Clinical implications of plasma ctDNA features and dynamics in gastric cancer treated with HER2-targeted therapies

Mechanisms of resistance to tyrosine kinase inhibitor-targeted therapy and overcoming strategies

Tyrosine kinase inhibitor (TKI)-targeted therapy has revolutionized cancer treatment by selectively blocking specific signaling pathways crucial for tumor growth, offering improved outcomes with fewer side effects compared with conventional chemotherapy. However, despite their initial effectiveness, resistance to TKIs remains a significant challenge in clinical practice. Understanding the mechanisms underlying TKI resistance is paramount for improving patient outcomes and developing more effective treatment strategies. In this review, we explored various mechanisms contributing to TKI resistance, including on-target mechanisms and off-target mechanisms, as well as changes in the tumor histology and tumor microenvironment (intrinsic mechanisms). Additionally, we summarized current therapeutic approaches aiming at circumventing TKI resistance, including the development of next-generation TKIs and combination therapies. We also discussed emerging strategies such as the use of dual-targeted antibodies and PROteolysis Targeting Chimeras. Furthermore, we explored future directions in TKI-targeted therapy, including the methods for detecting and monitoring drug resistance during treatment, identification of novel targets, exploration of dual-acting kinase inhibitors, application of nanotechnologies in targeted therapy, and so on. Overall, this review provides a comprehensive overview of the challenges and opportunities in TKI-targeted therapy, aiming to advance our understanding of resistance mechanisms and guide the development of more effective therapeutic approaches in cancer treatment.

Recent developments in immunotherapy for gastrointestinal tract cancers

The past few decades have witnessed the rise of immunotherapy for Gastrointestinal (GI) tract cancers. The role of immune checkpoint inhibitors (ICIs), particularly programmed death protein 1 (PD-1) and PD ligand-1 antibodies, has become increasingly pivotal in the treatment of advanced and perioperative GI tract cancers. Currently, anti-PD-1 plus chemotherapy is considered as first-line regimen for unselected advanced gastric/gastroesophageal junction adenocarcinoma (G/GEJC), mismatch repair deficient (dMMR)/microsatellite instability-high (MSI-H) colorectal cancer (CRC), and advanced esophageal cancer (EC). In addition, the encouraging performance of claudin18.2-redirected chimeric antigen receptor T-cell (CAR-T) therapy in later-line GI tract cancers brings new hope for cell therapy in solid tumour treatment. Nevertheless, immunotherapy for GI tumour remains yet precise, and researchers are dedicated to further maximising and optimising the efficacy. This review summarises the important research, latest progress, and future directions of immunotherapy for GI tract cancers including EC, G/GEJC, and CRC.

Circulating tumor DNA (ctDNA) application in investigation of cancer: Bench to bedside

Now, genomics forms the core of the precision medicine concept. Comprehensive investigations of tumor genomes have made it possible to characterize tumors at the molecular level and, specifically, to identify the fundamental processes that cause condition. A variety of kinds of tumors have seen better outcomes for patients as a result of the development of novel medicines to tackle these genetic-driving processes. Since therapy may exert selective pressure on cancers, non-invasive methods such as liquid biopsies can provide the opportunity for rich reservoirs of crucial and real-time genetic data. Liquid biopsies depend on the identification of circulating cells from tumors, circulating tumor DNA (ctDNA), RNA, proteins, lipids, and metabolites found in patient biofluids, as well as cell-free DNA (cfDNA), which exists in those with cancer. Although it is theoretically possible to examine biological fluids other than plasma, such as pleural fluid, urine, saliva, stool, cerebrospinal fluid, and ascites, we will limit our discussion to blood and solely cfDNA here for the sake of conciseness. Yet, the pace of wider clinical acceptance has been gradual, partly due to the increased difficulty of choosing the best analysis for the given clinical issue, interpreting the findings, and delaying proof of value from clinical trials. Our goal in this review is to discuss the current clinical value of ctDNA in cancers and how clinical oncology systems might incorporate procedures for ctDNA testing.

