[Regulation of the Tumor Microenvironment through HER2 Signaling-Insights from Gastric Cancer Cases with Heterogeneous HER2 Overexpression].

HER2, a member of the human epidermal growth factor receptor(HER)family, exhibits gene amplification, protein overexpression, or both in 13-27% of gastric cancer(GC)cases. Through the activation of downstream Akt and ERK pathways, HER2 promotes the survival and proliferation of gastric cancer cells. The impact of HER2 signaling on the tumor microenvironment(TME)in GC remains unclear, and the heterogeneity of HER2 overexpression in GC tissues is considered a contributing factor. In this study, we focused on differences in the TME between HER2-positive and HER2-negative areas in HER2-positive GC and found that HER2 signaling, particularly the HER2-Akt cascade, may suppress stimulator of interferon genes (STING)expression and reduce CD8+ T cell infiltration in tumor cells. Overall, our findings suggest the potential for a novel therapeutic approach to activate the anti-tumor immune response in HER2-positive GC.

The tumor cell-intrinsic cGAS-STING pathway is associated with the high density of CD8+ T cells after chemotherapy in esophageal squamous cell carcinoma.

BACKGROUND: Chemotherapy has the potential to induce CD8+ T-cell infiltration in the tumor microenvironment (TME) and activate the anti-tumor immune response in several cancers including esophageal squamous cell carcinoma (ESCC). The tumor cell-intrinsic cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway has been known as a critical component for regulating immune cell activation in the TME. However, its effect on the infiltration of immune cells induced by chemotherapy in the ESCC TME has not been investigated. METHODS: We examined the effect of the tumor-cell intrinsic cGAS-STING pathway on the infiltration of CD8+ T cells induced by chemotherapy in ESCC using ESCC cell lines and surgically resected ESCC specimens from patients who received neoadjuvant chemotherapy (NAC). RESULTS: We found that chemotherapeutic agents, including 5-fluorouracil (5-FU) and cisplatin (CDDP), activated the cGAS-STING pathway, consequently inducing the expression of type I interferon and T-cell-attracting chemokines in ESCC cells. Moreover, the tumor cell-intrinsic expression of cGAS-STING was significantly and positively associated with the density of CD8+ T cells in ESCC after NAC. However, the tumor cell-intrinsic expression of cGAS-STING did not significantly impact clinical outcomes in patients with ESCC after NAC. CONCLUSION: Our findings suggest that the tumor cell-intrinsic cGAS-STING pathway might contribute to chemotherapy-induced immune cell activation in the ESCC TME.

Down-regulation of stimulator of interferon genes (STING) expression and CD8+ T-cell infiltration depending on HER2 heterogeneity in HER2-positive gastric cancer.

BACKGROUND: HER2 signaling might be involved in the regulation of immune cell activation in the tumor microenvironment (TME) of gastric cancer (GC). However, the relationship between HER2 status and immune cell condition in the HER2-positive GC TME is not clearly understood. METHODS: To investigate the effect of HER2 signaling on the activation of the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway, which contributes to immune cell activation in the GC TME, we evaluated the associations among the expressions of HER2, cGAS-STING, and the number of CD8+ tumor-infiltrating lymphocytes (TIL) by considering HER2 heterogeneity in HER2-positive GC tissues. We also examined the effect of HER2 signaling on the activation of STING signaling in vitro using human HER2-positive GC cell lines. RESULTS: The expression of HER2 is highly heterogeneous in HER2-positive GC tissues, and we found that the number of CD8+ TIL in HER2 high areas was significantly lower than that in HER2 low areas in HER2-positive GC tissues. Intriguingly, the tumor cell-intrinsic expression of STING, but not cGAS, was also significantly lower in the HER2 high areas than the HER2 low areas in HER2-positive GC tissues. Moreover, in vitro experiments, we demonstrated that the blockade of HER2 signaling increased the expression of STING and its target genes, including IFNB1, CXCL9/10/11, and CCL5, in HER2-positive GC cell lines. CONCLUSIONS: Our results suggest that HER2 signaling might suppress immune cell activation in the GC TME by inhibiting STING signaling in tumor cells in HER2-positive GC.

