Successful control of heavily pretreated metastatic gastric cancer with the mTOR inhibitor everolimus (RAD001) in a patient with PIK3CA mutation and pS6 overexpression

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.

The PI3K/Akt/mTOR signaling pathway in gastric cancer; from oncogenic variations to the possibilities for pharmacologic interventions

Genetic and epigenetic alterations have been under concentrated investigations for many years in order to unearth the molecules regulating human cancer pathogenesis. However, the identification of a wide range of dysregulated genes and their protein products has raised a question regarding how the results of this large collection of alterations could converge into a formation of one malignancy. The answer may be found in the signaling cascades that regulate the survival and metabolism of the cells. Aberrancies of each participant molecule of such cascades may well result in augmented viability and unlimited proliferation of cancer cells. Among various signaling pathways, the phosphatidylinositol-3-kinase (PI3K) axis has been shown to be activated in about one-third of human cancers. One of the malignancies that is mostly affected by this axis is gastric cancer (GC), one of the most fatal cancers worldwide. In the present review, we aimed to illustrate the significance of the PI3K/Akt/mTOR axis in the pathogenesis of GC and also provided a wide perspective about the application of the inhibitors of this axis in the therapeutic strategies of this malignancy.

Identification of specific modules and hub genes associated with the progression of gastric cancer

Gastric cancer (GC) has high morbidity and mortality rates worldwide. Abundant literature has reported several individual genes and their related pathways intimately involved in tumor progression. However, little is known about GC progression at the gene network level. Therefore, understanding the underlying mechanisms of pathological transition from early stage to late stage is urgently needed. This study aims to identify potential vital genes and modules involved in the progression of GC. To understand the gene regulatory network of GC progression, we analyzed micro RNAs and messenger RNA s expression profiles by using a couple of bioinformatics tools. miR-205 was identified by differentially expressed analysis and was further confirmed through using multiple kernel learning-based Kronecker regularized least squares. Using weighted gene co-expression network analysis, the gastric cancer progression-related module, which has the highest correlation value with cancer progression, was obtained. Kyoto Encyclopedia of Genes and Genomes pathways and biological processes of the GCPR module genes were related to cell adhesion. Meanwhile, large-scale genes of GCPR module were found to be targeted by miR-205, including two hub genes SORBS1 and LPAR1. In brief, through multiple analytical methods, we found that miR-205 and the GCPR module play critical roles in GC progression. In addition, miR-205 might maintain cell adhesion by regulating SORBS1 and LPAR1. To screen the potential drug candidates, the gene expression profile of the GCPR module was mapped connectivity map (Cmap), and the mTOR inhibitor (Sirolimus) was found to be the most promising candidate. We further confirmed that Sirolimus can suppress cell proliferation of GC cell in vitro.

Collecting ducts carcinoma: An orphan disease. Literature overview and future perspectives

Collecting ducts carcinoma (CDC) is a rare and aggressive histological subtype of renal cancer accounting for only 1% of renal tumors. Usually patients present in bad clinical conditions due to a symptomatic disease with synchronous metastasis. Due to the rarity of CDC, data from prospective trials evaluating the best treatment for these patients are limited. The prognosis is poor with a median overall survival of around 11 months for patients with metastatic disease. The best treatment option today is considered a doublet chemotherapy with platinum salt plus gemcitabine as a result from a prospective phase II trial, but survival outcomes remain unsatisfactory. The interest in the in-depth understanding the biology of this orphan disease is growing, leading to find potential new biological-driven treatment approaches. Here we review the up-to-date literature evidences to address the best management of this rare and unfavorable clinical condition.

mTOR: Role in cancer, metastasis and drug resistance

Mammalian target of rapamycin (mTOR) is a serine/threonine kinase that gets inputs from the amino acids, nutrients, growth factor, and environmental cues to regulate varieties of fundamental cellular processes which include protein synthesis, growth, metabolism, aging, regeneration, autophagy, etc. The mTOR is frequently deregulated in human cancer and activating somatic mutations of mTOR were recently identified in several types of human cancer and hence mTOR is therapeutically targeted. mTOR inhibitors were commonly used as immunosuppressors and currently, it is approved for the treatment of human malignancies. This review briefly focuses on the structure and biological functions of mTOR. It extensively discusses the genetic deregulation of mTOR including amplifications and somatic mutations, mTOR-mediated cell growth promoting signaling, therapeutic targeting of mTOR and the mechanisms of resistance, the role of mTOR in precision medicine and other recent advances in further understanding the role of mTOR in cancer.

