Kezar Life Sciences (KZR) Jefferies Global Healthcare Conference 2025 summary

Company overview and lead asset

• Focused on developing zidomipzomib (Zido), a selective immunoproteasome inhibitor, for autoimmune hepatitis (AIH).

• Zido is the only agent in clinical development for refractory AIH, a disease affecting about 100,000 people in the U.S.

• Recent positive top-line data from the Portola study, the first randomized trial of a new agent in refractory AIH.

Mechanism of action and clinical results

• Zido modulates immune responses across all immune cell types without causing cell depletion or immunosuppression.

• Demonstrated rapid inflammation resolution and allowed significant steroid reduction or discontinuation in AIH patients.

• Over 30% of Zido-treated patients achieved remission with steroid taper; 25% achieved steroid-free remission.

• Median duration of response was just under seven months, exceeding expectations.

Safety, regulatory status, and next steps

• Partial clinical hold imposed due to fatalities in a lupus nephritis (LN) study, with fatalities balanced across arms and consistent with global LN trial rates.

• Safety profile in AIH is favorable; higher SAE rates in LN attributed to sicker populations and regional factors.

• Preparing an integrated safety summary for FDA review, aiming for a single 30-day review to lift the hold.

• Planning to present full data at AASLD in November and initiate pivotal study discussions with FDA upon hold release.