Abstract

Medulloblastoma is one of the most common malignant pediatric brain tumors. There remain significant challenges in investigating oncogenic mechanisms and evaluating therapeutic efficacy due to the limited available models that accurately reflect tumor heterogeneity. To overcome this limitation, we established 10 patient-derived medulloblastoma organoids (MBOs) that retain the histological characteristics, and cellular diversity of the original tumors. These MBOs demonstrate strong infiltration capabilities, both in vitro through co-culture with human embryonic stem cell-derived cerebral organoids and in vivo following orthotopic or subcutaneous transplantation, establishing a potential platform for investigating interactions within the tumor microenvironment. Using integrated RNA sequencing, whole-exome sequencing, and DNA methylation profiling, we demonstrated that MBOs faithfully preserve the transcriptional, genomic, and epigenetic landscapes of their parental tumors. Single-cell transcriptomic analysis revealed conserved cellular subpopulation between MBOs and primary tumors. Our findings suggest that photoreceptor-related pathways may play an unprecedented role in the pathogenesis of Group 4 medulloblastoma and may be associated with interactions within the tumor microenvironment. Furthermore, we developed a prognostic nomogram based on IMPG2, BNC2, PAPPA2, ITGBL1and UNC13C expression levels in tumor cells to predict survival outcomes. Notably, tumor-infiltrating lymphocytes (TILs) expanded from patient specimens exhibited significant cytotoxic activity against autologous MBOs co-cultured in vitro and effectively suppressed the growth of subcutaneous MBO xenografts in vivo . These findings demonstrate the potential of TIL-based immunotherapy for medulloblastoma treatment. Collectively, our MBO system faithfully recapitulates critical tumor characteristics and serves as a valuable platform for investigating tumorigenic mechanisms and assessing therapeuti