Key Takeaways MRK's I-DXd earned the FDA's Breakthrough Therapy tag for extensive-stage small cell lung cancer.The FDA's decision was based on data from the phase II IDeate-Lung01 study of I-DXd.Merck co-develops I-DXd with Daiichi, expanding an ADC-focused cancer drug collaboration.Merck (MRK) announced that the FDA has granted the Breakthrough Therapy designation (BTD) to its B7-H3-directed DXd antibody-drug conjugate (ADC), ifinatamab deruxtecan (I-DXd), for treating adult patients with extensive-stage s ...