Two antibody drug conjugates (ADCs), ARX788 and ARX517, are being further investigated to address unmet medical needs for patients with breast cancer and prostate cancer. 1 During the virtual analyst and investor day on February 24, 2023, experts, including Hope S. Rugo, MD, FASCO, and Paula R. Pohlmann, MD, MS, PhD, discussed what has already been seen with ARX788 for patients with HER2-positive metastatic breast cancer, and what their expectations are for the agent moving forward. Then, the first-in-human APEX-01 trial (NCT04662580) was highlighted, and the role of ARX517 for patients with prostate cancer, a proprietary anti-PSMA ADC, was discussed. While trastuzumab deruxtecan (Enheurtu; T-DXd) has shown benefits in patients with breast cancer, data has shown that 24.2% of patients progress while on the agent within 12 months. At 12 months, the progression-free survival (PFS) was 75.8 months (95% CI, 69.8-80.7) with T-DXd and 34.1 months (95% CI, 27.7-40.5) with trastuzumab emtansin...