Recent advances in the HER2 targeted therapy of gastric cancer

Efficacy of anti-HER2 drugs in the treatment of patients with HER2-mutated cancers: a systematic review and meta-analysis

Anti-human epidermal growth factor receptor-2 (anti-HER2) therapy has shown excellent efficacy in patients with HER2 overexpression and amplification. Although HER2 mutations are rarely expressed in several cancers, when they occur, they can activate the HER2 signaling pathway. In recent years, studies have shown that anti-HER2 drugs have promising efficacy in patients with HER2 mutations. Based on keywords, we searched databases, such as PubMed, Embase, and Cochrane Library, and the main conference abstracts. We extracted data on objective response rate (ORR), clinical benefit rate (CBR), duration of response (DOR), progression-free survival (PFS), and overall survival (OS) from studies on the efficacy of anti-HER2 therapies in patients with HER2-mutated cancers, and analyzed grade 3 or higher adverse events (AEs). We included 19 single-arm clinical studies and 3 randomized controlled trials (RCTs), containing a total of 1017 patients with HER2 mutations, involving seven drugs and nine cancers, and 18 studies enrolled a high proportion of heavily pretreated patients who had received multiple lines of therapy. Our results showed pooled ORR and CBR of 25.0% (range, 3.8-72.7%; 95% CI, 18-32%) and 36.0% (range, 8.3-63.0%; 95% CI, 31-42%) for anti-HER2 therapy in HER2-mutated cancers. The pooled median PFS, OS, DOR were 4.89 (95% CI, 4.16-5.62), 12.78 (95% CI, 10.24-15.32), and 8.12 (95% CI, 6.48-9.75) months, respectively. In a subgroup analysis, we analyzed the ORR for different cancers, showing 27.0, 25.0, 23.0, and 16.0% for breast, lung, cervical, and biliary tract cancers, respectively. ORR analyses were performed for different drugs as monotherapy or in combination, showing 60.0% for trastuzumab deruxtecan (T-DXd), 31.0% for pyrotinib, 26.0% for neratinib combined with trastuzumab, 25.0% for neratinib combined with fulvestrant, 19.0% for trastuzumab combined with pertuzumab, and 16.0% for neratinib. In addition, we found that diarrhoea, neutropenia, and thrombocytopenia were the most common grade ≥ 3 AEs associated with anti-HER2 therapeutic agents. In this meta-analysis of heavily pretreated patients with HER2 mutations, anti-HER2 therapies, DS-8201 and trastuzumab emtansine, showed promising efficacy and activity. Anti-HER2 therapies showed different efficacies in different or the same cancer settings and all had a tolerable safety profile.

p70S6K/Akt dual inhibitor DIACC3010 is efficacious in preclinical models of gastric cancer alone and in combination with trastuzumab

The PI3K-Akt-mTOR (PAM) pathway is implicated in tumor progression in many tumor types, including metastatic gastric cancer (GC). The initial promise of PAM inhibitors has been unrealized in the clinic, presumably due, in part, to the up-regulation of Akt signaling that occurs when the pathway is inhibited. Here we present that DIACC3010 (formerly M2698), an inhibitor of two nodes in the PAM pathway, p70S6K and Akt 1/3, blocks the pathway in in vitro and in vivo preclinical models of GC while providing a mechanism that inhibits signaling from subsequent Akt up-regulation. Utilizing GC cell lines and xenograft models, we identified potential markers of DIACC3010-sensitivity in Her2-negative tumors, i.e., PIK3CA mutations, low basal pERK, and a group of differentially expressed genes (DEGs). The combination of DIACC3010 and trastuzumab was evaluated in Her2-positive cell lines and models. Potential biomarkers for the synergistic efficacy of the combination of DIACC3010 + trastuzumab also included DEGs as well as a lack of up-regulation of pERK. Of 27 GC patient-derived xenograft (PDX) models tested in BALB/c nu/nu mice, 59% were sensitive to DIACC3010 + trastuzumab. Of the 21 HER2-negative PDX models, DIACC3010 significantly inhibited the growth of 38%. Altogether, these results provide a path forward to validate the potential biomarkers of DIACC3010 sensitivity in GC and support clinical evaluation of DIACC3010 monotherapy and combination with trastuzumab in patients with HER2- negative and positive advanced GCs, respectively.

HER3 PET Imaging Predicts Response to Pan Receptor Tyrosine Kinase Inhibition Therapy in Gastric Cancer

PURPOSE

New generation of receptor tyrosine kinase inhibitors (RTKIs) have shown to improve survival in many solid tumors. However, an imaging biomarker is needed for patient selection and prediction of treatment response. This study evaluates the use of quantitative changes of HER3 on ⁶⁸ Ga-NOTA-HER3P1 PET/MRI for prediction of early response to pan-RTKIs in gastric cancer (GCa).

PROCEDURES

GCa cell lines were evaluated for expression of RTKs, and downstream signaling pathways (AKT and MAPK). Cell viability was assessed following 24-72 h of treatment with 0.01-1 µmol/L of afatinib, a pan-RTKI. HER3-expressing afatinib-sensitive (NCI-N87) and resistant cells (SNU16) were selected for evaluation of changes in RTKs expression and downstream pathways, with 24-72 h of 0.1 µmol/L afatinib treatment. ⁶⁸ Ga-NOTA-HER3P1 PET/MRI was performed in subcutaneous NCI-N87 and SNU16 xenografts (nu:nu, n = 12/group) at baseline and 4 days after afatinib treatment (10 mg/kg, PO, daily). Temporal changes in PET measures were correlated to HER3 expression in tumors, tumor growth rate, and treatment response.

RESULTS

With afatinib therapy, NCI-N87 cells showed increased total HER3 expression, and reduction of other RTKs and downstream nodes within 72 h, while SNU16 cells showed no significant change in total HER3 and downstream nodes. ⁶⁸ Ga-HER3P1 PET/MRI showed increased uptake in NCI-N87 and no significant change in SNU16 tumors (day 4 vs. baseline SUV_mean: 3.8 ± 0.7 vs. 1.6 ± 0.6, p < 0.05 in NCI-N87, and 1.5 ± 0.7 vs. 1.7 ± 0.7, p > 0.05 in SNU16). These findings were in concordance with HER3 expression in histopathological analyses and tumor growth over 3 weeks of treatment (mean tumor volume in treated vs. control: 11 ± 17 mm³ vs. 293 ± 79 mm³, p < 0.001 in NCI-N87, and 238 ± 91 mm³ vs. 282 ± 35 mm³, p > 0.05 in SNU16).

