Dipg-04. The Benefit of Craniospinal Irradiation (Csi) Rescue in Phase 2 Randomized Study of Radiotherapy (Rt), Concomitant Nimotuzumab and Vinorelbine and Re-Irradiation at Relapse, Versus Multiple Elective Radiotherapy Courses With Concomitant Vinorelbine and Nimotuzumab for Newly Diagnosed Childhood and Adolescence Diffuse Intrinsic Pontine Glioma (Dipg)

Abstract BACKGROUND This trial evaluated feasibility,response,PFS/OS of a randomization comparing two different RT schedules for DIPG while administering the same systemic treatment. We moreover evaluated the benefit of craniospinal irradiation(CSI) in case of disseminated(D) relapse. METHODS Patients: 2-21 years-old with at least radiologically verified DIPG (MRI blindly reviewed at diagnosis,every 12 weeks thereafter) and symptoms duration below 6 months. Biopsy required if atypical imaging, also allowed after adequate consensus.Vinorelbine 20 mg/m2+nimotuzumab 150 mg/m2 were administered weekly for 12; thereafter every other week until tumor progression or for up to 2 years. Standard(ST) arm was full brainstem/focal tumor site RT at total dose of 54Gy(1.8Gy/day); for local progression re-irradiation was proposed at 19.8Gy, in case of dissemination CSI at 36Gy was offered.Experimental(SP) arm included three elective courses of RT at defined time-points(36Gy, 19.8Gy and 19.8Gy) with reirradiation for relapse at 9 Gy/36 Gy as above described. Incidences of local(L) and D progression were assessed in a competing risk setting. RESULTS 55 patients were included from 4 Italian centers,27 in ST,30 males, median age 7.1 years. Median follow-up 39.1 months. Fifteen patients needed a shunt,13 during treatment;23 were biopsied,in 21 according to local protocols.22/23 tumors had H3.3K27 mutation. 53 relapsed, 34 L,13 D,6 L+D.Fifteen/19 with a D component receiving CSI had a median survival of 7.6 months after relapse, significantly higher than that of the 4 without CSI(median 2.9 months,P=0.020). Patients submitted to biopsies had more D(P=0.017) and less L progression(P=0.058). SP irradiation and any reirradiation at relapse were feasible and never produced significant radionecrosis.Median EFS/OS for the whole series were 8.4/14 months, respectively; not significantly different between patients with local vs. disseminated relapses. CONCLUSIONS Reirradiation, even if CSI, confirmed feasible and benefitted patients OS.Randomization results will be later reported.