New clinical trial design in precision medicine: discovery, development and direction

In the era of precision medicine, it has been increasingly recognized that individuals with a certain disease are complex and different from each other. Due to the underestimation of the significant heterogeneity across participants in traditional "one-size-fits-all" trials, patient-centered trials that could provide optimal therapy customization to individuals with specific biomarkers were developed including the basket, umbrella, and platform trial designs under the master protocol framework. In recent years, the successive FDA approval of indications based on biomarker-guided master protocol designs has demonstrated that these new clinical trials are ushering in tremendous opportunities. Despite the rapid increase in the number of basket, umbrella, and platform trials, the current clinical and research understanding of these new trial designs, as compared with traditional trial designs, remains limited. The majority of the research focuses on methodologies, and there is a lack of in-depth insight concerning the underlying biological logic of these new clinical trial designs. Therefore, we provide this comprehensive review of the discovery and development of basket, umbrella, and platform trials and their underlying logic from the perspective of precision medicine. Meanwhile, we discuss future directions on the potential development of these new clinical design in view of the "Precision Pro", "Dynamic Precision", and "Intelligent Precision". This review would assist trial-related researchers to enhance the innovation and feasibility of clinical trial designs by expounding the underlying logic, which be essential to accelerate the progression of precision medicine.

Comprehensive next-generation sequencing reveals double primary colorectal carcinoma missed by diagnostic imaging: A case report

BACKGROUND

Multiple primary colorectal carcinoma (MPCC) is a rare clinical disease, which is challenging to differentiate from metastatic disease using histopathological methods. Next-generation sequencing (NGS) has been employed to identify multiple primary cancers.

CASE SUMMARY

This study a rare case of a 63-year-old male patient diagnosed with MPCC by targeted NGS, which was initially missed by radiological evaluation. The patient was found to have two tumors located on the surface of the colorectum which had distinct genomic alterations. Based on wild-type KRAS detected in the unresected tumor, the patient benefited from the epidermal growth factor receptor (EGFR) inhibitor cetuximab treatment, but developed novel mutations including KIF5B-RET fusion, which provides a possible resistance mechanism to anti-EGFR therapy.

CONCLUSION

Our case highlights the necessity of using genetic testing for primary tumor diagnosis and the application of serial plasma circulating tumor DNA profiling for dynamic disease monitoring.

Genomic and transcriptomic profiling indicates the prognosis significance of mutational signature for TMB-high subtype in Chinese patients with gastric cancer

INTRODUCTION

Gastric cancer (GC)is the third leading cause of cancer-related deaths in China and immunotherapy emerging as a revolutionary treatment for GC recently. Tumor mutational burden (TMB) is a predictive biomarker of immunotherapy in multiple cancers. However, the prognostic significance and subtype of TMB in GC is not fully understood.

OBJECTIVES

This study aims to evaluate the prognostic value of TMB in Chinese GC and further classify TMB-high GC (GCTMB-H) patients combing with mutational signatures.

METHODS

Genomic profiling of 435 cancer-gene panel was performed using 206 GC samples from Chinese people. Actionable genetic alterations were compared across all the samples to generate actionable subtyping. The prognostic value of TMB in Chinese GC was evaluated. Mutational signatures were analyzed on TMB-H subtype to stratify the prognosis of TMB. Transcriptomic analysis was applied to compare the distributed immunocytes among different subtypes.

RESULTS

88.3% (182/206) of GC samples had at least one mutation, while 45.1% (93/206) had at least one somatic copy number alteration (SCNA). 29.6% (61/206) of GC samples were TMB-H, including 13 MSI-H and 48 MSS tumors. According to distinct genetic alteration profiles of 69 actionable genes, we classified GC samples into eight molecular subtypes, including TMB-H, ERBB2 amplified, ATM mutated, BRCA2 mutated, CDKN2A/B deleted, PI3KCA mutated, KRAS mutated, and less-mutated subtype. TMB-H subtype presented a remarkable immune-activated phenotype as determined by transcriptomic analysis that was further validated in the TCGA GC cohort. GCTMB-H patients exhibited significantly better survival (P = 0.047). But Signature 1-high GCTMB-H patients had relatively worse prognosis (P = 0.0209, HR = 2.571) than Signature 1-low GCTMB-H patients from Chinese GC cohort, also validated in TCGA GC cohort, presenting highly activated carbohydrate, fatty acid or lipid metabolism.

CONCLUSION

The Signature 1-high GCTMB-H could be a marker of poor prognosis and is associated with metabolism disorder.

