LGG-12. SAFETY AND EFFICACY OF DUAL THERAPY WITH DABRAFENIB AND TRAMETINIB IN AN INFANT WITH BRAF V600E MUTANT INOPERABLE LOW GRADE GLIOMA

To describe safety and efficacy of dual targeted therapy with dabrafenib (BRAFi) and trametinib (MEKi) in an infant with inoperable low grade glioma with BRAF V600E mutation.

Safety and efficacy of dual targeted therapy with BRAFi and MEKi for pediatric low grade glioma (pLGG) is currently being evaluated, however, infants are usually not included in these clinical trials.

We report a case of a 2-month-old male infant who presented with involuntary movements and gaze deviation concerning for seizures. MRI brain revealed a tumor involving the medulla, T2/FLAIR dimensions: 2.5 x 2.2 x 2.7 cm and drop metastases to the cauda equina. An EEG ruled out seizure activity. Tumor biopsy was performed revealing Ganglioglioma, WHO grade I. IHC and somatic next generation sequencing revealed BRAF V600E point mutation. Germline testing was negative. Due to tumor progression on traditional chemotherapy, compassionate use of dual targeted therapy with dabrafenib (5.25mg/kg/day divided twice daily) and trametinib (0.032mg/kg daily) was initiated at 4.5 months of age. The patient has tolerated dual therapy for nearly 1 year without significant toxicity with exception of grade I skin rash. In terms of functional outcomes, previously noticed vocal cord paresis has resolved and our patient with global developmental delay continues to make developmental gains, albeit slowly. On recent neuroimaging, pLGG has continued to grow T2/FLAIR dimensions: 3.5 x 3.5 x 3.7 cm, however, combination therapy has halted the rate of growth of this tumor.

To our knowledge, our patient is the youngest to receive combination of BRAFi and MEKi. Tumor targeted therapy could be an important treatment option for infants with inoperable pLGG where aggressive surgery and radiation therapy are associated with significant morbidity. Multi-institutional clinical trials that include infants are needed to further comment on safety and efficacy of these agents.