Effects of platelets on characteristics of lymphocytes cultured in vitro and optimization of adoptive immunotherapy

T lymphocytes,the main participants of cellular immunity,can express a variety of surface molecules and form different lymphocyte subsets under the induction of different factors to play the functions of immune regulation and immune killing.Studies have shown that platelets play a crucial role in maintaining the stable differentiation of lymphocytes and the balance in immunomodulation.Therefore,it is necessary to study the effect of platelets on lymphocytes in vitro to better understand the role of platelets in the immune system and broaden the application of adoptive immunotherapy.Methods:Cell counting and microscopic observation were used to detect the effect of activated platelets on lymphocyte proliferation in vitro;Flow cytometry was used to detect whether changes in platelet activity affect the proportion of lymphocyte subpopulations in vitro,and to detect differences in the expression of granzyme B;lactate dehydrogenase assay(LDH)was used to determine the difference in lymphocyte killing activity caused by platelet activity in vitro.Results:This was the first to promote lymphocyte proliferation through the expression or release of certain molecules in vitro,demonstrating that platelet activation is one of the key factors.Secondly,activated platelets or inactivated platelets promoted lymphocyte subset differentiation by enhancing the proportion of CD3+CD8+T lymphocytes(CTL cells)but had a slight effect on the proportion of CD3+CD4+T(Th cells)and CD4+CD25+T lymphocytes(Treg cells).Then,it was found that either activated platelets or inactivated platelets down-regulated the proportion of natural killer(NK)T lymphocytes,while activated platelets significantly enhance the proportion of NK lymphocytes.Therefore,by further detecting the killing activity of PBMCs treated with platelets,it was found that activated platelets promoted the extensive anti-tumor activity of lymphocytes and significantly increased the expression of granzyme B.Conclusion:Our results suggest that activated platelets promote lymphocyte proliferation,optimize lymphocyte subpopulation ratio,and promote cytotoxic effect of lymphocytes in vitro,which may provide a new strategy for optimizing the adoptive immunotherapy culture system and improving its efficacy.

Prolonged overall survival in gastric cancer patients after adoptive immunotherapy

AIM:To assess the efficacy of immunotherapy with expanded activated autologous lymphocytes(EAALs) in gastric cancer.METHODS:An observational study was designed to retrospectively analyze the clinical data of 84 gastric cancer patients,of whom 42 were treated by EAAL immunotherapy plus conventional treatment and another 42 only received conventional treatment(control group).EAALs were obtained by proliferation of peripheral blood mononuclear cells from patients followed by phenotype determination.Clinical data including age,gender,clinical stage,chemotherapeutic regimens,hospitalization,surgical,radiotherapy,and survival data were collected along with EAAL therapy details and side effects.Patients were followed and the relationship between treatment and overall survival(OS) data obtained for the immunotherapy and control groups were compared retrospectively.The safety of EAAL immunotherapy was also evaluated.RESULTS:After in vitro culture and proliferation,the percentages of CD3+,CD3+CD8+,CD8+CD27+,CD8+CD28+,and CD3+CD16+/CD56+cells increased remarkably(P < 0.05),while the percentages of CD3+CD4+,CD4+CD25+,and CD3-CD16+/CD56+(natural killer cells) were overtly decreased(P < 0.05); no significant change was observed in CD4+CD25+CD127- cells(P =0.448).Interestingly,OS in the immunotherapy group was significantly higher than that in the control group,with 27.0 and 13.9 mo obtained for the two groups,respectively(P =0.028,HR =0.573,95%CI:0.347-0.945).These findings indicated a 42.7% decrease in the risk of death.In addition,we found that clinical stage and application of EAAL immunotherapy wereindependent prognostic factors for gastric cancer patients.Indeed,the OS in stage Ⅲc and Ⅳ patients that had received surgery was prolonged after EAAL immunotherapy(P < 0.05).Importantly,in vitro induction and proliferation of EAAL were easy and biologically safe.CONCLUSION:Overall,EAAL adoptive immunotherapy might prolong the OS in gastric cancer patients.

