The predictive capability of immunohistochemistry and DNA sequencing for determining TP53 functional mutation status: a comparative study of 41 glioblastoma patients

Abstract

Tumor protein 53 (p53) regulates fundamental pathways of cellular growth and differentiation. Aberrant p53 expression in glioblastoma multiforme, a terminal brain cancer, has been associated with worse patient outcomes and decreased chemosensitivity. Therefore, correctly identifying p53 status in glioblastoma is of great clinical significance. p53 immunohistochemistry is used to detect pathological presence of the TP53 gene product. Here, we examined the relationship between p53 immunoreactivity and TP53 mutation status by DNA Sanger sequencing in adult glioblastoma. Of 41 histologically confirmed samples, 27 (66%) were immunopositive for a p53 mutation via immunohistochemistry. Utilizing gene sequencing, we identified only eight samples (20%) with TP53 functional mutations and one sample with a silent mutation. Therefore, a ≥10% p53 immunohistochemistry threshold for predicting TP53 functional mutation status in glioma is insufficient. Implementing this ≥10% threshold, we demonstrated a remarkably low positive-predictive value (30%). Furthermore, the sensitivity and specificity with ≥10% p53 immunohistochemistry to predict TP53 functional mutation status were 100% and 42%, respectively. Our data suggests that unless reliable sequencing methodology is available for confirming TP53 status, raising the immunoreactivity threshold would increase positive and negative predictive values as well as the specificity without changing the sensitivity of the immunohistochemistry assay.

TP53 Co-Mutational Features and NGS-Calibrated Immunohistochemistry Threshold in Gastric Cancer

“…For different IHC positivity thresholds (0%, 10%, 20%, 30%, 50%, 60%, 90%, and 100%), we calculated their sensitivity and specificity using the NGS results as the reference, and the one with the highest accuracy was selected as the optimal IHC threshold for the specific antibody. 12 …”

“…It has been estimated that the false positive rate for using p53 IHC ranged from 2% to 45%, and Roshandel et al showed that the traditional threshold of 10% IHC positivity led to only 42% specificity in glioblastoma patients. 12 Although several researchers investigated the correlation between p53 IHC positivity and TP53 missense mutations in various cancers including glioma and astrocytomas, optimization of the p53 IHC threshold in gastric cancer is largely lagged behind.…”

Molecular Classification of Diffuse Gliomas

“…IHC detection of overexpressed protein is thus used as a surrogate method for mutation analysis, But it is not sensitive or specific. Over the last 25 years, studies have shown concordance rates between p53 IHC and TP53 mutation status ranging from 55 to 89% in grade I-IV gliomas [1,21,22].…”

“…This anomalous p53 structure may not be recognized during p53 IHC analysis resulting in false negativity. Some studies considered >10% tumor nuclei staining as positive for TP53 mutation status while others consider >50% as positive [21,22].…”

Proposed Additions to the NCCN Guidelines for Adult Medulloblastoma

“…Finally, although IHC may yield a quicker diagnosis, not every molecular change will result in a corresponding change at the protein level, potentially increasing false-negative results, as seen in gliomas. 33,34 Evaluations and Interventions at Baseline and Throughout the Course of the Disease Adults with medulloblastoma typically tolerate CSI 35 and chemotherapy 36 worse than children, despite most of them being young adults aged ,40 years. In addition, as with children, adults with medulloblastoma are at risk for multiple chronic adverse effects from the tumor and therapy, impacting symptom burden, quality of life, and endocrine and neurocognitive function.…”