Defining EGFR amplification status for clinical trial inclusion

Ensemble learning prediction framework for EGFR amplification status of glioma based on terahertz spectral features

Epidermal growth factor receptor (EGFR) plays a pivotal role in the initiation and progression of gliomas. In particular, in glioblastoma, EGFR amplification emerges as a catalyst for invasion, proliferation, and resistance to radiotherapy and chemotherapy. Current approaches are not capable of providing rapid diagnostic results of molecular pathology. In this study, we propose a terahertz spectroscopic approach for predicting the EGFR amplification status of gliomas for the first time. A machine learning model was constructed using the terahertz response of the measured glioma tissues, including the absorption coefficient, refractive index, and dielectric loss tangent. The novelty of our model is the integration of three classical base classifiers, i.e., support vector machine, random forest, and extreme gradient boosting. The ensemble learning method combines the advantages of various base classifiers, this model has more generalization ability. The effectiveness of the proposed method was validated by applying an individual test set. The optimal performance of the integrated algorithm was verified with an area under the curve (AUC) maximum of 85.8 %. This signifies a significant stride toward more effective and rapid diagnostic tools for guiding postoperative therapy in gliomas.

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.

Molecular diversity in isocitrate dehydrogenase-wild-type glioblastoma

In the dynamic landscape of glioblastoma, the 2021 World Health Organization Classification of Central Nervous System tumours endeavoured to establish biological homogeneity, yet isocitrate dehydrogenase-wild-type (IDH-wt) glioblastoma persists as a tapestry of clinical and molecular diversity. Intertumoural heterogeneity in IDH-wt glioblastoma presents a formidable challenge in treatment strategies. Recent strides in genetics and molecular biology have enhanced diagnostic precision, revealing distinct subtypes and invasive patterns that influence survival in patients with IDH-wt glioblastoma. Genetic and molecular biomarkers, such as the overexpression of neurofibromin 1, phosphatase and tensin homolog and/or cyclin-dependent kinase inhibitor 2A, along with specific immune cell abundance and neurotransmitters, correlate with favourable outcomes. Conversely, increased expression of epidermal growth factor receptor tyrosine kinase, platelet-derived growth factor receptor alpha and/or vascular endothelial growth factor receptor, coupled with the prevalence of glioma stem cells, tumour-associated myeloid cells, regulatory T cells and exhausted effector cells, signifies an unfavourable prognosis. The methylation status of O6-methylguanine-DNA methyltransferase and the influence of microenvironmental factors and neurotransmitters further shape treatment responses. Understanding intertumoural heterogeneity is complemented by insights into intratumoural dynamics and cellular interactions within the tumour microenvironment. Glioma stem cells and immune cell composition significantly impact progression and outcomes, emphasizing the need for personalized therapies targeting pro-tumoural signalling pathways and resistance mechanisms. A successful glioblastoma management demands biomarker identification, combination therapies and a nuanced approach considering intratumoural variability. These advancements herald a transformative era in glioblastoma comprehension and treatment.

Comprehensive clinical assays for molecular diagnostics of gliomas: the current state and future prospects

Glioma is one of the most intractable types of cancer, due to delayed diagnosis at advanced stages. The clinical symptoms of glioma are unclear and due to a variety of glioma subtypes, available low-invasive testing is not effective enough to be introduced into routine medical laboratory practice. Therefore, recent advances in the clinical diagnosis of glioma have focused on liquid biopsy approaches that utilize a wide range of techniques such as next-generation sequencing (NGS), droplet-digital polymerase chain reaction (ddPCR), and quantitative PCR (qPCR). Among all techniques, NGS is the most advantageous diagnostic method. Despite the rapid cheapening of NGS experiments, the cost of such diagnostics remains high. Moreover, high-throughput diagnostics are not appropriate for molecular profiling of gliomas since patients with gliomas exhibit only a few diagnostic markers. In this review, we highlighted all available assays for glioma diagnosing for main pathogenic glioma DNA sequence alterations. In the present study, we reviewed the possibility of integrating routine molecular methods into the diagnosis of gliomas. We state that the development of an affordable assay covering all glioma genetic aberrations could enable early detection and improve patient outcomes. Moreover, the development of such molecular diagnostic kits could potentially be a good alternative to expensive NGS-based approaches.

