Safety and Efficacy of Conversion Therapy After Systemic Chemotherapy in Advanced Esophageal Cancer with Distant Metastases: A Multicenter Retrospective Observational Study.

BACKGROUND: Patients with esophageal squamous cell carcinoma (ESCC) with distant metastasis were treated with systemic chemotherapy. Recent advances in multimodal treatments have made conversion therapy a viable option for patients with incurable ESCC. OBJECTIVE: We aimed to assess the safety and efficacy of conversion therapy for ESCC with distant metastases. METHODS: Conversion therapy was defined as surgery or chemoradiotherapy (CRT) used to cure tumors that were previously considered incurable because of distant metastasis. We conducted a retrospective review of patients who underwent ESCC conversion therapy and assessed the treatment outcomes, including adverse events and survival rates. RESULTS: A total of 147 patients from 22 institutions were included. Systemic chemotherapy was initially administered to all patients. The most common M1 factor was the para-aortic lymph node, accounting for 55% of cases. Following the initial treatment, 116 patients underwent surgery, with 31 receiving CRT as conversion therapy. Postoperative complications in surgery patients included pneumonia (16%), anastomotic leakage (7%), and recurrent laryngeal nerve palsy (6%). During CRT, 18% of patients developed grade 3 or higher non-hematological toxicities. The 5-year overall survival (OS) rate was 31.7%. Pathological responders had significantly longer OS than non-responders (hazard ratio 0.493, p = 0.012). The distribution of distant metastasis, regimen type, clinical response, and conversion therapy modality did not have a significant impact on OS. CONCLUSIONS: Conversion therapy can be safely performed for ESCC with distant metastasis and has a favorable prognosis.

Outcomes of laparoscopic and endoscopic cooperative surgery for gastric submucosal tumors: A retrospective multicenter study at 21 Japanese institutions.

Aim: We conducted a multicenter study on classical laparoscopic and endoscopic cooperative surgery (LECS) and LECS-related procedures to retrospectively clarify the safety, problems, and mid-term outcomes of these methods after their coverage by the national health insurance. Methods: A total of 201 patients who underwent classical LECS/LECS-related procedures for gastric submucosal tumors (G-SMTs) in 21 institutions affiliated with the Laparoscopy Endoscopy Cooperative Surgery Study Group from April 2014 to March 2016 were included. Data was retrospectively obtained from the patients' charts. Results: The most common surgical procedure was classical LECS (155 patients, 77.1%), non-exposed endoscopic wall inversion surgery (22 patients, 11.4%), a combination of laparoscopic and endoscopic approaches to neoplasia with non-exposure technique (16 patients, 8%), and closed LECS (two patients, 1%). Only six (3%) patients underwent LECS with gastrostomy. The mean operative time and blood loss were 188.4 (70-462) minutes and 23.3 (0-793) g, respectively. Ten (5%) patients developed postoperative complications (Clavien-Dindo classification grade II or higher). Two patients needed reoperation due to postoperative bleeding or anastomotic leakage. All tumors were resected with negative margins. A total of 127 (63.2%) patients underwent follow-up observations for over 36 months, one of whom had a recurrence of peritoneal dissemination and one had poor oral intake. Conclusion: Classical LECS and LECS-related procedures for G-SMTs have favorable short/mid-term outcomes.

High levels of tumor cell-intrinsic STING signaling are associated with increased infiltration of CD8+ T cells in dMMR/MSI-H gastric cancer.