CONCLUSIONS

Quantitative changes in HER3 PET could be used to predict response to pan-RTKI within few days after initiation of treatment and can help with personalizing GCa management.

ARID1A deficiency is targetable by AKT inhibitors in HER2-negative gastric cancer

BACKGROUND

The PI3K/AKT signaling pathway is frequently activated in gastric cancer (GC); however, AKT inhibitors are not effective in unselected GC patients in clinical trials. Mutations in AT-rich interactive domain 1A (ARID1A), which are found in approximately 30% of GC patients, activate PI3K/AKT signaling, suggesting that targeting the ARID1A deficiency-activated PI3K/AKT pathway is a therapeutic candidate for ARID1A-deficient GC.

METHODS

The effect of AKT inhibitors was evaluated using cell viability and colony formation assays in ARID1A-deficient and ARID1A knockdown ARID1A-WT GC cells as well as in HER2-positive and HER2-negative GC. The Cancer Genome Atlas cBioPortal and Gene Expression Omnibus microarray databases were accessed to determine the extent of dependence of GC cell growth on the PI3K/AKT signaling pathway.

RESULTS

AKT inhibitors decreased the viability of ARID1A-deficient cells and the inhibitory effect was greater in ARID1A-deficient/HER2-negative GC cells. Bioinformatics data suggested that PI3K/AKT signaling plays a greater role in proliferation and survival in ARID1A-deficient/HER2-negative GC cells than in ARID1A-deficient/HER2-positive cells, supporting the higher therapeutic efficacy of AKT inhibitors.

CONCLUSIONS

The effect of AKT inhibitors on cell proliferation and survival is affected by HER2 status, providing a rationale for exploring targeted therapy using AKT inhibitors in ARID1A-deficient/HER2-negative GC.

Deciphering the Impact of HER2 Alterations on Non-Small-Cell Lung Cancer: From Biological Mechanisms to Therapeutic Approaches

Despite the recent increase in the number of types of treatments, non-small-cell lung cancer (NSCLC) remains the major cause of death from cancer worldwide. So, there is an urgent need to develop new therapeutic strategies. The HER2 gene codes for tyrosine kinase receptor whose alterations are known to drive carcinogenesis. HER2 alterations, including amplification, mutations, and overexpression, have been mainly described in breast and gastric cancers, but up to 4% of NSCLC harbor actionable HER2 mutations. HER2-targeted therapy for NSCLC with trastuzumab, pertuzumab, and trastuzumab emtansine has failed to demonstrate an improvement in survival. Nevertheless, recent data from phase II trials have shed light on promising specific therapies for HER2-mutant NSCLC such as trastuzumab deruxtecan. Herein, we aimed to provide an updated review on the biology, epidemiology, molecular testing, and therapeutic strategies for NSCLC with HER2 molecular alterations.

Hyperpolarized [1-13C]Pyruvate Magnetic Resonance Spectroscopic Imaging for Evaluation of Early Response to Tyrosine Kinase Inhibition Therapy in Gastric Cancer

PURPOSE

To evaluate the use of hyperpolarized [1-13C]pyruvate magnetic resonance spectroscopic imaging (HP-13C MRSI) for quantitative measurement of early changes in glycolytic metabolism and its ability to predict response to pan-tyrosine kinase inhibitor (Pan-TKI) therapy in gastric cancer (GCa).

PROCEDURES

Pan-TKI afatinib-sensitive NCI-N87 and resistant SNU16 human GCa cells were assessed for GLUT1, hexokinase-II (HKII), lactate dehydrogenase (LDHA), phosphorylated AKT (pAKT), and phosphorylated MAPK (pMAPK) at 0-72 h of treatment with 0.1 μM afatinib. Subcutaneous NCI-N87 tumor-bearing nude mice underwent [18F]FDG PET/MRI and HP-13C MRSI at baseline and 4 days after treatment with afatinib 10 mg/kg/day or vehicle (n = 10/group). Changes in PET and HP-13C MRSI metabolic parameters were compared between the two groups. Imaging findings were correlated with tumor growth and histopathology over 3 weeks of treatment.

RESULTS

In vitro analysis showed a continuous decrease in LDHA, pAKT, and pMAPK in NCI-N87 compared to SNU16 cells within 72 h of treatment with afatinib, without a significant change in GLUT1 and HKII in either cell type. [18F]FDG PET of NCI-N87 tumors showed no significant change in PET measures at baseline and day 4 of treatment in either treatment group (SUVmean day 4/day 0: 2.7 ± 0.42/2.34 ± 0.38, p = 0.57 in the treated group vs. 1.73 ± 0.66/2.24 ± 0.43, p = 0.4 in the control group). HP-13C MRSI demonstrated significantly decreased lactate-to-pyruvate ratio (L/P) in treated tumors (L/P day 4/day 0: 0.83 ± 0.30/1.10 ± 0.20, p = 0.012 vs. 0.94 ± 0.20/0.98 ± 0.30, p = 0.75, in the treated vs. control group, respectively). Response to afatinib was confirmed with decreased tumor size over 3 weeks (11.10 ± 16.50 vs. 293.00 ± 79.30 mm3, p < 0.001, treated group vs. control group, respectively) and histopathologic evaluation.

CONCLUSIONS

HP-13C MRSI is a more representative biomarker of early metabolic changes in response to pan-TKI in GCa than [18F]FDG PET and could be used for early prediction of response to targeted therapies.

Ursolic acid silences CYP19A1/aromatase to suppress gastric cancer growth

INTRODUCTION

Gastric cancer (GCa) is a malignancy with few effective treatments. Ursolic acid (UA), a bioactive triterpenoid enriched in Hedyotis diffusa Willd, known to suppress GCa without identified target. CYP19A1 (cytochrome P450 family 19A1; also known as aromatase, Ar) was correlated to GCa prognosis. Relatedly, Ar silencers, which halt the expression of Ar exhibited anti-GCa effects in experimental models, are currently being investigated.

