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Background: Malignant pleural/peritoneal mesothelioma (MPM) is a rare, aggressive cancer with poor prognosis and high mortality of 65%-70% for pleural and 30% for peritoneal MPM. Patients who fail the standard therapy often survive less than 1 year, so it is urgent to develop new effective therapies for MPM patients. Chimeric antigen receptor (CAR)-T cells have been applied in MPM, but the efficacy was still limited due to immunosuppressive tumor microenvironment (TME). To overcome these obstacles, we developed armored CAR-T cells with nanobody targeting mesothelin (MSLN) and IFN-γ-activated secretion of PD-1 nanobody in a non-viral transposon system, named as BZDS1901. Preclinical studies have demonstrated cytotoxicity of the BZDS1901 in NCI-H226 lung/mesothelioma xenograft mouse model. To verify the safety and efficacy of BZDS1901, we conducted a single-arm, open label, dose-escalating clinical trials (NCT04503980, 05089266, 03615313) in solid tumors. Methods: Eligible patients were those who failed prior standard therapies with MSLN expression (≥50%) and PD-L1 positive in tumor specimen and voluntarily signed the informed consent. After apheresis and lymphodepletion with cyclophosphamide and fludarabine. BZDS1901 was administered intravenously in dose cohorts (1 × 106-2 × 107/kg) and the second infusion was given if no disease progression. After infusion, safety was evaluated during 28 days by the National Cancer Institute Common Terminology Criteria for Adverse Events version 5.0, efficacy was assessed by RECIST 1.1 or mRECIST with CT scan. Blood CAR copies were measured by qPCR, PD-1 nanobodies and cytokines by Meso Scale Discovery method, and T cell subtypes by flow cytometry. Patients’ progression-free survival (PFS) and overall survival (OS) were measured from the day of infusion to progression or death. Results: From July 20, 2020 to December 31, 2022, 11 MPM patients were enrolled and completed the assessment, while most patients received two infusions. BZDS1901 was safe, demonstrated by 54% grade 3 and 15% grade adverse events (AEs) that were hematological side effects due to lymphodepletion and reversible with supportive care. No on-target, off-tumor toxicity and dose-limiting toxicity were observed. All patients showed expansion of CAR-T cells and increased PD-1 nanobodies in circulation. CAR-T Cmax (cp/μg) copies number was 20062, and continually detectable in blood over 4 months. PD-1 Cmax (pg/ml) was 82841, and continually detectable in blood for up to 9 months. IFN- γ and IL-6 also increased at day 4 or Day 7. All patients obtained objective tumor response, one with complete response, six with partial response, and four with stable disease. The total objective response rate was 63.64%. All enrolled patients are still alive, and mPFS and mOS are not reached. The longest PFS was up to 26 months. Median follow-up was four months. Conclusions: PD-1 nanobody secreted and MSLN targeting CAR-T cells have demonstrated promising efficacy on MPM patients. Besides CAR-T direct tumor killing activity, secreted PD-1 nanobodies may provide additional clinical benefit by invigorating CAR-T from PD-L1 inhibition, activating TILs and relieving local immunosuppression. Citation Format: Zhuqing Liu, Yong Xia, Linlin Li, Yan Sun, Zhicai Lin, Lijie Rong, Zhongzheng Zhu, Zongchang Song, Hui Xue, Jianchun Duan, Shujing Shen, Jing Wang, Linjie Lv, Yaping Yang, Xue Tan, Liping Han, Wei Zhao, Jie Wang, Wenfeng Xu, Weimin Zhu, Zhong Li, Xingya Li, Jinxing Lou, Qing Xu, Qijun Qian. Non-viral mesothelin-targeted CAR-T cells armored with IFNg-induced secretion of PD-1 nanobody in treatment of malignant mesothelioma in phase I clinical trial [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT134.

