BioNTech and partner DualityBio advanced their B7‑H3 antibody‑drug conjugate into a phase 3 trial for metastatic castration‑resistant prostate cancer after encouraging phase 1/2 data, the partners announced. The planned phase 3 will be roughly half the size of the competing Merck & Daiichi Sankyo program, reflecting a strategic, potentially faster route to registrational data. The program targets B7‑H3, an antibody target with broad tumor expression; the move signals confidence in early safety and activity signals. The smaller trial size suggests a targeted design focusing on enriched populations or stronger effect size assumptions, which could compress timelines and costs if validated. Rivals and payers will watch comparative endpoints and biomarker strategies closely; success could rapidly alter the ADC competitive landscape in prostate cancer and inform ADC development tactics across solid tumors.