METHOD

The docking simulation score of UA was compared with Ar inhibitors, e.g., letrozole, exemestane, in Ar protein crystallization. Hedyotis diffusa Willd ethanol extract, UA, or 5-fluracil were applied onto AGS, SC-M1, MKN45 GCa cells for cancer inhibition tests. Immunoblot for measuring gene expressions upon drug treatments, or gene knockdown/overexpression. Treatments were also applied in a MKN45 implantation tumor model. A web-based GCa cohort for Ar expression association with prognosis was performed.

RESULT

The ethanol extracts of Hedyotis diffusa Willd, enrich with UA, exhibited cytotoxic activity against GCa cells. Molecular docking simulations with the 3D Ar structure revealed an excellent fitting score for UA. UA increase cytotoxic, and suppressed colony, in addition to its Ar silencing capacity. Moreover, UA synergistically facilitated 5-FU, (a standard GCa treatment) regimen in vitro. Consistent with those results, adding estradiol did not reverse the cancer-suppressing effects of UA, which confirmed UA acts as an Ar silencer. Furthermore, UA exhibited tumor-suppressing index (TSI) score of 90% over a 6-week treatment term when used for single dosing in xenograft tumor model. In the clinical setting, Ar expression was found to be higher in GCa tumors than normal parental tissue from the TCGA (The Cancer Genome Atlas) cohort, while high Ar expression associated with poor prognosis. Together, the results indicate UA could be used to treat GCa by silencing Ar expression in GCa. Hedyotis diffusa Willd ethanol extract could be an functional food supplements.

Immune microenvironment characteristics and their implications for immune checkpoint inhibitor efficacy in HER2-overexpressing gastric cancer

HER2-positive gastric cancer is a distinct tumor subtype, accounting for ~10% of gastric cancer cases. It is characterized by HER2 overexpression and responds well to HER2-targeting therapies. Recently, the addition of immune checkpoint inhibitors to HER2-targeting therapies produced satisfactory outcomes in these patients. In the present study, we used gene expression profiles and patient surgical sections to analyze the tumor immune microenvironment characteristics of gastric tumors with high HER2 expression. Several differentially enriched pathways were identified between the HER2 high-expression group and the low-expression group, such as pathways related to cytokine-cytokine receptor interactions, calcium signaling, and cell adhesion molecules. Tumors with high HER2 expression comprised fewer stromal cells and fewer immune cells, and had higher tumor purity. They also presented with lower expression of PD-1, PD-L1, CTLA-4, TIGIT, and LAG-3. In conclusion, our study provides a comprehensive blueprint of the immune microenvironment of HER2-positive gastric tumors. This analysis highlights the importance of considering the tumor microenvironment when assessing response to immune checkpoint inhibitors.

Engineered exosomes: desirable target-tracking characteristics for cerebrovascular and neurodegenerative disease therapies

As extracellular vesicles secreted by cells, exosomes are intercellular signalosomes for cell communication and pharmacological effectors. Because of their special properties, including low toxicity and immunogenicity, biodegradability, ability to encapsulate endogenous biologically active molecules and cross the blood-brain barrier (BBB), exosomes have great therapeutic potential in cerebrovascular and neurodegenerative diseases. However, the poor targeting ability of natural exosomes greatly reduces the therapeutic effect. Using engineering technology, exosomes can obtain active targeting ability to accumulate in specific cell types and tissues by attaching targeting units to the membrane surface or loading them into cavities. In this review, we outline the improved targeting functions of bioengineered exosomes, tracing and imaging techniques, administration methods, internalization in the BBB, and therapeutic effects of exosomes in cerebrovascular and neurodegenerative diseases and further evaluate the clinical opportunities and challenges in this research field.

Clinicopathologic features and treatment advances in cancers with HER2 alterations

HER2 is one of the most important proteins of the epidermal growth factor receptor (EGFR) family, whose alterations include amplification, overexpression and gene mutation. Growing attention has been given to HER2 as a biomarker for prognosis, an indicator for treatment response and a target for new drugs. Tumors with HER2 alterations have been well studied in multiple locations as distinct entities for treatment, especially breast cancer, gastric cancer, lung cancer and colorectal cancer. These four cancers are the leading causes of cancer incidence and cancer-related death worldwide. The present study details the landscape of HER2 amplification/overexpression and mutations and gives an up-to-date analysis of current clinical trials in the four cancers mentioned above. Different HER2-altered cancers not only respond differently to HER2-targeting therapies but also display diverse survival outcomes. Even in the same type of cancer, HER2 amplification/overexpression differs from HER2 mutation in terms of clinicopathologic features and treatment strategies. As an emerging strategy in cancer treatment, immune checkpoint inhibitors demonstrate distinct outcomes in HER2-altered breast cancer, gastric cancer and lung cancer.

Acquired resistance to trastuzumab/pertuzumab or to T-DM1 in vivo can be overcome by HER2 kinase inhibition with TAS0728

HER2‐targeting antibodies (trastuzumab, pertuzumab) and a HER2‐directed antibody‐drug conjugate (trastuzumab emtansine: T‐DM1) are used for the treatment of HER2‐overexpressing breast cancer. However, these treatments eventually become ineffective due to acquired resistance and there is an urgent need for alternative therapies. TAS0728 is a small‐molecule, irreversible selective HER2 kinase inhibitor. In the present study, we established new in vivo models of cancer resistance by continuous exposure to a combination of trastuzumab and pertuzumab or to T‐DM1 for evaluating the effect of TAS0728 on HER2 antibody‐resistant populations. Treatment with trastuzumab and pertuzumab or with T‐DM1 initially induced tumor regression in NCI‐N87 xenografts. However, tumor regrowth during treatment indicated loss of drug effectiveness. In tumors with acquired resistance to trastuzumab and pertuzumab or to T‐DM1, HER2‐HER3 phosphorylation was retained. Switching to TAS0728 resulted in a significant anti‐tumor effect associated with HER2‐HER3 signal inhibition. No alternative receptor tyrosine kinase activation was observed in these resistant tumors. Furthermore, in a patient‐derived xenograft model derived from breast cancer refractory to both trastuzumab/pertuzumab and T‐DM1, TAS0728 exerted a potent anti‐tumor effect. These results suggest that tumors with acquired resistance to trastuzumab and pertuzumab and to T‐DM1 are still dependent on oncogenic HER2‐HER3 signaling and are vulnerable to HER2 signal inhibition by TAS0728. These results provide a rationale for TAS0728 therapy for breast cancers that are refractory to established anti‐HER2 therapies.

