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Gregory J. Riely, MD, PhD


Case Report: Effect of Larotrectinib Treatment on Infant-Type Hemispheric Glioma With TPR::NTRK1 Fusion

By: Jenna Carter, PhD
Posted: Tuesday, September 20, 2022

In an article published in Pathobiology, researchers presented a case report of infantile hemispheric glioma (gliosarcoma subtype). Rui Manuel Reis, PhD, of the Molecular Oncology Research Center, Barretos Cancer Hospital, Brazil, and colleagues described the clinical course from diagnosis to treatment of a 9-month-old male, describing the histologic characteristics, radiologic features, and subsequent treatment of the tumor. Their overall findings revealed that the tumor tissue showed a TPR::NTRK1 gene fusion, which was treated with a TRK inhibitor, larotrectinib. Following treatment, the patient exhibited stable disease with a residual lesion after 8 months of targeted therapy.

“Gliosarcomas are a rare variant (2.4%) of [infantile hemispheric glioma] ...These deadly primary malignant brain tumors are observed in adults but uncommon in children…several clinical studies suggest that gliosarcoma patients have a slightly worse outcome, with median overall survival ranging between 13 and 17.5 months,” stated Dr. Reis and colleagues.

A 9-month-old boy with no family history of cancer presented with increased brain perimeter, bulging of the anterior fontanelle, and absence crisis. Brain MRI was performed to identify the tumor location, and the patient underwent tumor resection after scan positioning. Upon final diagnosis of gliosarcoma, the patient started chemotherapy treatment according to the BABY POG protocol for an 8-month period. Different pathologic and histologic analyses were performed using resected tumor tissue.

Pathologic and histologic findings revealed immature neoplasia, characterized by a proliferation of cells with intense pleomorphism. Molecular assays revealed the TPR::NTRK1 gene fusion characteristics of the tumor. Following treatment with an oral anti-TRK inhibitor, larotrectinib, for 3 months, the patient’s MRI scans revealed stable residual disease. At 8 months’ follow-up, the lesion presented with the same size; however, it exhibited a contrast hypo-uptake, suggesting stable disease and the absence of adverse effects. Based on these findings, the study authors concluded that molecular profiling to find key druggable targets can be a benefit to future patients.

Disclosure: The study authors reported no conflicts of interest.

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