Epidermal growth factor receptor variant III mutation in Chinese patients with squamous cell cancer of the lung

The Development of Positron Emission Tomography Tracers for In Vivo Targeting the Kinase Domain of the Epidermal Growth Factor Receptor

Multiple small molecule PET tracers have been developed for the imaging of the epidermal growth factor receptor (EGFR). These tracers target the tyrosine kinase (TK) domain of the receptor and have been used for both quantifying EGFR expression and to differentiate between EGFR mutational statuses. However, the approaches for in vivo evaluation of these tracers are diverse and have resulted in data that are hard to compare. In this review, we analyze the historical development of the in vivo evaluation approaches, starting from the first EGFR TK PET tracer [11C]PD153035 to tracers developed based on TK inhibitors used for the clinical treatment of mutated EGFR expressing non-small cell lung cancer like [11C]erlotinib and [18F]afatinib. The evaluation of each tracer has been compiled to allow for a comparison between studies and ultimately between tracers. The main challenges for each group of tracers are thereafter discussed. Finally, this review addresses the challenges that need to be overcome to be able to efficiently drive EGFR PET imaging forward.

Clinicopathological Characteristics And EGFR-TKIs Efficacies In Lung Squamous Cell Carcinoma Patients Harboring An EGFR Sensitizing Mutation

Objective

This study analyzed the relationship between the clinicopathological features and epidermal growth factor receptor (EGFR) mutation status of squamous cell lung cancer (SqCLC) patients. Mutation status was analyzed by comparing the amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) and next-generation sequencing (NGS). We also assessed the efficacies of EGFR tyrosine kinase inhibitors (TKIs).

Methods

Retrospective analysis was performed for 292 SqCLC patients treated at the Guangxi Medical University Affiliated Tumor Hospital from December 2013 to December 2018. The EGFR mutations in tumor tissues were identified by ARMS-PCR and NGS. The affiliation between EGFR mutation and clinicopathological features was analyzed. Efficacies of EGFR-TKIs and survival were evaluated using the benchmarks of response evaluation criteria in solid tumors 1.1 (RECIST 1.1) and the Kaplan–Meier method, respectively.

Results

Among the 292 SqCLC patients, 24 (8.2%) were identified to have an EGFR-sensitizing mutation. Both ARMS-PCR and NGS were equally effective in detecting EGFR mutations. Females and non-smokers had higher EGFR mutation rates than males and smokers (22.1% vs. 5.1%, P = 0.007 and 16.7% vs. 4.5%, P = 0.001, respectively). EGFR mutation was unrelated to the degree of differentiation, clinical stage, specimen type and level of serum carcino-embryonic antigen (CEA) and squamous cell carcinoma antigen (SCC) (P > 0.05). In the 14 EGFR mutant cases treated with EGFR-TKIs, the objective response rate (ORR) and disease control rate (DCR) were 28.6% and 78.6%, respectively. Median progression-free survival (mPFS) and overall survival (mOS) were 4.9 and 10.75 months, respectively, with fine tolerance and mild side-effects.

Conclusion

EGFR-sensitizing mutations are rare in SqCLC patients with females and non-smokers having a higher risk of harboring them. There was no difference in the detection rates of EGFR for both the ARMS-PCR and NGS methods. EGFR-TKIs showed modest efficacies and low toxicity profiles in EGFR mutant cases.

LncRNAs and EGFRvIII sequestered in TEPs enable blood-based NSCLC diagnosis

Background

Tissue biopsy-based cancer diagnosis has limitations because of the fact that tumor tissues are in constant evolution and extremely heterogeneous. The current study was aimed to examine whether tumor-educated blood platelets (TEPs) might be a potential all-in-one source for blood-based cancer diagnostics to overcome the limitations of conventional cancer biopsy.

