Chemotherapy for advanced gastric cancer: future perspective in Japan

Efficacy and safety of sintilimab combined with apatinib as third-line or above therapy for patients with advanced or metastatic gastric cancer

This study aimed to evaluate the efficacy and safety of the combination of sintilimab and apatinib for the treatment of patients with advanced or metastatic gastric cancer (GC) and gastroesophageal junction (GEJ) cancer. This retrospective study analyzed data from 34 patients who had advanced or metastatic GC/GEJ cancer and received the combination therapy of sintilimab and apatinib as a third-line or above treatment. The primary endpoint was progression-free survival (PFS), and secondary endpoints included objective response rate (ORR), disease control rate (DCR), overall survival (OS), and safety. Among the 34 patients, none achieved a complete response (CR), 3 patients (8.8%) achieved a partial response, 23 patients (67.6%) had stable disease, and 8 patients (23.5%) experienced progressive disease. The ORR and DCR were 8.8% and 76.5%, respectively. The median PFS was 6.0 months (95% CI: 3.6-8.4), and the median OS was 11.6 months (95% CI: 8.1-15.1). Subgroup analysis revealed significant differences in OS between patients with high and low Eastern Cooperative Oncology Group Performance Status scores and between patients with and without a history of gastrectomy. Common adverse events (AEs) during treatment included fatigue (52.9%), anemia (47.1%), leukopenia (26.5%), hypothyroidism (23.5%), nausea and vomiting (20.6%), neutropenia (20.6%), and thrombocytopenia (17.6%), most of which were grade 1 and 2 AEs. No deaths occurred due to AEs. These findings indicate that the combination of sintilimab and apatinib has a favorable therapeutic effect in patients with advanced GC. Moreover, the AEs associated with this therapy are generally manageable.

Activation of UBEC2 by transcription factor MYBL2 affects DNA damage and promotes gastric cancer progression and cisplatin resistance

Ubiquitin-conjugating enzyme E2 C (UBE2C) plays a carcinogenic role in gastric cancer (GC); yet, its role in cisplatin (DDP) resistance in GC is enigmatic. This study sought to probe into the impact of UBE2C on DDP resistance in GC and its concrete molecular mechanism in GC progression. Bioinformatics analysis was used to analyze differentially expressed mRNAs and predict upstream regulatory molecules in GC. Real-time quantitative reverse transcriptase polymerase chain reaction and western blot were used to detect the expression of UBE2C and MYB proto-oncogene like 2 (MYBL2). Dual luciferase and chromatin immunoprecipitation (ChIP) assays were used to verify the binding relationship. Cell counting kit-8 was used to detect cell viability and calculate IC50 values. Flow cytometry was used to detect the cell cycle. Comet assay was used to detect DNA damage. Western blot was used to detect the expression of DNA loss-related proteins (γ-H2AX, ATM/p-ATM). The knockdown of highly expressed UBE2C in GC cell lines could reduce cell viability, induce G2/M arrest, induce apoptosis, and promote DNA damage and DDP sensitivity. Bioinformatics analysis predicted that the substantially upregulated MYBL2 was an upstream transcription factor in UBE2C. The binding relationship between the UBE2C promoter region and MYBL2 was verified by dual luciferase and ChIP. Overexpression of UBE2C in the rescue experiment was found to reverse the inhibited GC progression and promoted DDP sensitivity brought by the knockdown of MYBL2. In conclusion, the MYBL2/UBE2C regulatory axis may be a potential way to overcome DDP resistance in GC.

Modified stomach-partitioning gastrojejunostomy for initially unresectable advanced gastric cancer with outlet obstruction: A case report

BACKGROUND

Chemotherapy followed by gastrojejunostomy remains the main treatment for unresectable gastric cancer (GC) in the middle- or lower-third regions with gastric outlet obstruction (GOO). Radical surgery is performed as part of a multimodal treatment strategy for selected patients who respond well to chemotherapy. This study describes a case of successful radical resection with completely laparoscopic subtotal gastrectomy after a modified stomach-partitioning gastrojejunostomy (SPGJ) for obstruction relief, in a patient with GOO.

