Delta-like ligand 3 (DLL3) is an inhibitory Notch ligand that is highly expressed in SCLC and other neuroendocrine tumors but minimally expressed in normal tissues.
In addition, we illustrate how the development of promising therapeutic strategies based on the identification of molecular targets (mTOR inhibitors in carcinoids and targeting of the Notch ligand DLL3 in SCLC) may require the assessment of predictive biomarkers, even in the group of neuroendocrine tumours of the lung.