Rovalpituzumab tesirine (Rova-T) is an antibody–drug conjugate (ADC) that comprises a humanised anti-delta-like protein 3 (DLL3) monoclonal antibody attached to a DNA-damaging pyrrolobenzodiazepine toxin.5 Rova-T is considered to be the first biomarker-directed treatment for SCLC and is particularly effective against TICs.5 This evidence concerns the gene DLL3 and small cell lung carcinoma.