Kezar Life Sciences is dropping its unpromising phase 1 solid tumor drug as the biotech goes all-in on its lead autoimmune hepatitis program.
A total of 61 patients have so far been enrolled in the phase 1 trial of the solid tumor candidate, dubbed KZR-261, but no objective responses have been reported to date, Kezar revealed in its second-quarter earnings report. Five patients experienced stable disease for four months or longer, of which two experienced stable disease for 12 months or longer.
While those 61 patients will continue to have access to KZR-261, enrollment in the trial has now been stopped, the company said.
Instead, the South San Francisco-based biotech’s sole focus will now be a selective immunoproteasome inhibitor called zetomipzomib. Kezar has enrolled all 24 patients in the phase 2 PORTOLA trial of the drug in patients with autoimmune hepatitis, with topline data expected to read out in the first half of 2025.
A global PALIZADE trial of zetomipzomib in active lupus nephritis is set to read out in 2026. Everest Medicines—which bought the rights for the drug in greater China, South Korea and Southeast Asia—has already dosed the first patient in China as part of that study.
“We are thrilled to announce completion of enrollment to our PORTOLA trial and look forward to sharing topline results earlier than expected in the first half of 2025,” CEO Chris Kirk, Ph.D., said in the release.
“This important milestone brings us one step closer to delivering zetomipzomib as a new treatment option for patients suffering from autoimmune hepatitis, a disease of significant unmet medical need,” Kirk added. “In addition, we are continuing to see strong enrollment activity in our global PALIZADE trial and look to continue this momentum by focusing our clinical resources on zetomipzomib development programs going forward.”
KZR-261 was the first candidate created from Kezar’s protein secretion platform. The asset survived a pipeline restructuring in fall 2023 that saw the biotech lose 41% of its staff, including former Chief Medical Officer Noreen Henig, M.D., and CEO John Fowler.
The company had been anticipating initial phase 1 data in solid tumors dropping in 2024 but decided at the time “to reduce the number of planned expansion cohorts to conserve cash resources while it continues to evaluate safety and biologic activity.”
Kezar had also been anticipating top-line data from a phase 2a trial in autoimmune hepatitis in mid-2025, although this goal appears to have been sidelined this year.