Molecular diagnostic tools for the World Health Organization (WHO) 2021 classification of gliomas, glioneuronal and neuronal tumors; an EANO guideline

In the 5th edition of the WHO CNS tumor classification (CNS5, 2021), multiple molecular characteristics became essential diagnostic criteria for many additional CNS tumor types. For those tumors, an integrated, "histomolecular" diagnosis is required. A variety of approaches exists for determining the status of the underlying molecular markers. The present guideline focuses on the methods that can be used for assessment of the currently most informative diagnostic and prognostic molecular markers for the diagnosis of gliomas, glioneuronal and neuronal tumors. The main characteristics of the molecular methods are systematically discussed, followed by recommendations and information on available evidence levels for diagnostic measures. The recommendations cover DNA and RNA next-generation-sequencing, methylome profiling, and select assays for single/limited target analyses, including immunohistochemistry. Additionally, because of its importance as a predictive marker in IDH-wildtype glioblastomas, tools for the analysis of MGMT promoter methylation status are covered. A structured overview of the different assays with their characteristics, especially their advantages and limitations, is provided, and requirements for input material and reporting of results are clarified. General aspects of molecular diagnostic testing regarding clinical relevance, accessibility, cost, implementation, regulatory, and ethical aspects are discussed as well. Finally, we provide an outlook on new developments in the landscape of molecular testing technologies in neuro-oncology.

Dynamic contrast-enhanced MRI radiomics model predicts epidermal growth factor receptor amplification in glioblastoma, IDH-wildtype

PURPOSE

To develop and validate a dynamic contrast-enhanced (DCE) MRI-based radiomics model to predict epidermal growth factor receptor (EGFR) amplification in patients with glioblastoma, isocitrate dehydrogenase (IDH) wildtype.

METHODS

Patients with pathologically confirmed glioblastoma, IDH wildtype, from January 2015 to December 2020, with an EGFR amplification status, were included. Patients who did not undergo DCE or conventional brain MRI were excluded. Patients were categorized into training and test sets by a ratio of 7:3. DCE MRI data were used to generate volume transfer constant (Ktrans) and extracellular volume fraction (Ve) maps. Ktrans, Ve, and conventional MRI were then used to extract the radiomics features, from which the prediction models for EGFR amplification status were developed and validated.

RESULTS

A total of 190 patients (mean age, 59.9; male, 55.3%), divided into training (n = 133) and test (n = 57) sets, were enrolled. In the test set, the radiomics model using the Ktrans map exhibited the highest area under the receiver operating characteristic curve (AUROC), 0.80 (95% confidence interval [CI], 0.65-0.95). The AUROC for the Ve map-based and conventional MRI-based models were 0.74 (95% CI, 0.58-0.90) and 0.76 (95% CI, 0.61-0.91).

CONCLUSION

The DCE MRI-based radiomics model that predicts EGFR amplification in glioblastoma, IDH wildtype, was developed and validated. The MRI-based radiomics model using the Ktrans map has higher AUROC than conventional MRI.

Genomic characterisation of de novo EGFR copy number gain and its impact on the efficacy of first-line EGFR-tyrosine kinase inhibitors for EGFR mutated non-small cell lung cancer

BACKGROUND

Non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutation generally respond well to epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs). However, genomic characterisation of de novo EGFR copy number gain (CNG) and its impact on the efficacy of first-line EGFR-TKIs remains unclear.

METHODS

This multicenter, retrospective and real-world study included two cohorts that enroled EGFR mutant NSCLC patients. EGFR CNG was tested by next-generation sequencing of untreated tissue specimens. Cohort 1 detected the impact of EGFR CNG on first-line EGFR-TKIs treatment, and cohort 2 explored the genomic characterisation.

RESULTS

Cohort 1 enroled 355 patients from four cancer centres between January 2013 and March 2022. The patients were divided into three groups, included the EGFR non-CNG, EGFR CNG, and EGFR uncertain-CNG. No significant difference in progression-free survival (PFS) was found between the three groups (10.0 months vs. 10.8 months vs. 9.9 months, respectively, p = 0.384). Furthermore, the overall response rate was not statistically significant in the EGFR CNG group compared to the EGFR non-CNG or uncertain arm (70.3% vs. 63.2% vs. 54.5%, respectively, p = 0.154). Cohort 2 included 7876 NSCLC patients with 16.4% showing EGFR CNG. Gene mutations such as TP53, IKZF1, RAC1, MYC, MET, CDKN2A/B and alterations of the metabolic-related and ERK signalling pathway were significantly associated with patients with EGFR CNG compared to those without.