Mismatch repair deficient (dMMR)/microsatellite instability-high (MSI-H) gastric cancer (GC) exhibits an immune-active tumor microenvironment (TME) compared to MMR proficient (pMMR)/microsatellite stable/Epstein-Barr virus-negative [EBV (-)] GC. The tumor cell-intrinsic cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway has been considered a key regulator of immune cell activation in the TME. However, its significance in regulating the immune-active TME in dMMR/MSI-H GC remains unclear. Here, we demonstrated that tumor cell-intrinsic cGAS-STING was highly expressed in dMMR GC compared to pMMR/EBV (-) GC. The expression of tumor cell-intrinsic STING was significantly and positively associated with the number of CD8+ tumor-infiltrating lymphocytes in GC. Analysis of TCGA datasets revealed that the expression of interferon-stimulated genes and STING downstream T-cell attracting chemokines was significantly higher in MSI-H GC compared to other subtypes of GC with EBV (-). These results suggest that tumor cell-intrinsic STING signaling plays a key role in activating immune cells in the dMMR/MSI-H GC TME and might serve as a novel biomarker predicting the efficacy of immunotherapy for GC treatment.

Prognostic factors of second-line nivolumab monotherapy for unresectable or metastatic esophageal cancer: a multi-institutional cohort study for 184 cases.

BACKGROUND: The real-world efficacy, prognostic factors, and adverse events of second-line nivolumab monotherapy and subsequent third-line therapy for unresectable or metastatic esophageal cancer have not been fully evaluated. METHODS: This multi-institutional retrospective cohort study evaluated 184 consecutive patients treated with second-line nivolumab monotherapy for esophageal cancer between March 2021 and December 2022. We assessed tumor response, adverse events, long-term survival, and prognostic factors. RESULTS: Among 128 patients with measurable lesions, the response rate was 23% and the disease control rate for all enrolled patients was 45%. The incidence of grade 3 or higher adverse events was 14%, but no treatment-related deaths presented. Median progression-free survival was 5.1 months and overall survival was 14 months, respectively. C-reactive protein level and performance status were identified as significant prognostic factors of overall survival through Cox proportional hazards analysis. The group with two favorable prognostic factors showed better overall survival than the groups with either one or zero prognostic factors (median overall survival: 22, 15, and 4.4 months, respectively). Among 69 patients who received third-line taxane anticancer agents, the progression-free survival was 6.7 months. CONCLUSIONS: Our study demonstrated that the real-world outcomes of second-line nivolumab monotherapy were comparable to those of previous randomized clinical trials in terms of tumor response, safety, and long-term survival. Furthermore, a good performance status and low C-reactive protein levels may identify patients who are likely to benefit from therapy. Third-line chemotherapy after nivolumab treatment may have an enhanced effect; however, further prospective studies are required to confirm this finding.

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.

The ratio of intratumoral CD15+ neutrophils to CD8+ lymphocytes predicts recurrence in patients with gastric cancer after curative resection.

BACKGROUND: An elevated neutrophil-to-lymphocyte ratio (NLR) in peripheral blood is an independent prognostic indicator of various cancers. AIMS: In this study, we aimed to investigate the prognostic relevance of the intratumoral immune cell balance in gastric cancer. METHODS AND RESULTS: The study included 82 patients who underwent curative resection for gastric cancer. The intratumoral cluster of differentiation (CD) 15- and CD8-positive cells were evaluated using immunohistochemical staining. Additionally, clinicopathological factors and prognoses were analyzed. Patients with high intratumoral CD15/CD8 ratios had significantly lower overall survival (OS) and relapse-free survival (RFS) compared to those with low CD15/CD8 ratios (p = .0026 and p < .0001, respectively). Additionally, a high CD15/CD8 ratio was associated with lymph node metastasis (p = .019). Patients with high NLR had a significantly lower RFS than those with low NLR (p = .0050). Multivariate analysis revealed that the intratumoral CD15/CD8 ratio, NLR, and venous invasion were independent prognostic indicators of RFS (CD15/CD8 ratio: p < .001, hazard ratio (HR) = 14.7, 95% confidence interval (CI) = 3.8-56.8; NLR: p = .010, HR = 5.4, 95% CI = 1.5-19.6; venous invasion: p = .005, HR = 7.4, 95% CI = 1.8-29.7). CONCLUSION: In summary, we found that the intratumoral CD15/CD8 ratio is an independent prognostic factor following gastric cancer resection and its increase is associated with lymph node metastasis and microscopic lymph vessel invasion. Immunological evaluation with additional aspects of innate immunity may be useful in predicting cancer prognosis.

