Abstract
PURPOSE
To assess radiological response to first-line chemotherapy in pediatric low-grade gliomas (pLGG) according to histopathology and BRAF alterations.
METHODS
We performed a population-based study of all patients diagnosed with a pLGG between 2006 and 2015 at Gustave Roussy and treated with vincristine-carboplatin, as first-line chemotherapy. Pathology samples were reviewed according to 2016 WHO classification. BRAF alterations were detected using immunohistochemistry, fluorescence in situ hybridization and/or sequencing. Tumor response was assessed by an independent central review.
RESULTS
Sixty-one patients were included in our cohort: 46 pilocytic astrocytomas (75.4%) and 15 gangliogliomas (24.6%). BRAF was found with an alteration in 44 samples (72%) and wild-type (WT) in 11 (18%) cases (molecular data incomplete = 6). Eleven pLGGs harbored the BRAF V600E mutation and 33 BRAF rearrangements. At the end of the first-line of chemotherapy, the objective response rate (complete or partial response) of pilocytic astrocytomas and gangliogliomas were 69% and 38%, respectively. The objective response rate of BRAF rearrangement, BRAF V600E and WT pLGGs were 72%, 22% and 60%, respectively. The 3-year event-free survival of patients with BRAF duplication pLGGs was 70% versus 45% for those with BRAF V600E pLGGs.
CONCLUSION
BRAF V600E pLGG constitutes a distinct entity with poor prognosis when treated with standard treatments.