NRCAM variant defined by microexon skipping is a targetable cell surface proteoform in high-grade gliomas

Area of Science:

• Oncology
• Neuroscience
• Immunology

Background:

• Pediatric high-grade glioma (pHGG) lacks specific surface antigens, hindering targeted therapies.
• Understanding aberrant splicing in pHGG is crucial for identifying novel therapeutic targets.

Purpose of the Study:

• To identify tumor-specific surface antigens in pediatric high-grade glioma by analyzing splicing patterns.
• To investigate the role of altered neuronal cell adhesion molecule (NRCAM) splicing in pHGG pathogenesis.
• To develop targeted immunotherapies against pHGG using identified NRCAM proteoforms.

Main Methods:

• Comparative analysis of splicing patterns in pHGG and normal brain samples.
• RNA sequencing (RNA-seq) to identify microexon skipping events in NRCAM.
• In vitro and in vivo functional assays to assess the role of Δex5Δex19 NRCAM.
• Development of a monoclonal antibody targeting Δex5Δex19 NRCAM for immunotherapy.

Main Results:

• Uniform skipping of NRCAM microexons 5 and 19 was observed in nearly all pHGG samples.
• The Δex5Δex19 NRCAM proteoform, but not full-length NRCAM, is critical for pHGG cell migration, invasion, and tumor growth.
• A novel monoclonal antibody targeting Δex5Δex19 NRCAM enables T-cell mediated killing of pHGG cells.

Conclusions:

• Aberrant splicing of NRCAM, specifically microexon skipping, creates a highly selective tumor antigen in pHGG.
• Targeting Δex5Δex19 NRCAM with antibody-based therapies offers a promising strategy for treating pediatric high-grade glioma.
• This approach may be applicable to other L1-immunoglobulin cell adhesion molecule (IgCAM) family members in various cancers.