Association of serum levels of deoxyribose 1-phosphate and S-lactoylglutathione with neoadjuvant chemotherapy sensitivity in patients with gastric cancer: A metabolomics study

The present study screened serum samples from patients with advanced-stage gastric cancer and known sensitivities to neoadjuvant chemotherapy, in order to identify metabolites that may serve as potential biomarkers for chemotherapy sensitivity. A total of 47 patients with stage III (T4b) or IV gastric cancer, including 31 in the training group and 16 in a validation group, were classified based on their responses to conversion therapy consisting of oxaliplatin, tegafur and continuous hyperthermic peritoneal perfusion with cisplatin. Serum samples were analyzed by liquid chromatography-mass spectrometry to obtain a metabolite profile of each patient. Patients who were responsive and non-responsive to neoadjuvant chemotherapy exhibited significant differences in serum levels of deoxyribose 1-phosphate, S-lactoylglutathione, lysophosphatidylcholine (16:0) and O-arachidonoyl ethanolamine. Logistic regression analysis indicated that deoxyribose 1-phosphate and S-lactoylglutathione were independently associated with chemosensitivity. Serum levels of deoxyribose 1-phosphate and S-lactoylglutathione were independently associated with the sensitivity of gastric cancer to neoadjuvant chemotherapy, therefore, serving as potential predictors of patient response.

HER2, NF-κB, and SATB1 Expression Patterns in Gastric Cancer and Their Correlation with Clinical and Pathological Parameters

Gastric cancer (GC) is currently recognized as one of the most common and fatal tumor worldwide. The identification of novel biomarkers in relation to clinical information as well as extending the knowledge on a multiple crosstalk between various oncogenic pathways implicated in GC carcinogenesis seems pivotal to limit the disease-associated mortality. Therefore, we assessed the expression of HER2, NF-κB, and SATB1 in a total of 104 gastric adenocarcinomas and 30 normal gastric samples and correlated the expression patterns with each other and with some clinicopathological variables. Protein expression was examined by immunohistochemistry (IHC) on tissue microarrays (TMAs), and fluorescence in situ hybridization (FISH) was employed to detect HER2 amplification. In the studied group, HER2 and SATB1 were found to be overexpressed in gastric cancer tissue in comparison to normal gastric mucosa. The expression status of the former protein was seen to differ according to some clinicopathological features, but without statistical significance, whereas the expression of the latter was not importantly associated with any of them. In turn, the NF-κB protein level was significantly related to the presence of lymph node metastasis. HER2 expression was not significantly correlated with that of other proteins, but a positive correlation was found between the expression of SATB1 and NF-κB. Further studies with a larger group of patients combined with in vitro mechanistic experiments are required to fully elucidate the role and relationship of HER2, NF-κB, and SATB1 expression in gastric cancer progression. However, to the best of our knowledge, this study is the first look at a simultaneous evaluation of these three markers in the samples of gastric cancer patients.

Preclinical evaluation of exemestane as a novel chemotherapy for gastric cancer

CYP19A1/aromatase (Ar) is a prognostic biomarker of gastric cancer (GCa). Ar is a critical enzyme for converting androstenedione to oestradiol in the steroidogenesis cascade. For decades, Ar has been targeted with Ar inhibitors (ARIs) in gynaecologic malignancies; however, it is unexplored in GCa. A single‐cohort tissue microarray examination was conducted to study the association between Ar expression and disease outcome in Asian patients with GCa. The results revealed that Ar was a prognostic promoter. Bioinformatics analyses conducted on a Caucasian‐based cDNA microarray databank showed Ar to be positively associated with GCa prognosis for multiple clinical modalities, including surgery, 5‐Fluorouracil (5‐FU) for adjuvant chemotherapy, or HER2 positivity. These findings imply that targeting Ar expression exhibits a potential for fulfilling unmet medical needs. Hence, Ar‐targeting compounds were tested, and the results showed that exemestane exhibited superior cancer‐suppressing efficacy to other ARIs. In addition, exemestane down‐regulated Ar expression. Ablating Ar abundance with short hairpin (sh)Ar could also suppress GCa cell growth, and adding 5‐FU could facilitate this effect. Notably, adding oestradiol could not prevent exemestane or shAr effects, implicating a nonenzymatic mechanism of Ar in cancer growth. Regarding translational research, treatment with exemestane alone exhibited tumour suppression efficacy in a dose‐dependent manner. Combining subminimal doses of 5‐FU and exemestane exerted an excellent tumour suppression effect without influencing bodyweight. This study validated the therapeutic potentials of exemestane in GCa. Combination of metronomic 5‐FU and exemestane for GCa therapy is recommended.

TAS0728, A Covalent-binding, HER2-selective Kinase Inhibitor Shows Potent Antitumor Activity in Preclinical Models

Activated HER2 is a promising therapeutic target for various cancers. Although several reports have described HER2 inhibitors in development, no covalent-binding inhibitor selective for HER2 has been reported. Here, we report a novel compound TAS0728 that covalently binds to HER2 at C805 and selectively inhibits its kinase activity. Once TAS0728 bound to HER2 kinase, the inhibitory activity was not affected by a high ATP concentration. A kinome-wide biochemical panel and cellular assays established that TAS0728 possesses high specificity for HER2 over wild-type EGFR. Cellular pharmacodynamics assays using MCF10A cells engineered to express various mutated HER2 genes revealed that TAS0728 potently inhibited the phosphorylation of mutated HER2 and wild-type HER2. Furthermore, TAS0728 exhibited robust and sustained inhibition of the phosphorylation of HER2, HER3, and downstream effectors, thereby inducing apoptosis of HER2-amplified breast cancer cells and in tumor tissues of a xenograft model. TAS0728 induced tumor regression in mouse xenograft models bearing HER2 signal-dependent tumors and exhibited a survival benefit without any evident toxicity in a peritoneal dissemination mouse model bearing HER2-driven cancer cells. Taken together, our results demonstrated that TAS0728 may offer a promising therapeutic option with improved efficacy as compared with current HER2 inhibitors for HER2-activated cancers. Assessment of TAS0728 in ongoing clinical trials is awaited (NCT03410927).

