The companies submitted the application seeking accelerated approval in the US.
Their decision to withdraw follows discussions with the US Food and Drug Administration (FDA), which indicated that the data, including those from the IDeate-Lung01 Phase II trial, did not meet the criteria necessary for approval.
The accelerated approval pathway, designed for earlier access to medicines for serious conditions with unmet medical needs, allows approval based on surrogate endpoints.
Despite the withdrawal, enrolment continues in the IDeate-Lung02 Phase III trial, which is assessing the safety and efficacy of ifinatamab deruxtecan compared to chemotherapy options like amrubicin, lurbinectedin, or topotecan for patients who have experienced disease progression after one line of platinum-based chemotherapy.
Ifinatamab deruxtecan, a potential first-in-class B7-H3 directed antibody drug conjugate (ADC), was discovered by Daiichi Sankyo and is being developed in partnership with MSD.
Daiichi Sankyo Therapeutic Area Oncology Development head Abderrahmane Laadem said: “Extensive-stage small cell lung cancer is a challenging disease to treat, leaving patients in need of new options.
“Enrolment into the IDeate-Lung02 Phase III trial is near completion and we look forward to assessing the potential for a future filing of ifinatamab deruxtecan with the FDA and other global regulatory authorities based on those results.”
Its development continues in other Phase III trials, namely IDeate-Prostate01, which targets castration-resistant prostate cancer, and IDeate-Esophageal01, focusing on oesophageal squamous cell carcinoma.
Designed with Daiichi Sankyo’s DXd ADC technology, ifinatamab deruxtecan comprises a humanised anti-B7-H3 IgG1 monoclonal antibody linked to DXd, a topoisomerase I inhibitor payload, using cleavable tetrapeptide-based linkers.
In April 2026, MSD and Daiichi Sankyo received priority review from the FDA for ifinatamab deruxtecan’s BLA to treat ES-SCLC.