Ifinatamab deruxtecan (I-DXd) is an investigational antibody-drug conjugate (ADC) targeting the B7-H3 protein, used in advanced cancers like small cell lung cancer (SCLC) and prostate cancer, showing promising response rates in Phase 2 trials, though it carries risks like fatigue, low blood counts, and lung issues, and is under development by Daiichi Sankyo & Merck.