Systemic inflammation score as a preoperative prognostic factor for patients with pT2-T4 resectable gastric cancer: a retrospective study.

BACKGROUND: Systemic inflammation has been reported to be associated with cancer progression and metastasis. Systemic inflammation score (SIS), calculated from preoperative serum albumin level and lymphocyte-to-monocyte ratio, has been shown to be a novel prognostic factor for several types of tumors. This study aimed to evaluate the prognostic value of the SIS in patients with pT2-4 resectable gastric cancer (GC). METHODS: Total 97 patients with pT2-4 GC who underwent curative surgery from 322 cases between 2009 and 2015 in Fukushima Medical University Hospital were included. We performed univariate and multivariate analyses to evaluate the usefulness of preoperative SIS and other prognostic factors for relapse-free survival (RFS) and overall survival (OS). RESULTS: The higher SIS score was associated with undifferentiated cancer and recurrence. Univariate analysis of RFS identified deeper tumor invasion and higher SIS were significant risk factors and multivariate analysis revealed that both of them were independent prognostic factors for RFS. As for OS, age, tumor invasion, SIS and LNR were significantly correlated with RFS. In multivariate analysis, tumor invasion, SIS and LNR were independent prognostic factors for OS. CONCLUSIONS: SIS was an independent prognostic factor for RFS and OS in pT2-4 resectable gastric cancer patients who underwent curative gastrectomy.

[The Potential of a Novel Therapeutic Strategy for Colorectal Cancer Targeting the cGAS-STING Pathway].

The cyclic GMP-AMP synthase(cGAS)-stimulator of interferon genes(STING)pathway is one of the important intracellular signaling pathways responsible for the recognition of exogenous DNA and subsequent induction of type Ⅰ interferon responses. Interestingly, in recent years, the importance of the cGAS-STING pathway in promoting anti-tumor immune responses has been highlighted. Decreased expression of cGAS-STING in tumor cells was reported in various cancers, including colorectal cancer(CRC), and it has been found to be involved in inhibiting the anti-tumor immune responses. In our recent investigation, we specifically examined the impact of tumor cell-intrinsic cGAS-STING pathway on the activation of immune cells within the CRC tumor microenvironment, focusing on mismatch repair deficient/microsatellite instability-high (dMMR/MSI-H)and mismatch repair proficient/microsatellite stable(pMMR/MSS)CRCs. We revealed that cGAS-STING expression in tumor cells was decreased in pMMR/MSS CRC compared to dMMR/MSI-H CRC, which correlated with the decreased infiltration of cytotoxic T cells. Here, we discuss the possibility of a novel therapeutic strategy for CRC targeting the tumor cell-intrinsic cGAS-STING pathway based on the findings from recent studies.

[Remodeling of the Tumor Microenvironment by Radiotherapy through the cGAS-STING Pathway in Esophageal Squamous Cell Carcinoma].

It has been reported that tumor cell-intrinsic cyclic GMP-AMP synthase(cGAS)-stimulator of interferon genes(STING) pathway is essential for radiotherapy(RT)-induced activation of anti-tumor immune responses. However, its role in the RT- induced remodeling of the tumor microenvironment(TME)in esophageal squamous cell carcinoma(ESCC), is largely unknown. In this study, we found that the tumor cell-intrinsic cGAS-STING pathway is a critical component for RT-induced activation of immune cells in the TME through the induction of type Ⅰ interferon and C-X-C motif chemokine ligand 10 in tumor cells in ESCC. However, at the same time, the tumor cell-intrinsic cGAS-STING pathway is also involved in RT-triggered infiltration and polarization of immunosuppressive CD163+ tumor-associated macrophages (TAM) through the induction of interleukin 34 (IL-34) in tumor cells in ESCC. Our findings suggest that targeting IL-34 to impede the infiltration and polarization of CD163+ TAM could potentially enhance the efficacy of RT-induced immune cell activation in ESCC TME.

