Kezar halts solid tumor trial to prioritize autoimmune disease candidate

Kezar Life Sciences, a clinical-stage biopharmaceutical company based in San Francisco, has decided to stop the Phase I trial of its solid tumour drug, KZR-261, to focus on its lead autoimmune disease drug, zetomipzomib. This decision was announced in the company's second-quarter financial results. The halted trial, identified as NCT05047536, involved patients with solid tumours. Out of the 61 patients enrolled, five experienced stable disease for four months or longer, with two of these patients maintaining stability for a year or more. However, no objective responses were recorded, leading to the discontinuation of further enrolment. Despite this, the 61 patients already enrolled will continue to receive KZR-261.

The company will now concentrate its efforts on zetomipzomib, a selective immunoproteasome inhibitor. This drug is currently being evaluated in two clinical trials: the Phase IIb PALIZADE trial (NCT05781750) for lupus nephritis and the Phase IIa PORTOLA trial (NCT05569759) for autoimmune hepatitis. In September 2023, Everest Medicines acquired the rights to zetomipzomib for Greater China, South Korea, and South-East Asia. The first patient in China has already been dosed in the PALIZADE trial, with topline data anticipated by mid-2026.

The PORTOLA trial has recruited 24 patients, who have been divided to receive either 60mg of zetomipzomib or a placebo over 24 weeks. Kezar expects to release topline data from this trial in the first half of next year. Zetomipzomib has shown promise in prior studies for lupus nephritis, including the Phase II MISSION trial, which involved 69 patients. The results from this trial showed that 64.7% of participants achieved the primary efficacy endpoint of overall renal response (ORR).

In an effort to extend its financial runway, Kezar, which originated from Amgen, cut its workforce by 41% in October 2023. While the clinical development of zetomipzomib and KZR-261 persisted, the company halted all preclinical programs. As of the end of the second quarter, Kezar reported having $164 million in cash and equivalents.

According to GlobalData’s Pharma Intelligence Center, zetomipzomib, if approved, could generate sales of $498 million by 2030. In a company update, Kezar’s CEO Chris Kirk expressed enthusiasm about the completion of enrolment for the PORTOLA trial and the prospect of sharing topline results sooner than expected, in the first half of 2025. He highlighted the significance of this milestone in bringing zetomipzomib closer to becoming a new treatment option for autoimmune hepatitis, a condition with substantial unmet medical needs.