Kezar Highlights Data from MISSION Phase 1b Study of KZR-616 during the Pan American Congress of Rheumatology

Kezar Life Sciences, Inc. (Nasdaq: KZR), a clinical-stage biotechnology company discovering and developing breakthrough treatments for immune-mediated and oncologic disorders, today highlighted data from the Phase 1b portion of the MISSION study demonstrating safety, tolerability and early efficacy signals of KZR-616 in patients with systemic lupus erythematosus (SLE) and lupus nephritis (LN) at the Pan-American Congress of Rheumatology (PANLAR 2020). The data were presented in a poster titled “Treatment of Systemic Lupus Erythematosus with the Immunoproteasome Inhibitor KZR-616: Results from the First 5 Cohorts of the MISSION Study, an Open-label Phase 1b Dose-Escalation Study” by study investigator Richard Furie, M.D., Chief, Division of Rheumatology, Northwell Health in New York. The poster can be found on Kezar’s corporate website under the “Science” section.

“Lupus and lupus nephritis are life-threatening diseases that disproportionately impact young Latina women in the prime of their life, and there is an urgent need for new treatment options that can target the full spectrum of their disease and don’t cause debilitating side effects that add to the disease burden,” said Dr. Furie. “These encouraging early positive data suggest that the novel mechanism of KZR-616 has the potential to address the underlying drivers of inflammation, resulting in improvements across organ systems in this disease.”

MISSION is a Phase 1b/2 study of KZR-616 in SLE patients with and without nephritis. The Phase 1b portion has completed enrollment in the final cohort, which is evaluating a 75 mg dose of KZR-616. The Phase 2 portion exclusively in LN is actively enrolling.

As of the May 4, 2020 data analysis, 39 patients were enrolled in the MISSION Phase 1b study across five dose cohorts evaluating 45 mg and step-up dosing to 60 mg weekly for 13 weeks. Patients are followed to week 25 and kept on stable background treatment. At this time point, 22 patients completed 13 weeks of treatment and are included in the exploratory efficacy measures reported below:

• Patients with increased DNA antibodies (serologic markers of SLE disease activity) at baseline that completed through week 25 of the study showed decreased titers following treatment.

Percent (%) Change from Baseline
	Mean Anti- dsDNA Level, IU/mL (Baseline)	End of