Tumor Infiltrating Effector Regulatory T Cells Express VEGF Receptor 2 in Patients With Colorectal Cancer.

BACKGROUND/AIM: Regulatory T cells (Tregs) suppress various anti-tumor immune responses in the tumor microenvironment (TME) and their control is considered essential to enhancing efficacy of cancer immunotherapy. The purpose of the study was to evaluate the strategy to regulate Tregs through the vascular endothelial growth factor (VEGF) pathway. MATERIALS AND METHODS: We evaluated VEGF receptor (VEGFR) expression in subtypes of Tregs by analysis of public databases and through flow cytometry by investigating surgically resected specimens and peripheral blood mononuclear cells (PBMCs) from 26 patients with advanced colorectal cancer (CRC). RESULTS: Analysis of The Cancer Genome Atlas colorectal adenocarcinoma dataset (n=592) showed that mRNA expression of both FLT1 (VEGFR1) and KDR (VEGFR2) was positively correlated with mRNA expression of FOXP3 as well as Treg signature. Clinical specimens revealed abundant VEGFR2 expression on Tregs, but very marginal VEGFR1 expression. The frequency of effector Tregs, the most immunosuppressive fraction of Tregs, was significantly higher in the tumor than in the PBMC and normal mucosa, and the majority of effector Tregs expressed VEGFR2. Furthermore, by using in vitro generated Tregs, the proportion of Tregs expressing IL-10 or TGF-ß1 was significantly inhibited by a VEGFR2 inhibitor. CONCLUSION: A therapeutic strategy targeting the VEGFR2 axis may have a potential to control effector Tregs in the CRC-TME.

TIM-3 Expression on Dendritic Cells in Colorectal Cancer.

TIM-3 was originally identified as a negative regulator of helper T cells and is expressed on dendritic cells (DCs). Since the inhibition of TIM-3 on DCs has been suggested to enhance T cell-mediated anti-tumor immunity, we examined its expression on DCs within the tumor microenvironment (TME) in colorectal cancer (CRC) using transcriptomic data from a public database (n = 592) and immunohistochemical evaluations from our cohorts of CRC (n = 115). The expression of TIM-3 on DCs in vitro was examined by flow cytometry, while the expression of its related molecules, cGAS and STING, on immature and mature DCs was assessed by Western blotting. The expression of HAVCR2 (TIM-3) was strongly associated with the infiltration of DCs within the TME of CRC. Immunohistochemical staining of clinical tissue samples revealed that tumor-infiltrating DCs expressed TIM-3; however, their number at the tumor-invasive front significantly decreased with stage progression. TIM-3 expression was higher on immature DCs than on mature DCs from several different donors (n = 6). Western blot analyses showed that the expression of STING was higher on mature DCs than on immature DCs, which was opposite to that of TIM-3. We demonstrated that TIM-3 was highly expressed on tumor-infiltrating DCs of CRC and that its expression was higher on immature DCs than on mature DCs.

The real-world data of immune-checkpoint inhibitor combination therapy for unresectable or metastatic esophageal cancer: a multi-institutional cohort study.

BACKGROUND: The real-world efficacy, feasibility, and prognostic factors of immune-checkpoint inhibitor combination therapy for unresectable or metastatic esophageal cancer are not fully established. METHODS: This multi-institutional retrospective cohort study evaluated 71 consecutive patients treated with immune-checkpoint inhibitor combination therapy for esophageal cancer between March 2021 and December 2022. We assessed tumor response, safety, and long-term survival. RESULTS: In patients with measurable lesions, the response rate was 58%, and the disease control rate for all enrolled patients was 80%. Five patients (7.0%) underwent successful conversion surgery. Grade 3 or higher immune-related adverse events occurred in 13% of patients, and one patient (1.4%) died due to cholangitis. Median progression-free survival was 9.7 (95% confidence interval: 6.5-not reached). C-reactive protein levels and performance status were identified as significant predictors of progression-free survival through Cox proportional hazards analysis. CONCLUSIONS: Immune-checkpoint inhibitor combination therapy for esophageal cancer demonstrated comparable tumor response, safety, and long-term survival to previous randomized clinical trials. Patients with good performance status and low C-reactive protein levels may be suitable candidates for this treatment.