[A Case of Perforation of the Duodenum during Chemotherapy with Ramucirumab plus Nab-Paclitaxel for Advanced Gastric Cancer].

A 70-year-old male patient was diagnosed with advanced gastric cancer with para-aortic lymph node metastasis. After diagnostic laparoscopy, the patient received 2 courses of neoadjuvant chemotherapy. Subsequently, distal gastrectomy, D2 plus para-aortic lymph node dissection, and Roux-en-Y reconstruction were performed. An enlarged lymph node(No. 16b2)was identified during surgery. The histopathological diagnosis revealed ypT4b, ypN3b, cM1(LYM; No. 16), Stage ⅣB. Chemotherapy with ramucirumab plus nab-paclitaxel was administered at 6 weeks postoperatively. However, after 2 courses of chemotherapy, the patient developed an abscess discharge from the wound, which was confirmed by an abdominal CT scan and diagnosed as an intra-abdominal abscess derived from duodenal perforation. The abscess was drained percutaneously. Subsequently, chemotherapy with nab-paclitaxel, nivolumab, and trifluridine/tipiracil hydrochloride was administered. After the appearance of brain metastases, the treatment was shifted to palliative care. The patient died 2 years and 7 months later from the primary disease.

[A Case of MSI-High Sigmoid Colon Cancer in Which Long-Term Survival Was Achieved by Pembrolizumab for Recurrent Lesions Resistant to Conventional Chemotherapy].

The patient underwent sigmoidectomy with D3 lymph node dissection and partial bladder resection for sigmoid colon cancer(cT4bN1M0, cStage Ⅲa), after preoperative chemotherapy with mFOLFOX plus panitumumab, and FOLFOXIRI plus bevacizumab. Postoperative adjuvant chemotherapy was performed by 8 courses of CAPOX. He relapsed hilar lymph nodes and peritoneal dissemination after 13 months after surgery, he underwent resection of the recurrent lesions. Four months after, he developed recurrence in liver and peritoneum. Although he was treated with FOLFIRI plus ramucirumab or aflibercept, resulted in progression of disease, then he received trifluridine tipiracil hydrochloride plus bevacizumab. At this point, the Japanese health insulance had started to cover pembrolizumab, this therapy was started as the fourth chemotherapy after the diagnosis of high frequency microsatellite instability(MSI), and then tumor markers rapidly declined. He underwent 38 courses of pembrolizumab, the recurrent lesions both liver and peritoneum disappeared. He had stoma closure, peritoneal dissemination disappeared not only intraoperatively but also in histologically from the peritoneal scar. He has received pembrolizumab for 4 years without another recurrence. Here, we report a case of MSI-high sigmoid colon cancer in which long-term survival was achieved by pembrolizumab for recurrent lesions resistant to conventional chemotherapy.

SH2D4A downregulation due to loss of chromosome 8p is associated with poor prognosis and low T cell infiltration in colorectal cancer.

