EGFRvIII Is Expressed in Cellular Areas of Tumor in a Subset of Glioblastoma

Near-Infrared Photoimmunotherapy in Brain Tumors-An Unexplored Frontier

Near-infrared photoimmunotherapy (NIR-PIT) is a promising cancer treatment that uses near-infrared light to activate a conjugate of a monoclonal antibody (mAb) and a photoactivatable silica phthalocyanine dye (IRDye700DX: IR700). Unlike conventional photodynamic therapy (PDT), NIR-PIT selectively destroys targeted tumor cells while preserving the surrounding normal tissue and providing superior tissue penetration. Recently, NIR-PIT has been approved for the treatment of unresectable recurrent head and neck cancers in Japan. It induces highly selective cancer cell death; therefore, it is expected to be a new curative treatment option for various cancers, including brain tumors. In this review, we compare the principles of NIR-PIT and PDT and discuss the potential applications of NIR-PIT for brain tumors. We selected targetable proteins across various types of brain tumors and devised a strategy to effectively pass the mAb-IR700 conjugate through the blood-brain barrier (BBB), which is a significant challenge for NIR-PIT in treating brain tumors. Innovative approaches for delivering the mAb-IR700 conjugate across the BBB include exosomes, nanoparticle-based systems, and cell-penetrating peptides. Small-molecule compounds, such as affibodies, are anticipated to rapidly accumulate in tumors within intracranial models, and our preliminary experiments demonstrated rapid uptake. NIR-PIT also induces immunogenic cell death and activates the anti-tumor immune response. Overall, NIR-PIT is a promising approach for treating brain tumors. It has the potential to overcome the limitations of conventional therapies and offers new hope to patients with brain tumors.

The Prognostic Significance of Epidermal Growth Factor Receptor Amplification and Epidermal Growth Factor Receptor Variant III Mutation in Glioblastoma: A Systematic Review and Meta-Analysis with Implications for Targeted Therapy

Glioblastoma (GBM) is the most aggressive and heterogeneous neoplasm among central nervous system tumors, with a dismal prognosis and a high recurrence rate. Among the various genetic alterations found in GBM, the amplification of epidermal growth factor receptor (EGFR) and the EGFR variant III (EGFRvIII) mutation are among the most common, though their prognostic value remains controversial. This systematic review and meta-analysis aimed to provide a comprehensive evaluation of the diagnostic and prognostic significance of EGFR amplification and the EGFRvIII mutation in GBM patients, incorporating recent studies published in the past few years to offer a more complete and up-to-date analysis. An extensive search of the PubMed, Web of Science, and Scopus databases was conducted, including studies that reported on EGFR and/or the EGFRvIII mutation status with detailed survival data. A total of 32 studies with 4208 GBM patients were included. The results indicated that EGFR amplification significantly correlated with worse OS (Overall survival) (HR = 1.27, 95% CI: 1.03-1.57), suggesting that EGFR amplification is an independent prognostic marker. The prognostic value of EGFRvIII was inconclusive, with a pooled hazard ratio for overall survival of 1.13 (95% CI: 0.94-1.36), indicating no significant effect on survival in the general population. However, a subgroup analysis suggested that EGFRvIII may be associated with poorer outcomes, particularly in recurrent GBM patients, where its prognostic significance became more evident. Furthermore, subgroup analyses based on geographic region revealed significant heterogeneity in the prognostic impact of EGFR amplification across different populations. In American cohorts, EGFR amplification was strongly associated with an increased risk of mortality (HR = 1.53, 95% CI: 1.28-1.84, p = 0.001), suggesting that it serves as a more reliable prognostic marker in this region. In contrast, no significant prognostic impact of EGFR amplification was observed in Asian (HR = 0.64, 95% CI: 0.35-1.17) or European (HR = 0.98, 95% CI: 0.80-1.19) populations. Overall, this study underscores the potential of EGFR amplification as a prognostic marker in GBM, while further research is needed to fully elucidate the role of the EGFRvIII mutation, particularly in specific patient subgroups. Clarifying these associations could offer important insights for targeted treatment strategies, improving patient outcomes.

