Ifinatamab deruxtecan (DS-7300) - (IDeate-Lung01 )

September 25, 2026: Daiichi Sankyo (TSE: 4568) and Merck (NYSE: MRK) voluntarily withdrew the U.S. BLA seeking accelerated approval of ifinatamab deruxtecan (I-DXd) for adults with extensive-stage small cell lung cancer (ES-SCLC) whose disease progressed on or after platinum-based chemotherapy. The companies said the decision followed FDA discussions that the application data, including results from the phase 2 IDeate-Lung01 trial, did not meet requirements to support accelerated approval for this indication.

The program remains active: enrollment is continuing and near completion in the phase 3 IDeate-Lung02 trial, which is comparing ifinatamab deruxtecan with physician’s choice of amrubicin, lurbinectedin, or topotecan in relapsed ES-SCLC after one prior platinum-based regimen. The companies said they will assess the potential for a future filing with FDA and other regulators based on those results.

Other ongoing phase 3 programs for ifinatamab deruxtecan mentioned are IDeate-Prostate01 in castration-resistant prostate cancer and IDeate-Esophageal01 in esophageal squamous cell carcinoma. IDeate-Lung01 enrolled 187 patients; its primary endpoint is objective response rate by blinded independent central review per RECIST v1.1.