Organization and Description of the Business	12 Months Ended
Dec. 31, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of the Business	Organization and Description of the Business Description of Business Kezar Life Sciences, Inc. (the “Company”) was incorporated in Delaware on February 19, 2015, and commenced operations in June 2015. The Company is a clinical-stage biotechnology company, developing novel small molecule therapeutics to treat unmet needs in immune-mediated diseases. The Company’s principal operations are in South San Francisco, California, and it operates in one segment. Liquidity Since commencing operations in mid-2015, substantially all of the Company’s efforts have been focused on research, development and the advancement of zetomipzomib as well as the Company’s former product candidates. The Company’s ultimate success depends on the outcome of the ongoing research and development activities. The Company has not yet generated product sales and as a result has experienced operating losses since inception and had an accumulated deficit of $490.5 million as of December 31, 2025. Management believes that its cash and cash equivalents as of December 31, 2025 will be sufficient to fund the Company’s cash requirements for at least 12 months following the issuance of these financial statements. Restructuring In October 2025, the Company announced plans to explore a full range of strategic alternatives focused on maximizing stockholder value. If the process for evaluating strategic alternatives does not result in the Company consummating a transaction or any other strategic outcome, the Board of Directors may decide to pursue a dissolution and liquidation of the Company. On November 6, 2025, the Company reduced its workforce by approximately 70% in connection with its strategic review process. In connection with the restructuring, the Company recorded a restructuring charge of $6.8 million in the fourth quarter of 2025. The restructuring charge includes one-time severance and termination benefit expense for employees terminated with separation dates before December 31, 2025, and a charge related to the impairment of property and equipment. Refer to Note 16 for additional information on the restructuring. The Company expects to incur additional losses in the future to fund its operations as it evaluates strategic alternatives. Failure to manage discretionary spending during this time may adversely impact the Company’s ability to achieve its intended business objectives.

Kezar Life Sciences, Inc. (the “Company”) was incorporated in Delaware on February 19, 2015, and commenced operations in June 2015. The Company is a clinical-stage biotechnology company, developing novel small molecule therapeutics to treat unmet needs in immune-mediated diseases. The Company’s principal operations are in South San Francisco, California, and it operates in one segment.

Since commencing operations in mid-2015, substantially all of the Company’s efforts have been focused on research, development and the advancement of zetomipzomib as well as the Company’s former product candidates. The Company’s ultimate success depends on the outcome of the ongoing research and development activities. The Company has not yet generated product sales and as a result has experienced operating losses since inception and had an accumulated deficit of $490.5 million as of December 31, 2025. Management believes that its cash and cash equivalents as of December 31, 2025 will be sufficient to fund the Company’s cash requirements for at least 12 months following the issuance of these financial statements.

In October 2025, the Company announced plans to explore a full range of strategic alternatives focused on maximizing stockholder value. If the process for evaluating strategic alternatives does not result in the Company consummating a transaction or any other strategic outcome, the Board of Directors may decide to pursue a dissolution and liquidation of the Company.

On November 6, 2025, the Company reduced its workforce by approximately 70% in connection with its strategic review process. In connection with the restructuring, the Company recorded a restructuring charge of $6.8 million in the fourth quarter of 2025. The restructuring charge includes one-time severance and termination benefit expense for employees terminated with separation dates before December 31, 2025, and a charge related to the impairment of property and equipment. Refer to Note 16 for additional information on the restructuring.

The Company expects to incur additional losses in the future to fund its operations as it evaluates strategic alternatives. Failure to manage discretionary spending during this time may adversely impact the Company’s ability to achieve its intended business objectives.