Although there have been no reports on the design and application of DLL3 receptor-based immunotoxins for SCLC treatment so far, Mattoo and colleagues utilized a combination of a chemical drug called navitoclax (a BCL-2 inhibitor) and an immunotoxin targeting the transferrin receptor called HB21-PE40 for SCLC treatment. Here, TFRC is linked to small cell lung carcinoma.