Targeting HER2-positive gastric cancer with a novel 18F-labeled ZHER2:342 probe

To realize the diagnosis of HER2-positive gastric cancer via PET imaging, herein, a new kind of ¹⁸F-labeled HER2 affibody probe was created; the bifunctional maleimide derivative 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA-MAL) was first coupled to a polypeptide, and the resulting compound was subsequently labeled with the ¹⁸FAl complex. The binding characteristics of the probe were assessed using both in vitro studies and in vivo microPET imaging and biodistribution experiments. Immunohistochemical staining was performed to confirm the expression level of HER2 in the studied cell lines and tumors. The probe was successfully produced with the radiochemical purity of more than 95%. The NCI N87 cell-associated radioactivity was 19.31 ± 1.01% AD, and it decreased to 0.83 ± 0.04% AD per 10⁶ cells after blocking HER2 as early as 15 minutes post-incubation (p < 0.05). A competition binding assay between radiolabeled and non-radioactive affibody molecules with NCI N87 indicated that the IC₅₀ was 8.10 nM. The microPET imaging and biodistribution of human gastric cancer xenografts demonstrated that the probe could specifically accumulate in tumors at early time points. Protein detection confirmed a strong HER2 expression in NCIN87 and a weak HER2 expression in SGC7901. In conclusion, ¹⁸FAl-NOTA-MAL-Cys-GGGRDN(M⁰)-Z_HER2:342 was successfully prepared via a one-step method. The favorable preclinical data showed specific and effective tumor targeting capacity of the proposed probe; this revealed that the probe proposed herein might have potential application in gastric cancer imaging.

Tumor targeting of the novel ¹⁸F-labeled Z_HER2:342 probe in HER2-positive gastric cancer xenograft models.

Characterization of PI3KCA and BRAF mutations in gastric adenocarcinoma: An approach to a personalized targeted therapy for Moroccan HER2 overexpressed patients

BACKGROUND AND STUDY AIMS

Targeted therapies have an increasing importance in digestive oncology. To our knowledge, we are the first to report the distribution of PI3KCA and BRAF mutations in Moroccan HER2 overexpressed patients, in order to introduce targeted therapy in the arsenal of therapeutic modalities for management in Morocco.

PATIENTS AND METHODS

98 gastric adenocarcinoma tissue samples were collected. Further histological and immunohistochemical examinations were carried out at the Laboratory of Anatomy Pathology in Pasteur Institute-Morocco, in order to select HER2 positive cases. Out of 98 cases, 16 were found to be HER2-positive. The molecular study was performed for 55 good quality tissue samples including the HER2-positive ones, and activating mutations in H1047R PI3KCA and V600E BRAF were analyzed by Cast-PCR and Real-time PCR, respectively, at the Department of Molecular Biology, ANOUAL Specialized Center-Casablanca, Morocco. Statistical analyses were performed using the Epi-info software (version 6.09).

RESULTS

Pi3KCA mutation was present in 8 cases (14,54%). BRAF mutation was present in 4 cases (7,27%) and 3 cases showed concomitant mutations. In total, 9 cases (16,36%) had PI3KCA and/or BRAF mutations.

CONCLUSION

The association between HER2 expression and PI3KCA alteration in gastric adenocarcinoma is most probably necessary to identify trastuzumab responders. Consequently, the 83,64% rate of HER2-positive patients harboring wild-type mutations possibly represents the portion of patients responding to trastuzumab while the 16,36% rate of patients carrying at least one of the studied mutations represents the portion of potentially non responsive patients to the targeted therapy, and thus may be considered as good candidates for multi-drug targeted therapy.

New drug developments in metastatic gastric cancer

Metastatic gastric cancer is associated with a poor prognosis and novel treatment options are desperately needed. The development of targeted therapies heralded a new era for the management of metastatic gastric cancer, however results from clinical trials of numerous targeted agents have been mixed. The advent of immune checkpoint inhibitors has yielded similar promise and results from early trials are encouraging. This review provides an overview of the systemic treatment options evaluated in metastatic gastric cancer, with a focus on recent evidence from clinical trials for targeted therapies and immune checkpoint inhibitors. The failure to identify appropriate predictive biomarkers has hampered the success of many targeted therapies in gastric cancer, and a deeper understanding of specific molecular subtypes and genomic alterations may allow for more precision in the application of novel therapies. Identifying appropriate biomarkers for patient selection is essential for future clinical trials, for the most effective use of novel agents and in combination approaches to account for growing complexity of treatment options.

Methods and significance of the combined detection of HER2 gene amplification and chemosensitivity in gastric cancer

OBJECTIVE

This study aims to investigate the significance of combined detection of HER2 gene amplification and chemosensitivity in gastric cancer.

METHODS

Immunohistochemistry (IHC), fluorescence in situ hybridization (FISH) and fluorescence reverse-transcription polymerase chain reaction (RT-PCR) were used to analyze the expression of HER2 protein, HER2 gene amplification and the mRNA expression of ERCC1, TUBB3 and TYMS genes in 135 cases of gastric carcinoma.

RESULTS

The expression rate of HER2 protein was 39.3% (53/135). Among these positive cases, patients with HER2 protein (3+) accounted for 9.6% (13/135), patients with HER2 protein (2+) accounted for 13.3% (18/135), and patients with HER2 protein (1+) accounted for 16.3% (22/135). The amplification rate of the HER2 gene was 35.8% (19/53). In the detection of the mRNA expression of ERCC1, TUBB3 and TYMS, 45 patients had low and moderate single gene expression, 50 patients had low and moderate double gene expression, 22 patients had low and moderate mRNA expression for ERCC1, TUBB3 and TYMS, and 18 patients had no low and moderate expression. Among the 53 patients with HER2 protein expression and 22 patients with low and moderate mRNA expression of ERCC1, TUBB3 and TYMS, 12 patients received chemotherapy and trastuzumab. Follow-up results revealed that HER2 gene status was positively correlated with the therapeutic effect of the combined treatment in patients with low mRNA expression of ERCC1, TUBB3 and TYMS. Among these patients, five patients with extensive HER2 (3+), HER2 cluster-specific amplification, and low mRNA expression of ERCC1, TUBB3 and TYMS had a total survival of up to 19.1 months.