Adoptive immunotherapy for acute leukemia:New insights in chimeric antigen receptors

Relapses remain a major concern in acute leukemia. It is well known that leukemia stem cells(LSCs) hide in hematopoietic niches and escape to the immune system surveillance through the outgrowth of poorly immunogenic tumor-cell variants and the suppression of the active immune response. Despitethe introduction of new reagents and new therapeutic approaches, no treatment strategies have been able to definitively eradicate LSCs. However, recent adoptive immunotherapy in cancer is expected to revolutionize our way to fight against this disease, by redirecting the immune system in order to eliminate relapse issues. Initially described at the onset of the 90's, chimeric antigen receptors(CARs) are recombinant receptors transferred in various T cell subsets, providing specific antigens binding in a non-major histocompatibility complex restricted manner, and effective on a large variety of human leukocyte antigen-divers cell populations. Once transferred, engineered T cells act like an expanding "living drug" specifically targeting the tumor-associated antigen, and ensure long-term antitumor memory. Over the last decades, substantial improvements have been made in CARs design. CAR T cells have finally reached the clinical practice and first clinical trials have shown promising results. In acute lymphoblastic leukemia, high rate of complete and prolonged clinical responses have been observed after anti-CD19 CAR T cell therapy, with specific but manageable adverse events. In this review, our goal was to describe CAR structures and functions, and to summarize recent data regarding pre-clinical studies and clinical trials in acute leukemia.

Is the CD4/CD8 Ratio an Effective Indicator for Clinical Estimation of Adoptive Immunotherapy for Cancer Treatment?

Background: The importance of immunotherapy in cancer treatment has been increased owing to its non-toxicity and application to personalized medicine. However, precise estimation indices of immunotherapy have yet to be established. To determine effective evaluation indices of immunotherapy for cancer treatment, we analyzed the CD4/CD8 ratio under various conditions in clinical patients with advanced cancer. Patients and Methods: Thirty-four patients who underwent one course of adoptive activated immunotherapy with or without additional conventional chemotherapy were enrolled. Before and after one course of immunotherapy, changes in the CD4/CD8 ratio were estimated by flow cytometry. Results: All patients showed a tendency toward a decrease in the CD4/CD8 ratio during a 3-month period after one course of adoptive activated T lymphocyte immunotherapy. Patients who had undergone prior surgery showed a remarkable increase in CD8 T cell number. Thus, adoptive activated T lymphocyte immunotherapy improves immunological ability against cancer invasion. The Eastern Cooperative Oncology Group’s performance status during one course of immunotherapy was significantly improved in the antecedent surgery group, with no evidence of improved PS in the non-antecedent surgery group. Patients with an increased CD4/CD8 ratio (n = 6) may have a worse outcome during adoptive activated T lymphocyte immunotherapy even with an additional course of immunotherapy. Improved actuarial survival rate of patients in the antecedent surgery group showed significant long-term benefit compared to those in the non-antecedent surgery group (p = 0.0298), as previously reported. Conclusion: The CD4/CD8 ratio is a significant indicator of outcome of adoptive activated T lymphocyte immunotherapy.

The status,limitation and improvement of adoptive cellular immunotherapy in advanced urologic malignancies

In recent years, immunotherapy has been gradually established as the fourth frequently adopted antitumor therapy, following surgery, chemotherapy and radiotherapy, for advanced urologic malignancies with an improved understanding of theoretical basis, such as molecular biology and immunology. Thereinto, adoptive cellular immunotherapy （ACI） has become one of the hotspots, which comprises a variety of treatment approaches, such as TIL, CIK cell, ~＇~ T cell, CAR-engineered T cell and Allogeneie stem cell transplantation （alloSCT）. Although preclinical efficacy has been demonstrated remarkably, clinical trials could not consistently show the benefit due to multi-factors in complex immnnosuppressive microenvironment in vivo compared to that of in vitro. Here we review some timely aspects of ACI for advanced urologic malignancies, and describe the current status and limitation of immunotherapy from the cellular level. It＇s our expectation to provide prompting consideration of novel combinatorial ACI strategies and a resurgence of interest in ACI for advanced urologic malignancies.

Autograft mediated adoptive immunotherapy of cancer in the context of autologous stem cell transplantation

The infused stem cell autograft in autologous stem cell transplantation(ASCT)has been viewed mainly as hematologic rescue from the myelosuppressive side effect of conditioning regimens.However,recent reports have shown that the immune effector cells collected at the same time as the stem cells can produce an autologous graft-versus-tumor effect,similar to the graft-versus-tumor effect seen in allogeneic stem cell transplantation without the detrimental effects of graftversus-host disease.In this article,we review the different immune effector cells collected and infused from the stem cell autograft and their association with clinical outcome post-ASCT,suggesting that ASCT can be viewed not only as a therapeutic maneuver to recover bone marrow function after deliver high-dose chemotherapy,but also as an adoptive immunotherapeutic intervention capable of eradicating residual tumor cells in patients with cancer.