Everolimus-containing therapy vs conventional therapy in the treatment of refractory breast cancer patients with PI3K/AKT/mTOR mutations: A retrospective study

Background

Previous case reports have shown the promising antitumor activity of everolimus in solid tumors containing molecular aberrations in PI3K/ATK/mTOR pathway, however, whether it is effective in patients with breast cancer remains unknown. Therefore, we conducted this retrospective cohort study to compare the efficacy of molecularly matched targeted therapy with everolimus to conventional therapy in refractory breast cancer patients harboring PI3K/ATK/mTOR pathway activating mutations.

Methods

Refractory metastatic breast cancer patients who have received molecular screening using next‐generation sequencing (NGS) between September 8, 2015 and October 30, 2017 in two sites were screened for this study. The primary outcome was progression‐free survival (PFS). The secondary outcomes were overall response rate (ORR), disease control rate (DCR), and safety profile.

Results

A total of 78 patients were screened for analysis, amongst all, 52 (66.7%) had at least one gene mutation in PI3K/AKT/mTOR pathway. The most common mutation fell in PIK3CA (76.9%, 40/52) with a mutational prevalence of 51.3%. Of the 32 patients who were eligible for efficacy analysis, patients in the everolimus group (n = 19) exhibited shorter PFS than those in the conventional group (n = 13) (median, 1.9 vs 6.1 months; HR, 3.6; 95% CI, 1.48‐8.81; P = .0005). ORR was 15.4% (2/13) in the everolimus group and 23.1% (3/13) in the conventional group (P = 1.000), and DCR was 30.8% (4/13) and 100% (13/13) for each group, respectively (P = .000). The incidence of grade 3‐5 adverse events was relatively higher in the conventional group (38.5%, 5/13) than that in the everolimus group (26.3%, 5/19).

Conclusions

Our findings suggested that everolimus might not be effective for cancer patients harboring mutations in PI3K/ATK/mTOR pathway and physicians should be cautious about its off‐label use in clinical practice.

Development of Personalized Therapeutic Strategies by Targeting Actionable Vulnerabilities in Metastatic and Chemotherapy-Resistant Breast Cancer PDXs

Human breast cancer is characterized by a high degree of inter-patients heterogeneity in terms of histology, genomic alterations, gene expression patterns, and metastatic behavior, which deeply influences individual prognosis and treatment response. The main cause of mortality in breast cancer is the therapy-resistant metastatic disease, which sets the priority for novel treatment strategies for these patients. In the present study, we demonstrate that Patient Derived Xenografts (PDXs) that were obtained from metastatic and therapy-resistant breast cancer samples recapitulate the wide spectrum of the disease in terms of histologic subtypes and mutational profiles, as evaluated by whole exome sequencing. We have integrated genomic and transcriptomic data to identify oncogenic and actionable pathways in each PDX. By taking advantage of primary short-term in vitro cultures from PDX tumors, we showed their resistance to standard chemotherapy (Paclitaxel), as seen in the patients. Moreover, we selected targeting drugs and analyzed PDX sensitivity to single agents or to combination of targeted and standard therapy on the basis of PDX-specific genomic or transcriptomic alterations. Our data demonstrate that PDXs represent a suitable model to test new targeting drugs or drug combinations and to prioritize personalized therapeutic regimens for pre-clinal and clinical tests.

A subset of diffuse-type gastric cancer is susceptible to mTOR inhibitors and checkpoint inhibitors

Background

Mechanistic target of rapamycin (mTOR) pathway is essential for the growth of gastric cancer (GC), but mTOR inhibitor everolimus was not effective for the treatment of GCs. The Cancer Genome Atlas (TCGA) researchers reported that most diffuse-type GCs were genomically stable (GS). Pathological analysis suggested that some diffuse-type GCs developed from intestinal-type GCs.

Methods

We established patient-derived xenograft (PDX) lines from diffuse-type GCs, and searched for drugs that suppressed their growth. Diffuse-type GCs were classified into subtypes by their gene expression profiles.

Results

mTOR inhibitor temsirolimus strongly suppressed the growth of PDX-derived diffuse-type GC-initiating cells, which was regulated via Wnt-mTOR axis. These cells were microsatellite unstable (MSI) or chromosomally unstable (CIN), inconsistent with TCGA report. Diffuse-type GCs in TCGA cohort could be classified into two clusters, and GS subtype was major in cluster I while CIN and MSI subtypes were predominant in cluster II where PDX-derived diffuse-type GC cells were included. We estimated that about 9 and 55% of the diffuse-type GCs in cluster II were responders to mTOR inhibitors and checkpoint inhibitors, respectively, by identifying PIK3CA mutations and MSI condition in TCGA cohort. These ratios were far greater than those of diffuse-type GCs in cluster I or intestinal-type GCs. Further analysis suggested that diffuse-type GCs in cluster II developed from intestinal-type GCs while those in cluster I from normal gastric epithelial cells.