Radiation enteritis is one of the most common side effects of ionizing radiation in patients with pelvic cancers. Increasing amounts of evidence indicate that pro-inflammatory responses significantly contribute to the development of radiation enteritis. In this study, we investigated the association between T regulatory (Treg) cells and the risk of developing radiation enteritis in cervical cancer patients. The following observations were made. First, the frequencies of CD25hiFoxp3+ Treg cells were significantly lower in patients with radiation enteritis than in both healthy subjects and cervical cancer patients without radiation enteritis. Also, patients with the more severe grade 3 enteritis presented significantly lower Treg levels than patients with the more common grade 1 enteritis. Second, the expression of several molecules associated with Treg function, including CTLA-4, IL-10, TGF-β, and perforin, was significantly lower in patients with radiation enteritis than in healthy subjects. In patients without radiation enteritis, however, only CTLA-4, but not other Treg-associated suppressive molecules, was reduced in Treg cells. Third, Treg cells can markedly suppress CD8 T cell proliferation, but in patients with radiation enteritis, this function of Treg cells was significantly impaired, in a manner that was associated with lower CTLA-4 expression. Overall, these data suggest that the frequency and function of Treg cells is negatively associated with the risk of developing enteritis following radiation. In clinical practice, the characteristics of Treg cells may be considered to evaluate the risk of developing enteritis if the cancer patient is receiving ionizing radiation.

e17535 Background: Ovarian cancer is the most lethal gynecologic malignancy and the fifth leading cause of cancer-related death among women. Most of patients often have refractory or relapse. We have developed a CAR T cell secreting PD-1 nanoantibodies and targeting mesothelin (αPD-1-mesoCAR-T) and conducted a phase I clinical trial for evaluation of safety and efficacy of the αPD-1-mesoCAR-T cells in gynecologic tumors. Methods: This study is a single-arm, open, dose-increasing clinical study and two infusions (interval 14-35 days). Patients with advanced gynecological cancer were enrolled when immunohistochemical analysis for positive mesothelin over 70% and failed second-line treatment in Mengchao Cancer Hospital affiliated to Shanghai University and Shanghai Tenth People's Hospital affiliated to Tongji University. All patients underwent lymphodepletion before infusion at a dose of 1 to 15x106/kg. CAR copies, nanobody levels, cytokines, T lymphocyte subtypes were determined before and after infusion. Results: a total of 7 patients were enrolled so far and completed the first evaluation. After treatment, most symptoms of the patients were alleviated, two patients (#2, #3) had their lesions decreased. By RECIST 1.1, all 7 patients’ diseases became stable, and the disease control rate was 100%. The PFS of #3 patient with stable disease (SD) was 5.3 months, the patient #2 was 4.1 months. The frequent adverse events were fever, fatigue, nausea and pruritus. No sever adverse events above grade 3 occurred. The number of CAR-T cells in the peripheral blood increased significantly during day 4-14 after the infusion, and the PD-1 nanoantibody levels and the contents of INF-γ、IL-6、IL-2 and MCP-1 also increased at day 1-4. Conclusions: The preliminary clinical study showed that the aPD-1-mesoCAR-T cells are safe for the treatment of gynecologic cancer and stabilized the diseases. More data of the treatment is warrantied to continually follow up these patients.

8559 Background: Malignant pleural/peritoneal mesothelioma (MPM) is an aggressive cancer characterized by poor therapeutic response and poor survival. Programmed cell death protein-1 (PD-1)-mediated immunosuppression is believed to be associated with T cell exhaustion and dysfunction in solid tumors. We generated chimeric antigen receptor (CAR-T) cells that can secret PD-1 nanobodies and target mesothelin (PD-1-mesoCAR-T). After identifying the anti-tumor activity and cytotoxicity of PD-1-mesoCAR-T cells by pharmacokinetics and pharmacodynamics, we conducted a proof-of-concept clinical trial in the Shanghai Tenth People's Hospital affiliated to Tongji University and the Mengchao Tumor Hospital affiliated to Shanghai University to evaluate the safety and efficacy of PD-1-mesoCAR-T cells in a dose-escalation study for malignant pleural/peritoneal mesothelioma. 6 patients received one or more infusions of the CAR-T cells with prior lymphodepletion and the longest survival is up to 18 months. Methods: This open-label, single-arm, multicenter, phase 1 study was enrolled patients with pathological diagnosis with malignant mesothelioma whose mesothelin expression in immunohistochemical samples was equal or greater than 50%. Immunohistochemical samples derived from surgical tissue, puncture tissue or pleural effusion. PD-1-mesoCAR-T cells were administered intravenously ranging 1×106−1.5×107/kg. Safety and efficacy were assessed in response-evaluable patients (ie, patients who received at least one dose of PD-1-mesoCAR-T and had at least one post-baseline response evaluation). Results: From July 20, 2020 to January 31, 2022, 9 patients were screened and enrolled and only 6 patients were evaluable. Mesothelin positive rate in the samples of these patients were from 50% to 100%. Three patients of them had PD-L1 positive staining in specimen. All patients underwent lymphodepletion before infusion. Two of patients (33.3%) had cytokine release syndrome, which were grade 1 and grade 3, respectively. Four patients (66.7%) developed fever. Two patients (25%) had grade 3 pulmonary infection. Stable disease was sustained for ≥3 months in 5 patients; 1 exhibited complete response and one partial response on PET or CT scan. The objective response rate (ORR) was 33.3%, but increased to 66.7% in the patients with PD-L1 positive. Only one patient of these patients appeared progression of disease after infusion. All enrolled patients are alive and observed continually. Conclusions: The clinical study of 6 patients with malignant mesothelioma shows that PD-1-mesoCAR-T cells are safe and feasible, indicating a promising curative effect. Effect of the CAR-T cells on the long term survival will be observed continually. Clinical trial information: 01722149.

