FDA grants Priority Review to ifinatamab deruxtecan, a B7-H3–directed ADC from Daiichi Sankyo and Merck, for previously treated extensive-stage small cell lung cancer, with a regulatory decision expected October 2026
Written by: Dr. Anuja Badgujar, BDS
Reviewed By: Pharmacally Editorial Team
Ifinatamab deruxtecan, a novel antibody-drug conjugate (ADC) jointly developed by Daiichi Sankyo and Merck, has received Priority Review from the U.S. Food and Drug Administration (FDA) following acceptance of a Biologics License Application (BLA) for adult patients with extensive-stage small cell lung cancer (ES-SCLC) whose disease has progressed on or after platinum-based chemotherapy. The FDA action date under the Prescription Drug User Fee Act is October 10, 2026.
The application is under Priority Review, Real-Time Oncology Review, and Project Orbis programs to accelerate assessment and enable concurrent international review. Ifinatamab deruxtecan previously received Breakthrough Therapy Designation for this indication.
Clinical Trial Evidence
The BLA is primarily based on the Phase 2 IDeate-Lung01 trial (NCT05280470), a global, multicenter, randomized, open-label study enrolling 187 patients across Asia, Europe, and North America. The study evaluated intravenous ifinatamab deruxtecan administered every three weeks in previously treated ES-SCLC patients. The primary endpoint is objective response rate assessed by blinded independent central review. Secondary endpoints include duration of response, progression-free survival, overall survival, disease control rate, pharmacokinetics, and safety. Supportive data come from the Phase 1/2 IDeate-PanTumor01 study, a first-in-human trial evaluating dose escalation and expansion cohorts across advanced solid tumors.
Leadership Opinions
John Tsai, MD, global head of R&D at Daiichi Sankyo, said the FDA’s Priority Review represents an important milestone in advancing ifinatamab deruxtecan as a potential first-in-class treatment for extensive-stage small cell lung cancer and emphasized continued collaboration with regulators to bring the therapy to patients as quickly as possible.
Eliav Barr, MD, senior vice president, head of global clinical development and chief medical officer of Merck Research Laboratories, highlighted the limited treatment options after progression in small cell lung cancer and noted that acceptance of the BLA underscores the potential of ifinatamab deruxtecan to help address this unmet need.
B7-H3 Targeting and Mechanism of Action
B7-H3 is a transmembrane protein of the B7 family that interacts with receptors in the CD28 family, including PD-1, and is overexpressed across multiple cancers such as small cell lung cancer, where it has been associated with poor prognosis and represents a potential therapeutic target with no approved B7-H3–directed therapies. Ifinatamab deruxtecan is an investigational, potential first-in-class B7-H3–directed antibody–drug conjugate developed using Daiichi Sankyo’s DXd ADC technology, consisting of a humanized anti-B7-H3 IgG1 monoclonal antibody linked via tetrapeptide-based cleavable linkers to a topoisomerase I inhibitor payload derived from exatecan.
Ongoing Development
A global clinical development program is evaluating ifinatamab deruxtecan as monotherapy and in combination across multiple cancers. The program includes Phase 3 trials in small cell lung cancer, castration-resistant prostate cancer, and esophageal squamous cell carcinoma.
References
About the Writer
Dr. Anuja Badgujar, BDS is a dentist with expertise in US healthcare data and medical data annotation. With four years of experience handling US healthcare datasets, she brings strong domain knowledge and precision to her work. She is also deeply passionate about medical writing, with a focus on translating complex medical information into clear and structured content.