CASE SUMMARY

During the initial esophagogastroduodenoscopy, an advanced growth was detected in the lower part of the stomach, which caused an obstruction in the pyloric ring. Following this, a computed tomography (CT) scan revealed the presence of lymph node metastases and tumor invasion in the duodenum, but no evidence of distant metastasis was found. Consequently, we performed a modified SPGJ, a complete laparoscopic SPGJ combined with No. 4sb lymph node dissection, for obstruction relief. Seven courses of adjuvant capecitabine plus oxaliplatin combined with Toripalimab (programmed death ligand-1 inhibitor) were administered thereafter. A preoperative CT showed partial response; therefore, completely laparoscopic radical subtotal gastrectomy with D2 lymphadenectomy was performed after conversion therapy, and pathological complete remission was achieved.

CONCLUSION

Laparoscopic SPGJ combined with No. 4sb lymph node dissection was an effective surgical technique for initially unresectable GC with GOO.

DEPTOR as a novel prognostic marker inhibits the proliferation via deactivating mTOR signaling pathway in gastric cancer cells

Aberrantly activated mTOR signaling pathway is commonly found in malignancies including gastric cancer (GC). DEPTOR, as a naturally occurred inhibitor of mTOR, functions in the pro- or anti-tumor manner depending on distinct tumor contexts. However, the roles of DEPTOR in GC remain largely unknown. In this study, DEPTOR expression was identified to be significantly decreased in GC tissues compared with matched normal gastric tissues, and reduced DEPTOR level was indicative of poor prognosis in patients. Restored DEPTOR expression inhibited the propagation in AGS and NCI-N87 cells, whose DEPTOR levels are low, via deactivating mTOR signaling pathway. Likewise, cabergoline (CAB) attenuated the proliferation in AGS and NCI-N87 cells via partially rescuing DEPTOR protein level. Targeted metabolomics analysis showed that several key metabolites, such as l-serine, significantly changed in AGS cells with DEPTOR restoration. These results revealed the anti-proliferation function of DEPTOR in GC cells, suggesting that restored DEPTOR expression using CAB may be a potential therapeutic approach for patients with GC.

Development of a CLDN18.2-targeting Immuno-PET Probe for Non-invasive Imaging in Gastrointestinal Tumors

Claudin18.2 (CLDN18.2) is a tight junction protein that is overexpressed in a variety of solid tumors such as gastrointestinal cancer and oesophageal cancer. It has been identified as a promising target and a potential biomarker to diagnose tumor, evaluate efficacy, and determine patient prognosis. TST001 is a recombinant humanized CLDN18.2 antibody that selectively binds to the extracellular loop of human Claudin18.2. In this study, we constructed a solid target radionuclide zirconium-89 (⁸⁹Zr) labled-TST001 to detect the expression of in the human stomach cancer BGC823^CLDN18.2 cell lines. The [⁸⁹Zr]Zr-desferrioxamine (DFO)-TST001 showed high radiochemical purity (RCP, >99%) and specific activity (24.15 ± 1.34 GBq/μmol), and was stable in 5% human serum albumin, and phosphate buffer saline (>85% RCP at 96 h). The EC₅₀ values of TST001 and DFO-TST001 were as high as 0.413 ± 0.055 and 0.361 ± 0.058 nM (P > 0.05), respectively. The radiotracer had a significantly higher average standard uptake values in CLDN18.2-positive tumors than in CLDN18.2-negative tumors (1.11 ± 0.02 vs. 0.49 ± 0.03, P = 0.0016) 2 days post injection (p.i.). BGC823^CLDN18.2 mice models showed high tumor/muscle ratios 96 h p.i. with [⁸⁹Zr]Zr-DFO-TST001 was much higher than those of the other imaging groups. Immunohistochemistry results showed that BGC823^CLDN18.2 tumors were highly positive (+++) for CLDN18.2, while those in the BGC823 group did not express CLDN18.2 (-). The results of ex vivo biodistribution studies showed that there was a higher distribution in the BGC823^CLDN18.2 tumor bearing mice (2.05 ± 0.16 %ID/g) than BGC823 mice (0.69 ± 0.02 %ID/g) and blocking group (0.72 ± 0.02 %ID/g). A dosimetry estimation study showed that the effective dose of [⁸⁹Zr]Zr-DFO-TST001 was 0.0705 mSv/MBq, which is within the range of acceptable doses for nuclear medicine research. Taken together, these results suggest that Good Manufacturing Practices produced by this immuno-positron emission tomography probe can detect CLDN18.2-overexpressing tumors.

