Targeted therapies plus radiotherapy for diffuse intrinsic pontine glioma: the randomized phase 2 BIOMEDE trial

Diffuse intrinsic pontine glioma (DIPG) is the pediatric tumor with the worst prognosis. BIOMEDE was a randomized phase 2 trial comparing the efficacy in terms of overall survival (OS) (primary endpoint) of epidermal growth factor receptor (EGFR) inhibitor erlotinib, mTOR inhibitor everolimus and multitargeted tyrosine kinase inhibitor dasatinib in combination with radiotherapy in patients with a biopsy-proven DIPG. Tumors were assessed centrally for immunohistochemical biomarkers (EGFR overexpression or PTEN loss) together with whole-exome and RNA sequencing. A cohort of 66 children with the same inclusion criteria and treated previously with temozolomide-based regimen was used to compare outcome. Treatment allocation was performed by randomization in 233 patients, designed so that a drug could not be allocated if the corresponding biomarker was absent: 36 received erlotinib, 102 received dasatinib and 95 received everolimus. The trial was ended for futility of the primary endpoint following the recommendations of the independent data monitoring committee: OS from biopsy was not different from the control cohort (median OS = 10.8 months (95% confidence interval (CI): 9.5-13.0)) in any of the three arms (median OS = 9.7 months (95% CI: 7.8-14.6) for erlotinib; 9.9 months (95% CI: 8.8-11.2) for dasatinib; and 11.9 months (95% CI: 10.7-14.2) for everolimus). Everolimus showed significantly less ocular, renal, skin and gastrointestinal side effects and treatment discontinuation for toxicity (secondary endpoint). TP53 mutations, frequently linked to multiple structural chromosomal aberrations, were the strongest predictor for poor survival in multivariate analysis (hazard ratio = 2.8 (95% CI: 1.9-4.2), P < 0.0001). Both mutations in and activation of the mTOR pathway were associated with a better response to everolimus. Four long-term survivors treated with an mTOR inhibitor were alive free of treatment over 6 years from diagnosis. With comprehensive tumor profiling, BIOMEDE validated prognostic biomarkers as well as informative theranostic biomarkers for future trials. ClinicalTrials.gov: NCT02233049 .