The Co-Expression and Cellular Location of HER Family Members, EGFRvIII, Putative Cancer Stem Cell Biomarkers CD44 and CD109 in Patients with Glioblastoma, and Their Impacts on Prognosis

BACKGROUND/OBJECTIVES

The aberrant expression and activation of HER family members is a known major oncogenic pathway for the proliferation, progression, and metastasis of a wide range of human malignancies. In this study, our aim was to examine the relative expression and prognostic significance of all members of the HER family, the type III EGFR mutant (EGFRvIII), and the putative stem cell markers CD44 and CD109 in patients with glioblastoma.

METHODS

The expression levels of wild-type EGFR (wtEGFR), HER2, HER3, HER4, EGFRvIII, CD44, and CD109 were determined in tumour specimens from 80 patients by immunohistochemistry. The staining was scored based on the percentage of positive tumour cells, the intensity, and the cellular location of immunostaining. The association between the expression level of the biomarkers and patient overall survival was evaluated using Chi-squared, Kaplan-Meier survival curves, and log-rank tests.

RESULTS

At a cut-off value of ≥5% with positive staining, 46% (wtEGFR), 75% (HER2), 19% (HER3), 71% (HER4), 85% (EGFRvIII), 95% (CD44), and 16% (CD109) of the cases were positive for these biomarkers. Interestingly, at the same cut-off value, the expression of wtEGFR in these patients was accompanied by co-expression with HER2 (35%), HER3 (0%), HER4 (30%), EGFRvIII (36%), CD44 (44%), HER2/EGFRvIII (28%), HER2/CD44 (31%), and EGFRvIII/CD44 (36%). In addition, the expression of EGFRvIII was accompanied by co-expression with HER2 (65%), HER3 (15%), HER4 (63%), CD44 (83%), CD109 (16%), wtEGFR/HER2 (28%), and 55% of the cases had co-expression of EGFRvIII/HER2/HER4/CD44. With the exception of HER2 expression, at cut-off values of ≥5% of tumour cells with positive staining, which was associated with better overall survival [HR = 0.57 (p = 0.038), HR = 0.56 (p = 0.034)], there was no significant association between the expression of other members of the HER family, EGFRvIII, CD44, and CD109 on the overall survival in both univariate and multivariate analysis. Conclusions Our results suggest that the co-expression of different members of the HER family, with EGFRvIII, CD44, and CD109, occurs in patients with glioblastoma. As the results of therapy with EGFR inhibitors have not been encouraging in patients with a brain tumour, further investigation should determine whether the co-expression of such biomarkers can be of predictive value for the response to the therapy with various types of HER inhibitors and their potential as therapeutic targets for co-targeted therapy.

Intratumoral heterogeneity and drug resistance in cancer

Intratumoral heterogeneity is the main cause of tumor treatment failure, varying across disease sites (spatial heterogeneity) and polyclonal properties of tumors that evolve over time (temporal heterogeneity). As our understanding of intratumoral heterogeneity, the formation of which is mainly related to the genomic instability, epigenetic modifications, plastic gene expression, and different microenvironments, plays a substantial role in drug-resistant as far as tumor metastasis and recurrence. Understanding the role of intratumoral heterogeneity, it becomes clear that a single therapeutic agent or regimen may only be effective for subsets of cells with certain features, but not for others. This necessitates a shift from our current, unchanging treatment approach to one that is tailored against the killing patterns of cancer cells in different clones. In this review, we discuss recent evidence concerning global perturbations of intratumoral heterogeneity, associations of specific intratumoral heterogeneity in lung cancer, the underlying mechanisms of intratumoral heterogeneity potentially leading to formation, and how it drives drug resistance. Our findings highlight the most up-to-date progress in intratumoral heterogeneity and its role in mediating tumor drug resistance, which could support the development of future treatment strategies.

