Low mutational load in pediatric medulloblastoma still translates into neoantigens as targets for specific T-cell...

Area of Science:

• Oncology
• Immunology
• Genetics

Background:

• Medulloblastoma is the most frequent malignant brain tumor in pediatric patients.
• This tumor type typically exhibits a low mutational load and weak immunogenicity.
• Distinct genetic alterations like TP53 mutations or MYC amplification are present in some cases.

Purpose of the Study:

• To identify tumor-specific mutations and neoantigens in pediatric medulloblastoma.
• To assess the immunogenicity of these neoantigens and their potential for T-cell immunotherapy.
• To explore therapeutic strategies for medulloblastoma based on identified neoantigens.

Main Methods:

• Next-generation sequencing of tumor DNA and RNA from pediatric medulloblastoma samples.
• In silico prediction of neoantigen peptide binding affinity to human leukocyte antigen (HLA) molecules.
• Synthesis of tumor-specific peptides and in vitro induction of T-cell responses.

Main Results:

• Identification of at least two immunogenic tumor-specific peptides per patient, despite low overall mutational burden.
• Confirmation of T-cell response induction, including interferon gamma and tumor necrosis factor alpha release from CD8+ cytotoxic T cells.
• Successful T-cell response induction against neoepitopes from specific genes: Histidine Ammonia-Lyase (HAL), Neuraminidase 2 (NEU2), Proprotein Convertase Subtilisin (PCSK9), Programmed Cell Death 10 (PDCD10), Supervillin (SVIL), and tRNA Splicing Endonuclease Subunit 54 (TSEN54).

Conclusions:

• Patient-specific, tumor-derived neoantigens can be detected even in low-mutation-load tumors.
• This discovery enables the molecular design of targets for T-cell immunotherapy in medulloblastoma.
• The identified neoantigens offer potential for future adoptive T-cell transfer, transgenic T-cell receptor transfer, or tumor vaccination strategies.