66 Case report: successful targeted treatments in NTRK fusion and BRAFV600E mutant gliomas

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Abstract Introduction It is rare to find targetable mutations in gliomas. The evidence for using targeted agents remains limited. NICE recommends performing Next Generation and Whole Genome Sequencing (NGS, WGS) for all patients with brain tumours, to identify targets for treatment. This abstract reports treating 2 patients, 1 with an NTRK fusion optic pathway glioma and 1 with a BRAFV600E mutant Grade 3 Pleomorphic Astrocytoma (PXA). Method Testing NGS and WGS is routine for all brain tumour patients at our tertiary cancer centre. Patient S is a 39y old who underwent repeat biopsy in 2024 for a previously treated, growing optic pathway glioma (OPG). WGS found an NTRK fusion, confirmed on IHC. Patient J is a 27y old with extensive progression of his previously irradiated PXA. A BRAFV600E mutation had been confirmed at initial diagnosis in 2021. Results Cancer Drugs Fund approval was gained in September 2024 to treat Patient S with Larotrectinib. She had an immediate response with significant shrinkage of her tumour after 3 cycles. Further shrinkage of her enhancing tumour occurred over the next 6 months with stable appearances for the last 6 months. Larotrectinib is being well tolerated with no dose reduction required, tiredness and dizziness are the reported side effects. In April 2024, compassionate access to encorafenib and binimetinib was obtained from Pierre Fabre to treat Patient J. He had significant shrinkage of his tumour after 3 cycles. There has been continued reduction in the tumour to date, with no enhancement visible after 24 cycles. Treatment has been extremely well tolerated with an initial rash settling quickly and mild fatigue. Conclusions Both patients have experienced rapid and sustained response to targeted treatment with minimal side effects.