EGFR/CEP7 high polysomy is separate and distinct from EGFR amplification in glioblastoma as determined by fluorescence in situ hybridization

EGFR amplification in gliomas is commonly defined by an EGFR/CEP7 ratio of ≥2. In testing performed at a major reference laboratory, a small subset of patients had ≥5 copies of both EGFR and CEP7 yet were not amplified by the EGFR/CEP7 ratio and were designated high polysomy cases. To determine whether these tumors are more closely related to traditionally defined EGFR-amplified or nonamplified gliomas, a retrospective search identified 22 out of 1143 (1.9%) gliomas with an average of ≥5 copies/cell of EGFR and CEP7 with an EGFR/CEP7 ratio of <2 displaying high polysomy. Of these cases, 4 had insufficient clinicopathologic data to include in additional analysis, 15 were glioblastomas, 2 were IDH-mutant astrocytomas, and 1 was a high-grade glial neoplasm, NOS. Next-generation sequencing available on 3 cases demonstrated one with a TERT promoter mutation, TP53 mutations in all cases, and no EGFR mutations or amplifications, which most closely matched the nonamplified cases. The median overall survival times were 42.86, 66.07, and 41.14 weeks for amplified, highly polysomic, and nonamplified, respectively, and were not significantly different (p =  0.3410). High chromosome 7 polysomic gliomas are rare but our data suggest that they may be biologically similar to nonamplified gliomas.

Abstract 212: True2 duplex sequencing reveals a diverse landscape of unique somatic mutations beyond the surgical margins of high- and low-grade diffuse gliomas

Introduction: High- and low-grade diffuse gliomas commonly recur regardless of therapy. Here, we sought to detect and profile molecular evidence of disease in nearby brain tissue absent of tumor by standard-of-care clinical imaging.

Methods: Twenty-two patients presenting to the University of Utah with radiographic evidence of a new high- to low-grade intrinsic brain tumor were enrolled after providing written informed consent. Using intraoperative stereotactic guidance, tissue was acquired from bulky tumor (36 samples) and beyond the surgical margins in peritumoral edema (29 samples). All samples underwent somatic mutation discovery using a custom-designed 114 kb panel (115 genes) and True2 duplex sequencing. True2 is a duplex adapter-based technology developed and empirically validated to achieve &gt;95% sensitivity for an allele frequency ≥0.1% at a false positive rate of &lt;1 per 100 kb panel positions.

Results: Somatic mutations were detected in all samples regardless of radiographic location. The mean number of mutations was similar between bulky tumor and peritumoral edema (5.6±2.4 vs. 5.1±2.9 mutations/sample, respectively; P=0.48). Although the mean allele frequency of variants was higher in tumor compared to edema (16.0±21.2% vs. 11.2±17.4%, respectively; P=0.017), there was a strong overlap in the allele frequency ranges (tumor: 0.07% to 90.3% vs. edema: 0.10% to 75.6%). Notably, one-third of all the somatic mutations detected had an allele frequency &lt;0.5%. Common diagnostic mutations specific to each tumor type were present in both tumor and edema - TERT promoter mutations in glioblastoma and oligodendroglioma; IDH1/2 mutations in astrocytoma and oligodendroglioma. In edema, mutations associated with glioblastoma but unique to a single sample occurred in TP53, EGFR, PTEN, NF1, ATRX, SCN9A, and MTOR at an allele frequency ranging from 0.10% to 20.22%. The edema of astrocytomas similarly harbored unique mutations in TP53, PTEN, and NF1, but mutations in EGFR, ATRX, SCN9A, and MTOR were absent. In contrast to both glioblastoma and astrocytoma, oligodendrogliomas exhibited a diverse collection of unique CIC and PAFAH1B3 mutations in edema at an allele frequency between 0.13% and 3.63%.

Conclusions: The application of True2 technology to conduct a discovery search for very-low frequency somatic mutations found the molecular burden between tumor and adjacent edema to be remarkably similar. Our findings indicate an extensive tumor presence beyond the surgical margins in diffuse gliomas with unique and abundant somatic mutations that may form the foundation of recurrent lesions. Molecular analysis of adjacent tissue identified as radiographically unaffected by bulky tumor to better characterize the mutational landscape of migratory subclones may directly impact personalized medicine for high- and low-grade diffuse glioma patients.

Citation Format: Hunter Underhill, Michael Karsy, Christian Davidson, Sabine Hellwig, Samuel Stevenson, Sydney Vincenti, Charlie Dean, Brion Harrison, Eric Goold, Mary Bronner, Howard Colman, Randy Jensen. True2 duplex sequencing reveals a diverse landscape of unique somatic mutations beyond the surgical margins of high- and low-grade diffuse gliomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 212.

Neuropathology Outreach in Ghana

Introduction/Objective

Ghana has a population of over 31 million people and approximately 15 neurosurgeons but is currently without a dedicated neuropathologist. Here we present a month of neuropathology outreach performed at the Komfo Anokye Teaching Hospital (KATH) in Kumasi and the Korle-Bu Teaching Hospital (KBTH) in Accra.