CONCLUSIONS

The detection of HER2 in gastric cancer is highly heterogeneity, and the combined detection of HER2 protein expression, HER2 gene amplification and chemosensitivity can provide important reference markers for the benefit of antitumor drugs.

Biomarkers of gastric cancer: Current topics and future perspective

Gastric cancer (GC) is one of the most prevalent malignant types in the world and an aggressive disease with a poor 5-year survival. This cancer is biologically and genetically heterogeneous with a poorly understood carcinogenesis at the molecular level. Although the incidence is declining, the outcome of patients with GC remains dismal. Thus, the detection at an early stage utilizing useful screening approaches, selection of an appropriate treatment plan, and effective monitoring is pivotal to reduce GC mortalities. Identification of biomarkers in a basis of clinical information and comprehensive genome analysis could improve diagnosis, prognosis, prediction of recurrence and treatment response. This review summarized the current status and approaches in GC biomarker, which could be potentially used for early diagnosis, accurate prediction of therapeutic approaches and discussed the future perspective based on the molecular classification and profiling.

Upregulation of bone morphogenetic protein 1 is associated with poor prognosis of late-stage gastric Cancer patients

Background

Gastric cancer is the eighth most common cancer in Taiwan, with a 40% 5-year survival rate. Approximately 40% of patients are refractory to chemotherapy. Currently, the anti-HER2 therapy is the only clinically employed targeted therapy. However, only 7% patients in Taiwan are HER2-positive. Identifying candidate target genes will facilitate the development of adjuvant targeted therapy to increase the efficacy of gastric cancer treatment.

Methods

Clinical specimens were analyzed by targeted RNA sequencing to assess the expression levels of target genes. Statistical significance of differential expression and correlation between specimens was evaluated. The correlation with patient survival was analyzed as well. In vitro cell mobility was determined using wound-healing and transwell mobility assays.

Results

Expression of BMP1, COL1A1, STAT3, SOX2, FOXA2, and GATA6 was progressively dysregulated through the stages of gastric oncogenesis. The expression profile of these six genes forms an ubiquitously biomarker signature that is sufficient to differentiate cancer from non-cancerous specimens. High expression status of BMP1 correlates with poor long-term survival of late-stage patients. In vitro, suppression of BMP1 inhibits the mobility of the gastric cancer cell lines, indicating a role of BMP1 in metastasis.

Conclusions

BMP1 is upregulated in gastric cancer and is correlated with poor patient survival. Suppression of BMP1 reduced gastric cancer mobility in vitro. Our finding suggests that anti-BMP1 therapy will likely augment the efficacy of standard chemotherapy and improve the treatment outcome.

Clinical significance of overexpression of NRG1 and its receptors, HER3 and HER4, in gastric cancer patients

BACKGROUND

Neuregulin 1 (NRG1), a ligand for human epidermal growth factor (HER) 3 and HER4, can activates cell signaling pathways to promote carcinogenesis and metastasis.

METHODS

To investigate the clinicopathologic significance of NRG1 and its receptors, immunohistochemistry was performed for NRG1, HER3, and HER4 in 502 consecutive gastric cancers (GCs). Furthermore, HER2, microsatellite instability (MSI), and Epstein-Barr virus (EBV) status were investigated. NRG1 gene copy number (GCN) was determined by dual-color fluorescence in situ hybridization (FISH) in 388 available GCs.

RESULTS

NRG1 overexpression was observed in 141 (28.1%) GCs and closely correlated with HER3 (P = 0.034) and HER4 (P < 0.001) expression. NRG1 overexpression was significantly associated with aggressive features, including infiltrative tumor growth, lymphovascular, and neural invasion, high pathologic stage, and poor prognosis (all P < 0.05), but not associated with EBV, MSI, or HER2 status. Multivariate analysis identified NRG1 overexpression as an independent prognostic factor for survival (P = 0.040). HER3 and HER4 expressions were observed in 157 (31.3%) and 277 (55.2%), respectively. In contrast to NRG1, expression of these proteins was not associated with survival. NRG1 GCN gain (GCN ≥ 2.5) was detected in 14.7% patients, including two cases of amplification, and was moderately correlated with NRG1 overexpression (κ, 0.459; P < 0.001).

CONCLUSIONS

Although our results indicate a lack of prognostic significance of HER3 and HER4 overexpression in GC, overexpression of their ligand, NRG1, was associated with aggressive clinical features and represented an independent unfavorable prognostic factor. Therefore, NRG1 is a potential prognostic and therapeutic biomarker in GC patients.

Prognostic implications of HER2 heterogeneity in gastric cancer

The prognostic implications of human epidermal growth receptor 2 (HER2) heterogeneity in gastric cancer (GC) are not well established. Therefore, the aim of the present study was to determine to the effect of HER2 status on the prognosis of GC patients. We retrieved data on 248 pathologically-confirmed, consecutive patients with primary adenocarcinoma of the stomach or gastro-esophageal junction who underwent surgical resection at Kurume University Medical Center between July 2000 and December 2012. HER2 status was classified as HER2 positive or negative and HER2 heterogeneity or homogeneity. The endpoint was overall survival (OS), which was compared using the generalized Wilcoxon test. HER2 status was positive in 36 patients (14.5%) and negative in 212 patients (85.5%). Among the 36 HER2 positive patients, 25 patients (69.4%) had HER2 heterogeneity and the remaining 11 patients (30.6%) had HER2 homogeneity. Among the 141 patients with stage III or IV disease, the prognosis of the HER2 homogeneity group was significantly worse than that of the HER2 heterogeneity group (p = 0.019; median OS 193 and 831 days, respectively). The prognosis was not significantly different between the HER2 positive group and the HER2 negative group (p = 0.84; median OS 552 and 556 days, respectively). The present study was conducted with small samples, however, the results of the study suggest that HER2 homogeneity but not HER2 positivity may represent a prognostic indicator in GC.

