Regulators and sponsors paused enrollment in the Phase 3 IDeate‑Lung02 study of the antibody‑drug conjugate ifinatamab deruxtecan after a higher‑than‑anticipated incidence of grade‑5 interstitial lung disease and related deaths. Daiichi Sankyo voluntarily halted recruitment in multiple European countries while the U.S. FDA issued a partial clinical hold; the companies said safety data will be reviewed by the independent data monitoring committee, the FDA and trial sponsors. The pause affects relapsed small‑cell lung cancer cohorts and raises immediate questions about ADC safety profiling, interstitial lung disease risk management, and ongoing monitoring requirements for similar payloads in development.