EPEN-10. SPINAL EPENDYMOMA WITH MYCN-AMPLIFICATION – A DISEASE OF CHILDHOOD AND YOUNG ADULTHOOD WITH DISMAL PROGNOSIS

Spinal ependymoma (EPN) with MYCN-amplification (SP-EPN-MYCN) was recently recognized as a distinct tumor type within the 2021 WHO classification of CNS tumors. To date, information about the epidemiological, clinical, and biological features of SP-EPN-MYCN remain sparse. Using DNA-methylation profiling, we collected a cohort of n = 71 (54 primaries, 17 relapses) SP-EPN-MYCNs. Based on the Heidelberg Methylation Brain Tumor Classifier V12.5, 95.6% (68/71) reached a classifier score of ≥ 0.9. In 68/71 cases, focal amplifications of MYCN were detected by copy number variation (CNV) analysis. Two tumors of pediatric patients harbored MYC-amplifications. Other repeated CNVs amongst the primary cases included gains of chromosomes 5 (5/54) and 18 (5/54), loss of chromosome 10 (14/51), and combined 17p loss and 17q gain (5/54). FISH (n = 17) and immunohistochemistry (n = 19) provided positive results for the detection of the MYCN-amplification. Epidemiological data was available for 63% (34/54) of all patients, showing an even sex distribution (17 female patients). Twenty-four percent (8/34) were children and adolescents younger than 20 years. The rest of the cohort consisted of an AYA-population with an overall median age of 31.5 years. Primary lesions were predominantly located in the thoracic (72%) and/or cervical (55%) spinal cord. Two patients showed extra-CNS metastasis to the humerus and the paraspinal musculature, respectively. At the point of analysis, 38% (10/26) of all patients had died, and 10/16 alive patients had already developed disseminated disease. Of patients with available information, 90% (18/20) had relapsed, whereas 10% (2/20) showed stable disease with leptomeningeal spread. Median PFS (n = 17) and OS (n = 25) were 15,5 (12 – 34) and 85 (61 – NA) months. In summary, SP-EPN-MYCN is a disease with dismal prognosis that can disseminate outside of the CNS and affects mainly children and AYA. Currently, comprehensive multi-omics analyses are ongoing.