Postoperative circulating tumor DNA detection and CBLB mutations are prognostic biomarkers for gastric cancer

BACKGROUND

Several studies have demonstrated that circulating tumor DNA (ctDNA) can be used to predict the postoperative recurrence of several cancers. However, there are few studies on the use of ctDNA as a prognosis tool for gastric cancer (GC) patients.

OBJECTIVE

This study aims to determine whether ctDNA could be used as a prognostic biomarker in GC patients through multigene-panel sequencing.

METHODS

Using next-generation sequencing (NGS) Multigene Panels, the mutational signatures associated with the prognosis of GC patients were identified. We calculated the survival probability with Kaplan-Meier and used the Log-rank test to compare survival curves between ctDNA-positive and ctDNA-negative groups. Potential application of radiology combined with tumor plasma biomarker analysis of ctDNA in GC patients was carried out.

RESULTS

Disease progression is more likely in ctDNA-positive patients as characterized clinically by a generally higher T stage and a poorer therapeutic response (P < 0.05). ctDNA-positive patients also had worse overall-survival (OS: P = 0.203) and progression-free survival (PFS: P = 0.037). The combined analysis of ctDNA, radiological, and serum biomarkers in four patients indicated that ctDNA monitoring can be a good complement to radiological and plasma tumor markers for GC patients. Kaplan-Meier analysis using a cohort of GC patients in the TCGA database showed that patients with CBLB mutations had shorter OS and PFS than wild-type patients (OS: P = 0.0036; PFS: P = 0.0027).

CONCLUSIONS

This study confirmed the utility and feasibility of ctDNA in the prognosis monitoring of gastric cancer.

Exploring potential molecular resistance and clonal evolution in advanced HER2-positive gastric cancer under trastuzumab therapy

HER2-positive gastric cancer (GC) makes up 15-20% of all GC incidences, and targeted therapy with trastuzumab is the standard of treatment. However, the mechanisms of resistance to trastuzumab are still not fully understood and presents a significant challenge in clinical practice. In this study, whole exome sequencing (WES) was performed on paired tumor tissues before trastuzumab treatment (at baseline) and at progressive disease (PD) in 23 GC patients. Clinicopathological and molecular features that may be associated with primary and/or acquired resistance to trastuzumab were identified. Lauren classification of intestinal type was associated with a more prolonged progression-free survival (PFS) than diffuse type (HR = 0.29, P = 0.019). Patients with low tumor mutation burden (TMB) showed significantly worse PFS, while high chromosome instability (CIN) was correlated with prolonged OS (HR = 0.27; P = 0.044). Patients who responded to treatment had a higher CIN than nonresponders, and a positive trend towards increasing CIN was observed as response improved (P = 0.019). In our cohort, the most common genes to acquire mutations are AURKA, MYC, STK11, and LRP6 with four patients each. We also discovered an association between clonal branching pattern and survival, with an extensive clonal branching pattern being more closely related to a shorter PFS than other branching patterns (HR = 4.71; P = 0.008). We identified potential molecular and clinical factors that provide insight regarding potential association to trastuzumab resistance in advanced HER2-positive GC patients.

Potential predictive value of circulating tumor DNA (ctDNA) mutations for the efficacy of immune checkpoint inhibitors in advanced triple-negative breast cancer

Background: In recent years, tumor immunotherapy has become a viable treatment option for triple negative breast cancer (TNBC). Among these, immune checkpoint inhibitors (ICIs) have demonstrated good efficacy in advanced TNBC patients with programmed death-ligand 1 (PD-L1) positive expression. However, only 63% of PD-L1-positive individuals showed any benefit from ICIs. Therefore, finding new predictive biomarkers will aid in identifying patients who are likely to benefit from ICIs. In this study, we used liquid biopsies and next-generation sequencing (NGS) to dynamically detect changes in circulating tumor DNA (ctDNA) in the blood of patients with advanced TNBC treated with ICIs and focused on its potential predictive value.

Methods: From May 2018 to October 2020, patients with advanced TNBC treated with ICIs at Shandong Cancer Hospital were included prospectively. Patient blood samples were obtained at the pretreatment baseline, first response evaluation, and disease progression timepoints. Furthermore, 457 cancer-related genes were evaluated by NGS, and patients’ ctDNA mutations, gene mutation rates, and other indicators were determined and coupled with clinical data for statistical analysis.