CONCLUSIONS

De novo EGFR CNG had no effect on the efficacy of first-line EGFR-TKI treatment in EGFR mutant NSCLC patients, and tumours with EGFR CNG had more complex genomic profiles than those without.

Heterogeneity of resistant mechanisms in an EGFR-TKI relapsed patient with EGFR amplification and response to nimotuzumab: A case report

EGFR mutations are the most important drivers of gene alterations in lung adenocarcinomas and are sensitive to EGFR-TKIs. However, resistance to EGFR-TKIs is inevitable in the majority of EGFR-mutated lung cancer patients. Numerous resistant mechanisms have been revealed to date, and more are still under investigation. Owing to the selective pressure, intratumoral heterogeneity may exist after resistance, especially in patients after multiple lines of treatment. For those patients, it is important to choose therapies focused on the trunk/major clone of the tumor in order to achieve optimal clinical benefit. Here, we will report an EGFR-mutated lung adenocarcinoma patient with heterogeneity of resistant mechanisms including EGFR amplification, large fragment deletion of RB1, and histological transformations after targeted treatments. In our case, EGFR amplification seemed to be the major clone of the resistant mechanism according to the next-generation sequencing (NGS) results of both liquid biopsy monitoring and tissue biopsies. In consideration of the high EGFR amplification level, the patient was administered by combination treatment with EGFR-TKI plus nimotuzumab, an anti-EGFR monoclonal antibody (mAb), and achieved a certain degree of clinical benefit. Our case sheds light on the treatment of EGFR-mutant patients with EGFR amplification and indicates that a combination of EGFR-TKI with anti-EGFR mAb might be one of the possible treatment options based on genetic tests. Moreover, the decision on therapeutic approaches should focus on the major clone of the tumor and should make timely adjustments according to the dynamic changes of genetic characteristics during treatment.

Clinical, histopathological, and molecular features of IDH-wildtype indolent diffuse glioma: comparison with typical glioblastoma

PURPOSE

IDH-wildtype (IDHwt) diffuse gliomas are treated as glioblastoma, however, some of these may show less aggressive clinical courses. The authors investigated the clinical, histopathological, and molecular characteristics of such IDHwt indolent diffuse gliomas (iDGwt), which have not been well documented in the literature.

METHODS

Adult patients with IDHwt gliomas admitted between 2011 and 2020 were surveyed. In this particular study, the clinical indolence was defined mainly as having a small enhancing lesion and a stable period for more than 1 month before surgery. The current WHO diagnostic criteria were adapted for the diagnoses. Gene mutations and copy number changes in 43 representative glioma-associated genes, MGMT promoter methylation status, and survival data were compared with those of The Cancer Genome Atlas reference cohort.

RESULTS

Nine out of 180 surveyed cases (5.0%) fulfilled the present criteria of the iDGwt. Considering the representative regulatory pathways, 8 (88.9%), 4 (44.4%), and 1 (11.1%) case had genetic alterations in the PI3K/MAPK, TP53, and RB pathways, respectively. The frequency of the RB pathway alteration was significantly lower than that in the reference cohort (281 of 362 cases: 77.6%). Two cases (22.2%) showing EGFR amplification met the diagnostic criteria for glioblastoma, and the frequency was significantly lower than that in the reference cohort (412 of 426 cases: 96.7%). The overall survival (median: 37.5 months) in the present series was significantly longer than that in the reference cohort (n = 426, median: 13.9 months).

CONCLUSIONS

iDGwt lacked the molecular features of glioblastoma except for the PI3K/MAPK pathway alteration.

Diagnostic Yield and Complication Rate of Stereotactic Biopsies in Precision Medicine of Gliomas

Background

An integrated diagnosis consisting of histology and molecular markers is the basis of the current WHO classification system of gliomas. In patients with suspected newly diagnosed or recurrent glioma, stereotactic biopsy is an alternative in cases in which microsurgical resection is deemed to not be safely feasible or indicated. In this retrospective study, we aimed to analyze both the diagnostic yield and the safety of a standardized biopsy technique.

