KEZAR LIFE SCIENCES ANNOUNCES POSITIVE TOPLINE RESULTS FROM THE MISSION PHASE 2 TRIAL

KEZAR LIFE SCIENCES ANNOUNCES POSITIVE TOPLINE RESULTS FROM THE MISSION PHASE 2 TRIAL EVALUATING ZETOMIPZOMIB FOR THE TREATMENT OF PATIENTS WITH LUPUS NEPHRITIS

•  11 of 17 patients (64.7%) achieved an overall renal response of 50% or greater reduction in urine protein to creatinine ratio (UPCR) at 6 months
  
•  6 of 17 patients (35.2%) achieved a complete renal response, including a UPCR of 0.5 or less at 6 months
  
•  Zetomipzomib continues to demonstrate a favorable safety and tolerability profile for administration over the 6-month treatment period
  
•  Improvement seen in exploratory measures of extra-renal disease activity associated with systemic lupus erythematosus (SLE) in patients who completed treatment
  
•  Company-hosted conference call and webcast to be held today at 4:30 p.m. ET

SOUTH SAN FRANCISCO, Calif.–(BUSINESS WIRE)–Jun. 27, 2022– Kezar Life Sciences, Inc. (Nasdaq: KZR), a clinical-stage biotechnology company discovering and developing breakthrough treatments for immune-mediated and oncologic disorders, today reported positive topline results from the MISSION Phase 2 clinical trial evaluating zetomipzomib, a novel, first-in-class selective immunoproteasome inhibitor, in patients with active lupus nephritis (LN).

“The MISSION Phase 2 topline results show a clinically meaningful overall renal response to zetomipzomib after 6 months, without high-dose induction therapy. Patients in the trial also experienced reductions in extra-renal manifestations of lupus. Zetomipzomib appears to be immunomodulatory, well-tolerated and steroid-sparing – all important attributes for patients with autoimmune disease who are often young and active,” said Noreen R. Henig, M.D., Kezar’s Chief Medical Officer. “Based on the strength of these results, we plan to continue developing zetomipzomib for patients with lupus nephritis, as well as evaluate development opportunities for systemic lupus erythematosus.”

The MISSION Phase 2 clinical trial is an open-label study designed to demonstrate the responder rate of zetomipzomib in patients with active LN. During the 24-week treatment period, patients received 60 mg of zetomipzomib subcutaneously once weekly (first dose of 30 mg) in addition to stable background therapy. End-of-treatment (EOT) assessments occurred at Week 25, with completion of study at Week 37. Patients in the MISSION Phase 2 clinical trial received zetomipzomib without induction therapy, which represents a significant difference from other recently published trials in LN.

The primary efficacy endpoint for the trial was the proportion of patients achieving an overall renal response (ORR), measured as a 50% or greater reduction in urine protein to creatinine ratio (UPCR) at EOT. A key secondary efficacy endpoint was the number of patients with a complete renal response (CRR), measured as an absolute reduction in proteinuria values to a UPCR of 0.5 or less, with preserved renal function (eGFR), and corticosteroid use of 10 mg or less prednisone/prednisone equivalent and no use of prohibited medication.

Summary of Topline Results

In this Phase 2 topline analysis, 17 of 21 patients enrolled in the trial reached end of treatment:

•  11 of 17 patients (64.7%) achieved an ORR measured as a 50% or greater reduction in UPCR at EOT compared to baseline, the primary efficacy endpoint of the clinical trial.
•  6 of 17 patients (35.2%) achieved a CRR of 0.5 UPCR or less, with all other protocol definitions satisfied.
•  Treatment benefit of zetomipzomib was maintained or deepened following the end of treatment, based on assessments at Week 29.
  • 16 of 17 patients (94.1%) reached an ORR at Week 29, and 6 patients maintained a CRR.
•  Mean daily prednisone background dosage was reduced from 19.2 mg at baseline to 9.1 mg at EOT and was further reduced at Week 29.
•  Mean eGFR (estimated glomerular filtration rate) remained stable from baseline to EOT.

Additionally, exploratory measures of extra-renal disease activity associated with SLE improved in patients completing the trial. Patients showed mean reduction in key SLE disease activity scores and normalization in biomarkers consistent with reduction in SLE disease activity.

Safety

Zetomipzomib was well tolerated over the course of the treatment period. Adverse events were generally mild-to-moderate (Grade 1 or 2) consistent with previous reports. Most common treatment-emergent adverse events (TEAEs) were injection site reaction, pyrexia (fever), headache, or nausea with or without vomiting. As previously reported, two patients experienced serious adverse events (SAEs) on the study. One patient had an acute protracted migraine related to zetomipzomib but completed treatment. The other patient discontinued following worsening pulmonary arterial hypertension, a urinary tract infection and an acute kidney injury, which were all deemed unrelated to zetomipzomib. Early terminations occurred in 4 out of 21 patients. No opportunistic or Grade 3 infections were reported in the trial.