Results: A total of 11 TNBC patients were included in this study. The overall objective response rate (ORR) was 27.3%, with a 6.1-month median progression-free survival (PFS) (95% confidence interval: 3.877–8.323 months). Of the 11 baseline blood samples, 48 mutations were found, with the most common mutation types being frame shift indels, synonymous single-nucleotide variations (SNVs), frame indel missenses, splicing, and stop gains. Additionally, univariate Cox regression analysis revealed that advanced TNBC patients with one of 12 mutant genes (CYP2D6 deletion and GNAS, BCL2L1, H3F3C, LAG3, FGF23, CCND2, SESN1, SNHG16, MYC, HLA-E, and MCL1 gain) had a shorter PFS with ICI treatment (p &lt; 0.05). To some extent, dynamic changes of ctDNA might indicate the efficacy of ICIs.

Conclusion: Our data indicate that ICI efficacy in patients with advanced TNBC may be predicted by 12 mutant ctDNA genes. Additionally, dynamic alterations in peripheral blood ctDNA might be used to track the effectiveness of ICI therapy in those with advanced TNBC.

Are High Levels of Microsatellite Instability and Microsatellite Stability Identical in DNA Mismatch Repair-Deficient Colorectal Cancer Patients?

Purpose

The purpose of the current study was to determine whether there is a difference between high levels of microsatellite instability (MSI-H) and microsatellite stability (MSS) in DNA mismatch repair-deficient (DMMR) colorectal cancer (CRC) patients.

Methods

A total of 452 CRC patients with DMMR from December, 2014, to April, 2021, in our hospital were selected retrospectively. However, only 105 patients underwent Sanger or next-generation-sequencing (NGS) to confirm their microsatellite status. Ultimately, 55 MSI-H patients and 20 MSS patients with intact medical record information were included in this study.

Results

The MSS group was associated with a higher mutation rate in the KRAS gene (P=0.011). Meanwhile, MSI-H was related to colon cancer (P < 0.01). However, no significant differences in other clinical characteristics were observed between the two groups of patients. There was no significant difference between the MSI-H and MSS groups in terms of overall survival (OS) (P=0.398) and disease-free survival (DFS) (P=0.307).

Conclusion

The MSI-H status was associated with colon cancer and a lower mutation rate of the KRAS gene in DMMR patients. In CRC-DMMR patients, the MSS group exhibited better OS and DFS than the MSI-H group, although these differences were not statistically significant. Accordingly, in clinical practice, we should not confuse these two types of patients.

Circulating Tumor DNA-A Novel Biomarker of Tumor Progression and Its Favorable Detection Techniques

Cancer is the second leading cause of death in the world and seriously affects the quality of life of patients. The diagnostic techniques for tumors mainly include tumor biomarker detection, instrumental examination, and tissue biopsy. In recent years, liquid technology represented by circulating tumor DNA (ctDNA) has gradually replaced traditional technology with its advantages of being non-invasive and accurate, its high specificity, and its high sensitivity. ctDNA may carry throughout the circulatory system through tumor cell necrosis, apoptosis, circulating exosome secretion, etc., carrying the characteristic changes in tumors, such as mutation, methylation, microsatellite instability, gene rearrangement, etc. In this paper, ctDNA mutation and methylation, as the objects to describe the preparation process before ctDNA analysis, and the detection methods of two gene-level changes, including a series of enrichment detection techniques derived from PCR, sequencing-based detection techniques, and comprehensive detection techniques, are combined with new materials. In addition, the role of ctDNA in various stages of cancer development is summarized, such as early screening, diagnosis, molecular typing, prognosis prediction, recurrence monitoring, and drug guidance. In summary, ctDNA is an ideal biomarker involved in the whole process of tumor development.

Bacterial Involvement in Progression and Metastasis of Adenocarcinoma of the Stomach

Simple Summary

Infectious bacteria influence primary gastric carcinogenesis, organotropism, and metastatic progression by altering the microenvironment at the primary and secondary tumors. Key species include Helicobacter pylori (H. pylori) and Mycoplasma hyorhinis (M. hyorhinis). Inflammation caused by H. pylori virulence factors, such as CagA, VacA, and oipA, disrupt epithelial integrity, which allows the primary tumor to progress through the metastatic process. Evidence supports the activation of aquaporin-5 by CagA-positive H. pylori infection, promoting epithelial–mesenchymal transition via the extracellular signal-regulated kinase/mitogen-activated protein kinase (MEK/ERK) pathway, thus laying the foundation for metastatic disease. M. hyorhinis has also been implicated in gastric neoplasia via β-catenin stabilization and subsequent activation of the WNT-signaling pathway, promoting gastric cancer cell motility and inciting cancer progression.