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.

Combination of oligo-fractionated irradiation with nivolumab can induce immune modulation in gastric cancer.

BACKGROUND: Tumor-associated antigen (TAA)-specific CD8(+) T cells are essential for nivolumab therapy, and irradiation has been reported to have the potential to generate and activate TAA-specific CD8(+) T cells. However, mechanistic insights of T-cell response during combinatorial immunotherapy using radiotherapy and nivolumab are still largely unknown. METHODS: Twenty patients included in this study were registered in the CIRCUIT trial (ClinicalTrials.gov, NCT03453164). All patients had multiple distant metastases and were intolerance or had progressed after primary and secondary chemotherapy without any immune checkpoint inhibitor. In the CIRCUIT trial, eligible patients were treated with a total of 22.5 Gy/5 fractions/5 days of radiotherapy to the largest or symptomatic lesion prior to receiving nivolumab every 2 weeks. In these 20 patients, T-cell responses during the combinatorial immunotherapy were monitored longitudinally by high-dimensional flow cytometry-based, multiplexed major histocompatibility complex multimer analysis using a total of 46 TAAs and 10 virus epitopes, repertoire analysis of T-cell receptor ß-chain (TCRß), together with circulating tumor DNA analysis to evaluate tumor mutational burden (TMB). RESULTS: Although most TAA-specific CD8(+) T cells could be tracked longitudinally, several TAA-specific CD8(+) T cells were detected de novo after irradiation, but viral-specific CD8(+) T cells did not show obvious changes during treatment, indicating potential irradiation-driven antigen spreading. Irradiation was associated with phenotypical changes of TAA-specific CD8(+) T cells towards higher expression of killer cell lectin-like receptor subfamily G, member 1, human leukocyte antigen D-related antigen, T-cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domain, CD160, and CD45RO together with lower expression of CD27 and CD127. Of importance, TAA-specific CD8(+) T cells in non-progressors frequently showed a phenotype of CD45RO(+)CD27(+)CD127(+) central memory T cells compared with those in progressors. TCRß clonality (inverted Pielou's evenness) increased and TCRß diversity (Pielou's evenness and Diversity Evenness score) decreased during treatment in progressors (p=0.029, p=0.029, p=0.012, respectively). TMB score was significantly lower in non-progressors after irradiation (p=0.023). CONCLUSION: Oligo-fractionated irradiation induces an immune-modulating effect with potential antigen spreading and the combination of radiotherapy and nivolumab may be effective in a subset of patients with gastric cancer.

[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.

TIM-3 Expression and M2 Polarization of Macrophages in the TGFß-Activated Tumor Microenvironment in Colorectal Cancer.

TGFß signaling in the tumor microenvironment (TME) drives immune evasion and is a negative predictor of immune checkpoint inhibitor (ICI) efficacy in colorectal cancer (CRC). TIM-3, an inhibitory receptor implicated in anti-tumor immune responses and ICI resistance, has emerged as an immunotherapeutic target. This study investigated TIM-3, M2 macrophages and the TGFß-activated TME, in association with microsatellite instability (MSI) status and consensus molecular subtypes (CMSs). Transcriptomic cohorts of CRC tissues, organoids and xenografts were examined (n = 2240). TIM-3 and a TGFß-inducible stromal protein, VCAN, were evaluated in CRC specimens using immunohistochemistry (n = 45). TIM-3 expression on monocytes and generated M2 macrophages was examined by flow cytometry. We found that the expression of HAVCR2 (TIM-3) significantly correlated with the transcriptional signatures of TGFß, TGFß-dependent stromal activation and M2 macrophage, each of which were co-upregulated in CMS4, CMS1 and MSI CRCs across all datasets. Tumor-infiltrating TIM-3+ immune cells accumulated in TGFß-responsive cancer stroma. TIM-3 was increased on M2-polarized macrophages, and on monocytes in response to TGFß treatment. In conclusion, we identified a close association between TIM-3 and M2-like polarization of macrophages in the TGFß-rich TME. Our findings provide new insights into personalized immunotherapeutic strategies based on the TME for CRCs.