Material and Methods

The institutional database was screened for frame-based biopsy procedures (January 2016 until March 2021). Only patients with a suspected diagnosis of glioma based on imaging were included. All tumors were classified according to the current WHO grading system. The clinical parameters, procedural complications, histology, and molecular signature of the tissues obtained were assessed.

Results

Between January 2016 and March 2021, 1,214 patients underwent a stereotactic biopsy: 617 (50.8%) for a newly diagnosed lesion and 597 (49.2%) for a suspected recurrence. The median age was 56.9 years (range 5 months−94.4 years). Magnetic resonance imaging (MRI)-guidance was used in 99.3% of cases and additional positron emission tomography (PET)-guidance in 34.3% of cases. In total, stereotactic serial biopsy provided an integrated diagnosis in 96.3% of all procedures. The most frequent diagnoses were isocitrate dehydrogenase (IDH) wildtype glioblastoma (n = 596; 49.2%), oligodendroglioma grade 2 (n = 109; 9%), astrocytoma grade 3 (n = 108; 8.9%), oligodendroglioma grade 3 (n = 76; 6.3%), and astrocytoma grade 2 (n = 66; 5.4%). A detailed determination was successful for IDH 1/2 mutation in 99.4% of cases, for 1p/19q codeletion in 97.4% of cases, for TERT mutation in 98.9% of cases, and for MGMT promoter methylation in 99.1% of cases. Next-generation sequencing was evaluable in 64/67 (95.5%) of cases and DNA methylome analysis in 41/44 (93.2%) of cases. Thirteen (1.1%) cases showed glial tumors that could not be further specified. Seventy-three tumors were different non-glioma entities, e.g., of infectious or inflammatory nature. Seventy-five out of 597 suspected recurrences turned out to be post-therapeutic changes only. The rate of post-procedural complications with clinical symptoms of the Common Terminology Criteria for Adverse Events (CTCAE) grade 3 or higher was 1.2% in overall patients and 2.6% in the subgroup of brainstem biopsies. There was no fatal outcome in the entire series.

Conclusion

Image-guided stereotactic serial biopsy enables obtaining reliable histopathological and molecular diagnoses with a very low complication rate even in tumors with critical localization. Thus, in patients not undergoing microsurgical resection, this is a valuable tool for precision medicine of patients with glioma.

EGFR Amplification Is a Phenomenon of IDH Wildtype and TERT Mutated High-Grade Glioma: An Integrated Analysis Using Fluorescence In Situ Hybridization and DNA Methylome Profiling

Gliomas are the most common intrinsic brain tumors in adults, and in accordance with their clinical behavior and patients’ outcome, they are graded by the World Health Organization (WHO) classification of brain tumors. One very interesting candidate for targeted tumor therapy may be epidermal growth factor receptor (EGFR) amplification. Here, we performed an integrated comparative analysis of EGFR amplification in 34 glioma samples using standard fluorescence in situ hybridization (FISH) and Illumina EPIC Infinium Methylation Bead Chip and correlated results with molecular glioma hallmarks. We found that the EPIC analysis showed the same power of detecting EGFR amplification compared with FISH. EGFR amplification was detectable in high-grade gliomas (25%). Moreover, EGFR amplification was found to be present solely in IDH wildtype gliomas (26%) and TERT mutated gliomas (27%), occurring independently of MGMT promoter methylation status and being mutually exclusive with 1p/19q codeletion (LOH). In summary, EPIC Bead Chip analysis is a reliable tool for detecting EGFR amplification and is comparable with the standard method FISH. EGFR amplification is a phenomenon of IDH wildtype TERT mutated high-grade gliomas.

