Daiichi Sankyo and Merck's investigational antibody-drug conjugate (ADC), ifinatamab deruxtecan (I-DXd), achieved a 48.2% objective response rate (ORR) in the phase 2 registrational trial (IDeate-Lung01) for extensively pretreated small cell lung cancer (ES-SCLC)135.
The ORR includes three complete responses and 63 partial responses out of 137 dosed patients; an additional 54 patients had stable disease3.
Median progression-free survival (PFS) was 4.9 months, and median overall survival (OS) was 10.3 months in this heavily pretreated population1.
The trial performance is slightly lower than earlier reports (54.8% ORR in dose optimization), likely due to inclusion of more third-line patients in the latest analysis; patients in the second-line setting had a higher ORR of 56.3%13.
Ifinatamab deruxtecan is a potential first-in-class B7-H3 directed ADC specifically engineered for lung cancer, and these results support ongoing discussions with regulatory authorities for potential accelerated approval15.
Based on the IDeate-Lung01 trial data, ifinatamab deruxtecan has also been granted Breakthrough Therapy Designation by the FDA for the treatment of adults with ES-SCLC who progressed after platinum-based chemotherapy4.
Sources:
1. https://www.fiercebiotech.com/biotech/daiichi-mercks-advanced-lung-cancer-adc-sees-48-response-registrational-trial
3. https://www.biospace.com/drug-development/merck-daiichi-sankyo-stage-lung-cancer-rally-with-strong-pivotal-data-for-i-dxd
4. https://www.daiichisankyo.com/files/news/pressrelease/pdf/202508/20250818_E.pdf
5. https://www.merck.com/news/ifinatamab-deruxtecan-demonstrated-clinically-meaningful-response-rates-in-patients-with-extensive-stage-small-cell-lung-cancer-in-ideate-lung01-phase-2-trial/