Abstract

Gastric cancer metastasis is a process in which the tumor microenvironment may carry significant influence. Helicobacter pylori (H. pylori) infection is well-established as a contributor to gastric carcinoma. However, the role that these bacteria and others may play in gastric carcinoma metastasis is a current focus of study. A review of the literature was conducted to elucidate the process by which gastric adenocarcinoma metastasizes, including its ability to utilize both the lymphatic system and the venous system to disseminate. Studies that investigate the tumor microenvironment at both the primary and secondary sites were assessed in detail. H. pylori and Mycoplasma hyorhinis (M. hyorhinis) were found to be important drivers of the pathogenesis of gastric adenocarcinoma by modifying various steps in cell metastasis, including epithelial–mesenchymal transition, cell migration, and cell invasion. H. pylori is also a known driver of MALT lymphoma, which is often reversible simply with the eradication of infection. M. hyorhinis has been implicated in gastric neoplasia via β-catenin stabilization and subsequent activation of the WNT-signaling pathway, promoting gastric cancer cell motility and inciting cancer progression. Fusobacterium nucleatum (F. nucleatum) and its association with worse prognosis in diffuse-type gastric adenocarcinoma are also reviewed. Recognition of the roles that bacteria play within the metastatic cascade is vital in gastrointestinal adenocarcinoma treatment and potential reoccurrence. Further investigation is needed to establish potential treatment for metastatic gastric carcinoma by targeting the tumor microenvironment.

Molecular evolutionary process of advanced gastric cancer during sequential chemotherapy detected by circulating tumor DNA

BACKGROUND

Efficacy of conventional sequential chemotherapy paradigm for advanced gastric cancer (AGC) patients has largely plateaued. Dynamic molecular changes during and after sequential chemotherapy have not been fully delineated. We aimed to profile the molecular evolutionary process of AGC patients during sequential chemotherapy by next generation sequencing (NGS) of plasma circulating tumor DNA (ctDNA).

METHODS

A total of 30 chemo-naïve patients who were diagnosed with unresectable advanced or metastatic stomach adenocarcinoma were enrolled. All patients received sequential chemotherapy regimens following the clinical guideline. One hundred and eight serial peripheral blood samples were collected at baseline, radiographical assessment and disease progression. Plasma ctDNA was isolated and a customized NGS panel was used to detect the genomic features of ctDNA including single nucleotide variants (SNVs) and gene-level copy number variations (CNVs). KEGG pathway enrichment analysis was performed.

RESULTS

Platinum-based combination chemotherapy was administrated as first-line regimen. Objective response rate was 50% (15/30). Patients with higher baseline values of copy number instability (CNI), CNVs and variant allel frequency (VAF) were more sensitive to platinum-based first-line regimens. Tumor mutation burden (TMB), CNI and CNV burden at partial response and stable disease were significantly lower than those at baseline, where at progressive disease they recovered to baseline levels. Dynamic change of TMB (ΔTMB) was correlated with progression-free survival of first-line treatment. Fluctuating changes of SNVs and gene-level CNVs could be observed during sequential chemotherapy. Under the pressure of conventional chemotherapy, the number of novel gene-level CNVs were found to be higher than that of novel SNVs. Such novel molecular alterations could be enriched into multiple common oncologic signaling pathways, including EGFR tyrosine kinase inhibitor resistance and platinum drug resistance pathways, where their distributions were found to be highly heterogenous among patients. The impact of subsequent regimens, including paclitaxel-based and irinotecan-based regimens, on the molecular changes driven by first-line therapy was subtle.

CONCLUSION

Baseline and dynamic changes of genomic features of ctDNA could be biomarkers for predicting response of platinum-based first-line chemotherapy in AGC patients. After treatment with standard chemotherapy regimens, convergent oncologic pathway enrichment was identified, which is yet characterized by inter-patient heterogenous gene-level CNVs.