Chronic hepatitis B virus (HBV) infection is a complex disease with dysregulations in the immune system. Follicular helper T (Tfh) cells are professional B helper cells that are crucial to the development of antibody responses and are involved in a variety of diseases. In this study, we examined the circulating Tfh cells in patients with chronic HBV infection. We observed that CD3+CD4+CXCR5+ circulating Tfh cells contained a CD25+Foxp3+ Treg-like subset that was significantly enriched in patients with chronic HBV infections. The CD25+ Tfh subset presented distinctive cytokine secretion profile, such as lower interferon (IFN)-γ and interleukin (IL)-17, and higher transforming growth factor (TGF)-β secretion, compared to the CD25- Tfh subset. When incubated with autologous naive CD10-CD27-CD19+ B cells, the CD25+ Tfh subset was less capable of mediating CD20-/loCD38+ plasmablast differentiation than the CD25- Tfh subset. In terms of Ig production, CD25+ Tfh cells were more potent at inducing IgM but less potent at inducing IgG and IgA than CD25- Tfh cells. Interestingly, B cells following incubation with CD25+ Tfh cells presented elevated regulatory function, with higher production of IL-10 and enhanced capacity of suppressing autologous CD8+ T cell inflammation. In the chronic HBV-infected patients, the frequency of IL-10+ B cells and the HBV viral load were positively correlated with the frequency of CD25+Foxp3+ CD4+CXCR5+ Tfh cells. Together, this study presented that CD25+Foxp3+ Treg-like Tfh cells were enriched in chronic HBV-infected patients and could promote regulatory B cell functions.

IL10 is generally regarded as a broad-spectrum regulatory cytokine. However, the role of IL10 in CD8 T cells remains controversial. In this study, we investigated the characteristics of endogenous IL10 by CD8 T cells in gastric cancer (GC) patients. Using intracellular staining, we found that in both GC patients and healthy controls, the majority of IL10-expressing CD8 T cells also presented concurrent IFNg expression. Interestingly, the frequency of IFNg+IL10+ CD8 T cells was significantly higher in GC patients than in healthy controls, while the frequency of IFNg+IL10- CD8 T cells was significantly lower in GC patients than in healthy controls. Compared to the IFNg-IL10- CD8 T cells, both IFNg+IL10- and IFNg+IL10+ CD8 T cells presented significantly higher expression of activation/inhibitory markers. Interestingly, the IFNg+IL10+ cells presented lower PD1 and TIM3 and higher KLRG1 than the IFNg+IL10- CD8 T cells. Remarkably, the IFNg+IL10+ CD8 T cells, but not the IFNg+IL10- CD8 T cells, were highly enriched in the CD45RO+CXCR5+ subset. Prolonged activation resulted in significant enrichment of IFNg+IL10+ CD8 T cells over time. Interestingly, compared to the CD45RO+CXCR5- CD8 T cells, the CD45RO+CXCR5+ CD8 T cells presented stronger proliferation capacity at later stages of stimulation, and higher viability throughout the stimulation process. Overall, our investigation demonstrated that GC patients were enriched with a distinctive population of IFNg+IL10+ double positive CD8 T cells, which resembled T follicular cytotoxic cells and could persist longer during prolonged activation., Highlights • Gastric cancer patients presented an enrichment of IFNg+IL10+ CD8 T cells. • IFNg+IL10+ CD8 T cells showed unique patterns of PD1, KLRG1, and TIM3 expression. • IFNg+IL10+ CD8 T cells were enriched during prolonged stimulation. • CD45RO+CXCR5+ CD8 T cells presented better proliferation and lower death.

