Impact of EGFR and EGFR ligand expression on treatment response in patients with metastatic colorectal cancer

Prognostic and predictive biomarkers for anti-EGFR monoclonal antibody therapy in RAS wild-type metastatic colorectal cancer: a systematic review and meta-analysis

BACKGROUND

RAS mutations affect prognosis in patients with metastatic colorectal cancer (mCRC) and have been identified as strong negative predictive markers for anti-epidermal growth factor receptor monoclonal antibody (anti-EGFR mAb) therapy, but many tumors containing wild-type RAS genes still do not respond to these therapies. Some additional biomarkers may have prognostic or predictive roles, but conclusions remain controversial.

METHODS

We performed a meta-analysis and systematic review of randomized controlled trials comparing anti-EGFR mAb therapy with alternative therapy that investigated the prognostic and predictive impact of additional biomarkers in RAS wild-type (wt) mCRC patients. Hazard ratios (HRs) and 95% confidence intervals (CIs) for progression-free survival (PFS) and overall survival (OS) and odds ratios (ORs) for objective response rate (ORR) were calculated. The prognostic value of biomarkers was investigated by separately pooling HR and OR for different treatment groups in an individual study. The predictive value was assessed by pooling study interactions between treatment effects and biomarker subgroups.

RESULTS

Thirty publications reporting on eighteen trials were selected, including a total of 13,507 patients. In prognostic analysis, BRAF mutations were associated with poorer PFS [HRs = 3.76 (2.47-5.73) and 2.69 (1.82-3.98)] and OS [HRs = 2.66 (1.95-3.65) and 2.45 (1.55-3.88)] in both the experimental and control arms; low miR-31-3p expression appeared to have longer PFS and OS. In terms of predictive effect, a lack of response to anti-EGFR therapy was observed in patients with BRAF mutant tumors (Pinteraction < 0.01 for PFS). Patients with tumors with any mutation in the KRAS/NRAS/BRAF/PIK3CA gene also showed similar results compared with all wild-type tumors (Pinteraction for PFS, OS, and ORR were < 0.01, < 0.01 and 0.01, respectively). While low miR-31-3p expression could predict PFS (Pinteraction = 0.01) and OS (Pinteraction = 0.04) benefit. The prognostic and predictive value regarding PIK3CA mutations, PTEN mutations or deletions, EGFR, EREG/AREG, HER2, HER3, and HER4 expression remains uncertain.

CONCLUSIONS

In RAS wt mCRC patients receiving EGFR-targeted therapy, BRAF mutation is a powerful prognostic and therapy-predictive biomarker, with no effect found for PIK3CA mutation, PTEN mutation or deletion, but the combined biomarker KRAS/NRAS/BRAF/PIK3CA mutations predict resistance to anti-EGFR therapy. Low miR-31-3p expression may have positive prognostic and therapy predictive effects. Evidence on the prognostic and predictive roles of EGFR and its ligands, and HER2/3/4 is insufficient.

Detection of Circulating Tumor Cells Using the Attune NxT

Circulating tumor cells (CTCs) have been detected in many patients with different solid malignancies. It has been reported that presence of CTCs correlates with worse survival in patients with multiple types of cancer. Several techniques have been developed to detect CTCs in liquid biopsies. Currently, the only method for CTC detection that is approved by the Food and Drug Administration is CellSearch. Due to low abundance of CTCs in certain cancer types and in early stages of disease, its clinical application is currently limited to metastatic colorectal cancer, breast cancer and prostate cancer. Therefore, we aimed to develop a new method for the detection of CTCs using the Attune NxT-a flow cytometry-based application that was specifically developed to detect rare events in biological samples without the need for enrichment. When healthy donor blood samples were spiked with variable amounts of different EpCAM+EGFR+ tumor cell lines, recovery yield was on average 75%. The detection range was between 1000 and 10 cells per sample. Cell morphology was confirmed with the Attune CytPix. Analysis of blood samples from metastatic colorectal cancer patients, as well as lung cancer patients, demonstrated that increased EpCAM+EGFR+ events were detected in more than half of the patient samples. However, most of these cells showed no (tumor) cell-like morphology. Notably, CellSearch analysis of blood samples from a subset of colorectal cancer patients did not detect CTCs either, suggesting that these blood samples were negative for CTCs. Therefore, we anticipate that the Attune NxT is not superior to CellSearch in detection of low amounts of CTCs, although handling and analysis of samples is easier. Moreover, morphological confirmation is essential to distinguish between CTCs and false positive events.

miR-146 Relieves Acute Asthma via Decreasing Epidermal Growth Factor Receptor/Toll-Like Receptor 4 (EGFR/TLR4) and Enhancing Autophagy