BACKGROUND: Colorectal cancer (CRC) develops through chromosomal instability (CIN) or microsatellite instability (MSI) due to deficient mismatch-repair (dMMR). We aimed to characterise novel cancer-associated genes that are downregulated upon malignant transformation in microsatellite stable (MSS) CRCs, which typically exhibit CIN with proficient mismatch-repair (pMMR). METHODS: Comprehensive screening was conducted on adenomas, MSI/MSS CRCs and cell lines, followed by copy number analysis, and their genetic and prognostic relevance was confirmed in microarray and RNA-seq cohorts (n = 3262, in total). Immunohistochemistry for SH2D4A was performed in 524 specimens of adenoma, carcinoma in situ and dMMR/pMMR CRC. The functional role of SH2D4A was investigated using CRC cell lines. RESULTS: A set of 11 genes, including SH2D4A, was downregulated during the adenoma-carcinoma sequence in MSS/CIN CRCs, mainly due to chromosome 8p deletions, and their negative prognostic impact was validated in independent cohorts. All adenomas were SH2D4A positive, but a subset of CRCs (5.3%) lacked SH2D4A immunohistochemical staining, correlating with poor prognosis and scarce T cell infiltration. SH2D4A depletion did not affect cell proliferation or IL-6-induced STAT3 phosphorylation. CONCLUSIONS: Our findings suggest that downregulation of multiple genes on chromosome 8p, including SH2D4A, cooperatively contribute to tumorigenesis, resulting in the immune cold tumour microenvironment and poor prognosis.

Role of the cGAS-STING pathway in regulating the tumor-immune microenvironment in dMMR/MSI colorectal cancer.

Deficient mismatch repair (dMMR)/microsatellite instability (MSI) colorectal cancer (CRC) has high immunogenicity and better prognosis compared with proficient MMR (pMMR)/microsatellite stable (MSS) CRC. Although the activation of the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway has been considered to contribute to the high number of CD8+ TILs, its role in dMMR/MSI CRC is largely unknown. In this study, to examine the role of the cGAS-STING pathway on the recruitment of CD8+ TILs in dMMR/MSI CRC, we used public datasets and clinical tissue samples in our cohorts to evaluate the expression of cGAS, STING, and CD8+ TILs in pMMR/MSS and dMMR/MSI CRCs. According to the analysis of public datasets, the expression of cGAS-STING, CD8 effector gene signature, and CXCL10-CCL5, chemoattractants for CD8+ TILs which regulated by the cGAS-STING pathway, was significantly upregulated in dMMR/MSI CRC, and the expression of cGAS-STING was significantly associated with the expression of CD8 effector gene signature. Immunohistochemistry staining of the clinical tissue samples (n = 283) revealed that cGAS-STING was highly expressed in tumor cells of dMMR CRC, and higher expression of cGAS-STING in tumor cells was significantly associated with the increased number of CD8+ TILs. Moreover, we demonstrated that the downregulation of MMR gene in human CRC cell lines enhanced the activation of the cGAS-STING pathway. Taken together, for the first time, we found that dMMR/MSI CRC has maintained a high level of cGAS-STING expression in tumor cells, which might contribute to abundant CD8+ TILs and immune-active TME.

Incidence of upper extremity deep vein thrombosis in the retrosternal reconstruction after esophagectomy.

BACKGROUND: Upper extremity deep vein thrombosis (UEDVT) is relatively rare but cannot be negligible because it can cause fatal complications. Although it is reported that the occurrence rate of UEDVT has increased due to central venous catheter (CVC), cancer, and surgical invasion, there is still limited information for esophagectomy. The aim of this study was to evaluate the clinical factors, including CVC placement and thromboprophylaxis approach, as well as retrosternal space's width as a predictive factor for UEDVT in patients receiving esophagectomy. METHODS: This study included 66 patients who underwent esophagectomy with retrosternal reconstruction using a gastric tube. All patients routinely underwent contrast-enhanced computed tomography (CT) on the 4th postoperative day. Low-molecular-weight-heparin (LMWH) was routinely administered by the 2nd postoperative day. To evaluate retrosternal space's width, (a) The distance from sternum to brachiocephalic artery and (b) the distance from sternum to vertebra were measured by preoperative CT, and the ratio of (a) to (b) was defined as the width of retrosternal space. RESULTS: Among all patients, 11 (16.7%) suffered from UEDVT, and none was preoperatively received CVC placement, while 7 were inserted in non-UEDVT cases. Retrosternal space's width in patients with UEDVT was significantly smaller than that in patients without UEDVT (0.17 vs. 0.26; P < 0.0001). A cutoff value of the width was 0.21, which has high sensitivity (87%) and specificity (82%) for UEDVT prediction, respectively. CONCLUSION: The existence of CVC may not affect the development of UEDVT, but preoperative evaluation of retrosternal ratio may predict the occurrence of UEDVT.