Overexpression of secretory clusterin (sCLU) induces chemotherapy resistance in human gastric cancer cells by targeting miR-195-5p

Recent focus has turned to secretory clusterin (sCLU) as a key contributor to chemoresistance of anticancer agents, but the role of sCLU on chemotherapy drug response to gastric cancer cells is not fully understood. Previous research found that sCLU was overexpressed in the induced multidrug-resistant MGC-803/5-FU cell line, suggesting that sCLU upregulation was closely related to chemoresistance to anticancer agents. In the present study, we aimed to clarify the role and mechanisms of sCLU in regulating the chemoresistance of gastric cancer cells. Cell apoptosis and cell viability were evaluated by annexin V/propidium iodide staining and CCK8. Expression of sCLU and miR-195-5P was detected using quantitative RT-PCR assays. The expression of sCLU in gastric cancer tissues was detected by RT-PCR assays. Upregulating or downregulating sCLU or miR-195-5P in gastric cancer cells was used to evaluate the mechanisms of chemoresistance. We found that sCLU was significantly elevated in the MGC-803/5-FU and SGC-7901 cells, and the downregulating sCLU sensitized MGC-803/5-FU and SGC-7901 cells to cisplatin and Docetaxel by upregulation of miR-195-5P. Upregulating sCLU in MGC-803 and HGC-27 cells was resistant to cisplatin and Docetaxel by downregulating miR-195-5p. Targeting miR-195-5P reduced the sensitivity of MGC-803 cells to 5-FU, and miR-195-5P overexpression enhanced the sensitivity of MGC-803/5-FU cells to 5-FU. The overexpression of sCLU in gastric cancer tissues was associated with chemoresistance. Our findings suggest that overexpression of sCLU induced chemoresistance in gastric cancer cells by downregulating miR-195-5p, thus providing a potential target for the development of agents that targeting sCLU for gastric cancer therapy.

Expression and clinical significance of SYNE1 and MAGI2 gene promoter methylation in gastric cancer

Gastric cancer is the fifth most common cancer and the third leading cause of cancer-related mortality globally. Abnormal DNA methylation is closely related to gastric cancer. The purpose of the study was to investigate the methylation of the SYNE1 and MAGI2 gene promoter and its relationship with the clinical-pathological factors, chemotherapy efficacy, and survival, thus providing a new biomarker for the prognosis and chemotherapy efficacy in gastric cancer.The methylation status of SYNE1 and MAGI2 in gastric cancer and adjacent tissues was detected by MSP method in 70 cases of advanced gastric cancer paraffin specimens.The methylation rate of the SYNE1 and MAGI2 gene promoter region was higher in gastric cancer tissues compared with adjacent tissues. The methylation status of SYNE1 was associated with the age at diagnosis and the size of the primary tumors, but no clinical or pathological factors have been found to be related with the methylation status of MAGI2 promoter. A high level of SYNE1 promoter methylation was associated with poorer chemotherapy efficacy in recurrent patients with gastric cancer. Thirty-three percent of the 70 patients exhibited highly methylated MAGI2; in this group, the median progression-free survival time was 4.1 months, shorter than those with negative methylated MAGI2 whose PFS was 5.1 months.MAGI2 is more methylated in gastric cancer than in adjacent tissues suggesting that hypermethylation changes in MAGI2 may be one of the mechanisms of tumorigenesis in gastric cancer. The methylation status of the SYNE1 and MAGI2 promoter regions may affect the chemotherapy efficacy of advanced gastric cancer. The prognosis of MAGI2-negative patients was better than that of positive ones, suggesting that MAGI2 may be an independent prognostic factor for PFS in patients with advanced gastric cancer.