Phospholipase Cγ1 (PLCG1) overexpression is associated with tumor growth and poor survival in IDH wild-type lower-grade gliomas in adult patients

Gliomas are the most common and recalcitrant intracranial tumors, approximately a quarter of which are classified as lower-grade gliomas (WHO II-III). Although the prognosis of lower-grade gliomas (LGGs) is significantly better than that of higher-grade gliomas, as a highly heterogeneous tumor type, the prognosis of LGGs varies greatly based on the molecular diagnosis. IDH wild-type used to be regarded as a dismal prognostic biomarker in LGGs; however, several studies revealed that IDH wild-type LGGs might not always be equivalent to glioblastoma (WHO IV). Hence, we hypothesize that underlying biological events in LGGs can result in different prognosis. In our study, transcriptome profiling was performed in 24 samples of LGG, and the results showed that the expression of phospholipase Cγ1 (PLCG1) was significantly correlated with IDH1/2 status and patients' clinical outcome. Furthermore, the cancer genome atlas (TCGA) and the Chinese glioma genome atlas (CGGA) databases verified that elevated PLCG1 expression was associated with tumor progression and poor survival in LGG patients. Moreover, PLCG1-targeted siRNA dramatically affected the growth, migration and invasiveness of IDH wild-type LGG cell lines. In in vitro and in vivo experiments, the PLC-targeted drug significantly suppressed the tumor growth of IDH wild-type LGG cell lines in vitro and tumors in mouse models. Taken together, our results demonstrated that higher PLCG1 expression was associated with tumor growth and worse prognosis in IDH wild-type LGGs and PLCG1 could serve as a potential therapeutic target for IDH wild-type LGG patients.

The EGFRvIII transcriptome in glioblastoma, a meta-omics analysis

Background

EGFR is among the genes most frequently altered in glioblastoma, with exons 2-7 deletions (EGFRvIII) being among its most common genomic mutations. There are conflicting reports about its prognostic role and it remains unclear whether and how it differs in signaling compared with wildtype EGFR.

Methods

To better understand the oncogenic role of EGFRvIII, we leveraged 4 large datasets into 1 large glioblastoma transcriptome dataset (n = 741) alongside 81 whole-genome samples from 2 datasets.

Results

The EGFRvIII/EGFR expression ratios differ strongly between tumors and range from 1% to 95%. Interestingly, the slope of relative EGFRvIII expression is near-linear, which argues against a more positive selection pressure than EGFR wildtype. An absence of selection pressure is also suggested by the similar survival between EGFRvIII-positive and -negative glioblastoma patients. EGFRvIII levels are inversely correlated with pan-EGFR (all wildtype and mutant variants) expression, which indicates that EGFRvIII has a higher potency in downstream pathway activation. EGFRvIII-positive glioblastomas have a lower CDK4 or MDM2 amplification incidence than EGFRvIII-negative (P = .007), which may point toward crosstalk between these pathways. EGFRvIII-expressing tumors have an upregulation of “classical” subtype genes compared to those with EGFR-amplification only (P = 3.873e⁻⁶). Genomic breakpoints of the EGFRvIII deletions have a preference toward the 3′-end of the large intron-1. These preferred breakpoints preserve a cryptic exon resulting in a novel EGFRvIII variant and preserve an intronic enhancer.

Conclusions

These data provide deeper insights into the complex EGFRvIII biology and provide new insights for targeting EGFRvIII mutated tumors.

The Evolving Molecular Landscape of High-Grade Gliomas

ABSTRACT

The classification, diagnosis, and biological understanding of high-grade gliomas has been transformed by an evolving understanding of glioma biology. High-grade gliomas, in particular, have exemplified the impact of molecular alterations in pathology. The discovery of mutations in a key metabolic enzyme (IDH), histone genes (H3-3A), and large-scale chromosome changes (+7/-10, 1p/19q) are examples of specific alterations that now supplant traditional histologic interpretation. Here, we review established and recently defined types of adult and pediatric high-grade gliomas with discussion of key molecular alterations that have been leveraged for subclassification, grading, or prognosis.

Depatuxizumab Mafodotin (Depatux-M) Plus Temozolomide in Recurrent Glioblastoma Patients: Real-World Experience from a Multicenter Study of Italian Association of Neuro-Oncology (AINO)

Simple Summary

Depatux-M is an antibody-drug conjugate against activated EGFR. The efficacy and tolerability of the Depatux-M and temozolomide combination in recurrent glioblastoma patients were recently analyzed in the INTELLANCE-2/EORTC 1410 phase 2 trial. Despite the trial was negative, it showed interesting results for patients received this combination therapy versus standard treatment. For the first time worldwide, we investigated this treatment in a real-life population. Interestingly, we reported encouraging clinical benefits close to that reported in the previous randomized INTELLANCE 2 trial. Ocular toxicity was manageable. Likely, a subgroup of patients could benefit of this treatment and so, significant molecular predictors of treatment efficacy such as EGFR SNVs should be better investigated in a larger prospective study.