Uterine perivascular epithelioid tumors (PEComas) with lung metastasis showed good responses to mTOR and VEGFR inhibitors: A case report

Perivascular epithelioid cell tumors (PEComas) are extremely rare mesenchymal neoplasms for which the uterus is the most common site. The prognosis of malignant PEComa is poor as it is characterized by resistance to classical chemotherapies. Both mTOR inhibitors and VEGFR inhibitors exhibited clinical utility in treating malignant PEComas, but the combination of these two regimens has rarely been reported. In the present case, a uterine PEComa patient developed lung and bone metastases after the failure of chemotherapies and derived benefit from the combination regimen of an mTOR inhibitor (everolimus) and a VEGFR inhibitor (apatinib), achieving a 15-month progression-free survival. Targeted NGS revealed TP53 and TSC2 mutations in the patient’s primary uterine tumors and plasma ctDNA at disease progression. Plasma ctDNA clearance was consistent with a radiologic partial response determined by RECIST 1.1 and a reduction of neuron-specific enolase (NSE) and cancer antigen 125 (CA125) levels. Thus, we provided clinical evidence supporting the administration of combined therapy of mTOR and VEGFR inhibitors to metastatic uterine PEComa patients and highlighted the application of serial plasma ctDNA profiling for dynamic disease monitoring.

From Anti-HER-2 to Anti-HER-2-CAR-T Cells: An Evolutionary Immunotherapy Approach for Gastric Cancer

Current Therapeutic modalities provide no survival advantage to gastric cancer (GC) patients. Targeting the human epidermal growth factor receptor-2 (HER-2) is a viable therapeutic strategy against advanced HER-2 positive GC. Antibody-drug conjugates, small-molecule tyrosine kinase inhibitors (TKIs), and bispecific antibodies are emerging as novel drug forms that may abrogate the resistance to HER-2-specific drugs and monoclonal antibodies. Chimeric antigen receptor-modified T cells (CAR-T) targeting HER-2 have shown considerable therapeutic potential in GC and other solid tumors. However, due to the high heterogeneity along with the complex tumor microenvironment (TME) of GC that often leads to immune escape, the immunological treatment of GC still faces many challenges. Here, we reviewed and discussed the current progress in the research of anti-HER-2-CAR-T cell immunotherapy against GC.

Circulating Tumor DNA: An Emerging Tool in Gastrointestinal Cancers

Circulating tumor DNA (ctDNA) is tumor-derived fragmented DNA in the bloodstream that has come from primary or metastatic cancer sites. Neoplasm-specific genetic and epigenetic abnormalities are increasingly being identified through liquid biopsy: a novel, minimally invasive technique used to isolate and analyze ctDNA in the peripheral circulation. Liquid biopsy and other emerging ctDNA technologies represent a paradigm shift in cancer diagnostics because they allow for the detection of minimal residual disease in patients with early-stage disease, improve risk stratification, capture tumor heterogeneity and genomic evolution, and enhance ctDNA-guided adjuvant and palliative cancer therapy. Moreover, ctDNA can be used to monitor the tumor response to neoadjuvant and postoperative therapy in patients with metastatic disease. Using clearance of ctDNA as an endpoint for escalation/de-escalation of adjuvant chemotherapy for patients considered to have high-risk disease has become an important area of research. The possibility of using ctDNA as a surrogate for treatment response-including for overall survival, progression-free survival, and disease-free survival-is an attractive concept; this surrogate will arguably reduce study duration and expedite the development of new therapies. In this review, we summarize the current evidence on the applications of ctDNA for the diagnosis and management of gastrointestinal tumors. Gastrointestinal cancers-including tumors of the esophagus, stomach, colon, liver, and pancreas-account for one-quarter of global cancer diagnoses and contribute to more than one-third of cancer-related deaths. Given the prevalence of gastrointestinal malignancies, ctDNA technology represents a powerful tool to reduce the global burden of disease.

