AB055. Infantile high-grade glioma (IHG)-a case series of Hong Kong experience.

BACKGROUND: Infantile high-grade glioma (IHG) is diagnosed in patients less than 12 months of age. Studies have shown that it displays a more stable genome and is usually single mutation-driven. The most identifiable mutations are receptor tyrosine kinase (RTK) fusion, such as neurotrophic tyrosine receptor kinase (NTRK) family, reactive oxygen species (ROS1), anaplastic lymphoma kinase (ALK), and mesenchymal-epithelial transition (MET) factor. The current principal treatment remains to be surgery, but it is challenging for a complete resection due to hemispheric involvement. Use of chemotherapeutic drugs for IHG is still under debate, with targeted therapy showing efficacy in promoting tumor shrinkage. Despite being a challenging central nervous system (CNS) tumor, the overall survival of IHG is superior to other high-grade gliomas. CASE DESCRIPTION: This is a retrospective review of local IHG patients and their outcome. Up till the end of 2022, we identified eight IHG patients in our local data. Mean age of diagnosis was 3 months. There were four males and four females. Seven patients had histological diagnosis of glioblastoma and one patient had a diagnosis of anaplastic astrocytoma. One patient had her tumor located in the infratentorial region. Four patients had multilobar involvement. NTRK fusion was found in four patients (ETV6-NTRK3 fusion and TPR-NTRK1 fusion). ALK fusion was found in one patient (HMBOX1-ALK). ROS1 fusion was found in one patient (ZCCHZ8-ROS1). All patients underwent chemotherapy, with four patients switched to NTRK inhibitors and one patient to ROS1 inhibitors afterward. Surgery was performed at various time points for these patients. Two patients passed away, at 22 and 35 months of age at submission of this abstract. CONCLUSIONS: Infantile high-grade glioma should be regarded as a unique tumor entity and a multidisciplinary approach is paramount in improving survival for this group of patients.