DIPG-61. RESCUE REGIMENS AFTER BIOMEDE: POSSIBLE INFLUENCE ON OS ASSESSMENT

BIOMEDE is a multicentric randomized phase II trial to evaluate in DIPG the OS of patients treated with dasatinib, erlotinib or everolimus. The OS is the result of the first line treatment but it could also be affected by re-irradiation and the second line treatment received after progression, especially in case of a possible crossover outside of the trial. This preliminary analysis focuses on the first patients enrolled at Gustave Roussy (n=37). The median age at diagnosis was 7 years, median interval from diagnosis to progression and median survival after progression were 7 (1–20) and 2 (0–13) months respectively. Initial treatment was everolimus for 13, dasatinib for 20, erlotinib for 4 patients. The most frequent targetable molecular alterations were mTOR pathway in 6, PDGRFA in 4, ACVR1 in 3 patients. Out of the 31 patients who relapsed and were evaluable, 18 and 13 had a median survival < 3 and > 3 months respectively. At relapse patients have received different types of therapies, in 6 cases matching the molecular profile of the tumour obtained by sequencing. At progression, seven patients switched from dasatinib to mTOR inhibitors and 2 patients switched from everolimus to dasatinib. Patients with OS after progression > 3 months had higher rate of reirradiation (77% vs 5%), steroid weaning (69% vs 33%) and Lansky/Karnowsky > 50% (85 vs 67%). Extended results on the entire cohort will be presented. It will be important to consider the distribution of reirradiation to interpret the results of the randomisation on OS.