Comprehensive Genomic Profiling Accurately Determines 1p19q Codeletion Status In Gliomas

Abstract BACKGROUND Genomic profiling of gliomas is vital to ensure diagnostic accuracy, inform prognosis, and identify therapeutic options for primary and recurrent tumors. The integration of genomic biomarkers into brain tumor classification has improved the diagnostic accuracy and led to the development of molecularly stratified clinical trials. DESIGN Comprehensive genomic profiling (CGP) was performed on FFPE material from 310 (162 FoundationOne® and 148 FoundationOne® CDx) samples of brain tumors with available 1p19q FISH results, initially diagnosed by submitting institutions based on histology. Via CGP, we analyzed tumors in up to 395 cancer-associated genes (including IDH1/2) and predicted 1p19q codeletion using a custom research-use only algorithm. Progression-free (PFS) and overall survival (OS) were determined for 519 patients based on computationally predicted 1p19q codeletion status. RESULTS For all samples, regardless of their IDH1/2 mutation status, concordance between 1p19q status based on FISH and our algorithm was 97.1%, (301/310), with a positive predictive value (PPV) of 100% (133/133) and sensitivity of 93.7% (133/142). All discordant samples were called as positive for codeletion by FISH and negative by our CGP-based algorithm. Discordant samples were either IDH1/2 wild-type (2) or IDH1/2, ATRX, and TP53 altered (7), consistent with the genomic profile of diffuse astrocytomas. For IDH1/2-mutated samples, concordance was 96.7% (238/246). In the clinical outcomes dataset, median PFS was 35 months for the codeletion group compared to 13 months for the non-codeletion group (hazard ratio (HR): 0.60; 95% CI: 0.40-0.88; p=0.009). Similarly, median OS was 160 and 34 months respectively for codeleted versus intact (HR: 0.46; 95% CI: 0.28-0.76; p=0.002). CONCLUSIONS 1p19q codeletion status derived from CGP is highly concordant with FISH results suggesting that CGP-derived 1p19q codeletion status may be a reliable substitute for traditional FISH testing. Patients with CGP-derived 1p19q codeletion showed increased PFS and OS compared to non-codeleted counterparts.