Repurposing Osimertinib and Gedatolisib for Glioblastoma Treatment: Evidence of Synergistic Effects in an In Vitro Phenotypic Study

Background/Objectives: Glioblastoma is a malignant tumor with a poor prognosis for the patient due to its high lethality and limited chemotherapy available. Therefore, from the point of view of chemotherapy treatment, glioblastoma can be considered an unmet medical need. This has led to the investigation of new drugs for monotherapy or associations, acting by synergistic pharmacological mechanisms. Methods: Here, we propose the combination of Osimertinib (a potent EGFR inhibitor) and Gedatolisib (a potent PI3K/mTOR dual inhibitor) through an in vitro phenotypic study using five human GB lines and establish the cytotoxic potency, selectivity, and effect on proliferation, apoptosis, and cell cycle by simultaneously inhibiting EGFR, PI3K, and mTOR. Results: Cytotoxic potency of Gedatolisib and Osimertinib in the selected GB cell lines was determined, which highlighted the synergistic response from their combination and its impact on migration reduction, G0/G1 cell cycle arrest, GB cytotoxicity, and apoptosis-inducing effects for different GB cell lines. Conclusions: From the drug combination studies in phenotypic in vitro models, it was possible to suggest a new potential treatment for glioblastoma that justifies further safe in vivo phases of preclinical trials with the combination.

Current progress of anti‑PD‑1/PDL1 immunotherapy for glioblastoma (Review)

Glioblastoma (GBM) is the most common central nervous system malignancy in adults. GBM may be classified as grade IV diffuse astrocytoma according to the 2021 World Health Organization revised classification of central nervous system tumors, which means it is the most aggressive, invasive, undifferentiated type of tumor. Immune checkpoint blockade (ICB), particularly anti‑programmed cell death protein‑1 (PD‑1)/PD‑1 ligand‑1 immunotherapy, has been confirmed to be successful across several tumor types. However, in GBM, this treatment is still uncommon and the efficacy is unpredictable, and <10% of patients show long‑term responses. Recently, numerous studies have been conducted to explore what factors may indicate or affect the ICB response rate in GBM, including molecular alterations, immune expression signatures and immune infiltration. The present review aimed to summarize the current progress to improve the understanding of immunotherapy for GBM.

Reliable detection of genetic alterations in cyst fluid DNA for the diagnosis of brain tumors

PURPOSE

Liquid biopsy of cyst fluid in brain tumors has not been extensively studied to date. The present study was performed to see whether diagnostic genetic alterations found in brain tumor tissue DNA could also be detected in cell-free DNA (cfDNA) of cyst fluid in cystic brain tumors.

METHODS

Cyst fluid was obtained from 22 patients undergoing surgery for a cystic brain tumor with confirmed genetic alterations in tumor DNA. Pathological diagnoses based on WHO 2021 classification and diagnostic alterations in the tumor DNA, such as IDH1 R132H and TERT promoter mutation for oligodendrogliomas, were detected by Sanger sequencing. The same alterations were analyzed by both droplet digital PCR (ddPCR) and Sanger sequencing in cyst fluid cfDNA. Additionally, multiplex ligation-dependent probe amplification (MLPA) assays were performed to assess 1p/19q status, presence of CDKN2A loss, PTEN loss and EGFR amplification, to assess whether differentiating between astrocytomas and oligodendrogliomas and grading is possible from cyst fluid cfDNA.

RESULTS

Twenty-five genetic alterations were found in 22 tumor samples. All (100%) alterations were detected in cyst fluid cfDNA by ddPCR. Twenty of the 25 (80%) alterations were also detected by Sanger sequencing of cyst fluid cfDNA. Variant allele frequency (VAF) in cyst fluid cfDNA was comparable to that of tumor DNA (R = 0.62, Pearson's correlation). MLPA was feasible in 11 out of 17 (65%) diffuse gliomas, with close correlation of results between tumor DNA and cyst fluid cfDNA.

CONCLUSION

Cell-free DNA obtained from cyst fluid in cystic brain tumors is a reliable alternative to tumor DNA when diagnosing brain tumors.

