Michael Chang, Mohamed Sherief, Maria Ioannou, Viveka Chinnasamy, Lucy Chen, Michael Frost, Michelle Mattson-Hoss, Herb Sarnoff, David O Kamson, Matthias Holdhoff, Debraj Mukherjee, Chetan Bettegowda, Jordina Rincon-Torroella, Victoria Croog, Peng Huang, Fausto J Rodriguez, Calixto-Hope G Lucas, Karisa C Schreck
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引用次数: 0
Abstract
Background: NF1 inactivation is associated with sensitivity to MEK inhibitor targeted therapy in low-grade and some high-grade gliomas. NF1 loss may also be a harbinger of exploitable vulnerabilities in IDH-wildtype glioblastoma (GBM). Accurate and consistent detection of NF1 loss, however, is fraught given the large gene size, challenges with complete coverage and variant calling upon sequencing, and mechanisms of mRNA and protein regulation that result in early degradation in the absence of genomic alterations. Here, we seek to perform a composite analysis for NF1 loss accounting for genomic alterations and protein expression via immunohistochemistry. We also characterize the landscape of NF1 alterations in GBM.
Methods: We assembled a single-institution, retrospective cohort of 542 IDH-wildtype GBM with somatic next generation sequencing to investigate the frequency and nature of detected NF1 alterations. We selected 69 GBMs from which to build a tissue microarray (TMA) of 44 NF1-wildtype and 25 NF1-mutant cases. We performed NF1 immunohistochemistry using two different NF1 antibodies (NFC, Sigma-Aldrich; and iNF-07E, iNFixion Bioscience) and correlated results with clinical, genomic, and other immunohistochemical features.
Results: In our retrospective cohort, we identified 88 IDH-wildtype GBM with NF1 alterations (16%). NF1 alterations were mutually exclusive with EGFR and MDM2 alterations (p-adj < 0.001, 0.05, respectively), but co-occurred with PIK3R1 alterations (Log2(OR) = - 1.6, p-adj = 0.03). Of the 63 scorable sporadic GBMs in the TMA, 14 harbored NF1 inactivating alterations and of those, 12 (86%) demonstrated minimal NF1 immunoreactivity by NFC antibody, compared to 8 (57%) by iNF-07E antibody. Among the 42 scorable NF1-wildtype GBM in the TMA, NF1 immunostaining was minimal in 18 (43%) by NFC antibody compared to 4 (10%) by iNF-07E antibody, potentially reflecting false positives or differential protein regulation. Minimal immunoreactivity by NFC antibody was associated with decreased median overall survival (8.5 vs. 16.4 months, p = 0.011). Cox proportional hazards model correcting for prognostic variables in this subset revealed HR 3.23 (95% CI 1.29-8.06, p = 0.01) associated with decreased NF1 expression by IHC.
Conclusion: NF1 immunostaining may serve as a sensitive surrogate marker of NF1 genomic inactivation and a valuable extension to next-generation sequencing for defining NF1 status. Minimal NF1 immunoreactivity is a poor prognostic marker, even in IDH-wildtype glioblastoma without apparent NF1 genomic alterations, but the underlying molecular mechanism requires further investigation.
期刊介绍:
"Acta Neuropathologica Communications (ANC)" is a peer-reviewed journal that specializes in the rapid publication of research articles focused on the mechanisms underlying neurological diseases. The journal emphasizes the use of molecular, cellular, and morphological techniques applied to experimental or human tissues to investigate the pathogenesis of neurological disorders.
ANC is committed to a fast-track publication process, aiming to publish accepted manuscripts within two months of submission. This expedited timeline is designed to ensure that the latest findings in neuroscience and pathology are disseminated quickly to the scientific community, fostering rapid advancements in the field of neurology and neuroscience. The journal's focus on cutting-edge research and its swift publication schedule make it a valuable resource for researchers, clinicians, and other professionals interested in the study and treatment of neurological conditions.