Abstract

Background: Depatuxizumab Mafodotin (Depatux-M; ABT-414) is an antibody-drug conjugate consisting of a specific antibody against activated EGFR and a cytotoxic agent with antimicrotubule activity. The INTELLANCE 2/EORTC 1410 phase 2 trial produced interesting results for the combination regimen of Depatux-M and temozolomide in EGFR-amplified glioblastoma patients at first recurrence. For the first time worldwide, our work investigated the clinical outcome and safety of this combination in a real-life population. Materials and Methods: Patients were enrolled from seven AINO (Italian Association of Neuro-Oncology) Institutions. The major inclusion criteria were: histologically confirmed diagnosis of glioblastoma, EGFR-amplified, one or more prior systemic therapies and ECOG PS ≤ 2. According to the original schedule, patients received Depatux-M 1.25 mg/kg every 2 weeks combined with temozolomide. The primary endpoints of the study were overall survival and safety. Results: A total of 36 patients were enrolled. The median age was 57 years, ECOG PS was 0–1 in 28 patients (88%), MGMT methylated status was found in 22 (64%), 15 patients (42%) received the combined treatment as second-line therapy. The median OS was 8.04 months (95% CI, 5.3–10.7), the 12 month-OS was 37%. On univariate and multivariate analyses, the MGMT methylation status was the only factor resulting significantly associated with survival. Grade 3 ocular toxicity occurred in 11% of patients; no grade 4 ocular toxicity was reported. No death was considered to be drug-related. Conclusions: The study reported the first “real world” experience of Depatux-M plus temozolomide in recurrent glioblastoma patients. Encouraging clinical benefits were demonstrated, even though most patients were treated beyond second-line therapy. Overall, the results are close to those reported in the previous phase 2 trial. Toxicity was moderate and manageable.

Use of Gefitinib in EGFR-Amplified Refractory Solid Tumors: An Open-Label, Single-Arm, Single-Center Prospective Pilot Study

BACKGROUND

Treatment options for patients with chemotherapy-refractory solid tumors are limited.

OBJECTIVE

We conducted an open-label, single-arm, single-center phase II trial to evaluate the efficacy and safety of gefitinib in patients with chemotherapy-refractory solid tumors and EGFR amplification or sensitivity to an EGFR inhibitor identified through a drug-screening platform with patient-derived tumor cells (PDCs).

PATIENTS AND METHODS

EGFR amplification was detected by targeted sequencing. Sensitivity to an EGFR inhibitor was established in chemical screening using PDCs. Gefitinib (250 mg daily) was administered continuously in 28-day cycles until the occurrence of disease progression, unacceptable toxicity, or death due to any cause. The primary endpoint was the objective response rate (ORR).

RESULTS

In total, 15 patients were assigned to the present study. The most common tumor type was glioblastoma multiforme (n = 9, 60%), followed by gastric cancer (n = 3, 20%), anal squamous cancer, rectal cancer, and sarcoma (each n = 1, 6.7%). Among 13 evaluable patients, one patient had a partial response and five had stable disease, with an ORR of 7.7% and a disease control rate of 46.1%. The median progression-free survival was 2.1 months (95% confidence interval [CI] 0.77-3.43). The most common adverse events were diarrhea (26.7%) and skin rash (26.7%).

CONCLUSION

Gefitinib demonstrated modest anti-tumor activity and a manageable safety profile in chemotherapy-refractory solid tumors with EGFR amplification or sensitivity to an EGFR inhibitor identified through a drug-screening platform with PDCs. CLINICALTRIALS.

GOV IDENTIFIER

NCT02447419.

Prognostic impact of CDKN2A/B deletion, TERT mutation, and EGFR amplification on histological and molecular IDH-wildtype glioblastoma

Background

We aimed to evaluate the clinical outcomes of molecular glioblastoma (mGBM) as compared to histological GBM (hGBM) and to determine the prognostic impact of TERT mutation, EGFR amplification, and CDKN2A/B deletion on isocitrate dehydrogenase (IDH)-wildtype GBM.