Purpose: Malignant gliomas are the most common tumors in the central nervous system with a poor prognosis. Recently, CD4+ cytotoxic T cells (CTLs) are being increasingly recognized as possessing antitumor capacity. However, their presence, activity and regulation in glioma have not been investigated in detail. Methods: To examine this, 72 grade II and grade III Han Chinese glioma patients and 30 Han Chinese healthy controls were investigated. Results: We found that compared to healthy controls, glioma patients had significantly upregulated frequencies of circulating CD4+ CTLs, identified by the expression of granzyme A (GzmA), granzyme B (GzmB) and/or perforin. The stimulated CD4+ CTLs in grade II and grade III glioma patients also had less proliferative ability than those in healthy controls, a feature of suppression that progressed with tumor grade. The frequencies of GzmB-expressing circulating CD4+ CTLs were directly associated with prognosis. We hypothesized that the programed death 1 (PD-1)/PD-ligan...

Gastric cancer is one of the most lethal malignancies worldwide. Chronic Helicobacter pylori (H. pylori) infection can induce an inflammatory response that promotes atrophic gastritis, a preceding event to cancer development. The type 1 regulatory T (Tr1) cells have recently emerged as a critical participant in maintaining self-tolerance. In this study, we examined Tr1 cells in H. pylori infection and gastric cancer development. While H. pylori-uninfected (uninfected) subjects presented low Tr1 frequency in the peripheral blood, H. pylori-infected asymptomatic (infected) individuals and H. pylori-infected gastric cancer (cancer) individuals both presented elevated Tr1 frequency. Although the Tr1 cells from infected asymptomatic subjects were functionally more potent than those from uninfected healthy subjects, the Tr1 cells in cancer individuals demonstrated several functional impairments, such as reduced interleukin 10 (IL-10) expression, lower secretion of cytolytic factors including granzyme B and perforin, and lower capacity to suppress CD4+CD25- T cell and CD8+ T cell proliferation. In addition, the frequency and function of Tr1 cells were positively correlated with the disease-free survival of the gastric cancer patients. These results suggest that Tr1 cells might be involved in the regulating immune responses in H. pylori infection and gastric cancer development. The fact that Tr1 cells could suppress inflammation and produce cytotoxic molecules at the same time has made them attractive potential candidates for future immunotherapies.

Recent researches have suggested that autophagy may play critical roles in tumorigenesis. Immunity-related GTPase family M (IRGM) is a human protein highlighted for its contribution to autophagy upon inflammation and infections. Studies have shown that IRGM is involved in the development of several cancers. In the current study, we investigated expression of IRGM and gastric cancer. Levels of messenger RNA (mRNA) and protein were examined by real-time reverse transcription PCR (RT-PCR) and Western blot, respectively. Data showed that mRNA level of IRGM was significantly increased in peripheral blood mononuclear cells (PBMCs) of gastric cancer patients than in PBMCs from healthy controls (p > 0.05). Moreover, both mRNA and protein levels were significantly higher in cancer tissues compared to adjacent noncancerous stomach tissues (1.28-fold, p < 0.001; 1.19-fold, p < 0.01, respectively). However, the level of IRGM seemed not to be affected by Helicobacter pylori infection. In addition, we investigated the correlation between IRGM expression and cancer stages and identified that stage IV patients had upregulated mRNA level and protein level of IRGM in cancer tissues than those stage I patients. Our findings suggest that expression of IRGM is dysregulated in gastric cancer and that the molecule may affect progression of the disease.

Background/Aims: Gastric cancer is a highly aggressive tumor containing cancer stem cells (CSCs), which participate in tumor initiation, therapeutic resistance, and tumor relapse. Proline-rich protein 11 (PRR11) has been shown to be up-regulated in human cancers; however, its role in gastric CSCs is unknown. We hypothesize that PRR11 may affect tumorigenicity of gastric CSCs. In this study, we explored the biological function and regulation of PRR11 in gastric CSCs. Methods: Expression of PRR11 was evaluated in gastric CSC cell line by real-time quantitative PCR and western blot. The effect of PRR11 on tumorigenicity was examined by interference with gene expression using lentiviral vector-loaded shRNA. A xenograft tumor model using NOD/SCID mice was established to examine the role of PRR11 in tumor development. Results: Data showed that PRR11 was highly expressed in gastric CSCs. PRR11 was responsible for the maintenance of self-renewal and tumorigenicity of gastric CSCs, and overexpression of exogenous PRR11 could restore the self-renewal of gastric non-CSCs. Furthermore, interference with PRR11 altered the expression of stemness transcription factors. Interestingly, MAPK signaling controlled PRR11 expression by increasing PRR11 protein stability, and maintained gastric CSCs self-renewal in a PRR11 dependent manner. Conclusions: PRR11 regulated self-renewal and tumorigenicity of gastric CSCs through MAPK signaling, and could be used as a therapeutic target for gastric cancer.

