Transcriptomic and Protein Analysis of Small-cell Bladder Cancer (SCBC) Identifies Prognostic Biomarkers and DLL3 as...

Area of Science:

• Oncology
• Genomics
• Translational Research

Background:

• Small-cell bladder cancer (SCBC) is an aggressive malignancy with limited treatment options.
• Understanding the molecular landscape of SCBC is crucial for identifying novel therapeutic targets and biomarkers.

Purpose of the Study:

• To investigate the transcriptomic profiles of SCBC to identify molecular subtypes and potential therapeutic targets.
• To correlate gene expression patterns with clinical phenotypes and patient survival.
• To evaluate the efficacy of a DLL3-targeting antibody-drug conjugate (ADC) in a SCBC patient-derived xenograft (PDX) model.

Main Methods:

• Gene expression profiling was performed on 46 SCBC samples (39 primary tumors, 1 metastatic, 6 normal urothelium).
• Unsupervised hierarchical clustering was used to identify molecular subtypes.
• Protein expression of DLL3, PDL1, CD56, and ASCL1 was assessed by immunohistochemistry (IHC).
• A SCBC PDX model was used to test the in vivo efficacy of a DLL3-targeting ADC.

Main Results:

• Four distinct molecular clusters were identified, correlating with clinical phenotypes and overall survival (OS).
• Tumors with a "metastasis-like" gene expression pattern had the shortest OS (P = 0.047).
• DLL3, PDL1, ASCL1, and CD56 protein expression was confirmed in a significant proportion of samples.
• High DLL3 (>10%) and CD56 (>30%) expression were independently prognostic of shorter OS (P = 0.03 each).
• A DLL3-targeting ADC demonstrated durable antitumor efficacy in the SCBC PDX model.

Conclusions:

• Gene expression patterns in SCBC are associated with distinct clinical phenotypes and survival outcomes.
• DLL3 is frequently overexpressed in SCBC and serves as a negative prognostic biomarker.
• A DLL3-targeting ADC shows significant in vivo efficacy, suggesting its potential as a novel therapeutic strategy for SCBC.