FDA Grants Priority Review To Daiichi Sankyo And Merck’s Ifinatamab Deruxtecan Lung Cancer ADC Therapy

Daiichi Sankyo and Merck & Co. (known as MSD outside the U.S. and Canada) have announced that the U.S. Food and Drug Administration has accepted their Biologics License Application (BLA) for ifinatamab deruxtecan (I-DXd). The application has been granted Priority Review for the treatment of adult patients with extensive-stage small cell lung cancer (ES-SCLC) who have progressed following platinum-based chemotherapy, with a PDUFA decision date set for October 10, 2026.

Ifinatamab deruxtecan is a novel, potentially first-in-class antibody-drug conjugate (ADC) targeting the B7-H3 protein. Originally discovered by Daiichi Sankyo, the therapy is being jointly developed with Merck. Its mechanism is designed to selectively deliver cytotoxic treatment to cancer cells, offering a targeted approach for a disease with limited treatment options and poor prognosis.

“Small cell lung cancer remains one of the toughest cancers to treat, with few options if the disease progresses after standard of care treatments,” said Eliav Barr, MD, senior vice president, head of global clinical development and chief medical officer, Merck Research Laboratories. “The FDA’s acceptance of the BLA reinforces the important role that ifinatamab deruxtecan could play in helping to address the needs of patients with extensive-stage small cell lung cancer.”

The FDA is reviewing the application under multiple expedited programs, including Priority Review, Real-Time Oncology Review (RTOR), and Project Orbis. These initiatives aim to accelerate the availability of promising cancer therapies by enabling earlier, more collaborative regulatory evaluations across global health authorities.

“The FDA’s granting of Priority Review for ifinatamab deruxtecan marks a significant milestone in our effort to provide new and innovative treatment options for patients with extensive-stage small cell lung cancer,” said John Tsai, MD, global head, R&D, Daiichi Sankyo. “We look forward to continuing to work with the FDA to bring this potential first-in-class B7-H3 directed DXd antibody drug conjugate to patients as quickly as possible.”

The submission is supported by clinical data from the IDeate-Lung01 Phase 2 trial, along with findings from the IDeate-PanTumor01 Phase 1/2 study. Results from these studies were presented at the World Conference on Lung Cancer 2025 and published in the Journal of Clinical Oncology. The therapy had previously received Breakthrough Therapy Designation from the FDA in August 2025, further underscoring its potential to address a critical unmet need in lung cancer treatment.