Gastric cancer is one of the most common and aggressive malignancies. Both bacterial virulence factors and host chronic inflammation are thought to promote gastric cancer development. In this study, we investigated the potential involvement of follicular helper T cells in gastric cancer. Functions of follicular helper T subsets were examined in Helicobacter pylori –infected gastric cancer patients and H. pylori –infected but asymptomatic individuals. We found that the follicular helper T cells in gastric cancer individuals were skewed toward the Th1 and Th17 subsets compared to those in H. pylori –infected but asymptomatic individuals. In a naive B cell–follicular helper T cell coculture, the Th1–follicular helper T cells by themselves were ineffective at stimulating a robust antibody response, unlike the Th2–follicular helper T and Th17–follicular helper T cells. However, Th1–follicular helper T cells significantly promoted the immunoglobulin G response in collaboration with other follicular helper T subsets, through the secretion of interferon gamma. We also found that Th1–follicular helper T cells suppressed the development of interleukin-10 + regulatory B cells, a cell type previously thought to protect H. pylori –infected individuals from tissue damage. In addition, the frequency of Th1–follicular helper T cells in gastric cancer patients was negatively correlated with the disease-free survival of gastric cancer patients after tumor resection. These results suggested that dysregulation of follicular helper T subsets in gastric cancer patients, characterized by increased Th1–follicular helper T cells, contributed to inflammation and tumor development.

The tumor microenvironment harbors multiple immunosuppressive mechanisms, many of which involve suppressive immune cells. B regulatory (Breg) cells, as critical regulators of immune responses, were investigated in patients with gastric carcinoma. In the present study, the B cells that expressed IL-10 were highly enriched in tumor-infiltrating B cells, and could also be found at reduced frequencies in circulating B cells. These cells expressed high CD19 and CD20, and were almost exclusively CD27+CD10-. The IL-10 expression was significantly higher in CD27+CD10--sorted B cells than in CD27-CD10--sorted B cells. In an in vitro coculture of B cells and autologous T cells, CD27+CD10- B cells were capable of reducing the levels of CD4 T cell-mediated IFNγ, TNF, and IL-17 expression and the levels of CD8 T cell-mediated IFNγ and TNF expression. These regulatory effects were dependent on IL-10 as well as CD80/CD86. Interestingly, CD27+CD10- B cells also significantly elevated IL-10 production from CD4 and CD8 T cells in an IL-10-dependent manner. Overall, we here report enrichment of IL-10-expressing CD27+CD10- B cells in the intratumoral environment, which could significantly alter the cytokine production profile by CD4 and CD8 T cells.

Malignant gliomas are the most common tumors in the central nervous system with a poor prognosis. Recently, CD4To examine this, 72 grade II and grade III Han Chinese glioma patients and 30 Han Chinese healthy controls were investigated.We found that compared to healthy controls, glioma patients had significantly upregulated frequencies of circulating CD4These data suggest that the CD4

While infection with H. pylori is a strong risk factor for gastric cancer, most H. pylori-colonized individuals, even those with the high-risk CagA(+)VacA(+) strain, remain asymptomatic over their lifetime. We hypothesized that the discordant outcomes were due to differences in the host immune responses. Previously, Tim-3-mediated immune modulation was observed in H. pylori-challenged mice. In this study, we compared Tim-3-related responses in CagA(+)VacA(+) H. pylori-infected asymptomatic individuals and H. pylori-associated gastric adenocarcinoma patients. We showed that compared to H. pylori-uninfected individuals, both H. pylori-infected asymptomatic and gastric cancer patients upregulated Tim-3 overall. However, the Tim-3 upregulation was enriched on Th1 cells in asymptomatic patients and on Treg and CD8(+) T cells in gastric cancer patients, with respective differences in T cell subset functions. In gastric cancer patients, high Tim-3 expression on Treg and CD8(+) T cells, but not on Th1 cells, was associated with worse prognosis. H. pylori-antigen presentation by tumor-associated macrophages upregulated Tim-3 expression more effectively than by blood monocyte-derived macrophages in vitro. The upregulation of Tim-3 in vitro depended on the concentration of H. pylori antigen but not on whether the cells were from asymptomatic or cancer patients. These data suggest that the discrepancy in Tim-3 upregulation in asymptomatic and cancer subjects is induced by cancer but not the other way around. Once gastric cancer is developed, Tim-3 expression is associated with worse prognosis.