Immunological Responses Associated With Neoadjuvant Therapy in the Tumor Microenvironment of Esophageal Squamous Cell Carcinoma.

BACKGROUND/AIM: Development of multidisciplinary therapies including immune checkpoint inhibitors for esophageal squamous cell carcinoma (ESCC) requires a clear understanding of immunological responses induced by chemotherapy with/without radiotherapy in the tumor microenvironment. PATIENTS AND METHODS: This is a retrospective analysis of paired pretreatment biopsy samples and surgically resected tumor samples of 49 patients who underwent radical surgery for ESCC with/without neoadjuvant therapy at Fukushima Medical University Hospital. The cohort included 30 patients treated with neoadjuvant chemotherapy (NAC), 11 treated with neoadjuvant chemoradiotherapy (NACRT), and eight who underwent surgery alone and did not receive neoadjuvant antitumor therapy. Chemotherapy included fluoropyrimidine- and platinum-based agents in all treated patients, and radiotherapy included 40 or 42 Gy administered in 20 or 21 fractions. Expression of CD8, human leukocyte antigen (HLA) class I-ABC, PD-L1, PD-L2, CEACAM-1, LSECtin, and p-STAT1, were determined using immunohistochemistry. RESULTS: The frequency of tumor-infiltrating CD8+ T cells was significantly increased by NAC (p<0.05), and the expression of HLA class I-ABC on tumor cells was significantly increased by NAC and NACRT (p<0.05). Furthermore, the ESCC cells expressed PD-L1, PD-L2, and CEACAM-1, whereas the expression of PD-L1 on ESCC cells was significantly correlated with the expression of p-STAT1 in ESCC cells (p<0.05). CONCLUSION: NAC and NACRT induced both positive and negative immunological responses in patients with ESCC. These results may be a part of basis for multidisciplinary therapy including immune checkpoint inhibitors for patients with advanced ESCC.

Phase I/II clinical trial of nivolumab in combination with oligo-fractionated irradiation for unresectable advanced or recurrent gastric cancer.

BACKGROUND: Although immune checkpoint inhibitors (ICI) targeting for PD-1 axis is a promising approach for advanced gastric cancer (GC) patients, the response rate is still limited. Induction of synergistic effect of irradiation with ICI targeting for the PD-1 axis can be an attractive strategy. The aim of this study was to assess the effect of the combination of irradiation with anti-PD-1 therapy for advanced GC. METHODS: We conducted a single-arm, phase I/II trial in GC patients treated with a combination of nivolumab and oligo-fractionated irradiation (22.5 Gy/5 fractions/5 days) (NCT03453164). Eligible patients (n = 40) had unresectable advanced or recurrent GC which progressed after primary and secondary chemotherapy with more than one lesion. The primary endpoint is the disease control rate (DCR) of non-irradiated target lesions and the secondary endpoints are the median survival time (MST), safety, and DCR of irradiated lesions. RESULTS: We observe that the DCR for the non-irradiated target as the abscopal effect is 22.5% (90% confidence interval (CI), 12.3-36.0), and the DCR for the irradiated lesion is 40.0% (90% CI, 26.9-54.2). The median survival time is 230 days (95% CI, 157-330), and grade 3 and higher adverse events (AEs) are observed in 16 patients (39 %) with no obvious additional AEs when adding irradiation. CONCLUSIONS: The present study suggests that the combination of nivolumab with oligo-fractionated irradiation has the potential to induce a promising anti-tumor effect for advanced GC.