Increasing the frequency of CIK cells adoptive immunotherapy may decrease risk of death in gastric cancer patients

AIM: To analyze the correlation between cytokineinduced killer (CIK) cells adoptive immunotherapy and cancer-related death in gastric cancer patients. METHODS: One hundred and fifty-six gastric cancer patients after operation at the Third Affiliated Hospital of Soochow University were enrolled in this study. Their clinical data including demographic characteristics, operation time, tumor size, pathological type and staging, tumor metastasis, outcome of chemotherapy or CIK cells adoptive immunotherapy, survival time or time of death were collected with a standard structured questionnaire. Kaplan-Meier method was used to estimate the median survival time, and the 2- and 5- year survival rates. Hazard risk (HR) and 95% confidence interval (95% CI) of CIK cells adoptive immunotherapy for gastric cancer were calculated using the two-stage time-dependent covariates Cox model. RESULTS: The survival time of gastric cancer patients was longer after CIK cells adoptive immunotherapy than after chemotherapy (χ 2 = 10.907, P = 0.001). The median survival time of gastric cancer patients was also longer after CIK cells adoptive immunotherapy than after chemotherapy (49 mo vs 27 mo, P < 0.05). The 2- and 5-year survival rates of gastric cancer patients were significantly higher after CIK cells adoptive immunotherapy than after chemotherapy (73.5% vs 52.6%, 40.4% vs 23.9%, P < 0.05). A significant difference was observed in the survival curve for patients who received CIK cells adoptive immunotherapy (0, 1-10, 11-25, and over 25 frequencies) (χ 2 = 14.534, P = 0.002). The frequencies of CIK cells adoptive immunotherapy were significantly related with the decreasing risk of death in gastric cancer patients after adjustment for sex and age of the patients, tumor stage and relapse (HR = 0.54, 95% CI: 0.36-0.80) when the first stage Cox model was used to define the subjects who remained alive beyond 36 mo as survivors. However, no correlation was observed between the frequencies of death in CIK cells adoptive immunotherapy and the risk of gastric cancer patients (HR = 1.09, 95% CI: 0.63-0.89) when the second stage Cox model was used to define the subjects who survived for more than 36 mo as survivors. CONCLUSION: The survival time of the gastric cancer patients treated with chemotherapy combined with CIK cells adoptive immunotherapy is significantly longer than that of the patients treated with chemotherapy alone and increasing the frequency of CIK cells adoptive immunotherapy seems to benefit patients more.

Immunotherapy of melanoma metastasis by adoptive transfer of M-CSF or/and IFN-γ gene modified macrophages pulsed with tumor extracts

Induction of tumor-specific cellular immune responseis very important in the cancer therapy. In this study,we used tumor antigen obtained by thaw of melanomacells to pulse M-CSF or/and IFN-γ gene-modificdmacrophages before in viro infusion. Tumor membraneantigens could be phagocytosed by macrophages inculture. Antigen processing and mcxlulation of thepresentation can be achieved before macrophageinjection. The tumor antigens will be processedintracellularly by macrophages and thereafter

Ex vivo expansion of tumor-infiltrating lymphocytes from nasopharyngeal carcinoma patients for adoptive immunotherapy

Establishing Epstein-Barr virus (EBV)-specific cytolytic T lymphocytes (EBV-CTLs) from peripheral blood mononuclear cells (PBMCs) for adoptive immunotherapy has been reported in EBV-associated malignancies including Hodgkin's lymphoma and nasopharyngeal carcinoma (NPC). In the current study,we performed ex vivo expansion of tumor-infiltrating lymphocytes (TILs) obtained from NPC biopsy specimens with a rapid expansion protocol using anti-CD3 monoclonal antibody (OKT3), recombinant human interleukin (IL)-2, and irradiated PBMCs from healthy donors to initiate the growth of TILs. Young TIL cultures comprised of more than 90% of CD3+T cells, a variable percentage of CD3+CD8+and CD3+CD4+T cells, and less than 10% of CD3-CD16+natural killer cells, a similar phenotype of EBV-CTL cultures from PBMCs. Interestingly, TIL cultures secreted high levels of the Th1 cytokines, interferon gamma (IFNγ) and tumor necrosis factor-alpha (TNF-α), and low levels of the Th2 cytokines, IL-4 and IL-10. Moreover, young TILs could recognize autologous EBV-transformed B lymphoblast cell lines, but not autologous EBV-negative blast cells or allogeneic EBV-negative tumor cells. Taken together, these data suggest that ex vivo expansion of TILs from NPC biopsy tissue is an appealing alternative method to establish T cell-based immunotherapy for NPC.