PD-L1 gene promoter methylation represents a potential diagnostic marker in advanced gastric cancer

Gastric cancer is one of the most prevalent malignant tumors worldwide. Immunological checkpoint inhibitors of the programmed death 1 (PD-1)/programmed cell death-ligand 1 (PD-L1) signaling pathway are effective in the treatment of various malignant tumor types, but the potential of such immunotherapeutic techniques for the treatment of gastric cancer is yet to be elucidated. The purpose of the present study was to investigate the methylation of the PD-L1 gene promoter and its clinical significance in advanced gastric cancer, as this may suggest the use of PD-L1 promoter methylation as a novel biomarker for gastric cancer progression. In a total of 70 samples, the methylation rate of the PD-L1 gene promoter region was significantly higher in gastric cancer tissues compared with adjacent tissues. A high level of PD-L1 promoter methylation was associated with lymph node staging, and resulted in poorer prognoses in patients with advanced gastric cancer. A total of 26 patients exhibited highly methylated PD-L1; in this group, the median progression-free survival time of patients receiving platinum/fluorouracil chemotherapy was 4.2 months longer than those receiving paclitaxel/fluorouracil chemotherapy, and the risk of disease progression in patients receiving paclitaxel/fluorouracil chemotherapy was 5.009 times higher compared with patients who received platinum/fluorouracil chemotherapy. Additionally, PD-L1 promoter methylation was significantly correlated with PD-L1 expression, and the progression of advanced gastric cancer. In conclusion, high methylation levels of the PD-L1 promoter region may be a faciliatory mechanism enabling gastric cancer tumorigenesis, and may also represent an independent prognostic factor for chemotherapeutic efficacy in patients with advanced gastric cancer.

Conversion Surgery for Stage IV Gastric Cancer

The prognosis of stage IV gastric cancer (GC) is poor, with palliative chemotherapy remaining the main therapeutic option. Studies increasingly indicate that patients with unresectable stage IV GC, who undergo gastrectomy with radical intention after responding to several regimens of combined chemotherapy, can achieve good survival outcomes. Thus, surgery aiming at radical resection for unresectable stage IV GC after combined chemotherapy has received increasing attention in recent years. This novel therapeutic strategy was defined as conversion surgery in patients with unresectable stage IV GC and it can associate with significant improved survival when R0 resection can be achieved. Despite the recent advances in conversion surgery for patients with unresectable stage IV GC, selection criteria for combination chemotherapy regimens, indications for conversion surgery, optimal timing to surgery, and postoperative chemotherapy all remain controversial. This article reviews the current state of conversion surgery for unresectable stage IV GC.