Conclusion

mTOR inhibitors and checkpoint inhibitors might be useful for the treatment of a subset of diffuse-type GCs which may develop from intestinal-type GCs.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1121-3) contains supplementary material, which is available to authorized users.

Expression and significance of EBV, ARID1A and PIK3CA in gastric carcinoma

AT-rich interaction domain 1A (ARID1A) and phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit α (PIK3CA) serve important roles in the formation and development of numerous malignancies including gastric cancer. Accumulating evidence has demonstrated that Epstein-Barr virus (EBV) is a pathogenic virus associated with gastric cancer. The present study aimed to investigate the association between EBV infection, and the expression levels of ARID1A and PIK3CA in gastric cancer. EBER in situ hybridization was performed to detect EBV infection. Immunohistochemistry was used to assess the expression levels of ARID1A and PIK3CA in gastric cancer and adjacent normal tissues. A total of 58 gastric cancer and 10 adjacent normal tissues were tested for genetic mutations via single nucleotide polymorphism genotyping assays. Fluorescent polymerase chain reaction was used to detect EBV infection; 9.3% (28/300) of gastric cancer samples were positive for EBV, whereas, all adjacent normal tissues were negative. ARID1A and PIK3CA were negatively correlated in gastric cancer (r=−0.167). The expression levels of ARID1A and PIK3CA in gastric cancer were significantly associated with the depth of invasion of gastric cancer. A total of 62.1% (36/58) of tumor samples exhibited mutations in ARID1A, whereas, 13.8% (8/58) presented mutations in PIK3CA. Notably, EBV-associated gastric cancer (EBVaGC) samples with PIK3CA mutations additionally exhibited ARID1A mutations. Although in the present study it was identified that ARID1A and PIK3CA were negatively correlated in EBVaGC, further studies are required to investigate the association among ARID1A, PIK3CA and EBV in gastric cancer.

PIK3CA mutations are associated with increased tumor aggressiveness and Akt activation in gastric cancer

PIK3CA mutations are frequent in gastric cancer. However, their pathological and clinical implications are still unclear. We analyzed the clinicopathological characteristics according to the PIK3CA mutation status of patients with stage IB–IV disease who underwent gastrectomy between May 2003 and Dec. 2005 (cohort 1; n = 302) and of those with stage IV disease who received gastrectomy between Jul. 2006 and Dec. 2012 (cohort 2; n = 120). PIK3CA mutations were detected in 40 patients (13.2%) in cohort 1. In these patients, PIK3CA-mutant tumors were more frequently located in the upper third of the stomach (p = 0.021) and significantly showed poorly differentiated histology (p = 0.018) and increased lymphatic (p = 0.015), vascular (p = 0.005), and perineural invasion (p = 0.026). In addition, these tumors showed significantly increased lymphocyte and neutrophil infiltration in cancer stroma (p < 0.001), Epstein–Barr virus positivity (p < 0.001), and microsatellite instability (p = 0.015). Cytoplasmic Akt expression was significantly increased in these tumors (p = 0.001). In cohort 2, PIK3CA mutations were identified in 15 patients (12.5%). PIK3CA-mutant tumors showed significantly increased vascular invasion (p = 0.019) and microsatellite instability (p = 0.041). In addition, cytoplasmic Akt expression was also significantly increased (p = 0.018). However, in both cohorts, PIK3CA mutations were not associated with the prognosis of patients. In conclusion, PIK3CA mutations were associated with increased tumor aggressiveness, especially in locoregional disease, and Akt activation in gastric cancer. Our data suggest that PIK3CA-mutated gastric cancer is a distinct disease entity, which might need a different therapeutic approach.

