DLL-3 is expressed highly in SCLC, and while selection for DLL-3-high patients has shown some evidence of tumour response in the third-line, a large randomised phase III study was recently halted owing to poorer survival in the rovalpitumab tesirine arm compared to the standard of care, topotecan arm [27,28]. This evidence concerns the gene DLL3 and small cell lung carcinoma.