Aurinia expands autoimmune portfolio via Kezar acquisition

Aurinia Pharmaceuticals Inc., (NASDAQ: AUPH) has entered into a definitive merger agreement to acquire Kezar Life Sciences, Inc. (NASDAQ: KZR) at USD 6.955 per share in cash plus one non-transferable contingent value right (CVR) per share. The transaction consolidates zetomipzomib, a first-in-class selective immunoproteasome inhibitor with Phase IIa data in autoimmune hepatitis, into Aurinia's existing autoimmune franchise anchored by LUPKYNIS (voclosporin).

The upfront consideration is USD 6.955 per share in cash, with no aggregate equity value disclosed in the source material. The CVR captures three distinct contingent streams: potential payments tied to the ongoing clinical development or disposition of zetomipzomib; proceeds from Kezar's collaboration with Everest Medicines and Kezar's prior sale of its Sec61-based program to Enodia Therapeutics; and 100% of Kezar's closing net cash in excess of USD 50 million, net of post-closing CVR-related expenses. Closing net cash exceeding USD 50 million is a stated condition of the transaction. Tang Capital Partners, LP, holding approximately 9.0% of Kezar's outstanding shares, has executed a tender and support agreement. The transaction is expected to close in Q2 2026, subject to customary conditions including majority share tender. TD Cowen acted as exclusive financial advisor to Kezar, with Cooley LLP as legal counsel.

Immunoproteasome inhibition and the zetomipzomib mechanism

Zetomipzomib (KZR-616) selectively inhibits the immunoproteasome, a specialised catalytic variant of the ubiquitin-proteasome system expressed predominantly in immune cells including macrophages, B cells, and T cells. By blocking immunoproteasome activity, zetomipzomib suppresses the generation of MHC class I peptides and attenuates downstream production of pro-inflammatory cytokines, disrupting multiple inflammatory pathways through a single molecular target. This mechanism differentiates zetomipzomib from conventional immunosuppressants such as corticosteroids or calcineurin inhibitors, which act on broader, less selective pathways and carry well-documented toxicity profiles with chronic use.

In the PORTOLA Phase IIa study in autoimmune hepatitis (AIH), zetomipzomib achieved a 36% steroid-sparing remission rate (corticosteroids ≤5 mg/day) versus 0% in the placebo arm. AIH has seen no successful therapeutic trial in approximately 30 years, and current standard of care relies on chronic immunosuppression with azathioprine and corticosteroids. Kezar has completed a positive FDA Type C meeting directed at accelerating zetomipzomib's development pathway in AIH, with a Phase IIb study in planning. The asset also generated positive data in the MISSION Phase II study in systemic lupus erythematosus and preliminary efficacy signals in the PALIZADE Phase IIb study in lupus nephritis, though Kezar subsequently narrowed its development focus to AIH.

Aurinia's existing commercial asset, Lupyknis (voclosporin), is approved for adult patients with active lupus nephritis, positioning the company within the immune-mediated renal and hepatic disease space. Zetomipzomib's prior lupus nephritis data and its active AIH programme represent a mechanistically and commercially adjacent expansion. Aurinia's stated development pipeline also includes aritinercept, a dual inhibitor of B cell-activating factor (BAFF) and a proliferation-inducing ligand (APRIL), further anchoring the company's strategy in B cell-driven autoimmune pathologies — a disease biology that overlaps with the immunoproteasome's role in antigen presentation and lymphocyte activation.

Geographic rights to zetomipzomib are divided by a pre-existing licensing agreement. Everest Medicines holds exclusive rights to develop and commercialise zetomipzomib across Greater China, South Korea, and several Southeast Asian markets. Aurinia's effective commercial territory is therefore the United States, Europe, and remaining global markets. Proceeds from the Everest Medicines collaboration flow to Kezar shareholders through CVR component (ii), preserving economic participation in the Asian territorial value without requiring Aurinia to manage those development programmes directly.

The Sec61-based discovery platform, previously a secondary asset within Kezar's portfolio, was divested to Enodia Therapeutics prior to the merger closing, with residual milestone-based upside retained through the CVR structure. This divestiture effectively rendered the Aurinia transaction a focused, single-asset acquisition, with the CVR architecture confirming that zetomipzomib's development trajectory is the primary determinant of post-closing value for Kezar shareholders.

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