xaluritamig (AMG 509)

P1, N=441, Recruiting, Amgen | Trial completion date: Mar 2028 --> Jul 2028

P1, N=441, Recruiting, Amgen | Trial completion date: Jun 2028 --> Mar 2028 | Trial primary completion date: Jun 2026 --> Mar 2026

Xaluritamig demonstrated encouraging responses (PSA and RECIST) compared with historical established treatments for patients with late-line mCRPC. This study provides proof of concept for T-cell engagers as a potential treatment for prostate cancer, validates STEAP1 as a target, and supports further clinical investigation of xaluritamig in prostate cancer.

The avidity-driven activity of AMG 509 enables selectivity for tumor cells with high STEAP1 expression compared with normal cells. AMG 509 is the first STEAP1 TCE to advance to clinical testing, and we report a case study of a mCRPC patient who achieved an objective response on AMG 509 treatment.

Preliminary PK showed dose-proportional increase in exposure with a mean terminal half-life of approximately 3-4 days. Conclusions Xaluritamig was tolerable with low-grade CRS (occurring primarily cycle 1) with encouraging preliminary efficacy in heavily pretreated pts with mCRPC.

Preliminary PK showed dose-proportional increase in exposure with a mean terminal half-life of approximately 3-4 days. Table: 1765O Lower DLs (DL 1–7) Higher DLs (DL8–15) Overall PSA evaluable N = 43 N = 46 N = 89 PSA ≥ 50%, n (%) 17 (39.5) 25 (54.3) 42 (47.2) PSA ≥ 90%, n (%) 8 (18.6) 16 (34.8) 24 (27.0) RECIST evaluable N = 30 N = 36 N = 66 PR, n (%) 1 (3.3) 14 (38.9) 15 (22.7) SD, n (%) 18 (60.0) 12 (33.3) 30 (45.5) Conclusions Xaluritamig was tolerable with low-grade CRS (occurring primarily cycle 1) with encouraging preliminary efficacy in heavily pretreated pts with mCRPC.

P1, N=464, Recruiting, Amgen | Trial completion date: Nov 2027 --> Jun 2028 | Trial primary completion date: Nov 2025 --> Jun 2026

Key inclusion criteria: men ≥18 years with histologically/cytologically confirmed mCRPC who are refractory to novel hormonal therapy (e.g., abiraterone and/or enzalutamide) and have failed 1–2 taxane regimens or are medically unsuitable for or have refused taxanes; ongoing castration with total serum testosterone ≤50 ng/dL; evidence of progressive disease; ECOG performance status 0–1; life expectancy ≥3 months; and adequate hematologic, renal, hepatic, and cardiac function. Key exclusion criteria: pure small cell or neuroendocrine carcinoma of the prostate; untreated CNS metastases or leptomeningeal disease; any anticancer therapy or immunotherapy, radiation therapy, or major surgery <4 weeks from first dose; history of or current autoimmune disease or any disease requiring immunosuppressive therapy (≤10 mg/d prednisone permitted); prior STEAP1-targeted therapy; infection requiring IV antimicrobials <7 days from first dose. The study opened in January 2020 and is recruiting patients.

Key inclusion criteria: men ≥18 years with histologically/cytologically confirmed mCRPC who are refractory to novel hormonal therapy (e.g., abiraterone and/or enzalutamide) and have failed 1–2 taxane regimens or are medically unsuitable for or have refused taxanes; ongoing castration with total serum testosterone ≤50 ng/dL; evidence of progressive disease; ECOG performance status 0–1; life expectancy ≥3 months; and adequate hematologic, renal, hepatic, and cardiac function...Key exclusion criteria: pure small-cell or neuroendocrine carcinoma of the prostate; untreated CNS metastases or leptomeningeal disease; any anticancer therapy or immunotherapy, radiation therapy, or major surgery <4 weeks from first dose; history of or current autoimmune disease or any disease requiring immunosuppressive therapy (≤10 mg/d prednisone permitted); prior STEAP1-targeted therapy; infection requiring IV antimicrobials <7 days from first dose. The study opened in January 2020 and is recruiting patients. Research Funding: Amgen Inc.