Management of non-small cell lung cancer with EGFR mutation: the role of radiotherapy in the era of tyrosine kinase inhibitor therapy-opportunities and challenges

Effect of thoracic radiotherapy dose on the prognosis of advanced lung adenocarcinoma harboring EGFR mutations

Background

The aim of this study was to investigate the effects of different thoracic radiotherapy doses on OS and incidence of radiation pneumonia which may provide some basis for optimizing the comprehensive treatment scheme of these patients with advanced EGFR mutant lung adenocarcinoma.

Methods

Data from 111 patients with EGFR-mutant lung adenocarcinoma who received thoracic radiotherapy were included in this retrospective study. Overall survival (OS) was the primary endpoints of the study. Kaplan–Meier method was used for the comparison of OS. The Cox proportional-hazard model was used for the multivariate and univariate analyses to determine the prognostic factors related to the disease.

Results

The mOS rates of the patients, who received radiotherapy dose scheme of less than 50 Gy, 50–60 Gy (including 50 Gy), and 60 Gy or more were 29.1 months, 34.4 months, and 51.0 months, respectively (log-rank P = 0.011). Although trend suggested a higher levels of pneumonia cases with increasing radiation doses, these lack statistical significance (χ2 = 1.331; P = 0.514). The multivariate analysis showed that the thoracic radiotherapy dose schemes were independently associated with the improved OS of patients (adjusted hazard ratio [HR], 0.606; 95% CI, 0.382 to 0.961; P = 0.033).

Conclusions

For the patients with advanced EGFR-mutant lung adenocarcinoma, the radical thoracic radiotherapy dose scheme (≥ 60 Gy) could significantly prolong the OS of patients during the whole course management.

Nuclear accumulation of KPNA2 impacts radioresistance through positive regulation of the PLSCR1-STAT1 loop in lung adenocarcinoma

Lung adenocarcinoma (ADC) is the predominant histological type of lung cancer, and radiotherapy is one of the current therapeutic strategies for lung cancer treatment. Unfortunately, biological complexity and cancer heterogeneity contribute to radioresistance development. Karyopherin α2 (KPNA2) is a member of the importin α family that mediates the nucleocytoplasmic transport of cargo proteins. KPNA2 overexpression is observed across cancer tissues of diverse origins. However, the role of KPNA2 in lung cancer radioresistance is unclear. Herein, we demonstrated that high expression of KPNA2 is positively correlated with radioresistance and cancer stem cell (CSC) properties in lung ADC cells. Radioresistant cells exhibited nuclear accumulation of KPNA2 and its cargos (OCT4 and c‐MYC). Additionally, KPNA2 knockdown regulated CSC‐related gene expression in radioresistant cells. Next‐generation sequencing and bioinformatic analysis revealed that STAT1 activation and nuclear phospholipid scramblase 1 (PLSCR1) are involved in KPNA2‐mediated radioresistance. Endogenous PLSCR1 interacting with KPNA2 and PLSCR1 knockdown suppressed the radioresistance induced by KPNA2 expression. Both STAT1 and PLSCR1 were found to be positively correlated with dysregulated KPNA2 in radioresistant cells and ADC tissues. We further demonstrated a potential positive feedback loop between PLSCR1 and STAT1 in radioresistant cells, and this PLSCR1‐STAT1 loop modulates CSC characteristics. In addition, AKT1 knockdown attenuated the nuclear accumulation of KPNA2 in radioresistant lung cancer cells. Our results collectively support a mechanistic understanding of a novel role for KPNA2 in promoting radioresistance in lung ADC cells.

The novel FAT4 activator jujuboside A suppresses NSCLC tumorigenesis by activating HIPPO signaling and inhibiting YAP nuclear translocation

FAT atypical cadherin 4 (FAT4) has been identified as a tumor suppressor in lung cancers. However, no agent for lung cancer treatment targeting FAT4 has been used in the clinic. Jujuboside A (JUA) is a major active compound in Semen Ziziphi Spinosae. Semen Ziziphi Spinosae is a traditional Chinese herbal medicine used clinically for tumor treatment to improve patients' quality of life. However, the anti-lung cancer activity and the underlying mechanisms of JUA are not yet fully understood. Here, we demonstrated the anti-lung cancer activity of JUA in two lung cancer mice models and three non-small cell lung cancer (NSCLC) cell lines, and further illustrated its underlying mechanisms. JUA suppressed the occurrence and development of lung cancer and extended mice survival in vivo, and suppressed NSCLC cell activities through cell cycle arrest, proliferation suppression, stemness inhibition and senescence promotion. Moreover, JUA directly bound with and activated FAT4, subsequently activating FAT4-HIPPO signaling and inhibiting YAP nuclear translocation. Knockdown of FAT4 diminished JUA's effects on HIPPO signaling, YAP nuclear translocation, cell proliferation and cellular senescence. In conclusion, JUA significantly suppressed NSCLC tumorigenesis by regulating FAT4-HIPPO-YAP signaling. Our findings suggest that JUA is a novel FAT4 activator that can be developed as a promising NSCLC therapeutic agent targeting the FAT4-HIPPO-YAP pathway.