[Expression of the cGAS-STING Pathway in dMMR/MSI-H in Colorectal Cancer].

Deficient mismatch repair (dMMR)/microsatellite instability (MSI)-H colorectal cancer (CRC) has high immunogenicity. Although the cyclic GMP-AMP synthase( cGAS)-stimulator of interferon genes( STING) pathway activation has considerably contributed to the high number of CD8+ tumor-infiltrating lymphocytes (TILs), its role in dMMR/MSI-H CRC is largely unknown. In this study, we investigated the association between cGAS-STING expression and CD8+ TILs in CRC. Data analysis using the TCGA dataset CRC cohort showed that cGAS, STING, and CD8 gene expression levels were significantly higher in the MSI group. Immunohistochemistry examination of resected clinical CRC samples showed that cGAS-STING expression in tumor cells was high in the MSI CRC, and CD8+ TILs was also significantly infiltrated in the MSI group. Moreover, significant CD8+ TILs infiltration was observed in CRC with high cGAS and STING expression levels. The results suggest that dMMR/MSI -H CRC has maintained a high cGAS-STING expression, which may contribute to abundant CD8+ TILs.

Functional benefits of the double flap technique after proximal gastrectomy for gastric cancer.

BACKGROUND: Proximal gastrectomy is a widely performed procedure that has become more common with an increasing number of proximal gastric cancer cases. Several types of reconstructive procedures after proximal gastrectomy have been developed, and it remains controversial which procedure is the most advantageous with regard to the preservation of postoperative gastric stump function and nutritional status. In the present study, we retrospectively analyzed reconstructive procedures in a consecutive case series for proximal gastrectomy, primarily focusing on postoperative body weight maintenance, nutritional status, and gastric remnant functional preservation. METHODS: We enrolled 69 patients who had undergone proximal gastrectomy for gastric cancer in our institute between 2005 and 2020. Short-term complications, preservation of gastric remnant functions, nutritional status, and post-operative weight changes were compared. RESULTS: After proximal gastrectomy, the numbers of patients who underwent direct esophago-gastrostomy, jejunal interposition, double tract reconstruction, and the double flap technique were 9, 10, 14, and 36, respectively. The patients in whom the double flap technique was performed suffered no reflux esophagitis after surgery. Prevalence of gastric residual at 12 months after surgery was lowest in the double flap technique group. Moreover, the double flap technique group had a better tendency regarding post-operative changes of serum albumin ratios. Furthermore, the post-operative body weight change ratio of the double flap technique group was smallest among all groups and was significantly better than that of the double tract group. CONCLUSIONS: The double flap technique after proximal gastrectomy was considered the most effective technique for reconstruction which leads to better bodyweight maintenance, and results in less reflux esophagitis.

[A Case of Laparoscopic Surgery for Preoperatively Diagnosed Gastric Metastasis of Lung Cancer].

The patient was a 66-year-old male who had undergone an operation for lung cancer and solitary brain metastases. Follow- up PET-CT after 1 year detected FDG accumulation in the stomach. We performed esophagogastroscopy and found an approximately 20 mm-sized Type 2 tumor on the greater curvature of the upper stomach. A pathological diagnosis of lung adenocarcinoma metastasis in the stomach was made. Laparoscopic surgery was performed on the metastatic lesion to prevent bleeding and perforation, and resection was achieved with minimal invasion. The current development of chemotherapy, including immunotherapy, has contributed to the improved prognosis of cancer patients, including those with lung metastasis in the stomach. Considering these backgrounds, preventive surgical resection under laparoscopy may be an effective approach for improving prognosis and preventing acute life-threatening adverse events. We report this case along with a literature review.