Benefit of everolimus in treatment of an intrahepatic cholangiocarcinoma patient with a PIK3CA mutation

Intrahepatic cholangiocarcinoma (ICC) is a relatively rare form of liver cancer with a poor prognosis. The therapeutic options for patients with advanced ICC are limited and usually ineffective. There is currently no approved targeted therapy for ICC, although accumulating evidence supports inhibition of the PI3K/Akt/mTOR signaling pathway as a promising therapeutic strategy in the treatment of ICC. Here, we report a patient with stage IV ICC harboring a PIK3CA mutation who responded well to the mTOR inhibitor everolimus. Computed tomography and magnetic resonance imaging demonstrated shrinkage of the tumor and maintenance of a partial response for 6.5 mo after everolimus treatment as the best response. To the best of our knowledge, this is the first clinical case report in the literature of clinical benefit from everolimus treatment in an ICC patient with PIK3CA mutation.

Pilot study of sirolimus in patients with PIK3CA mutant/amplified refractory solid cancer

In patients with refractory cancer, the effect of additional chemotherapy is very limited. Targeted agents for molecular pathways associated with cancer cell progression and survival have emerged as attractive options in several cancer types. The current pilot study assessed the efficacy and safety of sirolimus in patients with refractory cancer with PIK3CA mutation/amplification. Refractory cancer patients with PIK3CA mutation/amplification were enrolled, irrespective of tumor-types. Enrolled patients received a daily dose of 1 mg sirolimus and one cycle defined as 28 days. An assessment of the efficacy and safety of sirolimus was performed. Overall, 4 patients were enrolled between October 2014 and April 2015. The median of 2.5 cycles of sirolimus was administered. Three patients had advanced gastric cancer and one had advanced cholangiocarcinoma. The overall response rate was 0%, three patients (75%) had stable disease following one cycle and one patient (25%) received sirolimus for 4 cycles without disease progression. The median progression free survival was 1.9 months [95% confidence interval (CI), 0.3–3.5 months], and the median overall survival was 3.6 months (95% CI, 0.4–6.8 months). Grade 3 or greater hematologic/non-hematologic toxicity was not observed. Grade 1 nausea was reported in one patient each. There were no treatment-associated mortalities. Sirolimus had modest efficacy and a tolerable toxicity-profile in patients with refractory cancer with PIK3CA mutation/amplification.

Phosphorylation by mTORC1 stablizes Skp2 and regulates its oncogenic function in gastric cancer

Background

Both mTOR and Skp2 play critical roles in gastric cancer (GC) tumorigenesis. However, potential mechanisms for the association between these two proteins remains unidentified.

Methods

The regulatory role for mTORC1 in Skp2 stability was tested using ubiquitination assay. The functions of p-Skp2 (phosphorylation of Skp2) were studied in vitro and in vivo. Expression of p-Skp2 and p-mTOR (phosphorylation of mTOR) were shown in GC lines and in 169 human primary GC tissues.

Results

mTORC1 can directly interact with Skp2 and phosphorylated Skp2 at Ser64, which sequentially protect Skp2 from ubiquitination and degradation. Furthermore, the phospho-deficient p-Skp2 (S64) mutant significantly suppresses GC cell proliferation and tumorigenesis. The expression of p-Skp2 was associated with p-mTOR in GC cell lines and tissues. Interestingly, the combination of p-Skp2 and p-mTOR was a better predictor of survival than either factor alone.

Conclusion

The mTORC1 function to regulate Skp2 by Ser64 phosphorylation may represent an oncogenic event in GC tumorigenesis. Moreover, our study also indicates that Skp2 Ser64 expression is a potential indicator in the treatment of GC patients using mTORC1 inhibitor.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-017-0649-0) contains supplementary material, which is available to authorized users.

Progression inference for somatic mutations in cancer

Computational methods were employed to determine progression inference of genomic alterations in commonly occurring cancers. Using cross-sectional TCGA data, we computed evolutionary trajectories involving selectivity relationships among pairs of gene-specific genomic alterations such as somatic mutations, deletions, amplifications, downregulation, and upregulation among the top 20 driver genes associated with each cancer. Results indicate that the majority of hierarchies involved TP53, PIK3CA, ERBB2, APC, KRAS, EGFR, IDH1, VHL, etc. Research into the order and accumulation of genomic alterations among cancer driver genes will ever-increase as the costs of nextgen sequencing subside, and personalized/precision medicine incorporates whole-genome scans into the diagnosis and treatment of cancer.

Prospective phase II trial of everolimus in PIK3CA amplification/mutation and/or PTEN loss patients with advanced solid tumors refractory to standard therapy

Background

We designed a single-arm, open-label phase II trial of everolimus in PIK3CA amplification/mutation and/or PTEN loss patients with advanced solid tumors refractory to standard therapy (#NCT02449538).