New avenues for the treatment of immunotherapy-resistant pancreatic cancer

Pancreatic cancer(PC)is characterized by its extremely aggressive nature and ranks 14th in the number of new cancer cases worldwide.However,due to its complexity,it ranks 7th in the list of the most lethal cancers worldwide.The pathogenesis of PC involves several complex processes,including familial genetic factors associated with risk factors such as obesity,diabetes mellitus,chronic pancreatitis,and smoking.Mutations in genes such as KRAS,TP53,and SMAD4 are linked to the appearance of malignant cells that generate pancreatic lesions and,consequently,cancer.In this context,some therapies are used for PC,one of which is immunotherapy,which is extremely promising in various other types of cancer but has shown little response in the treatment of PC due to various resistance mechanisms that contribute to a drop in immunotherapy efficiency.It is therefore clear that the tumor microenvironment(TME)has a huge impact on the resistance process,since cellular and non-cellular elements create an immunosuppressive environment,characterized by a dense desmoplastic stroma with cancerassociated fibroblasts,pancreatic stellate cells,extracellular matrix,and immunosuppressive cells.Linked to this are genetic mutations in TP53 and immunosuppressive factors that act on T cells,resulting in a shortage of CD8+T cells and limited expression of activation markers such as interferon-gamma.In this way,finding new strategies that make it possible to manipulate resistance mechanisms is necessary.Thus,techniques such as the use of TME modulators that block receptors and stromal molecules that generate resistance,the use of genetic manipulation in specific regions,such as microRNAs,the modulation of extrinsic and intrinsic factors associated with T cells,and,above all,therapeutic models that combine these modulation techniques constitute the promising future of PC therapy.Thus,this study aims to elucidate the main mechanisms of resistance to immunotherapy in PC and new ways of manipulating this process,resulting in a more efficient therapy for cancer patients and,consequently,a reduction in the lethality of this aggressive cancer.

Revolutionizing gastric cancer treatment:The potential of immunotherapy

Gastric cancer,a prevalent malignancy worldwide,ranks sixth in terms of frequency and third in fatality,causing over a million new cases and 769000 annual deaths.Predominant in Eastern Europe and Eastern Asia,risk factors include family medical history,dietary habits,tobacco use,Helicobacter pylori,and Epstein-Barr virus infections.Unfortunately,gastric cancer is often diagnosed at an advanced stage,leading to a grim prognosis,with a 5-year overall survival rate below 5%.Surgical intervention,particularly with D2 Lymphadenectomy,is the mainstay for early-stage cases but offers limited success.For advanced cases,the National Comprehensive Cancer Network recommends chemotherapy,radiation,and targeted therapy.Emerging immunotherapy presents promise,especially for unresectable or metastatic cases,with strategies like immune checkpoint inhibitors,tumor vaccines,adoptive immunotherapy,and nonspecific immunomodulators.In this Editorial,with regards to the article“Advances and key focus areas in gastric cancer immunotherapy:A comprehensive scientometric and clinical trial review”,we address the advances in the field of immunotherapy in gastric cancer and its future prospects.

Advancements in Lynch Syndrome Management: Applying Immunotherapy for Therapeutic Success

Lynch syndrome is the fourth most common cancer in the United States, with an early age of onset and poor prognosis. Here, we present a unique case of a patient with progressive colon cancer due to a late diagnosis of Lynch syndrome showing excellent response to immunotherapy. A 59-year-old male with a history of rectal cancer 30 years ago came to the hospital due to a fever and further found a large necrotic colon mass. Biopsy was positive for colorectal cancer;however, due to the size of the tumor, the patient was deemed not a surgical candidate and offered hospice with palliative chemotherapy. Based on further workup, the patient was diagnosed with Lynch syndrome, with colon cancer determined to be responsive to Immunotherapy. He was started on JEMPERLI (Dosterlimab-gxly), and after three cycles of therapy, imaging and PET scan were repeated, showing decreased activity and extent of the tumor—a tremendous success.

Peptide drugs: a new direction in cancer immunotherapy

Cancer immunotherapy has emerged as a promising approach in cancer treatment and is considered a major advancement after surgical interventions, radiotherapy, chemotherapy, and targeted therapy. The clinical use of immunotherapeutic drugs, particularly antibody-based drugs that target immune checkpoints, has notably increased~1.

