Positive phase I results in small-cell lung cancer (SCLC) from Ideaya Biosciences Inc. and partner Hengrui Pharmaceuticals Co. Ltd. with IDE-849, a potentially first-in-class antibody-drug conjugate targeting delta-like ligand 3 (DLL3) and topoisomerase 1, sharpened interest in the DLL3 mechanism, which gave Zai Lab Ltd. a phase Ia/Ib win this year in extensive-stage (ES) SCLC.