TB-27: SUBGROUP-SPECIFIC OUTCOMES OF CHILDREN WITH MALIGNANT CHILDHOOD BRAIN TUMORS TREATED WITH AN IRRADIATION-SPARING PROTOCOL

The impact of subgroup affiliation on the outcome of children with malignant brain tumors treated with a radiation-sparing protocol is unknown. We performed a retrospective chart review of all pediatric patients who underwent surgery for a malignant brain tumor between 1991 and 2014 and were subsequently treated at NYU Langone Medical Center using a radiation-sparing approach. Tumor DNA was analyzed using the Illumina HumanMethylation450 BeadChip (450k) genome-wide methylation array profiling platform and a diagnostic classifier algorithm. Histopathologic review confirmed medulloblastoma (MB) (n = 11), ependymoma (n = 6), supratentorial PNET (n = 2), ATRT (n = 2) and choroid plexus carcinoma (n = 1). Methylation array profiling yielded information on molecular subgroups in 20 patients. Among MB, nearly all long-term survivors were SHH infantile type (n = 4, median age 26.5 months), whereas, Group 3 patients (n = 4, median age 30.5 months) had an median OS of 17 months only (range 4-35 months), including one toxic death. One long-term survivor was Group 4. In ependymoma patients (n = 6), median PFS was 20.5 months (range 7-25) and median OS was 61 months (range 10-80 months), with one long-term survivor typed as subgroup EPN_RELPOS. In two patients with supratentorial PNET (i.e., pineoblastoma and ETANTR), OS was 11 and 16 months respectively. In the ATRT group, (n = 2) one patient died from toxic death, and one patient is a long-term survivor. The choroid plexus carcinoma patient is also a long-term survivor. We conclude that the efficacy of radiation-sparing treatment approaches appears to be largely confined to favorable molecular subgroups of pediatric brain tumors, such as infant SHH MB.