Mentor Name: Jessica Blackburn

H3K27M-driven pediatric diffuse midline glioma (pDMG, formally known as DIPG) is an aggressive brain tumor with limited treatment options and a universally fatal prognosis. Over 70% of DIPG cases harbor TP53 mutations, which contribute to immune evasion and poor responses to therapy. While TP53 mutations are traditionally considered loss-of-function, emerging evidence, including CRISPR-based gene editing and multi-omics profiling from our lab, suggests that different TP53 mutations may have distinct functional effects on DIPG cells. However, their role in shaping tumor-microenvironment interactions, particularly immune cell infiltration and activity, remains poorly understood. Given that DIPG is an immunologically “cold” tumor, understanding how TP53 mutations modulate immune responses is critical for identifying new therapeutic strategies. This project aims to determine how TP53-mutant DIPG cells influence immune cell infiltration and function within the tumor microenvironment. Using zebrafish xenograft models, an innovative system that enables real-time visualization of tumor-immune interactions in vivo, this study will assess how different TP53 mutations impact immune cell recruitment and activation. Fluorescence microscopy and immune profiling techniques will be used to characterize immune cell dynamics within the tumor. Additionally, complementary in vitro co-culture experiments will be conducted using human DIPG cells and human immune cells to further elucidate how TP53-mutant DIPG cells interact with and potentially suppress immune responses. Findings from this research will provide novel insights into the mechanisms by which TP53 mutations contribute to DIPG immune evasion and may reveal mutation-specific vulnerabilities that can be targeted therapeutically. By combining in vivo and in vitro approaches, this study has the potential to inform the development of immunotherapeutic strategies aimed at overcoming the immune-suppressive nature of DIPG, ultimately improving treatment outcomes for children with this devastating disease.