[Pancreatic Adenosquamous Carcinoma That Developed after Resection of IPMA in the Pancreatic Tail].

Pancreatic adenosquamous carcinoma coexisting with intraductal papillary mucinous neoplasm(IPMN)is extremely rare. We report a rare case of pancreatic adenosquamous carcinoma that developed after resection of intraductal papillary mucinous adenoma(IPMA). A 67-year-old man was suspected of having a pancreatic cystic lesion. MRCP demonstrated a cystic lesion measuring 25mm in the pancreatic tail, which had an enhanced nodule. We therefore diagnosed branch duct type IPMN of the pancreas. Although pancreatic juice cytology did not indicate malignancy, we performed laparoscope-assisted distal pancreatectomy. The reason why the IPMN lesion had an enhanced nodule. The histopathological diagnosis was IPMA without malignancy. One year and 5 months after surgery, blood analysis showed an elevated tumor marker level, and abdominal CT demonstrated a pancreatic head tumor with lymphadenopathy. EUS-FNA was performed and the patient was diagnosed with pancreatic adenosquamous carcinoma based on immunohistochemical staining. We administered chemotherapy with gemcitabine and S-1. After 3 courses of this chemotherapy, the size of the pancreatic tumor and the tumor marker level decreased. The patient achieved a partial response. He is still receiving chemotherapy after 7 courses.

[A Case of AFP and PIVKA- II Producing Gastric Cancer Presenting with Metachronous Multiple Liver Metastases].

A 55-year old man underwent distal gastrectomy with lymphadenectomy for gastric cancer(T1N0M0, Stage I A). Six months after the radical operation, he presented with multiple liver metastases. Based on immunohistochemical examination, he was diagnosed with AFP-producing gastric cancer and metachronous liver metastases. He underwent a surgery to remove the liver metastases. Two months after the surgery, recurrent tumors were found in the lung and remnant liver. He received chemotherapy(S-1/CDDP and CPT-11/CDDP)for the recurrent tumor and lived for 15 months after the surgical intervention.

Thoracoscopic and endoscopic cooperative surgery for esophageal gastrointestinal stromal tumor: a case report.

BACKGROUND: Esophageal gastrointestinal stromal tumors (GISTs) are relatively rare, accounting for 2-5% of all GISTs. Typically, the treatment is surgery in nature. However, no standard procedure established for esophageal GISTs, and in many cases, subtotal esophagectomy or local resection via thoracoscopy or mediastinoscopy is performed. Thoracoscopic and endoscopic cooperative surgery (TECS) is a surgical approach similar to laparoscopic and endoscopic cooperative surgery used for gastric GIST; however, no reports of its use for esophageal GIST have been published to date. We herein report such a case along with a review of past literature. CASE PRESENTATION: The patient was a 60-year-old man. Upper gastrointestinal contrast imaging revealed a subepithelial lesion in the esophagus. An 18 × 17 mm subepithelial lesion was identified in the left wall, 35 cm from the upper incisors, during upper gastrointestinal endoscopy, and was diagnosed as a GIST through endoscopic ultrasound-guided fine needle biopsy. TECS was therefore performed. The patient was placed in a prone position with his face to the left. After confirming the lesion under endoscopy and left thoracoscopy, the periesophageal area of the lesion was dissected under thoracoscopy. Subsequently, an endoscopic full-layer resection was performed. Finally, the excision site of the lesion was sutured under thoracoscopy. The operation took a total of 3 h and 22 min, with a blood loss of 50 mL. CONCLUSIONS: The appropriate surgical procedure for esophageal GIST should be considered according to the location and size of the lesion. TECS ensures that the resection margins are secured using an endoscopic or thoracoscopic approach. Furthermore, TECS is minimally invasive, avoiding esophagectomy and reconstruction, which makes it a potential surgical option for esophageal GISTs.

Cardiac tamponade caused by a ruptured coronary aneurysm treated with open-chest hemostasis after esophageal cancer surgery: a case report.

