The Phase III global program testing an antibody‑drug conjugate (I‑Dxd/ifinatamab deruxtecan) has been placed on partial hold after a higher‑than‑anticipated number of fatal interstitial lung disease (ILD) events were reported. Daiichi Sankyo and Merck voluntarily paused recruitment and enrollment in the IDeate‑Lung02 study and notified regulators as independent safety reviews begin. The U.S. FDA issued a partial clinical hold while regulators and an independent data monitoring committee review accumulated safety data across trial sites in multiple European countries. The sponsors said they will cooperate with the agency and the committee to determine next steps, including any protocol changes or additional monitoring requirements. The pause affects patients with relapsed small‑cell lung cancer enrolled in a late‑stage ADC study; investigators will need to reconcile the drug’s risk profile against its antitumor activity. The development halt raises immediate questions about the ADC class’s pulmonary toxicity signals and will likely slow timelines for any potential approval or label expansion tied to the trial’s endpoints.