AUTHOR=Cortinovis Diego Luigi , Colonese Francesca , Abbate Maria Ida , Sala Luca , Meazza Prina Marco , Cordani Nicoletta , Sala Elisa , Canova Stefania TITLE=Harnessing DLL3 inhibition: From old promises to new therapeutic horizons JOURNAL=Frontiers in Medicine VOLUME=Volume 9 - 2022 YEAR=2022 URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2022.989405 DOI=10.3389/fmed.2022.989405 ISSN=2296-858X ABSTRACT=Small-cell lung cancer (SCLC) is an aggressive neuroendocrine tumor with a high relapse rate, limited therapeutic options, and poor prognosis. The combination of chemotherapy and immune-checkpoint inhibitors leads to a new therapeutic era even if the lack of predictive biomarkers of response reduces the effectiveness in applying the treatment to the entire population of SCLC patients. The lack of treatments able to bind to a specific target has always been a substantial difference compared to the non-small cell lung cancer (NSCLC) counterpart. Delta-like canonical Notch ligand 3 is a protein frequently overexpressed in SCLC and is therefore being explored as a potentially promising therapeutic target in high-grade neuroendocrine lung cancers. In this article, we critically review the activity and efficacy of older antibody-drug conjugate (ADC) DLL3 inhibitors with their relative failures through the new compounds and their possible applications to clinical practice with particular attention to a new molecular SCLC classification.