Cardiac tamponade is a rare postoperative complication of esophagectomy, with no previous reports of association with coronary artery aneurysm rupture. We present a case of cardiac tamponade caused by coronary aneurysm rupture following esophageal cancer surgery. A 68-year-old man with no history of heart disease underwent robotic subtotal esophagectomy for esophageal squamous cell carcinoma. He experienced intermittent chest pain on postoperative day (POD) 17. Echocardiography revealed increasing pericardial fluid, and pericardiocentesis on POD 34 revealed bloody pericardial fluid. Contrast-enhanced computed tomography and coronary angiography revealed a ruptured coronary aneurysm causing cardiac tamponade. Emergency surgery with a median sternotomy achieved hemostasis, and the patient recovered successfully. Cardiac tamponade after esophageal surgery, particularly from coronary aneurysm rupture, is rare. Prompt diagnosis and treatment are crucial for patient survival. Despite its risks, median sternotomy was effective in achieving rapid hemostasis and patient recovery in this case.

The impact of CLDN18.2 expression on effector cells mediating antibody-dependent cellular cytotoxicity in gastric cancer.

Activating antibody-dependent cellular cytotoxicity (ADCC) by targeting claudin-18 isoform 2 (CLDN18.2) using zolbetuximab, a monoclonal antibody against CLDN18.2, has been considered a promising novel therapeutic strategy for gastric cancer (GC). However, the impact of CLDN18.2 expression on natural killer (NK) cells and monocytes/macrophages-crucial effector cells of ADCC-in GC has not been fully investigated. In the present study, we assessed the impact of CLDN18.2 expression on clinical outcomes, molecular features, and the frequencies of tumor-infiltrating NK cells and macrophages, as well as peripheral blood NK cells and monocytes, in GC by analyzing our own GC cohorts. The expression of CLDN18.2 did not significantly impact clinical outcomes of GC patients, while it was significantly and positively associated with Epstein-Barr virus (EBV) status and PD-L1 expression. The frequencies of tumor-infiltrating NK cells and macrophages, as well as peripheral blood NK cells and monocytes, were comparable between CLDN18.2-positive and CLDN18.2-negative GCs. Importantly, both CLDN18.2 expression and the number of tumor-infiltrating NK cells were significantly higher in EBV-associated GC compared to other molecular subtypes. Our findings support the effectiveness of zolbetuximab in CLDN18.2-positive GC, and offer a novel insight into the treatment of this cancer type, highlighting its potential effectiveness for CLDN18.2-positive/EBV-associated GC.

A Potential Biomarker of Dynamic Change in Peripheral CD45RA-CD27+CD127+ Central Memory T Cells for Anti-PD-1 Therapy in Patients with Esophageal Squamous Cell Carcinoma.

In order to develop a biomarker predicting the efficacy of treatments for patients with esophageal squamous cell carcinoma (ESCC), we evaluated the subpopulation of T cells in ESCC patients treated with chemotherapy (CT), chemoradiotherapy (CRT), and nivolumab therapy (NT). Fifty-five ESCC patients were enrolled in this study, and peripheral blood samples were collected before and after CT or CRT and during NT. Frequencies of memory, differentiated, and exhausted T cells were evaluated using flow cytometry among cStages, treatment strategies, pathological responses of CT/CRT, and during NT. The frequencies of PD-1+ or TIM-3+CD4+ T cells were significantly higher in patients with cStage IV. PD-1+CD4+ and TIM-3+CD8+ T-cell populations were significantly higher in patients treated with CRT but were not associated with treatment response. The frequencies of both CD4+ and CD8+ CD45RA-CD27+CD127+ central memory T cells (TCM) were significantly decreased during the course of NT in the progressive disease group. Taken together, the alteration in frequency of CD45RA-CD27+CD127+ TCM during NT may be a biomarker to predict its therapeutic response in ESCC patients.