Evodiamine suppresses Notch3 signaling in lung tumorigenesis via direct binding to γ-secretases

BACKGROUND

Notch activation requires proteolytic cleavage of the receptor by γ-secretase protein complex. Inhibition of Notch receptor activation (e.g. Notch3) with γ-secretase inhibitor is a potential new therapeutic approach for the targeted therapy of non-small cell lung cancer (NSCLC). However, only a few safe and effective γ-secretase inhibitors have been discovered. Evodiamine (EVO), a compound derived from Euodiae Fructus (Chinese name, Wu-Zhu-Yu), exhibits remarkable anti-NSCLC activities. However, the underlying mechanisms of action have yet to be fully elucidated.

PURPOSE

We sought to determine the involvement of Notch3 signaling in the anti-NSCLC effects of EVO, and to explore whether EVO suppressed Notch3 signaling by inhibiting γ-secretase in cultured A549 and H1299 NSCLC cells and in urethane-induced lung cancer FVB mouse model.

METHODS

Cell viability, migration, stemness and cell cycle distribution of EVO were examined by the MTT assay, wound healing assay, soft agar colony assay and flow cytometry analysis, respectively. The binding affinity of EVO and γ-secretase complex was analyzed by molecular docking. Cellular thermal shift assay (CETSA) was performed to study the drug-target interactions in NSCLC cells. Protein levels were determined by Western blotting.

RESULTS

EVO dramatically inhibited cell viability, induced G2/M cell cycle arrest, suppressed cell migration, and reduced stemness in NSCLC cells. Mechanistic studies indicated that EVO prevented the γ-secretase cleavage of Notch3 at the cell surface and hence inhibited Notch3 activation. Moreover, EVO notably reduced tumor growth in the mouse model and inhibited Notch3 activity in the tumors.

CONCLUSION

This study provides new insights into the anti-NSCLC action of EVO, and suggests that suppressing Notch3 signaling by inhibiting γ-secretase is a mechanism of action underlying the anti-NSCLC effect of EVO.

Specificity Assessment of CRISPR Genome Editing of Oncogenic EGFR Point Mutation with Single-Base Differences

In CRISPR genome editing, CRISPR proteins form ribonucleoprotein complexes with guide RNAs to bind and cleave the target DNAs with complete sequence complementarity. CRISPR genome editing has a high potential for use in precision gene therapy for various diseases, including cancer and genetic disorders, which are caused by DNA mutations within the genome. However, several studies have shown that targeting the DNA via sequence complementarity is imperfect and subject to unintended genome editing of other genomic loci with similar sequences. These off-target problems pose critical safety issues in the therapeutic applications of CRISPR technology, with particular concerns in terms of the genome editing of pathogenic point mutations, where non-mutant alleles can become an off-target with only a one-base difference. In this study, we sought to assess a novel CRISPR genome editing technique that has been proposed to achieve a high specificity by positioning the mismatches within the protospacer adjacent motif (PAM) sequence. To this end, we compared the genome editing specificities of the PAM-based and conventional methods on an oncogenic single-base mutation in the endothelial growth factor receptor (EGFR). The results indicated that the PAM-based method provided a significantly increased genome editing specificity for pathogenic mutant alleles with single-base precision.

Timing in combination with radiotherapy and patterns of disease progression in non-small cell lung cancer treated with EGFR-TKI

OBJECTIVES

Tyrosine kinase inhibitor (TKI) has been the standard of care for advanced non-small cell lung cancers (NSCLC) harboring epidermal growth factor receptor (EGFR) mutation, but these tumors invariably develop drug resistance. As progression most frequently advances in sites of original disease, our study sought to explore the time to response for NSCLC to TKI therapy and the patterns of disease progression, to provide evidence for timing and candidates for local therapy intervention.

