From Diagnosis to Targeted Therapy: MDT Insights for Biomarker Testing in pLGG

Molecular testing plays a foundational role in accurately diagnosing pLGGs and guiding treatment decisions. From the operating room, tumor samples are routinely sent for NGS panels that assess hundreds of cancer-related genes. At some institutions, such as the one described here, a comprehensive panel like the UCSF500 is used, along with high-resolution methylation profiling. The latter examines DNA methylation patterns to provide a more refined tumor classification, especially in cases where histology alone is inconclusive.

The turnaround time for these molecular results can vary. Initial pathology, including immunohistochemistry (IHC) staining, typically returns within a week, offering a preliminary diagnosis and tumor grade. Specific mutations, like BRAF V600E, may also be detected early using targeted IHC stains. Full NGS and methylation array results usually follow within 2 to 4 weeks. This timing can influence the urgency and type of treatment initiated, especially in symptomatic or progressive cases. For less-aggressive presentations, clinicians may choose to wait for the molecular data before finalizing a treatment plan.

Access to advanced testing varies across institutions, with some sites limited by resources or platform availability. Nevertheless, collaborative networks often allow for shared testing resources, ensuring patients can still receive comprehensive molecular profiling. This testing not only confirms diagnosis but also identifies actionable mutations, such as BRAF alterations or neurofibromatosis type 1–associated tumors. In sum, molecular diagnostics are a critical component of pediatric neuro-oncology, increasingly shaping precision medicine strategies that improve both outcomes and quality of life for young patients.