Methods

IDH-wildtype GBM patients treated with radiation therapy (RT) between 2012 and 2019 were retrospectively analyzed. mGBM was defined as grade II-III IDH-wildtype astrocytoma without histological features of GBM but with one of the following molecular alterations: TERT mutation, EGFR amplification, or combination of whole chromosome 7 gain and whole chromosome 10 loss. Overall survival (OS) and progression-free survival (PFS) were calculated from RT and analyzed using the Kaplan-Meier method. Multivariable analysis (MVA) was performed using Cox regression to identify independent predictors of OS and PFS.

Results

Of the 367 eligible patients, the median follow-up was 11.7 months. mGBM and hGBM did not have significantly different OS (median: 16.6 vs 13.5 months, respectively, P = .16), nor PFS (median: 11.7 vs 7.3 months, respectively, P = .08). However, mGBM was associated with better OS (hazard ratio [HR] 0.50, 95% CI 0.29-0.88) and PFS (HR 0.43, 95% CI 0.26-0.72) than hGBM after adjusting for known prognostic factors on MVA. CDKN2A/B deletion was associated with worse OS (HR 1.57, 95% CI 1.003-2.46) and PFS (HR 1.57, 95% CI 1.04-2.36) on MVA, but TERT mutation and EGFR amplification were not.

Conclusion

Criteria for mGBM may require further refinement and validation. CDKN2A/B deletion, but not TERT mutation or EGFR amplification, may be an independent prognostic biomarker for IDH-wildtype GBM patients.

Simultaneous detection of EGFR amplification and EGFRvIII variant using digital PCR-based method in glioblastoma

Epidermal growth factor receptor (EGFR) amplification and EGFR variant III (EGFRvIII, deletion of exons 2-7) are of clinical interest for glioblastoma. The aim was to develop a digital PCR (dPCR)-based method using locked nucleic acid (LNA)-based hydrolysis probes, allowing the simultaneous detection of the EGFR amplification and EGFRvIII variant. Sixty-two patients were included. An exploratory cohort (n = 19) was used to develop the dPCR assay using three selected amplicons within the EGFR gene, targeting intron 1 (EGFR1), junction of exon 3 and intron 3 (EGFR2) and intron 22 (EGFR3). The copy number of EGFR was estimated by the relative quantification of EGFR1, EGFR2 and EGFR3 amplicon droplets compared to the droplets of a reference gene. EGFRvIII was identified by comparing the copy number of the EGFR2 amplicon to either the EGFR1 or EGFR3 amplicon. dPCR results were compared to fluorescence in situ hybridization (FISH) and next-generation sequencing for amplification; and to RT-PCR-based method for EGFRvIII. The dPCR assay was then tested in a validation cohort (n = 43). A total of 8/19 EGFR-amplified and 5/19 EGFRvIII-positive tumors were identified in the exploratory cohort. Compared to FISH, the EGFR3 dPCR assay detected all EGFR-amplified tumors (8/8, 100%) and had the highest concordance with the copy number estimation by NGS. The concordance between RT-PCR and dPCR was also 100% for detecting EGFRvIII using an absolute difference of 10.8 for the copy number between EGFR2 and EGFR3 probes. In the validation cohort, the sensitivity and specificity of dPCR using EGFR3 probes were 100% for the EGFR amplification detection compared to FISH (19/19). EGFRvIII was detected by dPCR in 8 EGFR-amplified patients and confirmed by RT-PCR. Compared to FISH, the EGFR2/EGFR3 dPCR assay was estimated with a one-half cost value. These results highlight that dPCR allowed the simultaneous detection of EGFR amplification and EGFRvIII for glioblastoma.

Immunotherapy in Glioblastoma: Current Shortcomings and Future Perspectives

Glioblastomas are aggressive, fast-growing primary brain tumors. After standard-of-care treatment with radiation in combination with temozolomide, the overall prognosis of newly diagnosed patients remains poor, with a 2-year survival rate of less than 20%. The remarkable survival benefit gained with immunotherapy in several extracranial tumor types spurred a variety of experimental intervention studies in glioblastoma patients. These ranged from immune checkpoint inhibition to vaccinations and adoptive T cell therapies. Unfortunately, almost all clinical outcomes were universally disappointing. In this perspective, we provide an overview of immune interventions performed to date in glioblastoma patients and re-evaluate their performance. We argue that shortcomings of current immune therapies in glioblastoma are related to three major determinants of resistance, namely: low immunogenicity; immune privilege of the central nervous system; and immunosuppressive micro-environment. In this perspective, we propose strategies that are guided by exact shortcomings to sensitize glioblastoma prior to treatment with therapies that enhance numbers and/or activation state of CD8 T cells.