Methods

In the present study, we evaluated the expression pattern of MAGI2 antisense RNA 3 (MAGI2-AS3) and ZNFX1 antisense RNA 1 (ZFAS1) in both plasma and platelets of 101 non-small-cell lung cancer (NSCLC) patients. Receiver operating characteristic (ROC) curve was generated to evaluate their diagnostic potential. In addition, epidermal growth factor receptor (EGFR) mutations were detected in DNA and RNA samples of platelets for companion diagnostics.

Results

Our results showed that the levels of MAGI2-AS3 and ZFAS1 in both plasma and platelets of NSCLC patients were significantly downregulated than those in healthy controls. A positive correlation of long noncoding RNA expression was observed between platelets and plasma (r=0.738 for MAGI2-AS3, r=0.751 for ZFAS1, respectively). By ROC analysis, we found that molecular interrogation of MAGI2-AS3 and ZFAS1 in TEPs and plasma can offer valuable diagnostic performance for NSCLC patients (area under the ROC curve [AUC]_MAGI2-AS3= 0.853/0.892, and AUC_ZFAS1=0.780/0.744 for diagnosing adenocarcinoma and squamous cell carcinoma cases from controls, respectively). Clinicopathologic characteristic analysis further revealed that MAGI2-AS3 level significantly correlated with tumor–node–metastasis (TNM) stage (p=0.001 in TEPs, p=0.003 in plasma), lymph-node metastasis (p=0.016 in TEPs, p=0.023 in plasma), and distant metastasis (p=0.045 in TEPs, p=0.045 in plasma), while ZFAS1 level was only correlated with TNM stage (p=0.005 in TEPs, p=0.044 in plasma). Furthermore, EGFRvIII RNA existed in both TEPs and plasma, but EGFR intracellular mutations cannot be detected in DNA of TEPs isolated from NSCLC.

Conclusion

Our data suggested that TEP is a promising source for NSCLC diagnosis and companion diagnostics.

Efficacy of epidermal growth factor receptor-tyrosine kinase inhibitors for lung squamous carcinomas harboring EGFR mutation: A multicenter study and pooled analysis of published reports

Epidermal growth factor receptor (EGFR) mutations are common in lung adenocarcinoma (ADC) but rare in squamous cell carcinoma (SQC). The efficacy of EGFR-tyrosine kinase inhibitors (EGFR-TKIs) for SQC with EGFR mutations is unclear. The aim of this study was to evaluate the efficacy of EGFR-TKIs for these patients. We performed a retrospective matched-pair case-control study from 3 cancer centers, including 44 SQC and 44 ADC patients with EGFR mutation who were treated with EGFR-TKI. Subsequently, we performed a pooled analysis on the efficacy of EGFR-TKIs for EGFR-mutant SQC in 115 patients, including 71 patients selected from 25 published reports. In our multicenter study, EGFR-mutant SQC and ADC patients had similar objective response rate (ORR) (43.2% vs. 54.5%, p = 0.290), but SQC patients had lower disease control rate (DCR) (71.3% vs. 100%, p = 0.001), significant shorter median progression free survival (PFS) (5.1 vs. 13.0 months, p = 0.000) and median overall survival (OS) (17.2 vs. 23.6 months, p = 0.027). In pooled analysis, the ORR, DCR, PFS and OS of SQC patients were 39.1%, 71.3%, 5.6 months and 15.0 months, respectively. Performance status was the only independent predictor of PFS and erlotinib treatment was associated with a better survival. In conclusion, EGFR-TKI was less effective in EGFR-mutant SQC than in ADC but still has clinical benefit for SQC patients. Further study is need to evaluate the using of EGFR-TKIs in these SQC patients.