MATERIALS AND METHODS

A cohort of 105 EGFR-mutated IIIB or IV NSCLC patients treated with EGFR-TKI were retrospectively analyzed. The disease progression patterns were divided into 3 categories: progression in sites of original disease, progression in new distant sites, and combined progression.

RESULTS

Before cut-off date, 80 patients had disease progression. Thirty-three (41.25 %) patients had progression in sites of original disease, 34 (42.5 %) patients had progression in new sites and 13 (16.25 %) patients had combined progression, respectively. The median time to response for responders was 2.00 months (95 %CI 1.28-2.92 months), and the median time to maximal tumor shrinkage for SD patients was 2.00 months (95 %CI 1.42-2.58 months). Multivariate logistic regression model showed that the 21 exon mutation is related to the incidence of original site failure.

CONCLUSION

Over 1/3 of the patients progress at the original sites, which indicated that this subset of patients may benefit from local therapy. Moreover, as the results indicate that considerable shrinkage for TKI therapy occurs in first two months after TKI initiation, local therapy can be adopted after this timepoint, before disease progression. We also propose EGFR gene mutation type as potential inclusion criteria to identify candidates for combined local therapy.

Brain surgery in combination with tyrosine kinase inhibitor and whole brain radiotherapy for epidermal growth factor receptor-mutant non-small-cell lung cancer with brain metastases

The role of brain surgery (BS) on the survival of patients with non-small-cell lung cancer (NSCLC) and brain metastases (BM), particularly those with epidermal growth factor receptor (EGFR) mutations under tyrosine kinase inhibitors (TKIs) is yet to be defined. We aimed to investigate whether BS could improve the survival of patients in addition to the combination of TKIs and whole brain radiotherapy (WBRT). A cohort of 1394 NSCLC patients between 2011 and 2016 was retrospectively studied. One hundred patients with BM receiving TKI + RT were enrolled. Forty patients (40%) received TKI + BS + RT, and 60 patients (60%) received TKI + RT. Survival time was calculated from the date of BM diagnoses to the date of death or last follow-up. With a median follow-up of 25.6 months (95% CI, 18.6–35.7), the median survival after BM was 18.2 months (95% CI, 10.8 to 27.4) in the TKI + BS + RT group and 11.8 months (95% CI, 5.2 to18) in the TKI + RT group. Cox proportional hazards regression model for the patients with the largest BM over 1 cm showed that TKI + BS + RT group was associated with improved survival relative to TKI + RT group (HR, 0.49; 95% CI, 0.29 to 0.83; P = 0.008). BS adds significant survival benefits in addition to TKIs and WBRT, especially for patients with EGFR-mutant NSCLC and the largest BM over 1 cm.

Evodiamine, a Novel NOTCH3 Methylation Stimulator, Significantly Suppresses Lung Carcinogenesis in Vitro and in Vivo

Lung cancer is a leading cause of cancer-related deaths worldwide. NOTCH3 signaling is mainly expressed in non-small cell lung carcinoma (NSCLC), and has been proposed as a therapeutic target of NSCLC. While, few agents for preventing or treating NSCLC via targeting NOTCH3 signaling are used in modern clinical practice. Evodiamine (EVO), an alkaloid derived from Euodiae Fructus, possesses low toxicity and has long been shown to exert anti-lung cancer activity. However, the underlying anti-lung cancer mechanisms of EVO are not yet fully understood. In this study, we explored the involvement of NOTCH3 signaling in the anti-lung cancer effects of EVO. Urethane-induced lung cancer mouse model and two NSCLC cell models, A549 and H1299, were used to evaluate the in vivo and in vitro anti-lung cancer action of EVO. A DNA methyltransferase inhibitor was employed to investigate the role of NOTCH3 signaling in the anti-lung cancer effects of EVO. Results showed that EVO potently reduced tumor size and tumor numbers in mice, and inhibited NOTCH3 in the tumors. EVO also dramatically reduced cell viability, induced G2/M cell cycle arrest, inhibited cell migration and reduced stemness in cultured NSCLC cells. Mechanistic studies showed that EVO potently inhibited NOTCH3 signaling by activation of DNMTs-induced NOTCH3 methylation. Importantly, inhibition of NOTCH3 methylation in NSCLC cells diminished EVO's anti-NSCLC effects. Collectively, EVO, a novel NOTCH3 methylation stimulator, exerted potent anti-lung cancer effects partially by inhibiting NOTCH3 signaling. These findings provide new insight into the EVO's anti-NSCLC action, and suggest a potential role of EVO in lung cancer prevention and treatment.