plan. In addition, the Reverse Stock Split effected a reduction in the number of shares of common stock issuable upon the conversion of shares of Series A convertible preferred stock, or the Series A preferred stock, and upon the exercise of the stock options and warrants outstanding immediately prior to the effectiveness of the Reverse Stock Split. The reverse stock split affected all holders of common stock uniformly, and did not affect any stockholder's percentage of ownership interest. The par value of the Company's common stock remained unchanged at $0.0001 per share and the number of authorized shares of common stock remained the same after the Reverse Stock Split.

As the par value per share of the Company's common stock remained unchanged at $0.0001 per share, the change in the common stock recorded at par value has been reclassified to additional paid-in-capital on a retroactive basis. All references to shares of common stock and per share data for all periods presented in the accompanying financial statements and notes thereto have been adjusted to reflect the reverse stock split on a retroactive basis.

Calithera Biosciences, Inc. 10-K