Promising early results of MHB088C (B7-H3 ADC) in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC) from a phase 1/2 multicenter study.

作者：Lin Shen, Xue Meng, Yuping Sun, Yanqiu Zhao, Hai Huang, Liang Han, Zhen Zhang, Feng Chang, Yinghua Ji, Guobin Wu, Xiangcai Wang, Fangling Ning, Yuanyuan Ji, Lixin Wan, Yongzhong Luo, Qi Ma, Shudong Zhang, Shiyu Zhou, J. Shi, Guoqing Cao · 发表于：Journal of Clinical Oncology · 年份：2025 · DOI：10.1200/jco.2025.43.16_suppl.5051 · 被引用次数：4 · 研究领域：Prostate Cancer Treatment and Research、Radiopharmaceutical Chemistry and Applications、Cancer Immunotherapy and Biomarkers

5051 Background: MHB088C is a novel B7-H3-targeted antibody-drug conjugate (ADC) incorporating the potent SuperTopoi payload, which is 5 to 10 times more potent than Dxd. Early data from an ongoing phase 1/2 study have shown that MHB088C is generally well tolerated, with early signs of clinical activity (ASCO 2024, abstract #3012). Here, we present preliminary findings from the subset of pts with mCRPC. Methods: This study consisted of 2 parts: dose-escalation (part 1) and expansion (part 2). Part 1 evaluated the safety and tolerability of MHB088C at doses ranging from 0.8 to 4.0 mg/kg, administered intravenously every 2 (Q2W) or 3 weeks (Q3W). Part 2 explored multiple doses to assess safety and prospective efficacy of MHB088C in selected tumor types, including mCRPC. Results: As of January 3, 2024, 36 pts with mCRPC were enrolled and received at least one dose of MHB088C (1.6~2.4 mg/kg, n=35; 3.0 mg/kg, n=1). The median age was 69 years (range: 51-83) and all pts had an ECOG performance status ≤1. These pts were heavily pretreated, with 100% having received novel androgen axis drugs (NAAD) and 80% having received docetaxel. The objective response rate (ORR) was 14.3%, and the disease control rate (DCR) was 95.2% in pts with measurable disease (n=21). At data cutoff, 19 pts (52.8%) remained on the treatment. Six-month radiographic progression-free survival (rPFS) was 87%. Preliminary data also indicate improvements in prostate-specific antigen (PSA) levels. Safety data were c...