Merck & Co. Inc. (NYSE: MRK) and Daiichi Sankyo have voluntarily withdrawn their U.S. Biologics License Application (BLA) seeking accelerated approval for the lung cancer treatment ifinatamab deruxtecan (I-DXd). The decision was made following discussions with the U.S. Food and Drug Administration (FDA), which indicated that the current application data does not satisfy the requirements for the accelerated approval pathway.
The drug is intended to treat adults with extensive-stage small cell lung cancer (ES-SCLC) who have progressed after platinum-based chemotherapy. The companies shared response rates from the phase 2 IDeate-Lung01 trial in September 2025. In this study, 137 patients with previously treated ES-SCLC saw a confirmed objective response rate (ORR) of 48.2%. The results included three complete responses, 63 partial responses, and 54 cases of stable disease. The median duration of response was 5.3 months, and the disease control rate was 87.6%. Median progression-free survival was 4.9 months, and median overall survival was 10.3 months.
Further data was provided for specific patient subsets. In a group of 32 patients receiving the drug as a second-line treatment, the confirmed ORR was 56.3%. In a group of 105 patients receiving the drug in a third-line and beyond setting, the confirmed ORR was 45.7%. Additionally, an intracranial ORR of 46.2% was observed in a subset of 65 patients with brain metastases at baseline.
Despite the withdrawal of the BLA, the phase 3 IDeate-Lung02 trial continues to enroll patients. This trial compares I-DXd against standard physician-chosen chemotherapy options for relapsed ES-SCLC. Daiichi Sankyo originally discovered I-DXd, a targeted antibody-drug conjugate, and now jointly develops the therapy with Merck. The two companies are also evaluating the treatment in two additional phase 3 studies targeting advanced prostate and esophageal cancers.
In other business news, Merck announced an exclusive global license agreement with SciBrunch Therapeutics Co., Ltd. for SPR2015, an investigational preclinical oral KRAS G12D inhibitor. Under the terms of the agreement, SciBrunch will receive an upfront payment of $400 million and is eligible for milestone payments. The total potential aggregate value of the transaction is $2.13 billion. Merck will record a pre-tax charge of $400 million, or approximately 13 cents per share, in the third quarter of 2026.
