Investigational Drug
Xaluritamig
TrialFetch AI Analysis
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Overview
Xaluritamig (AMG 509) is an investigational immunotherapy being studied primarily for metastatic castration-resistant prostate cancer (mCRPC). Human results are available from early-phase, non-randomized studies; randomized phase 3 trials are underway to determine how it compares with established treatments. (aacrjournals.org)
Mechanism of action
Xaluritamig is a bispecific T-cell engager. It binds STEAP1 on cancer cells and CD3 on T cells, bringing the cells together to promote T-cell-mediated killing. Its “2+1” design has two STEAP1-binding sites and one CD3-binding site. (pmc.ncbi.nlm.nih.gov)
Efficacy
In a published phase 1 dose-exploration study of 97 patients with mCRPC, mostly previously treated with a taxane, 49% of 87 PSA-evaluable patients had a confirmed PSA50 response (a PSA decline of at least 50%). 24% of 67 patients with measurable disease had a confirmed partial tumor response. At higher target doses, these rates were 59% and 41%, respectively. These are responses within a single-arm study, not evidence of improved survival versus another treatment. (aacrjournals.org)
A separate phase 1 cohort tested xaluritamig with abiraterone and prednisolone in patients who had not received a taxane for mCRPC. In its 20-person dose-expansion group, confirmed PSA50 and objective tumor response rates were 58% (11/19 PSA-evaluable) and 43% (3/7 with measurable disease), respectively. The small, non-randomized study cannot establish how much benefit xaluritamig adds to abiraterone. (ascopubs.org)
Safety
In the published monotherapy study, the most common treatment-related adverse events were cytokine release syndrome (CRS; 72%), fatigue (45%), and muscle pain (34%). CRS occurred mainly during the first treatment cycle; two patients had grade 3 CRS, and none had grade 4 or 5 CRS. In the combination study, the most common treatment-emergent events were muscle pain (92%; 41% grade ≥3), CRS (64%; 7.7% grade ≥3), and anemia (46%; 12.8% grade ≥3). (pmc.ncbi.nlm.nih.gov)
Further reading
- Published first-in-human monotherapy study, Cancer Discovery (aacrjournals.org)
- Phase 1 xaluritamig–abiraterone results, 2026 ASCO abstract (ascopubs.org)
- Preclinical mechanism study, Cancer Discovery (pubmed.ncbi.nlm.nih.gov)
Last updated: Sep 2026
Active trials using Xaluritamig
Found 5 active trials using this drug:
TrialFetch AI summary: Adults with metastatic castration-resistant prostate adenocarcinoma that has progressed after at least one androgen receptor pathway inhibitor and exactly one taxane regimen for mCRPC receive xaluritamig alone. Xaluritamig is an investigational bispecific T-cell engager that binds STEAP1 on tumor cells and CD3 on T cells to promote tumor killing.
ClinicalTrials.gov ID: NCT07493512
TrialFetch AI summary: Adults with chemotherapy-naïve mCRPC progressing after exactly one prior androgen receptor pathway inhibitor are randomized to xaluritamig plus abiraterone or investigator’s choice of abiraterone, docetaxel, or cabazitaxel. Xaluritamig is an investigational STEAP1×CD3 bispecific T-cell engager designed to direct T cells against prostate cancer cells.
ClinicalTrials.gov ID: NCT07213674
TrialFetch AI summary: This study enrolls patients with newly diagnosed, de novo, high-volume metastatic hormone-sensitive prostate adenocarcinoma who recently started androgen deprivation therapy and have not had PSA progression. It evaluates xaluritamig, a STEAP1×CD3 bispecific T-cell engager, added to either darolutamide or abiraterone.
ClinicalTrials.gov ID: NCT07140900
TrialFetch AI summary: Adults with progressive mCRPC after at least one androgen receptor-directed therapy and exactly one taxane regimen for mCRPC are randomized to xaluritamig or investigator-selected cabazitaxel, abiraterone, or enzalutamide. Xaluritamig is an investigational bispecific T-cell engager that binds STEAP1 on prostate cancer cells and CD3 on T cells.
ClinicalTrials.gov ID: NCT06691984
TrialFetch AI summary: Adults with progressive metastatic castration-resistant prostate cancer and ECOG performance status 0–1 are enrolled across cohorts with varying prior-treatment requirements. They receive xaluritamig (AMG 509), an investigational STEAP1×CD3 bispecific T-cell engager, alone intravenously or subcutaneously or intravenously with abiraterone or enzalutamide; the subcutaneous cohort is closed to accrual.
ClinicalTrials.gov ID: NCT04221542