Deep insight into the B-cell associated tertiary lymphoid structure and tumor immunotherapy

Bod et al.1 recently published a study in Nature that garnered attention to B cell-associated anti-tumor immunity and immunotherapy of melanoma and other tumors1.As a promising supplemental immunotherapy to mainstream methods that target T and natural killer(NK)cells,B cell-associated anti-tumor immunotherapy is promising。

Gastric cancer immunotherapy:A scientometric and clinical trial review

This letter is intended to arouse your interest in a recent review of comprehensive scientometrics and clinical trials on immunotherapy for gastric cancer(GC).Our study reviews recent advances in immunotherapy in the field of GC and highlights its new prospects as a treatment for GC.Our research reveals China’s leadership in this field,as well as new therapeutic strategies such as immune checkpoint inhibitors,cellular immunotherapy,and vaccines.The combined findings highlight the potential of immunotherapy to improve survival and quality of life in patients with stomach cancer.We believe that this study will provide important guidance for the future direction of the GC treatment field.

Codelivery of anti-CD47 antibody and chlorin e6 using a dual pH-sensitive nanodrug for photodynamic immunotherapy of osteosarcoma

Osteosarcoma is a malignant tumor originating from bone tissue that progresses rapidly and has a poor patient prognosis.Immunotherapy has shown great potential in the treatment of osteosarcoma.However,the immunosuppressive microenvironment severely limits the efficacy of osteosarcoma treatment.The dual pH-sensitive nanocarrier has emerged as an effective antitumor drug delivery system that can selectively release drugs into the acidic tumor microenvironment.Here,we prepared a dual pH-sensitive nanocarrier,loaded with the photosensitizer Chlorin e6(Ce6)and CD47 monoclonal antibodies(aCD47),to deliver synergistic photodynamic and immunotherapy of osteosarcoma.On laser irradiation,Ce6 can generate reactive oxygen species(ROS)to kill cancer cells directly and induces immunogenic tumor cell death(ICD),which further facilitates the dendritic cell maturation induced by blockade of CD47 by aCD47.Moreover,both calreticulin released during ICD and CD47 blockade can accelerate phagocytosis of tumor cells by macrophages,promote antigen presentation,and eventually induce T lymphocyte-mediated antitumor immunity.Overall,the dual pH-sensitive nanodrug loaded with Ce6 and aCD47 showed excellent immune-activating and anti-tumor effects in osteosarcoma,which may lay the theoretical foundation for a novel combination model of osteosarcoma treatment.

Present situation and prospect of immunotherapy for unresectable locally advanced esophageal cancer during peri-radiotherapy

Four major studies(Checkmate577,Keynote-590,Checkmate649 and Attraction-4)of locally advanced esophageal cancer published in 2020 have established the importance of immunotherapy,represented by anti-programmed death protein(PD)-1 in postoperative adjuvant treatment and advanced first-line treatment of locally advanced or advanced esophageal cancer and esophagogastric junction cancer,from the aspects of proof of concept,long-term survival,overall survival rate and progression-free survival.For unresectable or inoperable nonmetastatic esophageal cancer,concurrent radiotherapy and chemotherapy is the standard treatment recommended by various guidelines.Because its curative effect is still not ideal,it is necessary to explore radical radiotherapy and chemotherapy in the future,and it is considered to be promising to combine them with immunotherapeutic drugs such as anti-PD-1.This paper mainly discusses how to combine radical concurrent radiotherapy and chemotherapy with immunotherapy for unresectable local advanced esophageal cancer.

Immunotherapy of gastric cancer:Present status and future perspectives

In this editorial,we comment on the article entitled“Advances and key focus areas in gastric cancer immunotherapy:A comprehensive scientometric and clinical trial review(1999-2023),”which was published in the recent issue of the World Journal of Gastroenterology.We focused on the results of the authors’bibliometric analysis concerning gastric cancer immunotherapy,which they analyzed in depth by compiling the relevant publications of the last 20 years.Before that,we briefly describe the most recent data concerning the epidemiological parameters of gastric cancer(GC)in different countries,attempting to give an interpretation based on the etiological factors involved in the etiopathogenesis of the neoplasm.We then briefly discuss the conservative treatment(chemotherapy)of the various forms of this malignant neoplasm.We describe the treatment of resectable tumors,locally advanced neoplasms,and unresectable(advanced)cases.Special attention is given to modern therapeutic approaches with emphasis on immunotherapy,which seems to be the future of GC treatment,especially in combination with chemotherapy.There is also a thorough analysis of the results of the study under review in terms of the number of scientific publications,the countries in which the studies were conducted,the authors,and the scientific centers of origin,as well as the clinical studies in progress.Finally,an attempt is made to draw some conclusions and to point out possible future directions.

