On April 13, Daiichi Sankyo and Merck jointly announced that their Biologics License Application (BLA) for ifinatamab deruxtecan (I-DXd) has been accepted and granted Priority Review status by the U.S. Food and Drug Administration (FDA) for the treatment of adult patients with extensive-stage small cell lung cancer (ES-SCLC) whose disease has progressed after prior platinum-based chemotherapy. The Prescription Drug User Fee Act (PDUFA) expires on October 10, 2026.Ifinatamab deruxtecan is a potential first-in-class antibody-drug conjugate (ADC) targeting B7-H3, specifically designed by Daiichi Sankyo. In October 2023, Daiichi Sankyo and Merck entered into a global co-development agreement excluding Japan. This BLA submission is primarily based on the results of the IDeate-Lung01 Phase II clinical trial and is supported by data from the IDeate-PanTumor01 Phase I/II trial.
Regarding the IDeate-Lung01 trial
IDeate-Lung01 is a global, multicenter, randomized, open-label, split-part Phase II trial designed to evaluate the safety and efficacy of ifinatamab deruxtecan in patients with ES-SCLC who have received at least one line of platinum-based chemotherapy (up to three lines). Patients with asymptomatic brain metastases (whether or not they have received treatment) are eligible to participate.• Part 1 of the trial (dosage optimization): Patients were randomized 1:1 to receive ifinatamab deruxtecan (8 mg/kg or 12 mg/kg) intravenously every three weeks.• Part 2 of the trial (dose extension): Patients received intravenous infusion of ifinatamab deruxtecan at a dose of 12 mg/kg every three weeks.• Primary endpoint: Objective response rate (ORR) assessed by blinded independent central review (BICR) according to RECIST v1.1 criteria.• Key secondary endpoints: These included duration of response (DOR), progression-free survival (PFS), disease control rate (DCR), time to response (TTR), overall survival (OS), pharmacokinetics, and safety. Intracranial ORR assessed by BICR was used as an exploratory analysis.• Patient Enrollment: The trial enrolled 187 patients across Asia, Europe, and North America. Trial data has not yet been released.
Regarding the IDeate-PanTumor01 experiment
IDeate-PanTumor01 is a global, multicenter, first-in-human, open-label phase I/II trial designed to evaluate the safety and efficacy of ifinatamab deruxtecan in patients with advanced/unresectable or metastatic solid tumors who are resistant to or intolerant of standard therapy or who have no alternative standard therapy.• Phase I (Dose Escalation): Evaluate the safety and tolerability of escalating doses of ifinatamab deruxtecan to determine the maximum tolerated dose and extended recommended dose (RDE).• Phase II (Dose Extension): Evaluate the safety and efficacy of ifinatamab deruxtecan in patients with squamous non-small cell lung cancer, metastatic castration-resistant prostate cancer, or esophageal squamous cell carcinoma at a controlled exposure (RDE) of 12 mg/kg.The trial plans to recruit approximately 250 patients in Asia and North America. Trial data has not yet been released.
Other key background information
•Ifinatamab deruxtecan was previously granted Breakthrough Therapy Designation by the FDA in August 2025 for the same indication.• The drug has also received orphan drug designation for the treatment of SCLC from the U.S. FDA, the European Commission, the Japanese Ministry of Health, Labour and Welfare, and the Taiwan Food and Drug Administration, and has also received orphan drug designation from the FDA for the treatment of esophageal cancer.
Small cell lung cancer and the B7-H3 target
Globally, approximately 250,000 patients are diagnosed with small cell lung cancer each year. In 2025, there are about 27,000 new cases of SCLC in the United States, accounting for about 12% of all lung cancer cases. SCLC is aggressive, easily progresses to distant metastases, and has a low five-year survival rate.B7-H3 is a transmembrane protein belonging to the B7 protein family. It is overexpressed in various cancer types, including SCLC, and its overexpression is associated with poor prognosis, making it a promising therapeutic target. Currently, no drugs targeting B7-H3 have been approved for cancer treatment.

https://mp.weixin.qq.com/s/Y4Rb4WGC9b2cKX21Zx1Ecg