Methods

Everolimus was administered orally at a daily dose of 10 mg continuously (28-day cycles). Treatment was continued until progression of the disease or intolerable toxicity was observed. Based on Simon’s two-stage optimal design, 10 patients were treated with everolimus during the first stage.

Results

The median age of the patients was 55.5 years (range, 42–72), and the median Eastern Cooperative Oncology Group (ECOG) performance status (PS) was 2 (range, 1–2). Most of the patients (50.0%) had gastric cancer (GC) as the site of their primary tumor followed by colorectal cancer (CRC), pancreatic cancer, and cholangiocarcinoma. Patients received everolimus as a third-line (3 patients), fourth-line (4 patients), fifth-line (1 patient) or sixth-line (2 patients) treatment. Complete or partial responses were not observed in any of the patients. Four patients showed stable disease, resulting in a disease control rate of 40%. The median PFS was 1.6 months (95% CI, 0.8–2.4 months). Grade 3 or greater hematologic/non-hematologic toxicity was not observed. Grade 2 diarrhea and stomatitis were reported in one patient each. There were no treatment-related deaths. There was less than one response out of the 10 initial patients during the first stage, and the study did not progress to the second stage.

Conclusions

The study did not meet its primary objective of demonstrating the anti-tumor activity of everolimus in PIK3CA amplification/mutation and/or PTEN loss patients with advanced solid tumors refractory to standard therapy. Further investigation using other genomic candidates and new-generation mTOR inhibitors is warranted in patients with treatment-refractory cancer.

Trial registration

#NCT02449538, April 2015.

Targeting the Phosphatidylinositol-3-kinase Pathway in Gastric Cancer: Can Omics Improve Outcomes?

Phosphatidylinositol-3-kinase (PI3K) pathway signaling is an established oncogenic signal transduction pathway implicated in multiple malignancies. Therapeutic targeting of PI3K pathway components has improved outcomes in chronic lymphocytic leukemia, kidney cancer, breast cancer, and neuroendocrine tumors. Gastric cancers harbor some of the highest rates of oncogenic alterations in PI3K but attempts to translate this genomic observation have met with limited clinical success and novel approaches are needed. In the following review we discuss PI3K signaling, previous preclinical and clinical investigations in gastric cancer, and discuss future strategies aimed at overcoming resistance and improving efficacy. Identification and refinement of molecular tumor subtypes, development of predictive biomarkers along, and rational drug combination strategies are key to capitalizing on the therapeutic potential of PI3K pathway directed therapies in gastric cancers.

mTOR activity and its prognostic significance in human colorectal carcinoma depending on C1 and C2 complex-related protein expression

AIMS

Tumour heterogeneity and altered activation of signalling pathways play important roles in therapy resistance. The PI3K/Akt/mTOR signalling network is a well-known regulator of several functions that contribute to tumour growth. mTOR exists in two functionally different multiprotein complexes. We aimed to determine mTOR activity-related proteins in clinically followed, conventionally treated colon carcinomas and to analyse the correlation between clinical data and mTORC1 and mTORC2 activity.

METHODS

Immunohistochemistry was performed with different antibodies on tissue microarray blocks from 103 patients with human colorectal adenocarcinoma. mTORC1- and mTORC2-related activity were scored on different stainings including analysis of the expression of Raptor and Rictor-specific elements of mTORC1 and C2 complexes. The staining scores and clinical/survival data were compared and analysed.

RESULTS

Detailed characterisation showed stage and grade independent high mTOR activity in 74% of cases. High mTOR activity was present in mTORC1 and/or mTORC2 complexes; >60% of cases had mTORC2-related high mTOR activity. Based on our analysis, high mTOR activity and Rictor overexpression could be markers of a bad prognosis. Combined phosphoprotein and Rictor/Raptor expression evaluation revealed even stronger statistical correlation with prognosis.

CONCLUSIONS

The presented staining panel could be appropriate and highly recommended for the accurate specification of mTORC1 and C2 activity of tumour tissues. This could help in the selection of mTOR inhibitors and can provide information about prognosis, which may guide decisions about the intensity of therapy.