High-Affinity Human Anti-c-Met IgG Conjugated to Oxaliplatin as Targeted Chemotherapy for Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most mortality-causing solid cancers globally and the second largest cause of death among malignancies. Oxaliplatin, a platinum-based drug, has been widely utilized in the treatment of malignancies such as colorectal cancer and hepatocellular carcinoma, yet its usage is limited because of severe side effects of cytotoxicity to normal tissues. c-Met, a receptor tyrosine kinase, is expressed aberrantly on the surface of HCC. The purpose of this study was to synthesise a humanized antibody against c-Met (anti-c-Met IgG) and conjugate it to oxaliplatin to develop a novel antibody-drug conjugate (ADC). Anti-c-Met IgG was detected to be loaded with ~4.35 moles oxaliplatin per mole of antibody. ELISA and FCM confirmed that ADC retained a high and selective binding affinity for c-Met protein and c-Met-positive HepG2 cells. In vitro, the cytotoxicity tests and biological function assay indicated that ADC showed much higher cytotoxicity and functioning in c-Met-positive HepG2 cells, compared with shMet-HepG2 cells expressing lower levels of c-Met. Furthermore, compared with free oxaliplatin, ADC significantly improved cytotoxicity to c-Met-positive tumours and avoided off-target cell toxicity in vivo. In conclusion, by targeting c-Met-expressing hepatoma cells, ADC can provide a platform to reduce drug toxicity and improve drug efficacy in vitro and in vivo.

MSC-regulated lncRNA MACC1-AS1 promotes stemness and chemoresistance through fatty acid oxidation in gastric cancer

Chemotherapy is the preferred treatment for advanced stage gastric cancer (GC) patients and chemotherapy resistance is the major obstacle to effective cancer therapy. Increasing evidence suggests that mesenchymal stem cells (MSCs) make important contributions to development of drug resistance. However, the underlying mechanism remains elusive. In this study, we discovered that abundant MSCs in tumor tissues predicted a poor prognosis in GC patients. MSCs promoted stemness and chemoresistance in GC cells through fatty acid oxidation (FAO) in vitro and in vivo. Mechanically, transforming growth factor β1 (TGF-β1) secretion by MSCs activated SMAD2/3 through TGF-β receptors and induced long non-coding RNA (lncRNA) MACC1-AS1 expression in GC cells, which promoted FAO-dependent stemness and chemoresistance through antagonizing miR-145-5p. Moreover, pharmacologic inhibition of FAO with etomoxir (ETX) attenuated MSC-induced FOLFOX regiment resistance in vivo. These results suggest that FAO plays an important role in MSC-mediated stemness and chemotherapy resistance in GC and FAO inhibitors in combination with chemotherapeutic drugs present as a promising strategy to overcome chemoresistance.

Expression of DNA damage response proteins in gastric cancer: Comprehensive protein profiling and histological analysis

Gastric cancer is the third major cause of cancer-related mortality in Japan. The aim of this study was to identify a factor implicated in the biology of gastric cancer by comprehensive protein profiling. Protein profiling was carried out by liquid chromatography-tandem mass spectrometry, using formalin-fixed paraffin-embedded specimens of 17 gastric cancer cases. Pathway analysis and orthogonal partial least square-discriminant analysis suggested the significant expression of ribonucleoproteins, heterogeneous nuclear ribonucleoproteins, interleukin binding factor 2 (ILF2), KU70 and KU80, which are involved in DNA damage response (DDR). Thus, the expression and phosphorylation levels of KU70, ILF2, CHK1 and CHK2 were examined by immunohistochemistry in 42 cases of gastric cancer. The expressions of ILF2 and CHK1 were unaffected in all cases. The expression and phosphorylation of CHK2 were absent in 2 cases. Despite the expression of proteins, the phosphorylation of KU70 and CHK2 appeared to be impaired in 1 and 4 cases, respectively. In 7 out of 42 cases (17%), DDR appeared to be impaired. Recurrence was noted in 2 out of these 7 cases (29%), whereas the recurrence was noted in 2 out of the remaining 35 cases (6%). The expression levels of KU70, ILF2, CHK1, CHK2 and TP53 were further examined in 4 gastric cancer cell lines. The expression and phosphorylation levels following exposure to ultraviolet radiation were abnormal in the 3 cell lines. The normal consecutive phosphorylation of CHK1 and CHK2, the upregulation of TP53 and an increase in apoptotic cell death following exposure to ultraviolet radiation was detected only in one cell line, suggesting that the preserved functions of DDR and TP53 are necessary for the determination of cell fate. It is thus suggested that DDR plays an important role in the pathobiology of gastric cancers.