Gastric adenocarcinoma expressing human epidermal growth factor receptor in South Asian population

BACKGROUND/AIM

Gastric cancer is the third leading cause of cancer mortality worldwide. Human epidermal growth factor (Her-2/neu) has shown strong therapeutic implication in breast cancer. Although the prevalence of Her-2/neu over-expression in gastric cancer has been reported across the world, it is still unknown from South Asia. The aim of this study is to evaluate Her-2/neu expression in gastric adenocarcinomas and to correlate with various clinicopathological variables.

PATIENTS AND METHODS

A total of 95 consecutive patients undergoing endoscopic biopsy or gastrectomy were recruited in this study. Clinicopathological parameters of all patients were recorded and hematoxylin and eosin (H and E) staining was performed. Over-expression of Her-2/neu was investigated by immunohistochemistry using α-Her-2 antibody. To quantify Her-2/neu over-expression, the Hofmann validation scoring system was used and further its association was seen with age, gender, histopathological type, grade, and stage of the tumor. Data were entered and analyzed using SPSS version 21. A P value of <0.05 was considered as significant.

RESULTS

Overall, 21 (22.1%) cases were positive for Her-2/neu overexpression from the total of 95 gastric adenocarcinomas. Her-2/neu was significantly expressed in low-grade gastric cancer (grade I = 50%, grade II = 34.5%, grade III = 14.5%; P = 0.030). Although there was insignificant difference between Her-2/neu over expression and other variables, Her-2/neu score 3+ was predominantly seen in females, age >60 years, Laurens intestinal type, and IIIC stage tumors.

CONCLUSION

Her-2/neu is over-expressed in a limited group of gastric cancer patients in our population and indicates a significant strong association with low grades of gastric cancer.

Antiangiogenic Therapy in Gastroesophageal Cancer

Antiangiogenesis therapy is one of only 2 biologically targeted approaches shown to improve overall survival over standard of care in advanced adenocarcinoma of the stomach or gastroesophageal junction (GEJ). Therapeutic targeting of vascular endothelial growth factor receptor 2 improves overall survival in patients with previously treated advanced gastric/GEJ adenocarcinoma. No antiangiogenesis therapy has demonstrated an overall survival benefit in patients with chemo-naïve or resectable esophagogastric cancer or in patients whose tumors arise from the esophagus. Promising ongoing clinical investigations include the combination of antiangiogenesis therapy with immune checkpoint inhibition and anti-human epidermal growth factor receptor 2 therapy.

Gastric cancer related genes

Gastric cancer is one of the most common malignant tumors. In addition to environmental, socioeconomic, and dietary factors, hereditary factors also play an important role in the development of gastric cancer. Although some driver genes have been identified in gastric cancer, the molecular compositions of gastric cancer have not been fully understood. Genome-wide association studies, copy number variations and next-generation sequencing provide systematic methods to identify all genetic alterations in the cancer genome, especially in the field of mutation detection. Here we make a brief review of the current status of research on gastric cancer genetics.

The genomics and therapeutics of HER2-positive gastric cancer-from trastuzumab and beyond

Gastric cancer is a biologically heterogeneous tumor. The identification of human epidermal growth factor receptor-2 (HER2) biomarker overexpression in gastric cancer represented a significant step towards unraveling the molecular complexity of this disease. Trastuzumab in combination with chemotherapy, in the first-line setting of patients with metastatic, HER2-positive gastric and gastroesophageal, represents the first targeted therapeutic to demonstrate improvement in response rate and survival in gastric cancer. However, not all patients with HER2-positive gastric cancer respond to trastuzumab and the majority of patients who do initially benefit from trastuzumab develop resistance to it. Advances in molecular oncology and cancer genomics have helped to classify gastric cancer into molecularly distinct subtypes. This information informs research efforts investigating the etiology of mechanisms of resistance to HER2-directed therapy and guides clinical investigation in methods to overcome this resistance. This article reviews anti-HER2-therapies that are currently used as standard of care in advanced, HER2-positive, breast cancer and are now under investigation as monotherapy and in combination with chemotherapy and/or a second HER2-directed agent in advanced HER2-positive gastric cancer. The future directions of clinical investigation in HER2-positive gastric cancer are also discussed including: novel HER2-directed therapies, the pharmacokinetics and pharmacodynamics of anti-HER2-therapies, the role of functional imaging, the potential of patient derived xenograft preclinical models and the importance of tumor genomic sequencing.

A bispecific anti-ErbB2 antibody potently induces ErbB2 internalization and suppresses ErbB2-overexpressing tumor growth

The anti-ErbB2 humanized antibody trastuzumab was approved for ErbB2-positive metastatic gastric and gastro-esophageal junction cancer in 2010. Despite the effectiveness of trastuzumab, its efficacy remains variable and often modest. Thus, there is an urgent need to improve ErbB2-targeting therapy. Down-regulation of surface receptors induced by monoclonal antibody (mAb) contributes to its antitumor efficacy. Previous studies have demonstrated that if two anti-ErbB2 mAbs did not compete with each other for binding to ErbB2, the combination of them can enhance ErbB2 internalization. In the present study, we investigated ErbB2 internalization-inducing ability of non-competitive anti-ErbB2 mAb combinations and surprisingly found that most of the mAb combinations tested did not down-regulate ErbB2. Only 4 of 18 non-competitive mAb pairs efficiently induced ErbB2 internalization. Interestingly, although the non-competitive anti-ErbB2 mAbs trastuzumab and pertuzumab, either alone or in combination, were ineffective at inducing ErbB2 internalization, TPL, a bispecific antibody engineered from trastuzumab and pertuzumab, potently down-regulated the ErbB2 molecule. Importantly, TPL exhibited a far greater antitumor effect on ErbB2-overexpressing gastric cancer cell line than trastuzumab plus pertuzumab, suggesting that it may be a promising agent for the treatment of gastric cancer.

HER2 testing in gastric cancer: An update

Human epidermal growth factor receptor 2 (HER2) overexpression is increasingly recognized as a frequent molecular abnormality in gastric and gastroesophageal cancer. With the recent introduction of HER2 molecular targeted therapy for patients with advanced gastric cancer, determination of HER2 status is crucial in order to select patients who may benefit from this treatment. This paper provides an update on our knowledge of HER2 in gastric and gastroesophageal cancer, including the prognostic relevance of HER2, the key differences between HER2 protein expression interpretation in breast and gastric cancer, the detection methods and the immunohistochemistry scoring system.