Methods/Case Report

In February of 2022, a second-year neuropathology fellow and a board-certified neuropathologist traveled to Ghana to give 40 approximately 1.5 hour neuropathology didactic and interactive teaching sessions. A two-week format of outreach was developed for each site in Ghana and consisted of didactic lectures and interactive sessions covering the WHO 2021 brain tumor classification system, neuroautopsy, neuroinfectious disease, neurodegenerative disease, neuromuscular disease, forensic neuropathology, neurodevelopment, and unknown case conferences. Meanwhile, a pathology trainee worked remotely to organize 12 one-hour virtual general pathology lectures and develop continuing outreach. A survey of 16 questions including 12 multiple choice questions and four short answer questions was used to assess each component and the overall satisfaction of the outreach.

Results (if a Case Study enter NA)

Eight brains were examined at four neuroautopsy conferences and ten case consultations were performed upon request. Survey results showed no statistical differences amongst the 20 sessions. Comments were positive and included one respondent planning to redesign their PhD research to focus on neurodegenerative disease in Ghana and several others commenting on the utility of molecular updates. Suggestions for improvement included quizzes, including more morphology and IHC in lectures, sending digital slides before future visits, teaching spinal cord removal, and the need for continuing outreach in neuropathology, dermatopathology, cytopathology and gynecologic pathology.

Conclusion

This experience provides a useful and well-appreciated approach to delivering international neuropathology outreach. Opportunities in neuropathology on an international level range from educational to clinical practice and research.

Primary Esophageal Angiosarcoma

Primary esophageal angiosarcoma is an extremely rare cancer. Thus, evidence-based guidance on diagnosis and treatment is lacking. The current workup and management is extrapolated from other esophageal and angiosarcoma pathology. We describe a case report that depicts unique diagnostic and therapeutic challenges.

Can fecal calprotectin serve as a screen for necrotizing enterocolitis in infants?

BACKGROUND

Researchers are debating if fecal calprotectin results are useful for infant patients, especially in screening for necrotizing enterocolitis (NEC). Currently, none of the FDA-approved calprotectin assays provide a cut-off for infant patients. We retrospectively analyzed data from a reference laboratory and university hospital to investigate if a cut-off could be established for infant patients.

METHODS

Data from a national reference laboratory of 5144 test results for fecal calprotectin were analyzed for infant patients, and a cut-off was estimated based on the distribution of results. Additionally, a literature proposed cut-off of 226 μg/g was also considered. Validation of either cut-off was attempted by review of the electronic medical record of our university hospital for 110 infant patients with results for fecal calprotectin.

RESULTS

Infants had a high percentage of elevated fecal calprotectin results when using the adult cut-offs set by the manufacturer. A cut-off of 247 μg/g was estimated based on the reference laboratory results for infants 0-2 months old, which is similar to a literature proposed cut-off of 226 μg/g. However, the positive predictive value (PPV) for both cut-offs was <0.6 when retrospectively analyzing data from a university hospital.

CONCLUSION

Due to the low PPVs, the two infant-specific cut-offs for fecal calprotectin would not be useful to screen for NEC in infants at our university hospital.

Trends of Fecal Calprotectin and Lactoferrin Results for Infants

Calprotectin and lactoferrin can be measured in stool to test for inflammation in the gastrointestinal tract associated with inflammatory bowel disease (IBD) versus irritable bowel syndrome (IBS). The clinical specificity of these markers decreases in children versus adults because of the broader differential diagnosis for intestinal inflammation in children. Surprisingly, these tests are frequently ordered for infants (age = 0 years). Therefore, we wanted to assess our historical data in order to understand how infant calprotectin and lactoferrin concentrations change over time and review literature for the potential differential diagnosis for intestinal inflammation in infants. Data were analyzed on 19,543 infants/toddlers ages 0 to 2 years who had a stool test result of either the quantitative ELISA calprotectin PhiCal assay (Eurospital) or qualitative ELISA Lactoferrin Chek assay (Techlab). For the quantitative calprotectin test, the averages and medians were graphed over time in infants. And for the qualitative lactoferrin test, the positivity rate was graphed over time in infants. Both were compared to toddlers of ages 1 to 2 years old. The average level of calprotectin in neonates (0-1 months old) was 336 ± 348 μg/g with a median of 192 μg/g. While these values were dramatically above the adult normal reference range of 0 to 50 μg/g, the average level decreased over time to 119 ± 218 μg/g with a median of 39 μg/g for toddlers 2 years old. The presence of elevated lactoferrin was detected in 89% of neonates versus 34% of toddlers age 2 years. These trends demonstrate that both calprotectin and lactoferrin may be elevated early in life for many infants, but rapidly decline with time. Ordering trends show that, for infants/toddlers age 0 to 2 years, fecal calprotectin ordering has grown rapidly, whereas fecal lactoferrin has remained stable. In conclusion, while fecal calprotectin and lactoferrin are widely used markers of pathologic intestinal inflammation in adults, results in infants must be interpreted with great care. An elevated calprotectin or lactoferrin concentration in infant stool may be pathological, perhaps due to necrotizing enterocolitis or food-associated enteropathy, but is also associated with nonpathological reasons such as intestinal exposure to food antigens or commensal bacteria. Literature studies have shown associations of elevated calprotectin or lactoferrin with diet, gestational age at birth, and even mode of delivery. Thus, it is essential that clinicians interpret calprotectin levels or the presence of elevated lactoferrin in the context of the entire clinical picture and understand the lack of specificity of these markers for pathological conditions in infants.