Dynamic detection of HER2 of circulating tumor cells in patients with gastric carcinoma and its clinical application

The aim of the present study was to construct and characterize human epidermal growth factor receptor 2 (HER2) lipid magnetic ball (H‑LMB) for separating circulating tumor cells (CTCs) in patients with gastric carcinoma (GC) and to compare the result of separated CTC counts with that of next‑generation sequencing (NGS) for single‑gene analysis to verify the consistency for evaluating the association between the detection results and the progress of clinical treatment, so as to facilitate early diagnosis and dynamic monitoring of GC. A lipid magnetic ball (LMB), coated with Fe₃O₄ nanoparticles, was synthesized by microemulsion technique and an anti‑HER2 antibody was conjugated to the surface of LMB to form H‑LMB, followed by the characterization of the prepared H‑LMB. The detection of capture efficiency of LMBs in GC cells was tested by MTT and expression of HER2 mRNA was determined by reverse transcription‑quantitative PCR. The positive detection rate of HER2 was verified by HER2‑fluorescence in situ hybridization (FISH) test on the separated CTCs from GC. Further verification was performed based on the consistency between the result of separated CTCs and that of single‑gene NGS assay of HER2, associated with the determination of clinical consistency. The constructed H‑LMB exhibited good stability and specificity. The mutation rate of HER2 by the FISH test was 14% in the blood samples of 50 patients with GC and was 14% by NGS assay. The mutation rate of HER2 was 12% in H‑LMB and the positive detection rate was 85.7% compared with the results of the FISH test, indicating consistency with the clinical diagnosis and pathological examination results. In conclusion, the anti‑HER2 antibody‑modified LMB can separate CTCs with HER2 abnormal expression, which exhibits an application potential in GC diagnosis and treatment and is of great clinical significance for the diagnosis and evaluation of its therapeutic effect on GC.

Altered Signaling Pathways Revealed by Comprehensive Genomic Profiling in Patients With Unknown Primary Tumors

Purpose

Carcinoma of unknown primary (CUP) is a clinically aggressive disorder with early tumor dissemination. Identifying molecular traits of CUP can be not only beneficial for a better therapeutic approach but also potentially valuable for patients with general metastatic dissemination.

Patients and Methods

We retrospectively investigated a total of 35 unique CUP cases. Tumor tissue samples were available in 26 patients, and plasma samples were available in 22 patients. Targeted sequencing was performed with a panel of 416 pan cancer-related genes.

Results

A genomic landscape of the CUP cohort showed that TP53 mutation was the most frequently observed mutation while MYC amplification was the most common CNV. Aberrant TP53, RTK-RAS, and PI3K signaling pathways were also prevalent, identified in more than half of the cases with tumor tissue. Around 58% of the CUP cases harbored homologous recombinant repair (HRR) pathway gene alterations. The tumor mutational load of CUP patients with altered HRR pathway displayed a significant increase than that of patients with intact HRR. Clinically actionable mutations were identified in eight patients, which may benefit from targeted therapies. Eight patients were treated with platinum-based chemotherapy, showing different responses, HRR, and LOH status.

Conclusion

Collectively, our data have provided much-need insights into the treatment options for patients diagnosed with CUP in the era of precision medicine.

Longitudinal Circulating Tumor DNA Profiling in Metastatic Colorectal Cancer During Anti-EGFR Therapy

Background

Metastatic colorectal cancer (mCRC) is a heterogenous disease with limited precision medicine and targeted therapy options. Monoclonal antibodies against epidermal growth factor receptor (EGFR) have been a crucial treatment option for mCRC. However, proper biomarkers for predicting therapeutic response remain unknown. As a non-invasive test, circulating tumor DNA (ctDNA) is appropriately positioned to reveal tumor heterogeneity and evolution, as it can be used in real-time genomic profiling. To evaluate the significance of ctDNA in monitoring the dynamic therapeutic response and prognosis of mCRC, we detected the baseline and dynamic changes of ctDNA in mCRC patients receiving anti-EGFR therapies.

Methods

A single-center study was conducted retrospectively. Plasma samples from mCRC patients who received anti-EGFR therapies were collected at baseline and continuous treatment points. The ctDNA was extracted and sequenced with a target panel of tumor-related genes via next-generation sequencing (NGS). Clinical information was also collected and analyzed.

Results

We conducted dynamic sampling of 22 mCRC patients, analyzed 130 plasma samples, obtained a baseline genomic mutation profile of the patients. In total, 54 variations were detected in 22 plasma samples, with a positive rate of 77.3% (17/22). TP53 was the most mutated gene (59.1%, 13/22), followed by APC (18.2%, 4/22). There was a high concordance rate of genomic characteristics between the tumor tissue test by polymerase chain reaction and ctDNA test by NGS. The mutation discrepancy increased with an extended course of treatment. During remission TP53 and APC were the most frequently decreased clonal mutations and KRAS, NRAS, ERBB2 and PIK3CA were the most decreased subclonal mutations. Both mutation types were increased during progression. The ctDNA decreased earlier than did the responses of computed tomography and traditional tumor markers (carbohydrate antigen 19-9 and carcinoembryonic antigen [CEA]). Lactate dehydrogenase level (P = 0.041), CEA level (P = 0.038), and primary lesion site (P = 0.038) were independent risk factors that influenced overall survival. Moreover, patients with RAS mutations tended to have a worse prognosis (P = 0.072).