There is a close relationship between acute asthma and autophagy. In addition, some studies claim that miR-146 can regulate autophagy and participate in acute asthma. This study further explores the role of miR-146 in acute asthma and underlying mechanism. Twenty BALB/c mice were selected and randomly divided into two groups, the model group and the control group, each with 10 mice. Lung tissues, peripheral blood, alveolar lavage fluid, and primary lymphocytes were separated into miR-146 over expression group (miR-146 mimic), miR-146 low expression group (miR-146 inhibitor), negative control group (NC), blank group, or SBI-0206965 group. Acute asthma was established and the expression levels of miR-146, EGFR, TLR4, LC3, beclin1, and ATG5 in each group was measured. The targeting relationship and correlation between miR-146 and EGFR were also investigated. The expression of IL-4 in model group was increased compared to control arm while the expression of IFN-γ was opposite (P < 0.05). The expressions of miR-146, LC3, beclin1, and the expression of ATG5 were decreased (P < 0.05). The expressions of miR-146 gene and LC3, beclin1, ATG5 mRNA and protein in the miR-146 mimic group were the highest, while the expressions of EGFR and TLR4 were the lowest. The SBI-0206965 group and the miR-146 inhibitor group are opposite to the miR-146 mimic group, the SBI-0206965 group and the miR-146 inhibitor group have significant differences (P < 0.05). miR-146 has a directly targeted EGFR and TLR4, and both showed a negative correlation (rEGFR=−0.397, P = 0.013; rTLR4=−0.402, P = 0.021). During the onset of asthma, miR-146 was abnormally decreased. miR-146 directly targets and negatively regulates EGFR. In addition, miR-146 down-regulates TLR4 gene to increase CD4+ lymphocytes’ aphagocytosis-related markers (LC3, beclin1, ATG5) which further promotes the autophagy process and ultimately alleviates the degree of acute asthma. Its main mechanism is related to the down-regulation of the EGFR/TLR4 through regulated the expression of autophagy. Our study provided a scientific reference for further understanding of acute pathogenesis of asthma.

Effects of GLP-1 Receptor Agonists on Biological Behavior of Colorectal Cancer Cells by Regulating PI3K/AKT/mTOR Signaling Pathway

Colorectal cancer (CRC) has become one of the top ten malignant tumors with a high incidence rate and mortality. Due to the lack of a good CRC screening program, most of the CRC patients are being transferred at the time of treatment. The conventional treatment cannot effectively improve the prognosis of CRC patients, and the target drugs can significantly prolong the overall survival of patients in the advanced stage. However, the use of single drug may lead to acquired drug resistance and various serious complications. Therefore, combined targeted drug therapy is the main alternative treatment with poor effect of single targeted drug therapy, which has important research significance for the treatment of CRC. Therefore, this study intends to culture CRC cell lines in vitro at the cell level and intervene with the GLP-1 receptor agonist liraglutide. The effects of liraglutide on the PI3K/Akt/mTOR signal pathway and CRC cell proliferation, cycle, migration, invasion, and apoptosis are explored by detecting cell proliferation, cycle, migration, invasion, and apoptosis and the expression of related mRNA and protein. The results showed that liraglutide, a GLP-1 receptor agonist, could block the CRC cell cycle, reduce cell proliferation, migration, and invasion and promote apoptosis by inhibiting the PI3K/Akt/mTOR signal pathway.

Epidermal Growth Factor Receptor as Target for Perioperative Elimination of Circulating Colorectal Cancer Cells

Surgical resection of the tumor is the primary treatment of colorectal cancer patients. However, we previously demonstrated that abdominal surgery promotes the adherence of circulating tumor cells (CTC) in the liver and subsequent liver metastasis development. Importantly, preoperative treatment with specific tumor-targeting monoclonal antibodies (mAb) prevented surgery-induced liver metastasis development in rats. This study investigated whether the epidermal growth factor receptor (EGFR) represents a suitable target for preoperative antibody treatment of colorectal cancer patients undergoing surgery. The majority of patients with resectable colorectal liver metastases were shown to have EGFR + CTCs. Three different anti-EGFR mAbs (cetuximab, zalutumumab, and panitumumab) were equally efficient in the opsonization of tumor cell lines. Additionally, all three mAbs induced antibody-dependent cellular phagocytosis (ADCP) of tumor cells by macrophages at low antibody concentrations in vitro, independent of mutations in EGFR signaling pathways. The plasma of cetuximab-treated patients efficiently opsonized tumor cells ex vivo and induced phagocytosis. Furthermore, neither proliferation nor migration of epithelial cells was affected in vitro, supporting that wound healing will not be hampered by treatment with low anti-EGFR mAb concentrations. These data support the use of a low dose of anti-EGFR mAbs prior to resection of the tumor to eliminate CTCs without interfering with the healing of the anastomosis. Ultimately, this may reduce the risk of metastasis development, consequently improving long-term patient outcome significantly.