Ideaya Biosciences received FDA alignment on a Phase 3 study design for IDE-849, its DLL3-targeted antibody-drug conjugate, moving the program into a late-stage development race. The alignment was described as opening a U.S. Phase 3 path and positioning the candidate alongside other DLL3-directed approaches targeting extensive-stage small-cell lung cancer. Ideaya previously reported positive Phase 1 data in small-cell lung cancer. The reported Phase 3 plan involves a randomized evaluation of IDE-849 monotherapy in extensive-stage SCLC previously treated with tarlatamab, which was approved in May 2024 under the brand Imdelltra. The FDA alignment intensifies the DLL3 ADC and bispecific competition by clarifying the regulatory runway for a next potential practice-changing trial readout.