Emerging mechanisms and implications of c GAS-STING signaling in cancer immunotherapy strategies

The intricate interplay between the human immune system and cancer development underscores the central role of immunotherapy in cancer treatment.Within this landscape,the innate immune system,a critical sentinel protecting against tumor incursion,is a key player.The cyclic GMP-AMP synthase(c GAS)and stimulator of interferon genes(STING)pathway has been found to be a linchpin of innate immunity:activation of this signaling pathway orchestrates the production of type I interferon(IFN-α/β),thus fostering the maturation,differentiation,and mobilization of immune effectors in the tumor microenvironment.Furthermore,STING activation facilitates the release and presentation of tumor antigens,and therefore is an attractive target for cancer immunotherapy.Current strategies to activate the STING pathway,including use of pharmacological agonists,have made substantial advancements,particularly when combined with immune checkpoint inhibitors.These approaches have shown promise in preclinical and clinical settings,by enhancing patient survival rates.This review describes the evolving understanding of the c GAS-STING pathway's involvement in tumor biology and therapy.Moreover,this review explores classical and non-classical STING agonists,providing insights into their mechanisms of action and potential for optimizing immunotherapy strategies.Despite challenges and complexities,the c GAS-STING pathway,a promising avenue for enhancing cancer treatment efficacy,has the potential to revolutionize patient outcomes.

Prognostic analysis of related factors of adverse reactions to immunotherapy in advanced gastric cancer and establishment of a nomogram model

BACKGROUND Immunotherapy for advanced gastric cancer has attracted widespread attention in recent years.However,the adverse reactions of immunotherapy and its relationship with patient prognosis still need further study.In order to determine the association between adverse reaction factors and prognosis,the aim of this study was to conduct a systematic prognostic analysis.By comprehensively evaluating the clinical data of patients with advanced gastric cancer treated by immunotherapy,a nomogram model will be established to predict the survival status of patients more accurately.AIM To explore the characteristics and predictors of immune-related adverse reactions(irAEs)in advanced gastric cancer patients receiving immunotherapy with programmed death protein-1(PD-1)inhibitors and to analyze the correlation between irAEs and patient prognosis.METHODS A total of 140 patients with advanced gastric cancer who were treated with PD-1 inhibitors in our hospital from June 2021 to October 2023 were selected.Patients were divided into the irAEs group and the non-irAEs group according to whether or not irAEs occurred.Clinical features,manifestations,and prognosis of irAEs in the two groups were collected and analyzed.A multivariate logistic regression model was used to analyze the related factors affecting the occurrence of irAEs,and the prediction model of irAEs was established.The receiver operating characteristic(ROC)curve was used to evaluate the ability of different indicators to predict irAEs.A Kaplan-Meier survival curve was used to analyze the correlation between irAEs and prognosis.The Cox proportional risk model was used to analyze the related factors affecting the prognosis of patients.RESULTS A total of 132 patients were followed up,of whom 63(47.7%)developed irAEs.We looked at the two groups’clinical features and found that the two groups were statistically different in age≥65 years,Ki-67 index,white blood cell count,neutrophil count,and regulatory T cell(Treg)count(all P<0.05).Multivariate logistic regression analysis showed that Treg count was a protective factor affecting irAEs occurrence(P=0.030).The ROC curve indicated that Treg+Ki-67+age(≥65 years)combined could predict irAEs well(area under the curve=0.753,95%confidence interval:0.623-0.848,P=0.001).Results of the Kaplan-Meier survival curve showed that progressionfree survival(PFS)was longer in the irAEs group than in the non-irAEs group(P=0.001).Cox proportional hazard regression analysis suggested that the occurrence of irAEs was an independent factor for PFS(P=0.006).CONCLUSION The number of Treg cells is a separate factor that affects irAEs in advanced gastric cancer patients receiving PD-1 inhibitor immunotherapy.irAEs can affect the patients’PFS and result in longer PFS.Treg+Ki-67+age(≥65 years old)combined can better predict the occurrence of adverse reactions.