Conclusions

This study demonstrates that ctDNA is a promising biomarker for monitoring the dynamic response to treatment and determining the prognosis of mCRC.

Case Report: Durable Clinical Response to Third-Line Pyrotinib After Resistance to Trastuzumab in a Gastric Cancer Patient

Background

Trastuzumab plus chemotherapy remains the standard first-line treatment strategy for HER2-positive gastric cancer (GC). Trastuzumab resistance, on the other hand, remains a significant issue. There are a few effective anti-HER2 agents for patients who develop resistance to trastuzumab.

Case Presentation

A 49-year-old female was diagnosed with stage IV GC with liver and lung metastasis in July 2017. She underwent gastrostomy, and the immunohistochemistry (IHC) result of postoperative tissue demonstrated HER2 (3+). She received first-line treatment of trastuzumab (440 mg), oxaliplatin (200 mg), and S-1 (40 mg). After treatment for 6 months, the patient achieved complete response (CR) with PFS up to 21 months. After progression, she subsequently received trastuzumab (440 mg) plus oxaliplatin (200 mg) as second-line treatment. However, the patient developed resistance to trastuzumab after 12 months of treatment. She started to receive third-line treatment of irinotecan (200 mg d1) and capecitabine (60 mg bid) plus pyrotinib (400 mg/day). After 2 months of treatment, the tumor is evaluated as partial response with PFS of 12 months.

Conclusions

We presented a patient with HER2-positive GC who benefited from the pyrotinib-based treatment after two lines of trastuzumab-based therapies failed. Further research is required to validate such conclusions.

Clinical Applications of Liquid Biopsy in Gastric Cancer

Liquid biopsy represents an exciting new area in the field of cancer diagnosis and management, offering a less invasive and more convenient approach to obtain a time-point image of the tumor burden and its genomic profile. Samples collected from several body fluids, mostly blood, can be used to gain access to circulating tumor cells and DNA, non-coding RNAs, microRNAs, and exosomes, at any moment, offering a dynamic picture of the tumor. For patients with GC, the use of blood-based biopsies may be particularly beneficial since tissue biopsies are difficult to obtain and cause real distress to the patient. With advantages such as repeatability and minimal invasion, it is no wonder that the field of liquid biopsy has received tremendous attention. However, the abundance of studies, involving a wide range of assays with different principles, prevented for the moment the reproducibility of the results and therefore the translation into the clinic of liquid biopsy. In this review, we present the latest technical development and data on circulating biomarkers available through liquid biopsy in gastric cancer with an emphasis on their clinical utility in areas such as cancer screening, prognostic stratification, and therapeutic management.

Establishment of an Immune Cell Infiltration Score to Help Predict the Prognosis and Chemotherapy Responsiveness of Gastric Cancer Patients

The immune microenvironment plays a critical role in tumor biology. The molecular profiles of immune components and related genes are of tremendous value for the study of primary resistance to immune checkpoint blockers (ICBs) for gastric cancer (GC) and serve as prognostic biomarkers to predict GC survival. Recent studies have revealed that tumor immune cell infiltration (ICI) is an indicator of the survival and responsiveness to chemotherapy in GC patients. Here, we describe the immune cell landscape based on the ESTIMATE and CIBERSORT algorithms to help separate GC into 3 ICI clusters using the unsupervised clustering method. Further in-depth analyses, such as differential expression gene (DEG) analysis and principal component analysis (PCA), help to establish an ICI scoring system. A low ICI score is characterized by an increased tumor mutation burden (TMB). The combination of the ICI score and TMB score better predicts the survival of GC patients. Analyses based on public and our own database revealed that the ICI scoring system could also help predict the survival and chemotherapy responsiveness of GC patients. The present study demonstrated that the ICI score may be an effective prognostic biomarker and predictive indicator for chemotherapy and immunotherapy.