07:51 AM EDT, 05/19/2025 (MT Newswires) -- Merck ( MRK ) said Monday it has dosed the first patient in a phase 3 study assessing ifinatamab deruxtecan against chemotherapy in patients with unresectable advanced or metastatic esophageal squamous cell carcinoma with disease progression after treatment with a platinum-containing systemic therapy and an immune checkpoint inhibitor.

The company said ifinatamab deruxtecan is being jointly developed with Daiichi Sankyo, which discovered the antibody drug conjugate.