Subsequent Events	3 Months Ended
Mar. 31, 2026
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Executive Separation Agreements On April 1, 2026, the Company entered into Separation Agreements with each of Christopher Kirk, Ph.D., the Company's Chief Executive Officer, Marc Belsky, the Company's Chief Financial Officer, and Mark Schiller, the Company's Chief Operating Officer (collectively, the “Separation Agreements”). Pursuant to the Separation Agreements, each executive's employment will be terminated on the closing date of the Merger, or such earlier date as determined by the applicable executive and the Company's board of directors. Each Separation Agreement provides for severance benefits consistent with those resulting from a Covered Termination (as defined in each executive's respective employment agreement) within three months prior to or twelve months following the effective date of a change in control. In addition, (i) Dr. Kirk will receive his Severance Payment (as defined in his respective Separation Agreement) in a lump sum payment, less applicable payroll deductions and withholdings, and (ii) each of Mr. Belsky and Mr. Schiller will receive a one-time cash payment equal to 12 months of cost of health insurance premiums at the time of termination. The foregoing severance benefits are contingent upon a general release of claims set forth in the Separation Agreements. In connection with the Separation Agreements, the vesting and exercisability of all outstanding stock options held by each executive will be accelerated in full upon such executive's termination date, and each executive's stock options may be exercised for a period of 90 days following such termination. Tender and Support Agreement In connection with the execution of the Merger Agreement, Tang Capital Partners, LP (the “Supporting Stockholder”), solely in its capacity as a holder of Shares, entered into a Tender and Support Agreement with Parent, Merger Sub and the Company, pursuant to which the Supporting Stockholder agreed, among other things, to tender all of the Shares held by the Supporting Stockholder in the Offer, subject to certain exceptions, including the valid termination of the Merger Agreement. The Supporting Stockholder held an aggregate of approximately 9.0% of the outstanding Shares as of March 30, 2026. The Tender and Support Agreement terminates upon the earliest of (i) the termination of the Merger Agreement and (ii) the effective time of the Merger. The Merger Agreement may be terminated by either the Company or Parent if the Offer has not been consummated on or before June 28, 2026 (the “Outside Date”), subject to certain conditions set forth in the Merger Agreement. Commencement of the Offer On April 13, 2026, pursuant to the Merger Agreement, Parent caused Merger Sub to commence the Offer to purchase all of the outstanding Shares at the Offer Price, consisting of (i) $6.955 per Share in cash, without interest, plus (ii) one CVR per Share. Legal Matters In April 2026, the Company began to receive demand letters on behalf of purported stockholders challenging certain disclosures in the recommendation statement filed with the SEC on April 14, 2026 (the “Recommendation Statement”), in connection with, among other things, the Merger Agreement. As of May 11, 2026, one complaint has been filed in federal court in Illinois by a purported stockholder against the Company and certain members of its Board in connection with the Merger: Elkerson v. Kezar Life Sciences, Inc., et al., Case No. 1:26-cv-05013 (N.D. Ill. filed April 30, 2026) (the “Merger Action”). The Merger Action asserts that the Recommendation Statement omitted certain allegedly material information regarding, among other things, purported conflicts of interest, transaction fees, and TD Cowen’s financial analyses, in violation of Sections 14(e) and 14(d)(4) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and Rule 14d-9 promulgated under the Exchange Act, rendering the Recommendation Statement false and misleading. The plaintiff in the Merger Action seeks, among other things, an injunction enjoining consummation of the Merger until the Company issues additional disclosures, rescission of the Merger if consummated or rescissory damages, and costs of the action, including attorneys’ fees and expert fees and expenses.

On April 1, 2026, the Company entered into Separation Agreements with each of Christopher Kirk, Ph.D., the Company's Chief Executive Officer, Marc Belsky, the Company's Chief Financial Officer, and Mark Schiller, the Company's Chief Operating Officer (collectively, the “Separation Agreements”). Pursuant to the Separation Agreements, each executive's employment will be terminated on the closing date of the Merger, or such earlier date as determined by the applicable executive and the Company's board of directors. Each Separation Agreement provides for severance benefits consistent with those resulting from a Covered Termination (as defined in each executive's respective employment agreement) within three months prior to or twelve months following the effective date of a change in control. In addition, (i) Dr. Kirk will receive his Severance Payment (as defined in his respective Separation Agreement) in a lump sum payment, less applicable payroll deductions and withholdings, and (ii) each of Mr. Belsky and Mr. Schiller will receive a one-time cash payment equal to 12 months of cost of health insurance premiums at the time of termination. The foregoing severance benefits are contingent upon a general release of claims set forth in the Separation Agreements. In connection with the Separation Agreements, the vesting and exercisability of all outstanding stock options held by each executive will be accelerated in full upon such executive's termination date, and each executive's stock options may be exercised for a period of 90 days following such termination.

In connection with the execution of the Merger Agreement, Tang Capital Partners, LP (the “Supporting Stockholder”), solely in its capacity as a holder of Shares, entered into a Tender and Support Agreement with Parent, Merger Sub and the Company, pursuant to which the Supporting Stockholder agreed, among other things, to tender all of the Shares held by the Supporting Stockholder in the Offer, subject to certain exceptions, including the valid termination of the Merger Agreement. The Supporting Stockholder held an aggregate of approximately 9.0% of the outstanding Shares as of March

In April 2026, the Company began to receive demand letters on behalf of purported stockholders challenging certain disclosures in the recommendation statement filed with the SEC on April 14, 2026 (the “Recommendation Statement”), in connection with, among other things, the Merger Agreement. As of May 11, 2026, one complaint has been filed in federal court in Illinois by a purported stockholder against the Company and certain members of its Board in connection with the Merger: Elkerson v. Kezar Life Sciences, Inc., et al., Case No. 1:26-cv-05013 (N.D. Ill. filed April 30, 2026) (the “Merger Action”). The Merger Action asserts that the Recommendation Statement omitted certain allegedly material information regarding, among other things, purported conflicts of interest, transaction fees, and TD Cowen’s financial analyses, in violation of Sections 14(e) and 14(d)(4) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and Rule 14d-9 promulgated under the Exchange Act, rendering the Recommendation Statement false and misleading. The plaintiff in the Merger Action seeks, among other things, an injunction enjoining consummation of the Merger until the Company issues additional disclosures, rescission of the Merger if consummated or rescissory damages, and costs of the action, including attorneys’ fees and expert fees and expenses.