Harnessing delta-like ligand 3: bridging biomarker discovery to next-generation immunotherapies in refractory small cell lung cancer
Kangkang Ji, Lin Guo, Dianbao Zuo, Mingqian Feng, Xin Chen, Zhenggang Zhao, Jing Tang, Guoping Chen
Abstract
Small cell lung cancer (SCLC), accounting for 10-20% of lung cancers, remains one of the most aggressive neuroendocrine malignancies, with fewer than 7% of patients surviving beyond five years. While the addition of immune checkpoint inhibitors (ICIs) to platinum-based chemotherapy has modestly improved outcomes, long-term benefits are limited to a subset of patients, highlighting the critical need for reliable biomarkers and innovative therapies. Delta-like ligand 3 (DLL3), a Notch signaling regulator overexpressed in 70-80% of SCLC tumors, has emerged as a simultaneous biomarker and therapeutic target. This review aims to synthesize recent advances in DLL3-targeted strategies, bridging biomarker-driven diagnostics to next-generation immunotherapies, while addressing clinical challenges and future directions. The 2024 FDA approval of tarlatamab-a bispecific T-cell engager (BiTE) targeting DLL3 and CD3-marks a pivotal advancement, demonstrating improvement in survival in refractory disease. This review examines three key advances reshaping SCLC management: (1) mechanistic links between DLL3-driven tumorigenesis and PD-L1-mediated immunosuppression, (2) clinical progress in antibody-drug conjugates (ADCs) with next-generation payloads (e.g., FZ-AD005), multispecific BiTEs (e.g., HPN328), and engineered CAR-T/NK cells with enhanced metabolic resilience, and (3) precision strategies combining liquid biopsy for dynamic DLL3 profiling with immuno-PET imaging using [89Zr]Zr-DFO-SC16. Emerging synergies, such as combining DLL3-targeted BiTEs with ICIs to amplify T-cell infiltration or reprogramming CAR-T mitochondrial metabolism, further underscore the potential of multimodal approaches. Together, these developments signal a transformative era in SCLC treatment, where molecular diagnostics and engineered immunotherapies converge to address unmet clinical needs.