EGFR amplification is a real independent prognostic impact factor between young adults and adults over 45yo with wild-type glioblastoma?

BACKGROUND

In 2019 a group of University of Pennsylvania (Hoffman et al., J Neurooncol 145: 321-328, 2019) aimed to explore the prognostic impact of expression of epidermal growth factor receptor (EGFR), one of the most common genetic alterations in WT-GBM, in young adults with IDH-WT GBM, suggesting an inferior outcomes in young adults (< 45yo) with newly diagnosed, IDH-WT GBM. At the same time, our group were considering the dimension of this subpopulation treated in our centre, and we performed the same analysis, comparing datas with affected elderly adults.

METHODS

We explore the prognostic impact of EGFR expression status in young adults with IDH-WT GBM, and compare this impact with the affected elderly adults. We therefore analyzed clinical characteristics, tumor genetics, and clinical outcomes in a cohort of adults aged 18-45 years with newly diagnosed WT GBM. We selected a total of 146 patients affected by newly diagnosed IDH-WT GBM who underwent surgery, radiation, and chemotherapy in our Institution in the period ranging between January 2014 and December 2016. We focused primarily on the prognostic impact of EGFR expression.

RESULTS

We confirmed through a Bivariate Analysis that the Age of the Patients, the Volume of the lesions, were statistically strongly associated with the survival parameters; The general OS of the cohort presented a breakthrough point between the patients who were respectively younger and older than 45 years, EGFR mutation was per se not associated to a survival reduction in all the cohort patients. When analyzing exclusively the Survival parameters of the patients whose age was under 40, it was possible to outline a non statistically significant trend towards a lesser OS in younger patients harboring an EGFR expression.

CONCLUSIONS

Once again the main difference in terms of OS in GBM is shown in a EOR and in Age. To our knowledge, ours is the second study (Hoffman et al., J Neurooncol 145: 321-328, 2019) to evaluate the prognostic impact of EGFR CN gain specifically in young adults with IDH-WT GBM and in the era of modern radiation and Temozolomide, but is the first one to compares this impact with a population of adults over 45, and correlates this date with clinical onset, dimension and localization of disease between this groups. We suggest other centers to evaluate this important finding with a larger number of patients and we are inclined to accept collaborations to increase the power of this study.

EGFR mutations are associated with response to depatux-m in combination with temozolomide and result in a receptor that is hypersensitive to ligand

Background

The randomized phase II INTELLANCE-2/EORTC_1410 trial on EGFR-amplified recurrent glioblastomas showed a trend towards improved overall survival when patients were treated with depatux-m plus temozolomide compared with the control arm of alkylating chemotherapy only. We here performed translational research on material derived from this clinical trial to identify patients that benefit from this treatment.

Methods

Targeted DNA-sequencing and whole transcriptome analysis was performed on clinical trial samples. High-throughput, high-content imaging analysis was done to understand the molecular mechanism underlying the survival benefit.

Results

We first define the tumor genomic landscape in this well-annotated patient population. We find that tumors harboring EGFR single-nucleotide variations (SNVs) have improved outcome in the depatux-m + TMZ combination arm. Such SNVs are common to the extracellular domain of the receptor and functionally result in a receptor that is hypersensitive to low-affinity EGFR ligands. These hypersensitizing SNVs and the ligand-independent EGFRvIII variant are inversely correlated, indicating two distinct modes of evolution to increase EGFR signaling in glioblastomas. Ligand hypersensitivity can explain the therapeutic efficacy of depatux-m as increased ligand-induced activation will result in increased exposure of the epitope to the antibody-drug conjugate. We also identified tumors harboring mutations sensitive to "classical" EGFR tyrosine-kinase inhibitors, providing a potential alternative treatment strategy.

Conclusions

These data can help guide treatment for recurrent glioblastoma patients and increase our understanding into the molecular mechanisms underlying EGFR signaling in these tumors.