Aptamer-conjugated PEGylated quantum dots targeting epidermal growth factor receptor variant III for fluorescence imaging of glioma

The extent of resection is a significant prognostic factor in glioma patients. However, the maximum safe resection level is difficult to determine due to the inherent infiltrative character of tumors. Recently, fluorescence-guided surgery has emerged as a new technique that allows safe resection of glioma. In this study, we constructed a new kind of quantum dot (QD)-labeled aptamer (QD-Apt) nanoprobe by conjugating aptamer 32 (A32) to the QDs surface, which can specially bind to the tumors. A32 is a single-stranded DNA capable of binding to the epidermal growth factor receptor variant III (EGFRvIII) specially distributed on the surface of glioma cells. To detect the expression of EGFRvIII in human brain tissues, 120 specimens, including 110 glioma tissues and 10 normal brain tissues, were examined by immunohistochemistry, and the results showed that the rate of positive expression of EGFRvIII in the glioma tissues was 41.82%, and 0.00% in normal brain tissues. Besides, the physiochemical properties of QD-Apt nanoparticles (NPs) were thoroughly characterized. Biocompatibility of the NPs was evaluated, and the results suggested that the QD-Apt was nontoxic in vivo and vitro. Furthermore, the use of the QD-Apt in labeling glioma cell lines and human brain glioma tissues, and target gliomas in situ was also investigated. We found that not only could QD-Apt specially bind to the U87-EGFRvIII glioma cells but also bind to human glioma tissues in vitro. Fluorescence imaging in vivo with orthotopic glioma model mice bearing U87-EGFRvIII showed that QD-Apt could penetrate the blood-brain barrier and then selectively accumulate in the tumors through binding to EGFRvIII, and consequently, generate a strong fluorescence, which contributed to the margins of gliomas that were visualized clearly, and thus, help the surgeons realize the maximum safe resection of glioma. In addition, QD-Apt can also be applied in preoperative diagnosis and postoperative examination of glioma. Therefore, these achievements facilitate the use of tumor-targeted fluorescence imaging in the diagnosis, surgical resection, and postoperative examination of glioma.

A brief perspective of drug resistance toward EGFR inhibitors: the crystal structures of EGFRs and their variants

The EGFR is one of the most popular targets for anticancer therapies and many drugs, such as erlotinib and gefitinib, have got enormous success in clinical treatments of cancer in past decade. However, the efficacy of these agents is often limited because of the quick emergence of drug resistance. Fundamental structure researches of EGFR in recent years have generally elucidated the mechanism of drug resistance. In this review, based on systematic resolution of full structures of EGFR and their variants via single crystal x-ray crystallography, the working and drug resistance mechanism of EGFR-targeted drugs are fully illustrated. Moreover, new strategies for avoiding EGFR drug resistance in cancer treatments are also discussed.

Mechanisms of resistance to EGFR-targeted drugs: lung cancer

Despite the improvement in clinical outcomes derived by the introduction of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (EGFR-TKIs) in the treatment of patients with advanced non-small cell lung cancer (NSCLC) whose tumours harbour EGFR-activating mutations, prognosis remains unfavourable because of the occurrence of either intrinsic or acquired resistance. We reviewed the published literature and abstracts of oral and poster presentations from international conferences addressing EGFR-TKIs resistance mechanisms discovered in preclinical models and in patients with NSCLC. The molecular heterogeneity of lung cancer has several implications in terms of possible mechanisms of either intrinsic or acquired resistance to EGFR-targeted inhibitors. Several mechanisms of resistance have been described to EGFR-TKIs, such as the occurrence of secondary mutation (T790M, C797S), the activation of alternative signalling (Met, HGF, AXL, Hh, IGF-1R), the aberrance of the downstream pathways (AKT mutations, loss of PTEN), the impairment of the EGFR-TKIs-mediated apoptosis pathway (BCL2-like 11/BIM deletion polymorphism) and histological transformation. Although some of the mechanisms of resistance have been identified, much additional information is needed to understand and overcome resistance to EGFR-TKI agents. The majority of resistance mechanisms described are the result of a selection of pre-existing clones; thus, studies on the mechanisms by which subclonal alterations have an impact on tumour biology and influence cancer progression are extremely important in order to define the best treatment strategy.