Kezar Life Sciences has reported positive topline data from the Phase II MISSION clinical trial of zetomipzomib (KZR-616) in active lupus nephritis (LN) patients.

Zetomipzomib is a new selective immunoproteasome inhibitor with extensive treatment potential across various autoimmune diseases. 

The open-label trial was designed to show the responder rate of zetomipzomib in active LN patients. 

The proportion of subjects attaining an overall renal response (ORR), evaluated as a 50% or larger decline in urine protein to creatinine ratio (UPCR) at the end-of-treatment (EOT) was the trial’s primary efficacy endpoint. 

Kezar noted that the number of subjects with a complete renal response (CRR), analysed as an absolute decline in proteinuria values to a UPCR of 0.5 or less, with preserved renal function (eGFR), and corticosteroid usage of 10mg or less prednisone/prednisone equivalent without the usage of prohibited therapies was the crucial secondary efficacy endpoint of the trial.

According to the findings, 64.7% of the trial subjects attained an ORR, the trial’s primary efficacy endpoint.

Furthermore, 35.2% of the patients attained a CRR of 0.5 UPCR or less, with all other protocol definitions met.

As per the evaluations at week 29, the treatment benefit of zetomipzomib was sustained or deepened after the EOT.

In subjects who completed the trial, improvement was observed in exploratory measures of extra-renal disease activity linked to systemic lupus erythematosus. 

In the trial, zetomipzomib showed a favourable safety and tolerability profile while adverse events were found to be usually mild-to-moderate.

Kezar Life Sciences chief medical officer Noreen Henig said: “The MISSION Phase II topline results show a clinically meaningful overall renal response to zetomipzomib after six 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.”

In October last year, the company dosed the first subject in the Phase I KZR-261-101 trial of KZR-261 in advanced solid tumour malignancies.