HGG-06. REMARKABLE RESPONSE TO BRAF INHIBITOR IN AN INFANT WITH DISSEMINATED DIFFUSE LEPTOMENINGEAL GLIONEURONAL TUMOR (DLGNT)

Abstract

INTRODUCTIONDiffuse Leptomeningeal Glioneuronal Tumor (DLGNT) are rare CNS tumors and in infants, they can be lethal. There are several anecdotal reports in infants with low grade gliomas (LGG) with treated with BRAF inhibitors.METHODSA six-month old baby girl presented with a 2-week history of absent visual contact and vomiting. Imaging revealed a large 4.7 X 4.2 X 2.8 cm suprasellar charismatic region mass and multiple small extra-axial plaques in spinal canal. The child developed significant ascites post VP shunt requiring shunt externalization, extensive protein infusion support and hospitalization for six weeks. Immunohisto-chemical staining revealed Olig-2 and S-100, GFAP and synaptophysin positive. EMA showed patchy cytroplasmic reactivity in stromal cells and CD99 showed diffuse reactivity in stromal and lesional cells. INI-1, IDH-1, and CD117 were negative. Ki-67 proliferation index was 8–10%. PCR for BRAF V600E/E2/D was detected and KIAA1549-BRAF fusion as negative. This was confirmed by Genome Wide Next Generation Sequencing. While waiting for GNS testing results, the baby received one dose of Vinblastine. However, within seven days of initiating Debrafenib, significant clinical and radiological responses were observed.CONCLUSIONThe baby continues safely on Debrafenib with continued dramatic radiological response. This suggest that there may be a role in early initiation of targeted therapy such as BRAF inhibitors rather than giving standard chemotherapy such as Vinblastine or Carboplatin-Vincristine in extremely ill infants with low grade gliomas.