Human Epidermal Growth Factor Receptor 2-Targeting Approaches for Colorectal Cancer: Clinical Implications of Novel Treatments and Future Therapeutic Avenues

Molecular mechanisms of HER2-targeted therapy and strategies to overcome the drug resistance in colorectal cancer

HER2 amplification is one of the mechanisms that induce drug resistance to anti-EGFR therapy in colorectal cancer. In recent years, data from several randomized clinical trials show that anti-HER2 therapies improved the prognosis of patients with HER2-positive colorectal cancer. These results indicate that HER2 is a promising therapeutic target in advanced colorectal cancer. Despite the anti-HER2 therapies including monoclonal antibodies, tyrosine kinase inhibitors, and antibody-drug conjugates improving the outcomes, less than 30 % of the patients achieve objective response and eventually have drug resistance. It is necessary to explore the primary and secondary mechanisms for the resistance to anti-HER2 therapies, which will pave the way to overcome the drug resistance. Several studies have reported the potential mechanisms for the resistance to anti-HER2 therapies. In this review, we present a comprehensive overview of the recent advances in clinical research, mechanisms of treatment resistance, and strategies for reversing resistance in HER2-positive colorectal cancer patients.

The Role of Circulating Tumor DNA for Management of Patients With Rectal Cancer: Challenges and Opportunities

ABSTRACT

Recently, organ preservation with total neoadjuvant therapy resulted in substantial progress in the management of locally advanced rectal cancer (LARC). The PROSPECT trial showed noninferiority of de-escalation of radiotherapy for patients with low-risk LARC who do not need abdominoperineal resection. Although these escalation and de-escalation approaches offer more personalized therapeutic approaches, the current state of care for patients with rectal cancer is far from individualized management. Circulating tumor DNA (ctDNA) is known to be one of the most powerful prognostic factors for early relapse and has been investigated in several interventional clinical trials to offer more precise treatment algorithms. In this review article, we discuss recent updates from studies examining the role of ctDNA for the prediction of treatment response and recurrence for patients with rectal cancer. We also elaborate on the future potential use of ctDNA in treatment escalation and de-escalation approaches for more personalized therapeutic interventions.

Targeting KRAS Oncogene for Patients With Colorectal Cancer: A New Step Toward Precision Medicine

KRAS mutations are common driver oncogenes associated with the development of several solid tumors. KRAS oncogene has been considered a highly challenging target for drug development because of structural features, including the lack of deep groove on its catalytic unit. However, by leveraging cysteine residues, covalent KRAS inhibitors irreversibly trap KRAS G12C mutants in their inactive GDP-bound state. These agents have resulted in significant clinical responses among patients with KRAS G12C-mutant solid tumors, including patients with colorectal cancer (CRC). Other allele-specific inhibitors of KRAS oncogene and panKRAS and panRAS inhibitors are also currently being investigated in clinical trials. This review article overviews recent clinical progress on KRAS G12C targeting for the management of patients with KRAS G12C-mutant CRC and provides an update on other RAS targeting approaches. We also discuss the unique biological features of RAS-mutant CRC, which require the combination of KRAS inhibitors and anti-epidermal growth factor receptor therapy, and elaborate on resistance mechanisms and novel therapeutic avenues that may define future treatment paradigms of patients with RAS-mutant CRC.

Exosome-Delivered EGFR Induced by Acidic Bile Salts Regulates Macrophage M2 Polarization to Promote Esophageal Adenocarcinoma Cell Proliferation

Purpose

Chronic gastroesophageal reflux disease (GERD) causes the abnormal reflux of acid and bile salts, which would induce Barrett's esophagus (BE) and esophageal adenocarcinoma (EAC). EGFR, as one of main components of the exosome, plays an important role in cancer progression. Here, we investigated the role of acidic bile salts (ABS)-induced exosomal EGFR in EAC cell proliferation.

Methods

Electronic microscopic examination and Western blot were used to identify exosomes. Western blot, siRNA transfection, enzyme-linked immunosorbent assay, qRT-PCR, cell viability detection, mouse xenograft tumor models, and immunohistochemical staining were performed to study the function of ABS-induced exosomal EGFR in cell proliferation.

Results

We found that ABS improved the exosomal EGFR level of normal human esophageal epithelial cells, BE cells, and BE-associated adenocarcinoma cells. The results were confirmed in the serum-derived exosomes from healthy persons and patients suffering from GERD, BE with or without GERD, and EAC with or without GERD. Moreover, cell line-derived exosomal EGFR was found to promote macrophage M2 polarization through the PI3K-AKT pathway. The co-incubation medium of macrophages and exosomes improved cell proliferation and tumor growth, which depended on the exosomal EGFR level. CCL18 was identified as the most effective component of the co-incubation medium to promote EAC cell proliferation by binding to its receptor PITPNM3 in vitro and in vivo.

Conclusion

Our findings demonstrate that ABS-induced exosomal EGFR regulates macrophage M2 polarization to promote EAC proliferation. This study provides an important insight into the role of ABS in EAC development.

