MDB-27. OUTCOMES FOR CHILDREN TREATED FOR MEDULLOBLASTOMA USING A RADIATION-SPARING APPROACH: A REPORT FROM THE CHILDREN’S BRAIN TUMOR NETWORK

To describe real-world outcomes in children with medulloblastoma treated with radiation-sparing chemotherapy in the USA.

Clinical and molecular data were obtained from the Children’s Brain Tumor Network (CBTN), a multi-institutional collaboration to collect and freely share biological samples and longitudinal clinical data from consented patients. Patients with medulloblastoma treated with radiation-sparing regimens were included. Clinical data included patient demographics, stage, extent of resection, treatment regimen, and survival. Three-year overall survival (OS3) was calculated from diagnosis to death from any cause or last follow-up with log-rank p-value.

Eighty-one patients (56% male, median age 2.51 [range 0-7.44] years) with medulloblastoma (32% metastatic) were included. Molecular group was available for 36 (44%). Patients were treated according to protocols CCG99703 (n=26), ACNS0334 Arm A (n=13), ACNS0334 Arm B (n=30), PBTC026 (n=10), and ACNS1221 (n=2). Only 29 (36%) were enrolled on a therapeutic study. Seventy-two patients had median follow-up of 2.7 years (range 0.3-13 years). OS3 was 79+6; OS3 by molecular group was 90+9 in SHH (n=14), 55+14 in Group 3 (n=16), 56+25 in Group 4 (n=6). OS3 was 92+5 for 55 patients with localized disease versus 53+12 for 26 with metastasis (p=0.001); 86+6 for 55 patients with gross total resection versus 62+11 in 26 with partial resection or biopsy (p=0.03). OS3 was not associated with upfront radiation, 80+7 for 54 patients who received no radiation before relapse versus 78+9 for 27 who received radiation before relapse (21 focal, 6 craniospinal). OS3 was 87+8 for 30 patients on a methotrexate-containing regimen versus 74+7 for 51 without methotrexate (p=0.27). Five patients developed second malignancy.

CBTN data report real-world survival for young children treated with radiation-sparing approaches, most not enrolled on studies. Ongoing molecular characterization of the CBTN cohort will facilitate additional analysis to improve risk stratification and therapy selection for young children.