From standard to new genome-based therapy of gastric cancer

Randomized trials and meta-analyses have established surgery, radiotherapy, chemotherapy and targeted therapy in the multidisciplinary treatment of gastric cancer. However, personalized prediction of both therapeutic resistance and recurrence or metastatic disease progression still remains a researcher's dream. In this editorial, we summarize standard treatment approaches as well as their limitations, with an effort to highlight novel, next-generation sequencing technology-based clinical approaches for gastric cancer treatment.

Significance of combined detection of HER2 gene amplification and markers of chemosensitivity in gastric cancer

AIM: To investigate the significance of combined detection of HER2 gene amplification and markers of chemosensitivity in gastric cancer.

METHODS: Immunohistochemistry (IHC), fluorescence in situ hybridization (FISH) and fluorescence RT-PCR were used to detect HER2 protein expression in 120 cases of gastric cancer, HER2 gene amplification, and ERCC1, TUBB3, and TYMS mRNA expression, respectively.

RESULTS: The positive rate of HER2 expression was 40.8% (49/120), and the rates of strong positivity (+++), moderate positivity (++), and weak positivity (+) were 10.8% (13/120), 14.2% (17/120), and 15.8% (19/120), respectively. The rate of HER2 gene amplification was 38.8% (19/49). With regards to ERCC1, TUBB3, and TYMS mRNA expression, 41 cases showed moderate or low expression of only one gene, 45 cases showed moderate or low expression of two genes, 19 cases showed moderate or low expression of three genes, and 15 cases showed no moderate or low expression of the genes. Of 19 cases showing moderate or low expression of the three genes, 11 cases received chemotherapy combined with trastuzumab treatment. Follow-up results showed that HER2 gene status and ERCC1, TUBB3, and TYMS gene expression were positively related to treatment response. In 5 cases with strong HER2 expression, HER2 gene amplification, and low expression of ERCC1, TUBB3, and TYMS, overall survival was 19.1 mo.

CONCLUSION: HER2 testing in gastric cancer has great heterogeneity, and simultaneous detection of HER2 protein expression, HER2 gene amplification and markers of chemosensitivity provides an important reference index for antitumor drug therapy.

Individualized molecular targeted therapy for gastric cancer based on human epidermal growth factor receptor 2 gene detection

Compared with traditional chemotherapy drugs, molecular targeted drugs have the advantages of high specificity and fewer side effects. Human epidermal growth factor receptor 2 (HER2) has been a focus of research in recent years, although the relationship between HER2 and prognosis of gastric cancer remains controversial. With the advent of trastuzumab, lapatinib, pertuzumab and other anti-HER2 drugs, many clinical studies have achieved good results; however, there are still some patients with unsatisfactory results due to the occurrence of drug resistance. Finding solutions to overcome drug resistance can increase the efficacy, and individualized molecular targeted therapy can better benefit gastric cancer patients.

Engineering hybrid exosomes by membrane fusion with liposomes

Exosomes are a valuable biomaterial for the development of novel nanocarriers as functionally advanced drug delivery systems. To control and modify the performance of exosomal nanocarriers, we developed hybrid exosomes by fusing their membranes with liposomes using the freeze–thaw method. Exosomes embedded with a specific membrane protein isolated from genetically modified cells were fused with various liposomes, confirming that membrane engineering methods can be combined with genetic modification techniques. Cellular uptake studies performed using the hybrid exosomes revealed that the interactions between the developed exosomes and cells could be modified by changing the lipid composition or the properties of the exogenous lipids. These results suggest that the membrane-engineering approach reported here offers a new strategy for developing rationally designed exosomes as hybrid nanocarriers for use in advanced drug delivery systems.

Embryonic Lethality in Homozygous Human Her-2 Transgenic Mice Due to Disruption of the Pds5b Gene

The development of antigen-targeted therapeutics is dependent on the preferential expression of tumor-associated antigens (TAA) at targetable levels on the tumor. Tumor-associated antigens can be generated de novo or can arise from altered expression of normal basal proteins, such as the up-regulation of human epidermal growth factor receptor 2 (Her2/ErbB2). To properly assess the development of Her2 therapeutics in an immune tolerant model, we previously generated a transgenic mouse model in which expression of the human Her2 protein was present in both the brain and mammary tissue. This mouse model has facilitated the development of Her2 targeted therapies in a clinically relevant and suitable model. While heterozygous Her2^+/- mice appear to develop in a similar manner to wild type mice (Her2^-/-), it has proven difficult to generate homozygous Her2^+/+ mice, potentially due to embryonic lethality. In this study, we performed whole genome sequencing to determine if the integration site of the Her2 transgene was responsible for this lethality. Indeed, we report that the Her2 transgene had integrated into the Pds5b (precocious dissociation of sisters) gene on chromosome 5, as a 162 copy concatemer. Furthermore, our findings demonstrate that Her2^+/+ mice, similar to Pds5b^-/- mice, are embryonic lethal and confirm the necessity for Pds5b in embryonic development. This study confirms the value of whole genome sequencing in determining the integration site of transgenes to gain insight into associated phenotypes.

Gastric cancer and gene copy number variation: emerging cancer drivers for targeted therapy

Gastric cancer (GC) is among the most common malignancy in the world with poor prognosis and limited treatment options. It has been established that gastric carcinogenesis is caused by a complex interaction between host and environmental factors. Copy number variation (CNV) refers to a form of genomic structural variation that results in abnormal gene copy numbers, including gene amplification, gain, loss and deletion. DNA CNV is an important influential factor for the expression of both protein-coding and non-coding genes, affecting the activity of various signaling pathways. CNV arises as a result of preferential selection that favors cancer development, and thus, targeting the amplified 'driver genes' in GC may provide novel opportunities for personalized therapy. The detection of CNVs in chromosomal or mitochondrial DNA from tissue or blood samples may assist the diagnosis, prognosis and targeted therapy of GC. In this review, we discuss the recent CNV discoveries that shed light on the molecular pathogenesis of GC, with a specific emphasis on CNVs that display diagnostic, prognostic or therapeutic significances in GC.