Amgen Launches Phase III Trial of STEAP1/CD3 Bispecific Antibody Xaluritamib in Metastatic Castration-Resistant Prostate Cancer

▎Armstrong

On November 18, 2024, Amgen registered a Phase III clinical trial for Xaluritamib (AMG 509), a STEAP1/CD3 bispecific antibody, to treat metastatic castration-resistant prostate cancer on the Clinicaltrials.gov website.

This Phase III clinical trial plans to enroll 675 patients with prostate cancer and is expected to be preliminarily completed by August 2028.

Xaluritamig, designed using Xencor's XmAb 2+1 technology, is currently in Phase I clinical trials, which means Amgen will proceed directly to Phase III clinical trials.

Xencor also has several other CD3 bispecific antibodies for solid tumors in progress, covering targets such as ENPP3, Claudin6, and B7H3, all utilizing XmAb 2+1 technology.

At this year's AACR conference, Amgen disclosed the Phase I clinical data of Xaluritamig. The efficacy data evaluated by PSA and RECIST are as follows: PSA50 was 49%, and PSA90 was 28%. According to RECIST evaluation, the ORR of the high-dose group was 41%, and the DCR was 79%.

Summary

Amgen has always been at the forefront of TCE. Blincyto, the CD3/CD19 bispecific antibody, is the world's first hematologic tumor TCE, and Tarlatamab, the DLL3/CD3 bispecific antibody, is the world's first solid tumor TCE. This time,The launch of Xaluritamib's Phase III clinical trial means the second solid tumor TCE has entered a pivotal clinical stage. Additionally, amid the surge of TCEs advancing into autoimmune diseases, Blincyto has taken the lead in initiating a Phase II clinical trial for the treatment of lupus.