Intratumoral thrombosis as a histological biomarker for predicting epidermal growth factor receptor alteration and poor prognosis in patients with glioblastomas

PURPOSE

Intratumoral thrombosis is a specific finding in glioblastomas and considered the origin of palisading necrosis. Its distribution and contribution to the glioblastoma pathophysiology and systemic thrombosis are obscure, although deep vein thrombosis is a common complication in glioblastoma cases.

METHODS

Clinicopathological and genetic analyses were performed on 97 glioblastoma tissue specimens to elucidate the role of thrombotic events and associated molecular abnormalities.

RESULTS

Morphologically, intratumoral thrombosis was observed more frequently in vessels composed of single-layered CD34-positive endothelium and/or αSMA-positive pericytes in the tumor periphery, compared to microvascular proliferation with multi-channeled and pericyte-proliferating vessels in the tumor center. Intratumoral thrombosis was significantly correlated with the female sex, high preoperative D-dimer levels, and epidermal growth factor receptor (EGFR) amplification. The presence of one or more thrombi in 20 high-power fields was a predictive marker of EGFR amplification, with a sensitivity of 81.5% and specificity of 52.6%. RNA sequencing demonstrated that the group with many thrombi had higher EGFR gene expression levels than the group with few thrombi. The tumor cells invading along the vessels in the tumor periphery were positive for wild-type EGFR but negative for EGFRvIII, whereas the cells around the microvascular proliferation (MVP) in the tumor center were positive for both wild-type EGFR and EGFRvIII. Intratumoral thrombosis is an independent poor prognostic factor.

CONCLUSIONS

Aberrant but exquisitely regulated EGFR can induce thrombosis in non-MVP vessels in the tumor invasion area and then promote palisading necrosis, followed by hypoxia, abnormal angiogenesis, and further tumor cell invasion.

A case of glioblastoma harboring non-amplified epidermal growth factor receptor variant III: Critical molecular detection using RNA-based panel analysis

Amplification of the epidermal growth factor receptor gene (EGFR) and its variants are the most commonly detected pathogenic gene alterations in glioblastoma. Herein, we report a case of molecularly defined glioblastoma harboring an EGFR variant III (EGFRvIII) without EGFR amplification. The initial histological diagnosis was isocitrate dehydrogenase (IDH)-wildtype low-grade glioma, due to an absence of anaplasia, necrosis, and microvascular proliferation, and a low Ki-67 labeling index. DNA-based next-generation sequencing (NGS) panel analysis revealed a TERTp promoter mutation but no EGFR mutation or amplification, supporting the diagnosis of "molecular glioblastoma." However, RNA-based NGS panel analysis revealed mRNA expression of EGFRvIII. Therefore, the final integrative diagnosis was glioblastoma with non-amplified EGFRvIII. Our report suggests that non-amplified EGFRvIII might be an early molecular event in glioblastoma tumorigenesis. In addition to the usual DNA-based analysis, RNA-based analysis is required to identify exon-skipping EGFR variants without EGFR amplification.

B7-H3-targeted CAR T cell activity is enhanced by radiotherapy in solid cancers

Adoptive cell therapy utilizing T cells genetically modified to express a chimeric antigen receptor (CAR) has demonstrated promising clinical results in hematological malignancies. However, solid cancers have not seen a similar success due to multiple obstacles. Investigating these escape mechanisms and designing strategies to counteract such limitations is crucial and timely. Growing evidence in the literature supports the hypothesis that radiotherapy has the potential to enhance the susceptibility of solid tumors to CAR T cell therapy, by overcoming mechanisms of resistance. Radiation treatment can increase the susceptibility of different types of solid cancers (TNBC, HNSCC, PDAC) to B7-H3 CAR T cell-mediated eradication. Multiple mechanisms, including reduced cancer cell proliferation, upregulation of the targeted antigen, modulation of apoptotic molecules may contribute to this signal. The information in the literature and the results we describesupport the ability of radiotherapy to improve the efficacy of CAR T cell therapy in solid tumors.