Immunotherapy is a type of treatment that triggers the immune system to kill cancers. Combining immunotherapy with radiotherapy may enhance its effects. We evaluated this in a clinical trial in which we treated patients with advanced or recurrent cancers of the stomach (gastric cancer) with a combination of immunotherapy and radiotherapy. The combination was able to control disease in a subset of patients and was safe, with no obvious additional adverse effects when adding radiotherapy. The median survival time­at which point half of the patients treated are still alive­was 230 days. While these results are promising, larger, more rigorous studies are needed to determine whether this combination therapy is better than alternative approaches to treating advanced or recurrent gastric cancers.

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.

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.

The Impact of Tumor Cell-Intrinsic Expression of Cyclic GMP-AMP Synthase (cGAS)-Stimulator of Interferon Genes (STING) on the Infiltration of CD8+ T Cells and Clinical Outcomes in Mismatch Repair Proficient/Microsatellite Stable Colorectal Cancer.

The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway plays a crucial role in activating immune cells in the tumor microenvironment, thereby contributing to a more favorable response to immune checkpoint inhibitors (ICI) in colorectal cancer (CRC). However, the impact of the expression of cGAS-STING in tumor cells on the infiltration of CD8+ T cells and clinical outcomes in mismatch repair proficient/microsatellite stable (pMMR/MSS) CRC remains largely unknown. Our findings reveal that 56.8% of all pMMR CRC cases were cGAS-negative/STING-negative expressions (cGAS-/STING-) in tumor cells, whereas only 9.9% of all pMMR CRC showed cGAS-positive/STING-positive expression (cGAS+/STING+) in tumor cells. The frequency of cGAS+/STING+ cases was reduced in the advanced stages of pMMR/MSS CRC, and histone methylation might be involved in the down-regulation of STING expression in tumor cells. Since the expression level of cGAS-STING in tumor cells has been associated with the infiltration of CD8+ and/or CD4+ T cells and the frequency of recurrence in pMMR/MSS CRC, decreased expression of cGAS-STING in tumor cells might lead to poor immune cell infiltration and worse prognosis in most pMMR/MSS CRC patients. Our current findings provide a novel insight for the treatment of patients with pMMR/MSS CRC.

Anti-PD-1 monoclonal antibody-resistant esophageal squamous cell carcinoma showing the abscopal effect: A case report with T-cell receptor/B-cell receptor repertoire analysis.

BACKGROUND: Several clinical trials of nivolumab have reported good results, including those in patients with advanced esophageal squamous cell carcinoma. However, the response rate of this drug remains poor. Notably, a rare phenomenon called abscopal effect refers to the regression of irradiated and nonirradiated distant tumors after local radiotherapy. Although the mechanism of this effect remains unclear, the antitumor immunity induced by radiotherapy is considered to be the most important factor. CASE: A 66-year-old man with recurrent nivolumab-resistant esophageal squamous cell carcinoma along with left-side cervical and abdominal para-aortic lymph node metastases was treated with a 40 Gy (10 fractions) dose of radiotherapy to the left-side cervical lymph node metastasis as a palliative treatment, which caused neck pain. In addition, nivolumab administration was resumed the day after completion of radiotherapy. Three months after radiotherapy, the irradiated lesion on the left neck had regressed to a scar-like lesion. Furthermore, the previously progressive abdominal para-aortic lymph nodes outside the irradiation area shrank (abscopal effect). T-cell receptor and B-cell receptor (TCR/BCR) repertoire analyses before and after radiotherapy revealed that radiotherapy led to changes in the TCR/BCR repertoire. CONCLUSION: Changes in the TCR/BCR repertoire may be a part of the mechanism underlying the abscopal effect. The findings of the present case suggest that the combination of immune checkpoint inhibitors and radiotherapy is a promising treatment approach even for patients with immune checkpoint inhibitor-resistant cancer.