Hsa_circRNA_001676 accelerates the proliferation, migration and stemness in colorectal cancer through regulating miR-556-3p/G3BP2 axis

Circular RNAs (circRNAs) play key roles in colorectal cancer (CRC) progression, but little is known about the biological functions of hsa_circRNA_001676 in CRC. Therefore, we explored the potential role of hsa_circRNA_001676 in CRC development. RT-qPCR was performed to determine hsa_circRNA_001676, miR-556-3p and Ras-GTPase-activating SH3 domain-binding-proteins 2 (G3BP2) levels in CRC tissues. Meanwhile, to evaluate the roles of hsa_circRNA_001676, miR-556-3p and G3BP2 on CRC, functional analysis of cell proliferation, migration and stemness were then performed. Our results showed that compared to normal tissues, hsa_circRNA_001676 and G3BP2 level was elevated, but miR-556-3p level was reduced in CRC tissues. Additionally, luciferase reporter results showed that hsa_circRNA_001676 was shown to target miR-556-3p, and G3BP2 was targeted by miR-556-3p. Hsa_circRNA_001676 or G3BP2 overexpression promoted CRC cell proliferation and migration. Conversely, miR-556-3p overexpression suppressed CRC cell proliferation and migration. Moreover, deficiency of hsa_circRNA_001676 or G3BP2 repressed the CRC cell proliferation, migration and stemness. Meanwhile, hsa_circRNA_001676 deficiency obviously reduced tumor growth and stemness in a CRC mouse xenograft model. Furthermore, hsa_circRNA_001676 deficiency notably reduced G3BP2 level, but elevated miR-556-3p level in tumor tissues from tumor-bearing mice. Mechanistically, hsa_circRNA_001676 targeted miR-556-3p to increase G3BP2 level, contributing to the progression of CRC. Collectively, hsa_circRNA_001676 was able to accelerate proliferation, migration and stemness in CRC through regulating miR-556-3p/G3BP2 axis, suggesting that hsa_circRNA_001676 may become a potential therapeutic target in treating CRC.

The Impact of Molecular Biology in the Seeding, Treatment Choices and Follow-Up of Colorectal Cancer Liver Metastases-A Narrative Review

There is a clear association between the molecular profile of colorectal cancer liver metastases (CRCLM) and the degree to which aggressive progression of the disease impacts patient survival. However, much of our knowledge of the molecular behaviour of colorectal cancer cells comes from experimental studies with, as yet, limited application in clinical practice. In this article, we review the current advances in the understanding of the molecular behaviour of CRCLM and present possible future therapeutic applications. This review focuses on three important steps in CRCLM development, progression and treatment: (1) the dissemination of malignant cells from primary tumours and the seeding to metastatic sites; (2) the response to modern regimens of chemotherapy; and (3) the possibility of predicting early progression and recurrence patterns by molecular analysis in liquid biopsy.

Erythroblastic oncogene B-2 status and intracranial metastatic disease in patients with gastrointestinal cancer: a systematic review

PURPOSE

The incidence of intracranial metastatic disease (IMD) in patients with gastrointestinal (GI) cancers is rising. Expression of the erythroblastic oncogene B-2 (ERBB2) is associated with an in increased risk of IMD in patients with breast cancer. The implications of ERBB2 expression for IMD risk in patients with GI cancers is less clear. The objective of this systematic review was to determine the incidence of IMD and OS in patients with ERBB2+ gastrointestinal cancers.

METHODS

A literature search of MEDLINE, EMBASE, CENTRAL, and grey literature sources was conducted from date of database inception to July 2021. Included studies reported outcomes on patients with IMD secondary to ERBB2 GI cancers.

RESULTS

Fourteen cohort studies met inclusion criteria, of which thirteen were retrospective. Eleven studies reported on gastric, esophageal, or gastroesophageal junction cancers. Three studies directly compared incidence of IMD based on ERBB2 status and among these, ERBB2+ patients had a higher incidence of IMD. One study indicated that ERBB2+ patients had significantly longer OS from the times of primary cancer (P = .015) and IMD diagnosis (P = .01), compared with patients with ERBB2- disease.

CONCLUSIONS

In this systematic review, patients with ERBB2+ GI cancer were more likely to develop IMD. Future study is required on the prognostic and predictive value of ERBB2 status in patients with GI cancers.

Precision Medicine in Metastatic Colorectal Cancer: Targeting ERBB2 (HER-2) Oncogene

Colorectal cancer (CRC) is the third most common cancer in terms of incidence rate in adults and the second most common cause of cancer-related death in Europe. The treatment of metastatic CRC (mCRC) is based on the use of chemotherapy, anti-vascular endothelial growth factor (VEGF), and anti-epidermal growth factor receptor (EGFR) for RAS wild-type tumors. Precision medicine tries to identify molecular alterations that could be treated with targeted therapies. ERBB2 amplification (also known as HER-2) has been identified in 2-3% of patients with mCRC, but there are currently no approved ERBB2-targeted therapies for mCRC. The purpose of this review is to describe the molecular structure of ERBB2, clinical features of these patients, diagnosis of ERBB2 alterations, and the most relevant clinical trials with ERBB2-targeted therapies in mCRC.