Targeting of palpable B16-F10 melanoma tumors with polyclonal antibodies on white blood cells

BACKGROUND

Antibodies and other recognition molecules direct cancer cell death by multiple types of immune cells. Therapy directed at only one target typically results in tumor regrowth because of tumor heterogeneity. Our goal is to direct therapy to multiple targets simultaneously. Our previous studies showed that multiple antibodies targeting mutated tumor proteins inhibited tumor growth when injected subcutaneously near the time of cancer cell implantation.

METHODS

A cocktail of rabbit antibodies against B16-F10 cell surface related mutated proteins were generated. Implanted B16-F10 cells were allowed to grow to palpable size before treatment. Antibodies were administered using different routes of exposure. Free antibody was compared to antibody armed on mouse splenic white blood cells (WBCs). Binding of the antibody cocktail was determined for mouse and human WBCs.

RESULTS

The antibody cocktail inhibited tumor growth and prolonged survival when administered as free antibody or armed on WBCs. The antibody cocktail armed on WBCs achieved similar tumor inhibition as free antibody but at a dose 1000-fold less. Armed WBCs achieved tumor inhibition by intravenous and subcutaneous administration. The antibody cocktail bound well to human WBCs and saturation dose was defined. Binding was stable under simulated in vivo condition in human plasma at 37 °C.

CONCLUSIONS

Antibodies targeting multiple tumor mutated proteins inhibited tumor growth and prolonged survival. Effective antibody dose was reduced 1000-fold by arming WBCs. Rabbit antibodies saturated human WBCs using <1 mg per billion cells. A phase I trial in cancer patients using this strategy has been approved by the FDA.

Phenotypical Flexibility of the EGFRvIII-Positive Glioblastoma Cell Line and the Multidirectional Influence of TGFβ and EGF on These Cells—EGFRvIII Appears as a Weak Oncogene

Background: The biological role of EGFRvIII (epidermal growth factor receptor variant three) remains unclear. Methods: Three glioblastoma DK-MG sublines were tested with EGF (epidermal growth factor) and TGFβ (transforming growth factor β). Sublines were characterized by an increased percentage of EGFRvIII-positive cells and doubling time (DK-MG^low to DK-MG^extra-high), number of amplicons, and EGFRvIII mRNA expression. The influence of the growth factors on primary EGFRvIII positive glioblastomas was assessed. Results: The overexpression of exoEGFRvIII in DK-MG^high did not convert them into DK-MG^extra-high, and this overexpression did not change DK-MG^low to DK-MG^high; however, the overexpression of RAS^G12V increased the proliferation of DK-MG^low. Moreover, the highest EGFRvIII phosphorylation in DK-MG^extra-high did not cause relevant AKT (known as protein kinase B) and ERK (extracellular signal-regulated kinase) activation. Further analyses indicate that TGFβ is able to induce apoptosis of DK-MG^high cells. This subline was able to convert to DK-MG^extra-high, which appeared resistant to this proapoptotic effect. EGF acted as a pro-survival factor and stimulated proliferation; however, simultaneous senescence induction in DK-MG^extra-high cells was ambiguous. Primary EGFRvIII positive (and SOX2 (SRY-Box Transcription Factor 2) positive or SOX2 negative) glioblastoma cells differentially responded to EGF and TGFβ. Conclusions: The roles of TGFβ and EGF in the EGFRvIII context remain unclear. EGFRvIII appears as a weak oncogene and not a marker of GSC (glioma stem cells). Hence, it may not be a proper target for CAR-T (chimeric antigen receptor T cells).

Highly sensitive EGFRvIII detection in circulating extracellular vesicle RNA of glioma patients

PURPOSE

Liquid biopsy offers an attractive platform for non-invasive tumor diagnosis, prognostication and prediction of glioblastoma clinical outcomes. Prior studies report that 30-50% of GBM lesions characterized by EGFR amplification also harbor the EGFRvIII mutation.

