PATH-47. AGE-, SEX-, AND GRADE-ASSOCIATED MOLECULAR DIFFERENCES IN A MULTI-INSTITUTIONAL COHORT OF CHOROID PLEXUS TUMORS

Abstract BACKGROUND Choroid plexus tumors (CPT) are central nervous system tumors where prognosis has been correlated to histologic grade, with aggressive clinical behavior and reduced survival rate in higher grade cases. Here, we present a genomic survey of a large multi-institutional cohort of CPTs across all grades. MATERIAL AND METHODS Fifty-eight CPT samples were analyzed by comprehensive genomic profiling (CGP) by a hybrid capture-based DNA sequencing platform (FoundationOne®CDx). Pathology reports, histopathology reviews, and patient clinical data were assessed. RESULTS Our cohort included 11 choroid plexus papillomas (CPP; grade 1), 16 atypical CPP (grade 2), and 31 choroid plexus carcinomas (CPC; grade 3). Males were slightly more affected than females (31 vs. 27 cases). Median patient age at tissue sampling was 11 years (range: 1–72 years). Median age of patients with CPC was younger at 3 years compared CPP at 34 years (p < 0.01). Genomic analyses identified three frequent, mutually exclusive mutations in TP53, TERTp, and DAXX. TP53 mutations (n = 15, 26%) were significantly more prevalent in CPC (n=14 CPC, p=0.0003), and were identified predominantly in children (n=12 CPC at <20 years). By contrast, TERT promoter mutations (TERTp; n = 5, 8.6%) were identified exclusively in CPP (p=0.019), predominantly grade 2 (4 of 5 cases), and exclusively in adult patients, with a median age of 48 years. DAXX mutations (n=4, 6.9%) were more common in CPC (n=3). Other alterations included PTEN (n=4, all adults) and MYCN amplification (n=3, all children <6 years), both exclusively in CPC. In 21 cases, including 9 out of the 11 Grade 1 CPP, no known cancer mutation was detected. CONCLUSION This study provides comprehensive genomic profiling of CPTs, highlighting distinct genetic alterations associated with different histological grades and patient demographics. These findings may inform future research and therapeutic strategies targeting specific molecular pathways in CPTs.