07:25 AM EDT, 08/18/2025 (MT Newswires) -- Merck ( MRK ) said Monday that the US Food and Drug Administration has granted ifinatamab deruxtecan breakthrough therapy designation as a treatment of adults with extensive-stage small cell lung cancer with disease progression on or after platinum-based chemotherapy.

The designation, based on data from phase 2 and phase 1/2 trials, will speed up development and regulatory review of the drug candidate, the company said.

The antibody drug conjugate was discovered by Japan's Daiichi Sankyo and being jointly developed by Daiichi Sankyo and Merck ( MRK ), the company said.