EXPERIMENTAL DESIGN

A novel digital droplet PCR (ddPCR) assay for high GC content amplicons was developed and optimized for sensitive detection of EGFRvIII in tumor tissue and circulating extracellular vesicle RNA (EV RNA) isolated from the plasma of glioma patients.

RESULTS

Our optimized qPCR assay detected EGFRvIII mRNA in 81% (95% CI, 68% - 94%) of EGFR amplified glioma tumor tissue, indicating a higher than previously reported prevalence of EGFRvIII in glioma. Using the optimized ddPCR assay in discovery and blinded validation cohorts, we detected EGFRvIII mutation in 73% (95% CI, 64% - 82%) of patients with a specificity of 98% (95% CI, 87% - 100%), compared with qPCR tumor tissue analysis. Additionally, upon longitudinal monitoring in 4 patients, we report detection of EGFRvIII in the plasma of patients with different clinical outcomes, rising with tumor progression, and decreasing in response to treatment.

CONCLUSION

This study demonstrates the feasibility of detecting EGFRvIII mutation in plasma using a highly sensitive and specific ddPCR assay. We also show a higher than previously reported EGFRvIII prevalence in glioma tumor tissue. Several features of the assay are favorable for clinical implementation for detection and monitoring of EGFRvIII positive tumors.

GZ17-6.02 Inhibits the Growth of EGFRvIII+ Glioblastoma

Epidermal Growth Factor Receptor (EGFR) is amplified in over 50% of glioblastomas and promotes tumor formation and progression. However, attempts to treat glioblastoma with EGFR tyrosine kinase inhibitors have been unsuccessful thus far. The current standard of care is especially poor in patients with a constitutively active form of EGFR, EGFRvIII, which is associated with shorter survival time. This study examined the effect of GZ17-6.02, a novel anti-cancer agent undergoing phase 1 studies, on two EGFRvIII+ glioblastoma stem cells: D10-0171 and D317. In vitro analyses showed that GZ17-6.02 inhibited the growth of both D10-0171 and D317 cells with IC₅₀ values of 24.84 and 28.28 µg/mL respectively. RNA sequencing and reverse phase protein array analyses revealed that GZ17-6.02 downregulates pathways primarily related to steroid synthesis and cell cycle progression. Interestingly, G17-6.02’s mechanism of action involves the downregulation of the recently identified glioblastoma super-enhancer genes WSCD1, EVOL2, and KLHDC8A. Finally, a subcutaneous xenograft model showed that GZ17-6.02 inhibits glioblastoma growth in vivo. We conclude that GZ17-6.02 is a promising combination drug effective at inhibiting the growth of a subset of glioblastomas and our data warrants further preclinical studies utilizing xenograft models to identify patients that may respond to this drug.

Frequency and Prognosis of Epidermal Growth Factor Receptor Variant III Mutations in Glioblastoma Multiforme among Indian Patients: A Single-Institution Study

Background  Glioblastoma multiforme (GBM) is a disease with poor outcome. Alterations or mutations in epidermal growth factor receptors (EGFRs) are found in GBM and may be targeted to improve outcomes.

Aims  We analyzed the frequency of EGFR variant III (vIII) mutations in patients with GBM and their outcomes after standard treatment.

Materials and Methods  This is a retrospective study conducted in a single tertiary cancer center in south India. Forty patients with GBM who had their entire treatment done at this center were identified, and their primary tumor tissue blocks were retrieved. Genomic DNA was extracted, and molecular analysis was performed and analyzed. The results of mutational analysis were correlated with treatment outcome of the patients.

Statistical Analysis  Survival outcome was analyzed using the Kaplan–Meier method. The log-rank test was used to assess the association between the groups and various parameters.

Results  Our study showed a similar incidence of EGFR vIII alterations as published in world literature, but we did not find any difference in overall survival (OS) and progression-free survival (PFS) in patients with EGFR vIII mutation compared with nonmutant cohort.

Conclusions  Contrary to the existing literature which indicated EGFR vIII alterations to be a negative prognostic indicator, our study did not find it to be an independent predictor of prognosis among Indian GBM patients treated with present standard of care.