Helicobacter pylori infection occurs in more than half of the world's population and is the main cause for gastric cancer. A series of lifestyle and nutritional factors, such as tobacco smoking and obesity, have been found to elevate the risk for cancer development. In this study, we sought to determine the immunological aspects during H. pylori infection and gastric cancer development. We found that B cells from H. pylori-infected patients presented altered composition and function compared to uninfected patients. IL-10-expressing CD24+CD38+ B cells were upregulated in H. pylori-infected patients, contained potent regulatory activity in inhibiting T cell pro-inflammatory cytokine secretion, and responded directly to H. pylori antigen stimulation. Interestingly, in H. pylori-infected smoking subjects and obese subjects, the number of IL-10+ B cells and CD24+CD38+ B cells were reduced compared to H. pylori-infected asymptomatic subjects. Regulatory functions mediated by CD24+CD38+ B cells were also impaired. In addition, gastric cancer positive patients had reduced IL-10-producing B cell frequencies after H. pylori-stimulation. Altogether, these data suggest that in H. pylori-infection, CD24+CD38+ B cell is upregulated and plays a role in suppressing pro-inflammatory responses, possibly through IL-10 production, a feature that was not observed in smoking and obese patients.

PRR11 is a potential candidate oncogene that has been implicated in the pathogenesis of lung cancer, however the role of PRR11 in gastric cancer is currently unclear. In the present study, we investigated the role of PRR11 in gastric cancer by evaluating its expression status in samples from a cohort of 216 patients with gastric cancer. PRR11 was found to be overexpressed in 107 (49.5%) patients by immunohistochemistry of tissue microarrays generated using the patient samples. Furthermore, PRR11 overexpression was found to correlate significantly with clinicopathologic features such as tumor invasion, tumor differentiation, and disease stage. Survival analysis of the cohort revealed that PRR11 is an independent prognostic factor for gastric cancer patients. PRR11 was stably silenced in a gastric carcinoma cell line using an shRNA-based approach, and treated cells showed decreased cellular proliferation and colony formation in vitro and cell growth in vivo, companied by decreased expression of CTHRC1 and increased expression of LXN, proteins involved in tumor progression. Evaluation of human gastric cancer samples demonstrated that PRR11 expression was also associated with increased CTHRC1 and decreased LXN expression. These data indicate that PRR11 may be widely activated in human gastric cancer and are consistent with the hypothesis that PRR11 functions as an oncogene in the development and progression of gastric cancer.

CD8+ T cells are considered to be critical in tumor surveillance and elimination. Increased CD8+ T cell frequency and function is associated with better prognosis in cancer patients. Interleukin 10 is a cytokine with controversial roles in CD8+ T cell–mediated anti-tumor immunity. We therefore examined the interleukin 10 expression and consumption in CD8+ T cells harvested from the peripheral blood and resected tumors of gastric cancer patients of stages II–IV. We found that the gastric cancer patients presented significantly elevated frequencies of interleukin 10–expressing cells in both CD4+ and CD8+ T cells compared to healthy controls. But distinctive from the interleukin 10–expressing CD4+ T cells, which increased in frequency in advanced cancer, the interleukin 10–expressing CD8+ T cells did not increase with cancer stage in the peripheral blood and actually decreased with cancer stage in resected tumor. Interleukin 10 and interleukin 10 receptor expression was also enriched in interferon gamma–expressing activated CD8+ T cells. Compared to interleukin 10–nonexpressing CD8+ T cells, interleukin 10 receptor–expressing CD8+ T cells secreted significantly elevated interferon gamma levels. Treatment of anti-CD3/CD28-stimulated, purified CD8+ T cells with interleukin 10 alone could significantly enhance CD8+ T cell survival, an effect dependent on interleukin 10 receptor expression. Interleukin 10 also increased CD8+ T cell proliferation synergistically with interferon gamma but not alone. Analysis of downstream signal transducer and activator of transcription molecules showed that interleukin 10 treatment significantly increased the phosphorylation of signal transducer and activator of transcription 3 and signal transducer and activator of transcription 1 to lesser extent. Together, these results demonstrate that interleukin 10 possessed stimulatory roles in activated CD8+ T cells from gastric cancer patients.