Expression Patterns of DLL3 Across Neuroendocrine and Non-Neuroendocrine Neoplasms Reveal Broad Opportunities for Therapeutic Targeting

Abstract Neuroendocrine neoplasms (NENs) encompass a diverse set of malignancies with limited precision therapy options. Recently, therapies targeting DLL3 have shown clinical efficacy in aggressive NENs, including small cell lung cancers and neuroendocrine prostate cancers. Given the continued development and expansion of DLL3-targeted therapies, we sought to characterize the expression of DLL3 and identify its clinical and molecular correlates across diverse neuroendocrine and non-neuroendocrine cancers. Here, we interrogated paired DNA and RNA-sequencing from 1,589 NENs across 29 sites, as well as 203,252 tumors across 47 cancer types. We found that high transcriptomic levels of DLL3 correlated with more aggressive histologic and mutational patterns in NENs, with adverse survival outcomes being reflected in NENs originating from the lung, pancreas, stomach, and small bowel. The heterogeneity in DLL3 expression across NENs was largely explained by site of origin, with lung, prostate, and bladder NENs exhibiting relatively high levels of DLL3 whereas gastroenteropancreatic (GEP) NENs displayed relatively low expression levels. Although the therapeutic targeting of DLL3 may be less applicable for GEP-NENs, we did find an upregulation of alternative targets such as SEZ6, CELSR3, and SSTR2 in these settings. Lastly, expanding our investigation into non-neuroendocrine cancers, we detected an enrichment of DLL3 in both low-grade and high-grade gliomas, Merkel cell carcinomas, medulloblastomas, and melanomas, with such enrichment being associated with prolonged overall survival in gliomas, but worse overall survival in melanomas. Altogether, we demonstrate that DLL3 represents an attractive target for subsets of neuroendocrine and non-neuroendocrine cancers and uncover opportunities for future therapeutic strategies.