Molecular classification of gastric cancer: Towards a pathway-driven targeted therapy

Gastric cancer (GC) is the third leading cause of cancer mortality worldwide. Although surgical resection is a potentially curative approach for localized cases of GC, most cases of GC are diagnosed in an advanced, non-curable stage and the response to traditional chemotherapy is limited. Fortunately, recent advances in our understanding of the molecular mechanisms that mediate GC hold great promise for the development of more effective treatment strategies. In this review, an overview of the morphological classification, current treatment approaches, and molecular alterations that have been characterized for GC are provided. In particular, the most recent molecular classification of GC and alterations identified in relevant signaling pathways, including ErbB, VEGF, PI3K/AKT/mTOR, and HGF/MET signaling pathways, are described, as well as inhibitors of these pathways. An overview of the completed and active clinical trials related to these signaling pathways are also summarized. Finally, insights regarding emerging stem cell pathways are described, and may provide additional novel markers for the development of therapeutic agents against GC. The development of more effective agents and the identification of biomarkers that can be used for the diagnosis, prognosis, and individualized therapy for GC patients, have the potential to improve the efficacy, safety, and cost-effectiveness for GC treatments.

Exploring the role of molecular biomarkers as a potential weapon against gastric cancer: A review of the literature

Gastric cancer (GC) is a global health problem and a major cause of cancer-related death with high recurrence rates ranging from 25% to 40% for GC patients staging II-IV. Unfortunately, while the majority of GC patients usually present with advanced tumor stage; there is still limited evidence-based therapeutic options. Current approach to GC management consists mainly of; endoscopy followed by, gastrectomy and chemotherapy or chemo-radiotherapy. Recent studies in GC have confirmed that it is a heterogeneous disease. Many molecular characterization studies have been performed in GC. Recent discoveries of the molecular pathways underlying the disease have opened the door to more personalized treatment and better predictable outcome. The identification of molecular markers is a useful tool for clinical managementin GC patients, assisting in diagnosis, evaluation of response to treatment and development of novel therapeutic modalities. While chemotherapeutic agents have certain physiological effects on the tumor cells, the prediction of the response is different from one type of tumor to the other. The specificity of molecular biomarkers is a principal feature driving their application in anticancer therapies. Here we are trying to focus on the role of molecular pathways of GC and well-established molecular markers that can guide the therapeutic management.

Recent updates of precision therapy for gastric cancer: Towards optimal tailored management

Signaling pathways of gastric carcinogenesis and gastric cancer progression are being avidly studied to seek optimal treatment of gastric cancer. Among them, hepatocyte growth factor (HGF)/c-MET, phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) and janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) pathways have been widely investigated. Their aberrant expression or mutation has been significantly associated with advanced stage or poor prognosis of gastric cancer. Recently, aberrations of immune checkpoints including programmed cell death-1/programmed cell death ligand-1 (PD-1/PD-L1) have been suggested as an important step in the formation of a microenvironment favorable for gastric cancer. Accomplishments in basic research have led to the development of novel agents targeting these signaling pathways. However, phase III studies of selective anti-HGF/c-MET antibodies and mTOR inhibitor failed to show significant benefits in terms of overall survival and progression-free survival. Few agents directly targeting STAT3 have been developed. However, this target is still critical issue in terms of chemoresistance, and SH2-containing protein tyrosine phosphatase 1 might be a significant link to effectively inhibit STAT3 activity. Inhibition of PD-1/PD-L1 showed durable efficacy in phase I studies, and phase III evaluation is warranted. Therapeutic strategy to concurrently inhibit multiple tyrosine kinases is a reasonable option, however, lapatinib needs to be further evaluated to identify good responders. Regorafenib has shown promising effectiveness in prolonging progression-free survival in a phase II study. In this topic highlight, we review the biologic roles and outcomes of clinical studies targeting these signaling pathways.

Targeting the PI3K/Akt signaling pathway in gastric carcinoma: A reality for personalized medicine?

Frequent activation of phosphatidylinositol-3 kinases (PI3K)/Akt/mTOR signaling pathway in gastric cancer (GC) is gaining immense popularity with identification of mutations and/or amplifications of PIK3CA gene or loss of function of PTEN, a tumor suppressor protein, to name a few; both playing a crucial role in regulating this pathway. These aberrations result in dysregulation of this pathway eventually leading to gastric oncogenesis, hence, there is a need for targeted therapy for more effective anticancer treatment. Several inhibitors are currently in either preclinical or clinical stages for treatment of solid tumors like GC. With so many inhibitors under development, further studies on predictive biomarkers are needed to measure the specificity of any therapeutic intervention. Herein, we review the common dysregulation of PI3K/Akt/mTOR pathway in GC and the various types of single or dual pathway inhibitors under development that might have a superior role in GC treatment. We also summarize the recent developments in identification of predictive biomarkers and propose use of predictive biomarkers to facilitate more personalized cancer therapy with effective PI3K/Akt/mTOR pathway inhibition.