Regulators and sponsors paused a Phase III study of the antibody‑drug conjugate I‑Dxd after an unexpectedly high incidence of fatal interstitial lung disease (ILD) events. Daiichi Sankyo voluntarily suspended recruitment and enrollment in its IDeate‑Lung02 trial in multiple European countries; the U.S. FDA placed a partial clinical hold while it, Daiichi and the independent data monitoring committee review accumulated safety data. Merck and Daiichi are cooperating with the FDA and regulators to evaluate causality and next steps; the companies reported the hold reflects a "higher‑than‑anticipated" mortality signal tied to ILD. The pause affects patients with relapsed small‑cell lung cancer and could delay a potential approval timeline if safety issues persist. The move underscores ongoing safety scrutiny facing ADC programs and will likely prompt sponsor reviews of dosing, patient selection and monitoring protocols for ADCs in lung indications. Investigators and investors are watching the review’s outcome for guidance on risk‑management and trial design in this class.