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Neuro Spot Light Oral

Neuro Spotlight

Pilomyxoid Astrocytoma: A Multi-Center Retrospective Analysis and Tissue Profiling Study

Saturday, May 4, 2024
1:42 PM – 1:44 PM CT
Location:  Booth 745 Neuro Spotlight
Disclosure(s):
SpiroAnthony Stathas, BA: No financial relationships to disclose
Introduction: Pilomyxoid astrocytoma (PMA) is a rare subtype of pilocytic astrocytoma (PA), often presenting during infancy with greater propensity for CNS dissemination and recurrence. Although initially recognized as an aggressive variant of PA and classified as WHO grade II, the 2016 WHO classification deferred grading PMA pending further clinical studies. Both tumors may have BRAF-KIAA1549 fusions or FGFR1, PTPN11, or NF1 mutations, but the genomic alterations that distinguish PMA from PA remain to be identified. Given the predilection of PMA for the hypothalamic and chiasmatic areas, achieving complete surgical resection is challenging.

Methods: Retrospective chart reviews were conducted for patients with PMA at Dartmouth-Hitchcock Medical Center (DHMC) between 2009 and present and Columbia University Irving Medical Center (CUMIC) between 2002-2017. Nine DHMC patients and fourteen CUIMC patients were identified. Overall survival was defined from date of pathologic diagnosis to date of death or present. We also characterized tissue from PMA patients on the Nanostring GeoMx Digital Spatial Profiler, using 45 protein targets across neural cell profiling, MAPK signaling, and PI3K/AKT signaling panels.

Results: In the DHMC cohort, patients were diagnosed at mean age of 7.7 years and gross total resection (GTR) was achieved in 44% of cases. For CUIMC patients, mean age at diagnosis was 3.7 years and GTR was achieved in 36% of cases. Overall survival did not significantly differ between institutions (DHMC: 98 months, CUIMC: 111 months; p=0.68). Molecular findings strongly suggest that MAPK signaling is upregulated across all PMA tumor regions compared to PI3K signaling, with ERK1/2 and RSK most active. In addition, Iba1, S100B, and GFAP were all highly expressed in PMA tissue.

Conclusion : We present demographic and clinical outcome data of PMA across two institutions. For the first time, we demonstrate the enrichment in PMA tumors of phosphorylated MAP kinase signaling proteins, which might be a potential therapeutic target.